Sniffer configuration: Difference between revisions

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'''This document provides a comprehensive reference for all parameters in the `voipmonitor.conf` configuration file. It is designed to help administrators understand and tune the VoIPmonitor sensor for their specific environment.'''
[[Category:Configuration]]
{{DISPLAYTITLE:Sniffer Configuration Reference (voipmonitor.conf)}}


The main configuration file is located at `/etc/voipmonitor.conf`. Additional configuration snippets can be placed in files within the `/etc/voipmonitor/conf.d/` directory (these should not contain the `[general]` section header).
'''Comprehensive reference for `/etc/voipmonitor.conf` parameters.''' Additional configuration snippets can be placed in `/etc/voipmonitor/conf.d/` (without `[general]` header).


'''Related documentation:'''
'''Related documentation:'''
* [[Sniffer_installation|Installation Guide]] - How to install the sniffer
* [[Sniffer_installation|Installation Guide]] - Installing the sniffer
* [[Sniffer_distributed_architecture|Distributed Architecture]] - Client/server deployment details
* [[Sniffer_distributed_architecture|Distributed Architecture]] - Client/server deployment
* [[Sniffer_troubleshooting|Troubleshooting]] - Common issues and solutions
* [[Sniffer_troubleshooting|Troubleshooting]] - Common issues and solutions
* [[Scaling|Scaling Guide]] - Performance tuning for high traffic
* [[Scaling|Scaling Guide]] - Performance tuning for high traffic
* [[Data_Cleaning|Data Cleaning]] - Retention and cleanup configuration
* [[Data_Cleaning|Data Cleaning]] - Retention and cleanup configuration


== General & Core Settings ==
= General & Core Settings =


=== Time and Sensor Identification ===
== Sensor Identification & Time ==
;<code>id_sensor = 1</code>
:(Default: unset) A unique numeric identifier (1-65535) for this sensor. This is '''essential''' in multi-sensor deployments to distinguish which sensor captured a call. The value is stored in the `cdr.id_sensor` column.


;<code>utc = yes</code>
{| class="wikitable"
:(Default: no) When set to `yes`, all timestamps for CDRs and PCAP files are stored in UTC. This is '''highly recommended''' for deployments with sensors in different timezones to ensure consistency.
! Parameter !! Default !! Description
|-
| <code>id_sensor</code> || unset || Unique numeric identifier (1-65535). '''Essential''' for multi-sensor deployments.
|-
| <code>utc</code> || no || Store timestamps in UTC. '''Recommended''' for multi-timezone deployments.
|-
| <code>timezone</code> || system || Override system timezone with zoneinfo path (e.g., <code>/usr/share/zoneinfo/UTC</code>).
|}


;<code>timezone = /usr/share/zoneinfo/UTC</code>
== Process Management ==
:(Default: system timezone) Overrides the system's default timezone by specifying a path to a valid zoneinfo file. Use this only if you need the sensor to operate in a timezone different from the server it's running on.


=== Process Management ===
{| class="wikitable"
;<code>watchdog = yes</code>
! Parameter !! Default !! Description
:(Default: no) If enabled, a watchdog process is created that automatically restarts the voipmonitor sensor if it crashes or is terminated unexpectedly.
|-
| <code>watchdog</code> || no || Auto-restart sensor on crash.
|-
| <code>watchdog_run_command</code> || unset || Custom restart command (e.g., <code>systemctl restart voipmonitor</code>).
|}


;<code>watchdog_run_command = systemctl restart voipmonitor</code>
== Deprecated Options (v2025.09.1+) ==
:(Default: unset) If specified, the watchdog will execute this command to restart the service instead of just re-running the binary. This is useful for proper service management with `systemd`.


== Database Configuration ==
{{Warning|1=The following options are '''unsupported and ignored''' in sniffer version 2025.09.1+. Remove them from your configuration.}}


=== Connection Settings ===
{| class="wikitable"
;<code>mysqlhost = localhost</code>
! Deprecated Option !! Modern Replacement
:IP address or hostname of the MySQL/MariaDB server.
|-
;<code>mysqlsocket = /var/run/mysqld/mysqld.sock</code>
| <code>vxlan</code>, <code>vxlan_port</code>, <code>vxlan_skipcrc</code> || <code>udp_port_vxlan = 4789</code>
:Path to the MySQL socket file for local connections (often faster than TCP).
|-
;<code>mysqlport = 3306</code>
| <code>packet_buffer_total_size</code> || <code>max_buffer_mem</code> (auto-managed)
:TCP port of the database server.
|-
;<code>mysqlusername = root</code>
| <code>udp_reassembly</code>, <code>udp_reassembly_max_size</code> || <code>udpfrag = yes</code>
:Username for the database connection.
|-
;<code>mysqlpassword =</code>
| <code>sipdefrag</code>, <code>sipdefrag_maxpacket</code>, <code>defragment_*</code> || Auto-managed; use <code>max_sip_packets_in_call</code>
:Password for the database connection.
|-
;<code>mysqldb = voipmonitor</code>
| <code>max_sip_size</code>, <code>interface_snaplen</code> || <code>snaplen = 3200</code>
:The name of the database to use. It will be created automatically if it doesn't exist.
|-
;<code>mysql_connect_timeout = 60</code>
| <code>sanity_checks</code>, <code>check_sip_header</code>, <code>ignore_sip_parsing_errors</code> || Built-in (cannot be disabled)
:(Default: 60) Timeout in seconds for establishing a connection to the database.
|}
;<code>mysql_client_compress = no</code>
:(Default: no) Enables compression for the MySQL connection. Only use this if the database is on a remote, slow network link.
;<code>mysql_reconnect = yes</code>
:(Default: no) Enables automatic reconnection to the database if the connection is lost.


=== Database SSL/TLS ===
{{Tip|After removing deprecated options, check logs for warnings: <code>journalctl -u voipmonitor -f</code>}}
;<code>mysqlsslkey = /etc/ssl/client-key.pem</code>
:Path to the client's SSL private key file.
;<code>mysqlsslcert = /etc/ssl/client-cert.pem</code>
:Path to the client's SSL certificate file.
;<code>mysqlsslcacert = /etc/ssl/ca-cert.pem</code>
:Path to the Certificate Authority (CA) certificate file.
;<code>mysqlsslcapath = /etc/ssl/capath</code>
:Directory containing CA certificates.
;<code>mysqlsslciphers =</code>
:List of allowed SSL ciphers.


=== Performance & Schema ===
= Database Configuration =
;<code>query_cache = yes</code>
:(Default: yes) This is a '''critical''' feature. When enabled, all SQL queries are first saved to a disk-based queue (qoq* files in the spool directory) before being sent to the database. This prevents data loss if the database is temporarily unavailable and prevents the sensor from running out of memory. When database connection is restored, the sensor writes the buffered CDRs from the queue files to the database. This process introduces a small delay but ensures no data loss during database downtime. If set to <code>no</code>, CDRs are held in sensor memory only during database outages, which can lead to OOM (Out Of Memory) situations and data loss if the database is offline for an extended period.
;<code>quick_save_cdr = no</code>
:(Default: no) Speeds up the visibility of calls in the GUI at the cost of higher system load. Options are `no` (10s delay, recommended), `yes` (3s delay), or `quick` (1s delay). Only change this if near-real-time CDR visibility is absolutely required.
;<code>cdr_partition = yes</code>
:(Default: yes) Enables partitioning for large tables (like `cdr`) by day. This is '''essential for performance and data management''' on any production system.
;<code>cdr_partition_by_hours = no</code>
:(Default: no) For extreme high-traffic environments (>= 15,000 CPS), this creates partitions per hour instead of per day to further improve performance.
;<code>disable_partition_operations = yes</code>
:(Default: no) Disables automatic partition creation. Useful when multiple sensors write to a single database and only one should manage partitions.
;<code>disable_dbupgradecheck = yes</code>
:(Default: no) If set to `yes`, the sniffer will not check for and apply database schema updates on startup.
;<code>mysqlloadconfig = yes</code>
:(Default: yes) Allows loading additional configuration parameters dynamically from the `sensor_conf` database table. '''Important:''' This setting also controls loading of the <code>manager_key</code> from the <code>system</code> table. If set to <code>no</code>, VoIPmonitor will NOT load the manager_key from the database, which will cause the sensor to fail to start with the error "failed read rsa key." For distributed manager/sensor deployments, ensure this option is enabled (or omitted for the default <code>yes</code> behavior) on both the manager and sensor to permit proper key exchange.
;<code>mysqlcompress_type = ...</code>
:(Default: auto-detected) You do not normally need to set this. The sniffer automatically chooses the best table compression method (LZ4 page compression) based on your MySQL/MariaDB version. Only change this for legacy systems.
;<code>mysql_enable_set_id = yes</code>
:(Default: no) In very high-traffic client/server deployments, this allows the central server to generate CDR IDs, which can improve batch insert performance.
;<code>cdr_force_primary_index_in_all_tables = no</code>
:(Default: no) Creates primary indexes on all tables. This is only required for specific database clustering technologies like MySQL/Galera Cluster and should not be enabled otherwise.
;<code>disable_cdr_fields_rtp = no</code>
:(Default: no) Disables all RTP-related statistics columns in the CDR table to save space.
;<code>sqlcallend = yes</code>
:(Default: yes) Enables storing `cdr.callend` (calldate + duration). Disable only if the column is missing.


=== SQL Queue Tuning ===
== Connection Settings ==
;<code>mysqlstore_concat_limit = 400</code>
:(Default: 400) Sets the global number of SQL statements to batch together before sending to the database.
;<code>mysqlstore_max_threads_cdr = 2</code>
:(Default: 2) The maximum number of parallel threads (and database connections) for writing CDRs. The sniffer will automatically scale up to this number if the queue grows.
;''Note: Separate `_concat_limit_*` and `_max_threads_*` options exist for `message`, `register`, `http`, etc.''
;<code>server_sql_queue_limit = 1000000</code>
:(Default: 1000000) Limits the SQL queue size on the server side in client/server deployments. Set to 0 to disable.
;<code>server_sql_concat_limit = 5000</code>
:(Default: 1000) Number of queries to batch before confirming receipt in client/server mode.


=== Database Cleaning ===
{| class="wikitable"
;<code>cleandatabase = 0</code>
! Parameter !! Default !! Description
:(Default: 0, disabled) The master setting for database cleaning. Defines the retention period in days for CDRs and several other tables. Requires partitioning to be enabled.
|-
;<code>cleandatabase_cdr = 0</code>
| <code>mysqlhost</code> || localhost || MySQL/MariaDB server address
:(Default: 0, disabled) Specific retention period for `cdr` and `message` tables.
|-
;<code>cleandatabase_rtp_stat = 2</code>
| <code>mysqlsocket</code> || unset || Socket path for local connections (faster than TCP)
:(Default: 2) Retention period in days for detailed RTP statistics.
|-
;<code>cleandatabase_register_failed = 0</code>
| <code>mysqlport</code> || 3306 || TCP port
:(Default: 0) Retention for `register_failed` table.
|-
;<code>cleandatabase_register_state = 0</code>
| <code>mysqlusername</code> || root || Database username
:(Default: 0) Retention for `register_state` table.
|-
;<code>cleandatabase_sip_msg = 0</code>
| <code>mysqlpassword</code> || empty || Database password
:(Default: 0) Retention for `sip_msg` table (OPTIONS/SUBSCRIBE/NOTIFY).
|-
;<code>cleandatabase_ss7 = 0</code>
| <code>mysqldb</code> || voipmonitor || Database name (auto-created if missing)
:(Default: 0) Retention for `ss7` table.
|-
;<code>cleandatabase_cdr_rtp_energylevels = 0</code>
| <code>mysql_reconnect</code> || no || Auto-reconnect on connection loss
:(Default: 0) Retention for energy levels table.
|}
;<code>partition_operations_enable_fromto = 1-5</code>
:(Default: 1-5) Restricts partition-dropping operations to a specific time window (e.g., 1 AM to 5 AM) to avoid impacting performance during peak hours.
;<code>cleandatabase_size = 500000</code>
:(Default: unset) An alternative cleaning method that removes old data to stay below a total database size limit (in MB).


=== CDR Summary (Aggregation) ===
=== SSL/TLS for Database ===
<syntaxhighlight lang="ini">
mysqlsslkey = /etc/ssl/client-key.pem
mysqlsslcert = /etc/ssl/client-cert.pem
mysqlsslcacert = /etc/ssl/ca-cert.pem
</syntaxhighlight>


The CDR Summary feature pre-aggregates call data into intervals for significantly faster dashboard and reporting queries. See [[CDR_Summary]] for complete documentation including GUI behavior.
== Performance & Schema ==


;<code>cdr_summary = yes</code>
{| class="wikitable"
:(Default: no) Enables the CDR summary feature. When enabled, the sniffer creates a <code>cdr_summary</code> table and continuously aggregates CDR data by sipcallerip, sipcalledip, payload, and last_sip_response.
! Parameter !! Default !! Description
;<code>cdr_summary_interval = 5</code>
|-
:(Default: 5) The aggregation interval in minutes. Data is grouped into buckets of this size.
| <code>query_cache</code> || yes || '''Critical:''' Queue SQL to disk (qoq* files) to prevent data loss during DB outages.
;<code>cleandatabase_cdr_summary = 0</code>
|-
:(Default: 0, uses cleandatabase setting) Optional separate retention period in days specifically for the <code>cdr_summary</code> table. If not set, the main <code>cleandatabase</code> setting is used.
| <code>quick_save_cdr</code> || no || CDR visibility delay: <code>no</code>=10s, <code>yes</code>=3s, <code>quick</code>=1s. Higher values increase load.
|-
| <code>cdr_partition</code> || yes || '''Essential:''' Daily table partitioning for performance.
|-
| <code>cdr_partition_by_hours</code> || no || Hourly partitions for extreme traffic (≥15k CPS).
|-
| <code>disable_partition_operations</code> || no || Disable auto partition management (for centralized DB).
|-
| <code>mysql_enable_set_id</code> || no || Central server generates CDR IDs (high-traffic client/server).
|}


=== SQL Error Logging ===
== Configuration Priority: File vs GUI ==
;<code>sql_log_all_errors = no</code>
:(Default: no) Logs all SQL errors to syslog.
;<code>sql_errors_log_file = /path/to/log</code>
:(Default: unset) Redirects SQL error logging to a specific file.
;<code>sql_errors_skip = 1054,1136</code>
:(Default: unset) A comma-separated list of SQL error codes to ignore and not log.


== Network Interface & Sniffing ==
;<code>mysqlloadconfig = yes</code>
This section configures how the sensor captures packets.
:(Default: yes) Load settings from database (<code>sensor_config</code> table). '''GUI settings take priority over file settings.'''


=== Interface Selection ===
{{Warning|1=Setting <code>mysqlloadconfig = no</code> prevents loading the <code>manager_key</code> from the database, causing "failed read rsa key" startup errors in distributed deployments.}}
;<code>interface = eth0</code>
:Specifies the network interface(s) to listen on. Use a comma-separated list for multiple interfaces (e.g., `eth0,eth1`). Using `any` will listen on all interfaces but will not enable promiscuous mode.
;<code>promisc = yes</code>
:(Default: yes) Puts the specified interface(s) into promiscuous mode to capture all traffic, not just traffic addressed to the server. Does not work with `interface = any`.
;<code>interfaces_optimize = yes</code>
:(Default: yes) Allows voipmonitor to automatically tune NIC settings like ring buffers and coalescing using `ethtool`.
;<code>eth_max_channels = 0</code>
:(Default: 0) Sets number of NIC interrupt queues. 0 means no change.
;<code>filter = udp or (vlan and udp)</code>
:(Default: unset) Applies a BPF filter (like in `tcpdump`) to the captured traffic. The `filter` option is processed by libpcap using Berkeley Packet Filter (BPF) syntax and supports tcpdump-style expressions including negation ('not'), logical operators ('and', 'or'), parentheses, and complex criteria matching IP addresses, ports, protocols, VLAN tags, and other packet fields. However, it can be CPU-intensive and complex to configure correctly. '''Warning:''' Using filters can accidentally exclude important traffic like VLAN-tagged or tunneled packets. Use with caution.


:'''Example: Exclude specific subnets from being captured'''
'''Diagnosing conflicts:'''
<pre>
<syntaxhighlight lang="bash">
# Exclude internal networks from capturing
systemctl restart voipmonitor
filter = not net 192.168.0.0/16 and not net 10.0.0.0/8
grep 'Configuration valu' /var/log/syslog | grep ' / '
</pre>
</syntaxhighlight>


:'''Example: Capture only UDP SIP traffic'''
'''Resolution options:'''
<pre>
* '''Option 1:''' Update settings via GUI (recommended)
filter = udp port 5060
* '''Option 2:''' Set <code>mysqlloadconfig = no</code> for file-only management
</pre>
* '''Option 3:''' Delete specific entries from <code>sensor_config</code> table


:When modifying the `filter` setting, you must restart the sniffer service for changes to take effect: `systemctl restart voipmonitor`.
== SQL Queue Tuning ==


;<code>interface_ip_filter = 192.168.0.0/24</code>
{| class="wikitable"
:(Default: unset) A CPU-efficient method to filter traffic by IP address or subnet. This option matches packets whose source or destination IP falls within the specified networks. Multiple lines can be used to define multiple allowed networks. Unlike the main `filter` option, `interface_ip_filter` is an '''allow-list''' (whitelist) that implicitly discards traffic not matching any of the specified networks. It does not support negation or complex BPF syntax.
! Parameter !! Default !! Description
|-
| <code>mysqlstore_concat_limit</code> || 400 || SQL statements per batch
|-
| <code>mysqlstore_max_threads_cdr</code> || 2 || Max parallel CDR write threads
|}


:'''Example: Allow only internal traffic'''
== Database Cleaning ==
<pre>
# Only process packets from/to these networks
interface_ip_filter = 192.168.0.0/24
interface_ip_filter = 10.0.0.0/8
</pre>
;<code>snaplen = 3200</code>
:(Default: 3200, 6000 if SSL/HTTP enabled) Packet capture length override. This parameter controls how many bytes of each packet are captured. If a SIP packet exceeds this limit, it is truncated and the sniffer may fail to parse the call correctly, resulting in missing CDRs.


=== Optimizing for Shared Server Deployments ===
See [[Data_Cleaning]] for detailed documentation.


When the VoIPmonitor sniffer runs on the same server as the PBX and RTP engine, resource contention can cause voice breakage and call lag. The sniffer competes for CPU cycles and network interrupts with the real-time media processing.
{| class="wikitable"
! Parameter !! Default !! Description
|-
| <code>cleandatabase</code> || 0 || Master retention period in days (0=disabled)
|-
| <code>cleandatabase_cdr</code> || 0 || CDR/message table retention
|-
| <code>cleandatabase_rtp_stat</code> || 2 || RTP statistics retention
|-
| <code>partition_operations_enable_fromto</code> || 1-5 || Partition drop time window (e.g., 1-5 AM)
|}


'''Symptoms:'''
== CDR Summary (Aggregation) ==
* Audio breakage (jitter, packet loss)
* Call lag or delay
* Issues resolve when the sniffer is stopped


'''Solution 1: Specify Specific Interfaces'''
Pre-aggregates call data for faster dashboard queries.
Instead of using `interface = any`, specify a comma-separated list of the exact network interfaces that handle VoIP traffic:
<syntaxhighlight lang="ini">
# Instead of:
# interface = any
 
# Use specific interfaces:
interface = ens192,ens224
</syntaxhighlight>
This creates a dedicated capture thread for each interface, improving performance on shared servers. Ensure the interfaces you specify are the ones carrying VoIP traffic.


'''Solution 2: Disable Automatic Interface Optimization'''
If performance issues persist after specifying specific interfaces, disable automatic NIC optimization:
<syntaxhighlight lang="ini">
<syntaxhighlight lang="ini">
# Disable automatic tuning of NIC settings
cdr_summary = yes
interfaces_optimize = no
cdr_summary_interval = 5  # minutes
</syntaxhighlight>
</syntaxhighlight>
Note: This option requires the `ethtool` utility to be installed on the system.


'''Solution 3: Reduce Sniffer Load'''
= Network Interface & Sniffing =
For immediate relief, configure the sniffer to reduce CPU consumption:
<syntaxhighlight lang="ini">
# Save only RTP headers (metadata only, no audio payload)
savertp = header


# Disable audio transcoding (very CPU intensive)
== Interface Selection ==
saveaudio = no
</syntaxhighlight>


'''Long-term Recommendation:'''
{| class="wikitable"
Move the VoIPmonitor sensor to a dedicated server connected via SPAN/Mirror port to eliminate resource contention entirely. See [[Sniffer_distributed_architecture]] for distributed deployment details.
! Parameter !! Default !! Description
|-
| <code>interface</code> || eth0 || Interface(s) to capture. Comma-separated for multiple. <code>any</code> = all (no promisc).
|-
| <code>promisc</code> || yes || Promiscuous mode (doesn't work with <code>any</code>).
|-
| <code>interfaces_optimize</code> || yes || Auto-tune NIC settings via ethtool.
|-
| <code>snaplen</code> || 3200 || Packet capture length. Increase for large SIP packets.
|}


Increase this value if you experience missing CDRs for calls with large SIP packets (e.g., INVITE requests with extensive SDP, many codec options, custom headers). Typical values are 65535 (maximum Ethernet frame size) or 20000.
== BPF Filtering ==


To diagnose if packet truncation is the issue, use `tcpdump` with the `-s0` flag to capture full packets and verify packet sizes on your network.
;<code>filter</code>
 
:BPF filter (tcpdump syntax). '''Warning:''' Can accidentally exclude important traffic.
=== High-Traffic Parallel Capture ===
<syntaxhighlight lang="ini">
For environments with very high packet rates (>2.2M pps), you can split traffic across multiple processing threads:
# Example: Exclude specific subnets
 
filter = not net 192.168.0.0/16 and not net 10.0.0.0/8
;<code>interface_libpcap_filter = eth0 : port 5060</code>
</syntaxhighlight>
:(Default: unset) Allows splitting traffic from a single physical interface into multiple parallel processing threads within voipmonitor, each with its own BPF filter. This is an advanced technique to overcome per-core CPU limits.


'''Example for splitting traffic:'''
;<code>interface_ip_filter</code>
:CPU-efficient IP allow-list (no negation). Multiple lines supported.
<syntaxhighlight lang="ini">
<syntaxhighlight lang="ini">
# Split SIP and non-SIP traffic into separate processing threads
interface_ip_filter = 192.168.0.0/24
interface_libpcap_filter = eth0 : port 5060
interface_ip_filter = 10.0.0.0/8
interface_libpcap_filter = eth0 : not port 5060
</syntaxhighlight>
</syntaxhighlight>


=== Multiple Sensor Instances on One Server ===
== Shared Server Optimization ==
When running multiple VoIPmonitor sensor instances on the same physical server to monitor different traffic sources, special configuration is required to prevent resource contention and excessive CPU usage.


Each instance will compete for CPU cores, memory, and database connections. Improper configuration can lead to high CPU load, memory exhaustion, and system instability after VoIPmonitor upgrades that introduce improved multi-threading capabilities.
When the sniffer runs on the same server as the PBX, resource contention can cause voice breakage.


;''Important:'' Newer VoIPmonitor versions have enhanced threading defaults. Existing multi-instance setups may experience unexpectedly high CPU load after an upgrade if the instances are not properly configured for resource sharing.
'''Symptoms:''' Audio jitter, packet loss, call lag that resolves when sniffer is stopped.


==== Memory Allocation ===
'''Solutions:'''
;<code>max_buffer_mem = 1000</code>
<syntaxhighlight lang="ini">
:(Default: 2000) Set this parameter in each instance's configuration file to limit the total buffer memory per instance. This prevents all instances from consuming all available RAM and causing swap usage. Set this value proportionally based on the number of instances and available RAM. For example, with 16GB RAM and 4 instances, set `max_buffer_mem = 4000` per instance.
# Solution 1: Specify interfaces (creates dedicated threads)
interface = ens192,ens224  # NOT 'any'


==== Database Thread Throttling ===
# Solution 2: Disable NIC optimization
When running multiple instances on one server, each instance spawning multiple database threads can overwhelm the MySQL connections pool and cause excessive CPU usage. Limit database threads per instance:
interfaces_optimize = no


;<code>mysqlstore_max_threads_cdr = 1</code>
# Solution 3: Reduce sniffer load
;(Default: 2) Set to 1 in multi-instance deployments to reduce thread overhead.
savertp = header
;<code>mysqlstore_max_threads_message = 1</code>
saveaudio = no
;(Default: 2) Limits parallel threads for storing MESSAGE records.
;<code>mysqlstore_max_threads_register = 1</code>
;(Default: 2) Limits parallel threads for storing REGISTER data.
;<code>mysqlstore_max_threads_http = 1</code>
;(Default: 2) Limits parallel threads for HTTP-related data.
 
;''Note:'' Reducing these values may slow down database writes during traffic bursts, but is necessary to prevent CPU overload when multiple instances compete for database resources.
 
==== Multi-Instance Configuration Example ===
<syntaxhighlight lang="ini">
# Instance 1 Configuration (/etc/voipmonitor/instance1.conf)
[general]
id_sensor = 1
pidfile = /var/run/voipmonitor/instance1.pid
interface = eth0
max_buffer_mem = 1000
mysqlstore_max_threads_cdr = 1
mysqlstore_max_threads_message = 1
mysqlstore_max_threads_register = 1
mysqlstore_max_threads_http = 1
 
# Instance 2 Configuration (/etc/voipmonitor/instance2.conf)
[general]
id_sensor = 2
pidfile = /var/run/voipmonitor/instance2.pid
interface = eth1
max_buffer_mem = 1000
mysqlstore_max_threads_cdr = 1
mysqlstore_max_threads_message = 1
mysqlstore_max_threads_register = 1
mysqlstore_max_threads_http = 1
</syntaxhighlight>
</syntaxhighlight>


;''Note on threading_expanded'': The modern `threading_expanded` parameter (enabled by default) automatically manages threads. In some multi-instance scenarios where you have limited CPU cores, you may need to disable this and use the legacy `threading_mod = 1` for single-threaded processing per instance. However, this is deprecated and should only be used as a last resort.
'''Long-term:''' Move sensor to dedicated server with SPAN/Mirror. See [[Sniffer_distributed_architecture]].
 
==== Troubleshooting High CPU After Upgrade ===
If a multi-instance deployment experiences high CPU load after a VoIPmonitor upgrade:
 
# Review system baseline load before the upgrade to determine if the server was already near capacity
# Apply the memory and thread throttling settings above to each instance
# Monitor `top` or `htop` to verify CPU usage is distributed properly
# If CPU load remains high after these changes, the root cause may be insufficient hardware capacity. Consider upgrading the server to provide more CPU cores or distributing instances across multiple physical servers.
 
;''See also:'' [[Sniffer_distributed_architecture|Client/Server mode]] for an alternative to multi-instance deployments on a single host.


=== Tunneling Protocol Support ===
== Packet Deduplication ==
VoIPmonitor can decode various tunneling protocols. To enable listening, uncomment and configure the relevant port.
;<code>udp_port_tzsp = 37008</code>
:(Default: 37008) Mikrotik TZSP protocol.
;<code>udp_port_l2tp = 1701</code>
:(Default: 1701) L2TP tunneling.
;<code>udp_port_vxlan = 4789</code>
:(Default: 4789) VXLAN, common in AWS and cloud environments.
;<code>udp_port_hperm = 7932</code>
:(Default: 7932) HP ERM protocol.
;<code>audiocodes = yes</code>
:(Default: no) Enables AudioCodes proprietary tunnel.
;<code>udp_port_audiocodes = 925</code>
:Port for AudioCodes mirroring.
;<code>audiocodes_rtp = yes</code>
:Enable AudioCodes RTP processing. Options: no, yes, only, only_for_audiocodes_sip.
;<code>ipfix = yes</code>
:(Default: no) Enables IPFIX, used by Oracle/ACME SBCs. See [[#IPFIX Support|IPFIX Support]] section.
;<code>hep = yes</code>
:(Default: no) Enables Homer Encapsulation Protocol. See [[#HEP Support|HEP Support]] section.
;<code>kamailio_port = 5888</code>
:(Default: unset) Enables mirroring from Kamailio's `siptrace` module.
;<code>ribbonsbc = yes</code>
:(Default: no) Enables Ribbon SBC mirroring. See [[#Ribbon SBC Mirroring|Ribbon SBC Mirroring]] section.
;<code>icmp_process_data = no</code>
:(Default: no) Extract SIP data from ICMP type 3 messages.


=== Packet Deduplication ===
Required when receiving same packets from multiple sources/interfaces.
When traffic is received from multiple sources or mirrored from multiple points, the same packet may arrive more than once. The deduplication feature identifies and discards duplicate packets based on checksum comparison.


'''Typical configuration for deduplication:'''
<syntaxhighlight lang="ini">
<syntaxhighlight lang="ini">
# Enable packet deduplication. Uses checksum to identify
# and discard duplicate packets. This is CPU intensive.
deduplicate = yes
deduplicate = yes
 
auto_enable_use_blocks = yes  # Required for deduplication
# Required for deduplication to work correctly when
deduplicate_ipheader = ip_only  # Recommended for different network paths
# packets are received from multiple sources or interfaces.
auto_enable_use_blocks = yes
 
# Count only IP addresses from IP header in the checksum.
# This is useful when the same packet arrives from different
# network paths with different TTL or other IP header fields.
deduplicate_ipheader = ip_only
</syntaxhighlight>
</syntaxhighlight>


;<code>deduplicate = yes</code>
{| class="wikitable"
:(Default: no) Enables packet deduplication based on a checksum (MD5 or the faster experimental "murmur" algorithm). Useful if you are receiving the same traffic stream from multiple sources or interfaces. '''Note:''' This is CPU intensive.
! Parameter !! Default !! Description
|-
| <code>deduplicate</code> || no || Enable checksum-based deduplication (CPU intensive)
|-
| <code>auto_enable_use_blocks</code> || no || '''Required''' for deduplication and correct RTP association across interfaces/VLANs
|-
| <code>deduplicate_ipheader</code> || yes || <code>ip_only</code> recommended when packets have different TTL
|}


;<code>use_block = yes</code>
== Tunneling Protocol Support ==
:(Default: no) Manually enables use of memory blocks for packet processing. This option is recommended in scenarios where the sniffer experiences high traffic loads or processing bottlenecks, particularly when symptoms include: (1) '''SIP registrations incorrectly shown as failed in the GUI''' even though packet captures on the sensor show the traffic is present, or (2) '''Missing call legs in CDRs''' despite complete packet captures. Memory blocks help the sniffer manage packet processing more efficiently, preventing drops during analysis bursts. This option is automatically enabled by `auto_enable_use_blocks = yes`, but can be set manually if needed.


;<code>auto_enable_use_blocks = yes</code>
{| class="wikitable"
:(Default: no) Required in two scenarios: (1) '''For deduplication''' when sniffing from multiple sources or interfaces to identify and discard duplicate packets, and (2) '''For correct RTP association''' when SIP signaling and RTP media arrive on different interfaces, NICs, or VLANs, preventing RTP packets from being associated with the wrong call leg. Automatically enables use of memory blocks for deduplication and defragmentation processing.
! Parameter !! Default !! Description
|-
| <code>udp_port_tzsp</code> || 37008 || Mikrotik TZSP
|-
| <code>udp_port_l2tp</code> || 1701 || L2TP tunneling
|-
| <code>udp_port_vxlan</code> || 4789 || VXLAN (AWS/cloud)
|-
| <code>audiocodes</code> || no || AudioCodes proprietary tunnel. See [[Audiocodes_tunneling]].
|-
| <code>ipfix</code> || no || Oracle/ACME SBC IPFIX
|-
| <code>hep</code> || no || Homer Encapsulation Protocol
|}


;<code>deduplicate_ipheader = ip_only</code>
== Scan PCAP Directory Mode ==
:(Default: yes, meaning full IP header) Controls how the IP header is used in the deduplication checksum:
:* <code>yes</code> (default): Include the full IP header in the checksum
:* <code>ip_only</code>: Count only the source and destination IP addresses from the IP header. '''Recommended''' when packets arrive from different network paths that may modify TTL or other IP header fields.
:* <code>no</code>: Exclude the IP header entirely from the checksum


;<code>deduplicate_ipheader_ignore_ttl = yes</code>
Process PCAP files instead of live capture. Useful for Windows hosts without SPAN ports.
:(Default: yes) Ignore the TTL (Time To Live) field in the IP header when comparing packets. This prevents false negatives when the same packet arrives via different network hops.


;<code>deduplicate_udpheader_ignore_checksum = yes</code>
<syntaxhighlight lang="ini">
:(Default: yes) Exclude the UDP header checksum when comparing packets. Useful because some network equipment may recalculate the UDP checksum, causing identical payload packets to have different checksums.
scanpcapdir = /var/spool/voipmonitor/scanpcap
scanpcapmethod = newfile
</syntaxhighlight>


=== Scan PCAP Directory Mode ===
'''Workflow:'''
;<code>scanpcapdir = /dev/shm/voipmonitor</code>
# Capture on source: <code>tcpdump -i eth0 udp -G 300 -w /path/dump.pcap</code>
:(Default: unset) A special mode where the sensor does not capture live traffic but instead processes PCAP files from a directory as they are created by another tool, like `tcpdump`.
# Transfer to VoIPmonitor server
;<code>scanpcapmethod = newfile</code>
# Sensor processes files automatically
:(Default: newfile) Method for detecting new files. Options: newfile, rename.


=== SIP Send (Third-Party Forwarding) ===
= SIP Configuration =
;<code>sip_send = 192.168.0.2:1555</code>
:(Default: unset) Forwards a copy of all captured SIP packets to a specified third-party destination over TCP or UDP. This is not for mirroring between sensors.
;<code>sip_send_udp = yes</code>
:(Default: no) Use UDP instead of TCP for sip_send.
;<code>sip_send_before_packetbuffer = yes</code>
:(Default: no) Send packets immediately without buffering.


== SIP Port & TCP Configuration ==
== Port Settings ==


=== SIP Port Settings ===
{| class="wikitable"
;<code>sipport = 5060</code>
! Parameter !! Default !! Description
:(Default: 5060) Specifies the SIP ports that VoIPmonitor will listen to. Multiple ports can be specified: `sipport = 5060,5061,5062,5070-5080`.
|-
;<code>cdr_sipport = yes</code>
| <code>sipport</code> || 5060 || SIP ports. Multiple: <code>5060,5061,5070-5080</code>
:(Default: yes) Store SIP source and destination ports in the database.
|-
;<code>cdr_rtpport = yes</code>
| <code>cdr_sipport</code> || yes || Store SIP ports in database
:(Default: yes) Store RTP destination port in the database.
|-
;<code>cdr_rtpsrcport = no</code>
| <code>cdr_country_code</code> || yes || Country code lookup for caller/called. Set <code>no</code> to disable country flags.
:(Default: no) Store RTP source port in the database.
|}


=== TCP Reassembly ===
== TCP Reassembly & UDP Fragmentation ==
;<code>sip_tcp_reassembly_ext = yes</code>
:(Default: yes) Enable TCP reassembly for SIP over TCP.
;<code>sip_tcp_reassembly_stream_max_attempts = 50</code>
:(Default: 50) Maximum TCP reassembly attempts.
;<code>sip_tcp_reassembly_ext_link_timeout = 10</code>
:(Default: 10) TCP reassembly link timeout in seconds.
;<code>sip_tcp_reassembly_ext_quick_mod = no</code>
:(Default: no) Experimental quick mode for high traffic. Options: no, yes, ext, comb_ext.


=== SIP Packet Limits ===
{| class="wikitable"
;<code>max_sip_packets_in_call = 2000</code>
! Parameter !! Default !! Description
:(Default: 2000) Maximum SIP packets per call.
|-
;<code>max_invite_packets_in_call = 10000</code>
| <code>sip_tcp_reassembly_ext</code> || yes || TCP reassembly for SIP over TCP
:(Default: 10000) Maximum SIP INVITE packets per call.
|-
| <code>udpfrag</code> || yes || '''Critical:''' IP fragment reassembly for large SIP messages
|-
| <code>max_sip_packets_in_call</code> || 2000 || Maximum SIP packets per call
|}


== SIP TLS/SSL Decryption ==
= TLS/SSL & SRTP Decryption =


To decrypt TLS-encrypted SIP traffic, you need to provide the private key. Note that Diffie-Hellman ciphers cannot be decrypted without session keys.
== SIP TLS Decryption ==


;<code>ssl = yes</code>
<syntaxhighlight lang="ini">
:(Default: no) Enable TLS/SSL decryption for SIP.
ssl = yes
ssl_ipport = 10.0.0.1:5061 /path/to/your.key
# Subnet with multiple keys:
ssl_ipport = 10.0.0.0/24:5061 /path/key1.pem,/path/key2.pem
</syntaxhighlight>


;<code>ssl_ipport = 10.0.0.1 : 5061 /path/to/your.key</code>
'''Keylogger support (for PFS/TLS 1.3):'''
:(Default: unset) Specify IP:port and private key for decryption. Multiple keys can be separated by commas.
<syntaxhighlight lang="ini">
 
ssl_sessionkey_udp = yes
;<code>ssl_ipport = 10.0.0.0/24 : 5061 /path/to/your.key,/path/to/other.key</code>
ssl_sessionkey_udp_port = 1234
:Example with subnet and multiple keys.
</syntaxhighlight>
 
;<code>ssl_ipport_reverse_enable = yes</code>
:(Default: no) Enable reverse detection logic for ssl_ipport.
 
;<code>ssl_store_sessions_expiration_hours = 12</code>
:(Default: 12) SSL sessions expire after this many hours.
 
;<code>ssl_sessionkey_udp = yes</code>
:(Default: no) Enable parsing of session keys sent via UDP (keylogger support).
 
;<code>ssl_sessionkey_udp_port = 1234</code>
:UDP port for receiving session keys.
 
;<code>ssl_store_sessions = persistent</code>
:(Default: persistent) How to store SSL keys: 'persistent' (InnoDB) or 'memory'.
 
'''Choosing Between Storage Options'''
 
The <code>ssl_store_sessions</code> parameter controls where VoIPmonitor stores encryption keys for SSL/TLS sessions:
 
* '''persistent''' (Recommended): Stores keys in the <code>ssl_sessions</code> InnoDB table on disk. This provides virtually unlimited storage space and eliminates "table full" errors.


* '''memory''' (Legacy): Stores keys in the <code>ssl_sessions_mem</code> MEMORY table in RAM. This provides faster performance but has a hard size limit defined by MySQL's <code>max_heap_table_size</code> and the table's <code>MAX_ROWS</code> definition. When this table becomes full, VoIPmonitor cannot write new session keys, leading to decryption failures and data insertion errors.
See [[Tls]] for complete TLS decryption documentation.
 
'''Recovering from a Full ssl_sessions_mem Table'''
 
If you encounter errors because the <code>ssl_sessions_mem</code> table is full:
 
1. On the main database server, identify which sensor(s) are still writing to the memory table:
<syntaxhighlight lang="sql">SELECT id_sensor, COUNT(*) FROM ssl_sessions_mem GROUP BY id_sensor;</syntaxhighlight>
 
2. Log into each identified sensor.
 
3. Edit <code>/etc/voipmonitor.conf</code> and ensure the setting is:
<pre>ssl_store_sessions = persistent</pre>
 
4. Restart the VoIPmonitor sniffer service on each sensor to apply the change. This will direct new SSL session keys to the persistent <code>ssl_sessions</code> InnoDB table:
<syntaxhighlight lang="bash">systemctl restart voipmonitor</syntaxhighlight>
 
5. (Optional) Clear the existing data from the memory table on the database server:
<syntaxhighlight lang="sql">TRUNCATE TABLE ssl_sessions_mem;</syntaxhighlight>
 
'''Note:''' After switching to persistent storage, ensure your regular database maintenance scripts or partitioning strategies account for the growth of the <code>ssl_sessions</code> table on disk to prevent the disk itself from filling up over time.
 
;<code>ssl_tls_12_sessionkey_mode = dssl</code>
:(Default: dssl) Decryption library: 'dssl' or 'wireshark'.
 
;<code>ssl_ignore_error_invalid_mac = yes</code>
:(Default: yes) Ignore SSL/TLS packets with invalid MAC.


== SRTP Configuration ==
== SRTP Configuration ==


This section deals with Secure RTP (SRTP) decryption, including both RTP and RTCP streams. Supported encryption algorithms: AES_CM_128_HMAC_SHA1_32, AES_CM_128_HMAC_SHA1_80.
{| class="wikitable"
! Parameter !! Default !! Description
|-
| <code>srtp_rtp</code> || no || Decrypt and store RTP data in PCAPs
|-
| <code>srtp_rtcp</code> || yes || Decrypt RTCP streams
|-
| <code>srtp_rtp_dtls</code> || yes || DTLS decryption (requires keylogger)
|-
| <code>ssl_dtls_boost</code> || no || '''Meta-parameter''' enabling aggressive DTLS decryption options
|}


;<code>srtp_rtp = no</code>
= Caller/Called Identity =
:(Default: no) Decrypt and store RTP data in PCAPs. By default, only RTCP is decrypted.


;<code>srtp_rtcp = yes</code>
{| class="wikitable"
:(Default: yes) Decrypt RTCP streams.
! Parameter !! Default !! Description
|-
| <code>remoteparty_caller</code> || unset || Update caller from Remote-Party-ID (<code>calling</code>/<code>called</code>)
|-
| <code>passertedidentity</code> || no || Use P-Asserted-Identity for caller
|-
| <code>destination_number_mode</code> || 1 || Source for called number: <code>1</code>=To header, <code>2</code>=INVITE URI
|-
| <code>sipoverlap</code> || yes || Update destination from subsequent INVITEs (overlap dialing)
|}


;<code>srtp_rtp_dtmf = no</code>
= Performance & Threading =
:(Default: no) Decrypt only RTP DTMF packets.


;<code>srtp_rtp_dtls = yes</code>
== Core Threading ==
:(Default: yes) Enable DTLS decryption. Requires keylogger or session keys.


;<code>ssl_dtls_queue = yes</code>
{| class="wikitable"
:(Default: no) Enable DTLS packet queue to prevent packet loss during decryption.
! Parameter !! Default !! Description
|-
| <code>t2_boost</code> || unset || Set to <code>high_traffic</code> for ≥1500Mbit. Fixes CPU bottlenecks where single defrag thread runs at 100%.
|-
| <code>threading_expanded</code> || yes || Modern multi-threaded engine. Set <code>high_traffic</code> for >5 Gbit/s.
|-
| <code>preprocess_rtp_threads</code> || 2 || Initial RTP preprocessing threads (auto-scales)
|-
| <code>rtpthreads</code> || CPU count || RTP processing threads
|}


;<code>ssl_dtls_queue_expiration = 10</code>
== Buffer Configuration ==
:(Default: 10) DTLS queue expiration time in seconds.


;<code>srtp_rtp_local_instances = no</code>
{| class="wikitable"
:(Default: no) Create separate decryption instance per RTP stream.
! Parameter !! Default !! Description
|-
| <code>ringbuffer</code> || 50 || Ringbuffer size MB. ≥500 recommended for >100 Mbit. Max 2000.
|-
| <code>max_buffer_mem</code> || 2000 || Max buffer memory MB. Increase to 10000+ for high concurrent calls.
|-
| <code>packetbuffer_compress</code> || no || Enable in distributed setups to reduce bandwidth.
|}


;<code>ssl_dtls_queue_keep = no</code>
== Thread Priority ==
:(Default: no) Keep DTLS packets in queue after first successful use.


;<code>ssl_sessionkey_keep = no</code>
<syntaxhighlight lang="ini">
:(Default: no) Keep keylogger keys until expiration instead of discarding after first use.
sched_pol_auto = prio -20  # Auto-elevate critical threads under load
sched_pol_auto_cpu_limit = 45  # CPU threshold for elevation
</syntaxhighlight>


;<code>ssl_dtls_handshake_safe = no</code>
= Distributed Operation =
:(Default: no) DTLS handling approach: no (queue), only (unified), yes (both, queue priority), ext (both, unified priority).


;<code>ssl_dtls_boost = no</code>
See [[Sniffer_distributed_architecture]] for complete documentation.
:(Default: no) A '''meta-parameter''' that enables a set of aggressive options for improving DTLS handshake and SRTP decryption success rates. When enabled, it sets:
:* ssl_dtls_queue_expiration = 30
:* ssl_sessionkey_keep = yes
:* ssl_dtls_queue_keep = yes
:* ssl_dtls_handshake_safe = ext
:* ssl_dtls_rtp_local = yes


== Caller/Called Identity Configuration ==
These options control how caller and called party information is extracted from SIP headers.
;<code>remoteparty_caller = calling</code>
:(Default: unset) Update caller number from Remote-Party-ID header. Use 'calling' or 'called' based on the party attribute.
;<code>remoteparty_called = called</code>
:(Default: unset) Update called number from Remote-Party-ID header.
;<code>passertedidentity = no</code>
:(Default: no) Use P-Asserted-Identity header for caller info.
;<code>ppreferredidentity = no</code>
:(Default: no) Use P-Preferred-Identity header for caller info.
;<code>remotepartypriority = no</code>
:(Default: no) Give Remote-Party-ID priority over P-Asserted-Identity and P-Preferred-Identity.
;<code>callernum_numberonly = yes</code>
:(Default: yes) Parse only the number part from identity headers.
;<code>destination_number_mode = 1</code>
:(Default: 1) Source for destination number: 1 = To header, 2 = INVITE URI.
;<code>sipoverlap = yes</code>
:(Default: yes) Update destination number from subsequent INVITEs (overlap dialing support per RFC 3578).
;<code>last_dest_number = no</code>
:(Default: no) Always take destination from latest INVITE regardless of source IP.
;<code>update_dstnum_onanswer = no</code>
:(Default: no) Update destination number when callee answers (useful for hunt groups).
== Performance & Threading ==
=== Core Threading Model ===
;<code>threading_expanded = yes</code>
:(Default: yes) Enables the modern, multi-threaded processing engine. The sniffer automatically spawns and manages threads based on traffic load and CPU capacity. Set to `high_traffic` for environments exceeding 5 Gbit/s or very high concurrent call loads (8,000-10,000+ calls) where PACKETBUFFER saturation occurs.
;<code>preprocess_rtp_threads = 2</code>
:(Default: 2) The initial number of threads for RTP preprocessing. The system will auto-scale from here.
;<code>preprocess_rtp_threads_max = 5</code>
:(Default: unlimited) Maximum RTP preprocessing threads.
;<code>pre_process_packets_next_thread = 4</code>
:For high network throughput (>= 5Gbit), set to 4.
;<code>pre_process_packets_next_thread_max = 4</code>
:Hard limit is 4 even if value is higher.
;<code>destroy_calls_in_storing_cdr = yes</code>
:(Default: no) Offloads the process of freeing call memory to a separate thread. Useful in very high-traffic scenarios (> 50,000 concurrent calls).
;<code>rtpthreads_start = 20</code>
:(Default: rtpthreads value or half of CPU count) Starting number of RTP processing threads. For high concurrent call loads (8,000-10,000+ calls), set to approximately half of the total CPU count or a specific value like 20. This parameter directly influences RTP thread initialization and helps prevent PACKETBUFFER saturation under heavy load.
;<code>rtpthreads = 0</code>
:(Default: CPU count) Number of threads for RTP packet processing. 0 disables threading.
=== Thread Scheduling & Priority ===
;<code>sched_pol_auto = prio -20</code>
:(Default: `prio -20`) Automatically elevates the priority (lowers the `nice` value) of critical threads if the system comes under load.
;<code>sched_pol_auto_heap_limit = 1</code>
:(Default: 1) Heap growth percentage threshold for priority elevation.
;<code>sched_pol_auto_cpu_limit = 45</code>
:(Default: 45) CPU usage threshold for priority elevation.
Manual thread priority settings (alternative to auto):
;<code>sched_pol_interface = prio -20</code>
;<code>sched_pol_pb = prio -20</code>
;<code>sched_pol_sip = prio -20</code>
;<code>sched_pol_rtp_prep = prio -20</code>
;<code>sched_pol_rtp_read = prio -20</code>
=== NUMA & Memory ===
;<code>numa_balancing_set = autodisable</code>
:(Default: autodisable) Manages the Linux kernel's NUMA balancing feature. The default setting will automatically disable NUMA balancing if it detects high overhead.
;<code>hugepages_max = 80000</code>
:(Default: 0, disabled) Enables the use of huge pages for memory allocation, which can improve performance on some systems by reducing TLB misses.
=== Buffer Configuration ===
;<code>ringbuffer = 50</code>
:(Default: 50) Ringbuffer size in MB. Recommended >= 500 for >100 Mbit traffic. Max 2000.
;<code>packetbuffer_enable = yes</code>
:(Default: yes) Enable packet buffer cache.
;<code>packetbuffer_compress = no</code>
:(Default: no) Enable packet buffer compression.
;<code>max_buffer_mem = 2000</code>
:(Default: 2000) Maximum buffer memory in MB. Increase to 10000 or higher for high concurrent call loads (8,000-10,000+ calls) to prevent "PACKETBUFFER: memory is FULL" errors. Ensure sufficient RAM is available.
;<code>memory_purge_interval = 30</code>
:(Default: 30) Memory purge interval in seconds.
;<code>memory_purge_if_release_gt = 500</code>
:(Default: 500) Memory purge threshold in MB.
== Distributed Operation: Client/Server & Mirroring ==
VoIPmonitor supports distributed deployments where remote sensors send data to a central server. There are two operational modes controlled by the <code>packetbuffer_sender</code> parameter:
<div style="overflow-x: auto;">
<kroki lang="mermaid">
<kroki lang="mermaid">
%%{init: {'flowchart': {'nodeSpacing': 15, 'rankSpacing': 40}}}%%
flowchart LR
flowchart LR
     subgraph "Local Processing Mode (packetbuffer_sender=no)"
     subgraph "Local Processing (packetbuffer_sender=no)"
         A1[Remote Sensor] -->|"Analyzes packets locally"| A2[CDR + Stats]
         A1[Remote Sensor] -->|"Analyzes locally"| A2[CDR + Stats]
         A2 -->|"Sends CDRs via TCP/60024"| A3[Central Server]
         A2 -->|"Sends CDRs"| A3[Central Server]
         A1 -->|"Stores PCAP locally"| A4[(Local Disk)]
         A1 -->|"Stores PCAP"| A4[(Local Disk)]
     end
     end
 
     subgraph "Packet Mirroring (packetbuffer_sender=yes)"
     subgraph "Packet Mirroring Mode (packetbuffer_sender=yes)"
         B1[Remote Sensor] -->|"Forwards packets"| B2[Central Server]
         B1[Remote Sensor] -->|"Forwards raw packets via TCP/60024"| B2[Central Server]
         B2 -->|"Analyzes & stores"| B3[(Central Disk)]
         B2 -->|"Analyzes & stores"| B3[(Central Disk)]
     end
     end
</kroki>
</kroki>
</div>
'''Key differences:'''
* '''Local Processing''' (<code>packetbuffer_sender=no</code>): Low network usage, PCAP files stored on remote sensor, higher CPU usage on sensor
* '''Packet Mirroring''' (<code>packetbuffer_sender=yes</code>): Higher network usage, all data centralized, minimal CPU usage on sensor


=== Modern Client/Server Model (Recommended) ===
== Client/Server Configuration ==
;<code>server_bind = 0.0.0.0</code>
:The IP address the central sensor will listen on for connections from remote clients.
;<code>server_bind_port = 60024</code>
:(Default: 60024) Port for client connections.
;<code>server_destination = 10.0.0.1</code>
:The IP address of the central server a remote sensor should connect to. Multiple IPs for failover: `192.168.0.1, 192.168.0.2`.
;<code>server_destination_port = 60024</code>
:(Default: 60024) Port of the central server.
;<code>server_password =</code>
:A shared password to authenticate clients and servers.
;<code>packetbuffer_sender = no</code>
:(Default: no) The operational mode. `no` for local processing (low network usage), `yes` for packet mirroring (low remote CPU usage).
;<code>packetbuffer_file_path = /path/to/directory</code>
:Path to a local directory where CDR packets will be cached to disk when the connection to the central server is lost or temporarily unavailable. This provides a fallback queue for packet transmission during network outages. When the connection is restored, cached packets are transmitted. Note that the server may discard packets that are too old upon reconnection. (Default: not set - packets are buffered in memory only and lost if connection fails)


{|
'''Central Server:'''
|- class="wikitable" style="background:#fff3cd; border:1px solid #ffc107;"
<syntaxhighlight lang="ini">
! colspan="2" style="background:#ffc107;" | Important: packetbuffer_sender Controls Packet Transmission
server_bind = 0.0.0.0
|-
server_bind_port = 60024
| style="vertical-align: top;" | '''Critical Behavior:'''
server_password = yourpassword
| When <code>packetbuffer_sender = yes</code>, '''all packets are transmitted''' (forwarded to central server or sent via packet buffer), which includes RTP packets regardless of your <code>savertp</code> setting. This option always transmits full packet streams for processing.
# CRITICAL: Exclude server port from sipport!
|-
sipport = 1-60023,60025-65535
| style="vertical-align: top;" | '''If RTP is recorded despite <code>savertp = no</code>:'''
| Check for <code>packetbuffer_sender = yes</code> in your configuration. This setting will cause RTP packets to be saved because the raw packet stream is being transmitted. Set <code>packetbuffer_sender = no</code> or comment out the line to disable packet transmission.
|}
;<code>server_type_compress = zstd</code>
:(Default: zstd) Compression algorithm for the client/server channel. Options: zstd, gzip, lzo, none.
;<code>receiver_check_id_sensor = yes</code>
:(Default: yes) Differentiate packets by originating sensor. Set to 'no' for multipath routing scenarios.
 
'''Important: Exclude server_bind_port from sipport'''
On central servers in client/server mode, ensure the <code>server_bind_port</code> (default 60024) is <strong>excluded</strong> from the <code>sipport</code> directive. Including this port causes the sensor-to-server communication traffic to be captured as SIP packets, leading to high and continuously increasing memory utilization.
 
Example for default <code>server_bind_port = 60024</code>:
<pre>
# WRONG - includes sensor communication port:
sipport = 1-65535
 
# CORRECT - excludes sensor communication port:
sipport = 1-60023
sipport = 60025-65535
</pre>
 
See [[Sniffer_distributed_architecture|Distributed Architecture]] for more details.
 
=== Time Synchronization ===
;<code>mirror_connect_maximum_time_diff_s = 2</code>
:(Default: 2) Maximum time difference for mirror connections.
;<code>client_server_connect_maximum_time_diff_s = 2</code>
:(Default: 2) Maximum time difference for client/server connections.
;<code>receive_packetbuffer_maximum_time_diff_s = 30</code>
:(Default: 30) Maximum time difference for packet buffer reception.
 
=== Legacy Mirroring Model ===
;<code>mirror_bind_ip = 0.0.0.0</code>
:The IP the receiver sensor listens on for the unencrypted, legacy mirroring protocol.
;<code>mirror_bind_port =</code>
:Port for legacy mirroring.
;<code>mirror_bind_sensor_id_by_sender = yes</code>
:(Default: no) Bind the sensor ID to the sending probe's IP address in mirroring mode. When enabled, packets received from different probes are automatically associated with the corresponding sensor ID configured on each probe. This is useful for distinguishing which probe sent the packets in distributed mirror mode deployments where multiple probes forward traffic to a single receiver.
;<code>mirror_destination_ip = 10.0.0.1</code>
:The IP of the receiver sensor that the sender should stream packets to.
;<code>mirror_destination_port =</code>
:Port for mirror destination.
;<code>mirror_require_confirmation = yes</code>
:(Default: yes) Require packet confirmation. Disable for higher throughput.
;<code>mirror_use_checksum = yes</code>
:(Default: yes) Enable block-level checksums.
;<code>pcap_queue_dequeu_window_length = 2000</code>
:(Default: 2000) Window length in ms for sorting packets from multiple mirrors.
 
== Storage & File Management (Spooldir) ==
 
=== Location and Permissions ===
;<code>spooldir = /var/spool/voipmonitor</code>
:The primary directory for storing all captured data (PCAP, GRAPH, AUDIO files).
;<code>spooldir_rtp =</code>
:Separate directory for RTP files.
;<code>spooldir_graph =</code>
:Separate directory for graph files.
;<code>spooldir_audio =</code>
:Separate directory for audio files. When set, audio files are saved directly to this directory without the default spooldir date/time nesting structure. '''Warning:''' This configuration spawns a separate audio conversion process for every call, which can overload the system with high call volumes. This method is not recommended for deployments with more than 100 concurrent calls. For high-traffic deployments, consider using <code>saveaudio_singlefolder</code> or a scripting workaround to move files from the default spooldir structure.
;<code>spooldir_2 = /var/spool/voipmonitor2</code>
:Secondary storage directory with separate autoclean setup. This directory is used exclusively for PCAPs from calls that match capture rules where the "Store pcaps to second spooldir" option is enabled. '''Note:''' This is NOT an automatic overflow directory when the primary <code>spooldir</code> becomes full. When the primary directory reaches its limit (defined by <code>maxpoolsize</code> or <code>maxpooldays</code>), the <code>cleanspool</code> process triggers and deletes the oldest files from the primary directory to free up space. Standard traffic continues to write to the primary <code>spooldir</code> based on your capture rules. Use this feature to store specific subsets of calls (e.g., VIP customers, legal holds) that require different retention policies (e.g., <code>maxpoolsize_2</code>, <code>maxpooldays_2</code>) than the standard traffic.
;<code>spooldir_file_permission = 0666</code>
;<code>spooldir_dir_permission = 0777</code>
:Allows setting specific filesystem permissions for newly created files and directories.
;<code>spooldir_owner = root</code>
;<code>spooldir_group = root</code>
:Owner and group for created files.
;<code>spooldir_by_sensor = no</code>
:(Default: no) If enabled, creates subdirectories within the spooldir for each `id_sensor`.
;<code>spooldir_by_sensorname = yes</code>
:Organize by sensor name instead of ID.
;<code>name_sensor = sensor1</code>
:Sensor name for directory organization.
;<code>cachedir = /dev/shm/voipmonitor</code>
:Cache directory for temporary storage. Use RAM or SSD for better performance.
 
=== PCAP/TAR Storage Strategy ===
;<code>tar = yes</code>
:(Default: yes) This is a key performance feature. Instead of writing thousands of small PCAP files, voipmonitor groups them into minute-based `.tar` archives, which drastically reduces disk I/O load.
;<code>tar_maxthreads = 8</code>
:(Default: 8) Maximum threads for tar compression.
;<code>tar_compress_sip = zstd</code>
:(Default: zstd) SIP TAR compression. Options: none, gzip, zstd, lzma.
;<code>tar_sip_level_zstd = 1</code>
:(Default: 1) Compression level for SIP TAR.
;<code>tar_compress_rtp = no</code>
:(Default: no) RTP TAR compression. Individual RTP pcaps are compressed with lzo by default.
;<code>tar_compress_graph = zstd</code>
:(Default: zstd) Graph TAR compression.
;<code>tar_graph_level_zstd = 1</code>
:(Default: 1) Compression level for graph TAR.
;<code>tar_move = yes</code>
:(Default: no) Move tar files to another directory after closing. Options: no, yes (move and delete), copy.
;<code>tar_move_destination_path = /mnt/nfs/storage</code>
:Destination for tar move.
;<code>tar_move_max_threads = 2</code>
:(Default: 2) Threads for moving tar files.
 
=== Saving Options ===
;<code>savesip = yes</code>
:Enables saving of SIP packets.
;<code>savertp = yes</code>
:Enables saving of RTP packets. Set to `header` to save only RTP headers, not the audio payload.
;<code>savertp_video = no</code>
:(Default: no) Save video RTP packets. Options: no, yes, header, cdr_only.
;<code>savertcp = yes</code>
:Enables saving of RTCP (RTP Control Protocol) packets.
;<code>savegraph = yes</code>
:Enables saving of call graph data.
;<code>null_rtppayload = no</code>
:(Default: no) Zero out all RTP payload data.
;<code>maxpcapsize = 500</code>
:(Default: unset) Maximum pcap file size in MB.
 
=== PCAP Compression ===
;<code>pcap_dump_zip = yes</code>
:(Default: yes) Enable file compression for pcap files.
;<code>pcap_dump_zip_sip = zstd</code>
:SIP compression. Options: no, zstd, gzip, lzo, lz4.
;<code>pcap_dump_zip_rtp = lzo</code>
:(Default: lzo) RTP compression.
;<code>pcap_dump_zip_graph = no</code>
:Graph compression.
;<code>pcap_dump_ziplevel = 3</code>
:(Default: 3) Compression level.
;<code>pcap_dump_writethreads = 1</code>
:(Default: 1) Initial compression threads. Auto-scales.
;<code>pcap_dump_writethreads_max = 32</code>
:(Default: 32) Maximum compression threads.
;<code>pcap_dump_asyncwrite = yes</code>
:(Default: yes) Enable asynchronous writing.
;<code>pcap_dump_bufflength = 8184</code>
:(Default: 8184) Buffer size in bytes.
 
=== Spool Cleaning ===
;<code>cleanspool = yes</code>
:(Default: yes) Enables the automatic cleaning process for the spool directory.
;<code>cleanspool_enable_fromto = 1-5</code>
:(Default: 0-24) Restrict cleaning to specific hours.
;<code>maxpoolsize = 102400</code>
:(Default: 100 GB) The primary retention setting. Deletes the oldest data hourly until the specified size limit is reached (in MB).
;<code>maxpooldays = 30</code>
:(Default: unset) An alternative policy that deletes all data older than the specified number of days.
;''Note: Separate `maxpoolsip*`, `maxpoolrtp*`, `maxpoolgraph*`, `maxpoolaudio*` options exist for granular policies.''
;<code>autocleanspoolminpercent = 1</code>
:(Default: 1%) Emergency cleaning trigger percentage.
;<code>autocleanmingb = 5</code>
:(Default: 5 GB) Emergency cleaning trigger in GB.
;<code>maxpool_clean_obsolete = yes</code>
:(Default: no) Clean files not in the index.
 
=== Audio File Generation ===
;<code>saveaudio = wav</code>
:(Default: no) If enabled, voipmonitor will generate an audio file (`.wav`, `.ogg`, or `.mp3`) for each call in addition to the PCAP file. Options: <code>wav</code>, <code>ogg</code>, <code>mp3</code>, or <code>yes</code>. Using <code>yes</code> will default to WAV format. '''Note:''' This is generally not necessary and adds significant CPU/I/O load.
;<code>save_audiograph = yes</code>
:(Default: no) Enables generation of audio graph files (waveform and spectrogram images) stored in the <code>spooldir/AUDIOGRAPH</code> directory. These graphs visualize audio quality (MOS, jitter, packet loss) without requiring audio playback. If <code>savertp = yes</code>, audio graph files can be generated directly from the PCAP file without needing to enable this option. For auto-cleaning configuration, see <code>maxpoolaudiographsize</code> and <code>maxpoolaudiographdays</code>.
;<code>audiograph_fftw_fork_mode = no</code>
:(Default: yes) Controls the FFTW (Fastest Fourier Transform) library's threading mode for audiograph generation. Setting to <code>no</code> disables the fork-based thread pool, preventing memory leaks in the sensor process. Use this setting if you experience intermittent audiograph generation failures or sensor crashes. This option resolves issues where audiographs become unavailable in the GUI due to process instability.
;<code>saveaudio_singlefolder = /var/spool/voipmonitor/audio</code>
:(Default: unset) Store all generated audio files in a dedicated directory separate from the main PCAP spooldir structure. Audio files are organized under the specified path with date-based subdirectories (e.g., <code>/var/spool/voipmonitor/audio/2025/01/05/</code>), which makes it easier to isolate audio storage for separate backup, mounting, or management purposes. This is the recommended approach for separating audio storage while maintaining organized directory structure. '''Prerequisite:''' <code>saveaudio</code> must be enabled (set to <code>wav</code>, <code>ogg</code>, <code>mp3</code>, or <code>yes</code>).
;<code>saveaudio_afterconnect = no</code>
:(Default: no) Store audio only for connected calls.
;<code>saveaudio_from_first_invite = yes</code>
:(Default: yes) Generate silence from first INVITE to match SIP signalization length.
;<code>saveaudio_stereo = yes</code>
:(Default: yes) Caller in left channel, called in right channel.
;<code>mp3_quality = 5</code>
:(Default: 5) MP3 quality (0-9, 9 is worst).
;<code>ogg_quality = 0.4</code>
:(Default: 0.4) OGG quality setting.
;<code>audioqueue_threads_max = 10</code>
:(Default: 10) Maximum audio processing threads.
;<code>curl_hook_wav = http://127.0.0.1:8080/your-script-path</code>
:Webhook URL called for each audio file.
 
== Call Processing & Protocol Logic ==
 
=== Call Identification & Merging ===
;<code>remoteparty_caller = calling</code>, `passertedidentity = no`, etc.
:A group of options that control which SIP headers are used to determine the caller/callee information. See [[#Caller/Called Identity Configuration|Caller/Called Identity Configuration]].
;<code>sipoverlap = yes</code>
:(Default: yes) Allows the destination number to be updated from subsequent INVITEs within the same dialog, necessary for overlap dialing.
;<code>matchheader = in-reply-to</code>
:Uses the specified SIP header to link different call legs into a single related call in the GUI.
;<code>callidmerge_header = Parent-Call-ID</code>
:A more advanced method to merge call legs based on a shared identifier in a custom header.
;<code>callidmerge_secret = yourSecretString</code>
:XOR secret for encrypted Call-ID merging header.
;<code>call_id_alternative = Session-ID,Join</code>
:Alternative unique identifiers for call merging (e.g., Cisco CUCM).
;<code>cdrproxy = yes</code>
:(Default: yes) Track all proxy IPs in `cdr_proxy` table.
 
=== Call Timeouts & Termination ===
;<code>absolute_timeout = 14400</code>
:(Default: 4 hours) Forcefully ends any call that lasts longer than this value to prevent runaway processes. Sets `cdr.bye = 102`.
;<code>rtptimeout = 300</code>
:(Default: 5 minutes) Closes a call if no RTP or RTCP packets have been received for this duration.
;<code>sipwithoutrtptimeout = 3600</code>
:(Default: 1 hour) Closes a SIP call that has no associated RTP stream after this duration.
;<code>bye_timeout = 1200</code>
:(Default: 1200) Timeout in seconds after BYE message.
;<code>bye_confirmed_timeout = 600</code>
:(Default: 600) Timeout after confirmed BYE.
;<code>onewaytimeout = 15</code>
:(Default: 15) Ends call if no reply from other side. Sets `cdr.bye = 101`.
;<code>ignore_rtp_after_response = 408;480;486;487;481;600;503</code>
:(Default: as shown) A list of SIP final response codes after which the sniffer should stop looking for RTP for that call.
;<code>ignore_rtp_after_bye = no</code>
:(Default: no) Stop RTP processing after BYE.
;<code>ignore_rtp_after_bye_confirmed = yes</code>
:(Default: yes) Stop RTP processing after confirmed BYE.
;<code>ignore_rtp_after_cancel_confirmed = yes</code>
:(Default: yes) Stop RTP processing after confirmed CANCEL.
;<code>redirect_response_300_timeout = 300</code>
:(Default: 300) Timeout for SIP 300 redirect.
;<code>get_reason_from_bye_cancel = yes</code>
:(Default: yes) Fetch Q.850 Reason header from BYE/CANCEL.
;<code>ignore_duration_after_bye_confirmed = yes</code>
:(Default: yes) Set duration based on confirmed BYE.
;<code>detect_alone_bye = no</code>
:(Default: no) Flag CDR if BYE is alone in dialog. Warning: Can cause high DB load.
 
=== Source Code Configuration (Advanced) ===
 
The following timeout values are configured at compile time by modifying the sniffer source code and recompiling. These are not available as configuration file options. To change them:
 
# Download the sniffer source code from GitHub:
<syntaxhighlight lang="bash">
cd /usr/src
git clone -b master https://github.com/voipmonitor/sniffer.git
cd sniffer
</syntaxhighlight>
</syntaxhighlight>


# Locate and modify the constant definition:
'''Remote Sensor:'''
;<code>destroy_call_at_bye</code>
<syntaxhighlight lang="ini">
:Timeout in seconds after BYE packet before stopping call interception. Edit the constant definition in <code>call_table.cpp</code> and set the desired value (e.g., <code>1200</code> for 20 minutes).
id_sensor = 2
 
server_destination = 10.0.0.1
# Recompile the sniffer:
server_destination_port = 60024
<syntaxhighlight lang="bash">
server_password = yourpassword
./configure
packetbuffer_sender = no  # or yes for packet mirroring
make
make install
systemctl restart voipmonitor
</syntaxhighlight>
</syntaxhighlight>


This forces the sniffer to stop intercepting a call after the specified timeout following a BYE packet, even if RTP streams are still active.
{{Warning|1=When <code>packetbuffer_sender = yes</code>, '''all packets including RTP are transmitted''' regardless of <code>savertp</code> setting.}}


=== RTP Processing ===
= Storage & File Management =
;<code>jitterbuffer_f1 = yes</code>
:(Default: yes) Fixed 50ms jitterbuffer simulation, saved in cdr.[ab]_f1.
;<code>jitterbuffer_f1_jbsize = 50</code>
:(Default: 50) Jitter buffer size in ms.
;<code>jitterbuffer_f2 = yes</code>
:(Default: yes) Fixed 200ms jitterbuffer simulation, saved in cdr.[ab]_f2.
;<code>jitterbuffer_adapt = yes</code>
:(Default: yes) Adaptive jitterbuffer up to 500ms.


;'''''Behavior:''' By default (<code>yes</code>), MOS is calculated and counted. CPU-intensive; disable some on resource-constrained systems. Setting to <code>no</code> skips MOS calculation and pushes static value 4.5 to GUI. Setting to <code>null</code> skips calculation and pushes '-' (NULL) to GUI. Disabling calculation saves CPU time on heavily loaded hosts.''''
== Spool Directory ==


;<code>mosmin_f2 = yes</code>
{| class="wikitable"
:(Default: yes) Calculate mos_min_mult10 only from f2 jitter simulator.
! Parameter !! Default !! Description
|-
| <code>spooldir</code> || /var/spool/voipmonitor || Primary storage directory
|-
| <code>spooldir_2</code> || unset || Secondary storage for capture rules with "Store to second spooldir"
|-
| <code>cachedir</code> || unset || Temp storage (use RAM/SSD for performance)
|}


=== RTP Tracking & SDP ===
{{Note|1=For GUI access to <code>spooldir_2</code>, configure "Sniffer second datapath" in GUI Settings > System Configuration > Basic.}}
;<code>sdp_multiplication = 3</code>
:(Default: 3) How many calls can share same IP:port. 0 = only newest call.
;<code>disable_process_sdp = no</code>
:(Default: no) Disable SDP processing. Only for very high CPS (>1000).
;<code>rtp_check_both_sides_by_sdp = no</code>
:(Default: no) Eliminate RTP duplication by checking source IP:port. Options:
:* <code>no</code>: Disabled (default)
:* <code>yes</code>: Verify both sides per SDP
:* <code>keep_rtp_packets</code>: Same as 'yes' but store unverified packets for debugging
:* <code>strict</code>: Allow unverified packets until first verified packet arrives
:* <code>very_strict</code>: No unverified packets allowed at any time
;<code>ignore_rtp_after_auth_failed = yes</code>
:(Default: yes) Close RTP ports on authentication failure.
;<code>disable_rtp_seq_probation = no</code>
:(Default: no) Disable RFC 3550 sequence validation.
;<code>allow-zerossrc = no</code>
:(Default: no) Allow RTP packets with zero SSRC.
;<code>check_diff_ssrc_on_same_ip_port = yes</code>
:(Default: yes) Check for different SSRC on same IP:port.
;<code>save_sdp_ipport = yes</code>
:(Default: yes) Store SDP IP/port in `cdr_sdp` table.
;<code>rtpfromsdp_onlysip = no</code>
:(Default: no) Only use RTP streams with same IP as SIP header.
;<code>rtpip_find_endpoints = yes</code>
:(Default: yes) Determine actual RTP endpoints (not proxies).


=== SRTP (Encrypted Media) ===
== TAR Storage Strategy ==
See [[#SRTP Configuration|SRTP Configuration]] section above.


=== NAT Handling ===
<syntaxhighlight lang="ini">
;<code>natalias = 1.1.1.1 10.0.0.3</code>
tar = yes  # Group PCAPs into minute-based archives (reduces I/O)
:Creates a mapping between a public IP and a private IP, helping the sniffer correctly associate call legs behind a NAT device. Multiple lines can be used.
tar_compress_sip = zstd
;<code>sdp_reverse_ipport = no</code>
tar_compress_graph = zstd
:(Default: no) Enable reverse IP:port sniffing for NAT scenarios. Use with caution.
</syntaxhighlight>
;<code>sdp_ignore_ip = 192.168.0.1</code>
:Ignore RTP streams from specific IPs.
;<code>sdp_ignore_ip_port = 192.168.0.1:100</code>
:Ignore RTP streams from specific IP:port.


=== SIP REGISTER, OPTIONS, SUBSCRIBE, NOTIFY ===
== Saving Options ==
;<code>sip-register = no</code>
:(Default: no) Enables the processing and storage of SIP `REGISTER` messages. Options: yes, nodb, no.
;<code>save-sip-register = no</code>
:(Default: no) Save REGISTER messages to disk.
;<code>sip-register-timeout = 5</code>
:(Default: 5) Timeout in seconds for REGISTER reply.
;<code>sip-register-active-nologbin = yes</code>
:(Default: yes) Skip binary logging for REGISTER active table.
;<code>sip-register-max-registers = 4</code>
:(Default: 4) Max request packets before terminating register session.
;<code>sip-register-max-messages = 20</code>
:(Default: 20) Max total packets before terminating register session.
;<code>sip-register-state-timeout = 600</code>
:(Default: 600) Interval between saving same states.
;<code>sip-register-state-compare-digest_ua = no</code>
:(Default: no) When enabled with <code>yes</code>, the sniffer will create a new record in the register state table whenever the SIP User-Agent (UA) string changes, even if other registration details remain the same. The alias <code>sip-register-state-compare-ua = yes</code> can also be used. This allows detection of UA changes by querying the database, but does not trigger a native GUI alert. Use with the anti-fraud system or custom database queries for detection.
;<code>sip-options = no</code>
:(Default: no) Enables the processing of SIP `OPTIONS` messages.
;<code>save-sip-options = no</code>
:(Default: no) Save OPTIONS to disk.
;<code>sip-subscribe = no</code>
:(Default: no) Enable SUBSCRIBE processing.
;<code>sip-notify = no</code>
:(Default: no) Enable NOTIFY processing.
;<code>sip-message = yes</code>
:(Default: yes) Enables processing for SIP `MESSAGE` requests.


=== SIP History for Requests ===
{| class="wikitable"
;<code>save_sip_history = no</code>
! Parameter !! Default !! Description
:(Default: no) Enables storage of ALL SIP requests (not just call-related SIP signaling) in the database. When set to <code>requests</code>, all SIP request methods observed on the network are logged to the <code>sip_request</code> table, including methods not typically associated with calls like PUBLISH, INFO, UPDATE, PRACK, REFER, and others. This enables searching and filtering these requests in the GUI using the "SIP requests" filter. Options: no, requests.
|-
| <code>savesip</code> || yes || Save SIP packets
|-
| <code>savertp</code> || yes || <code>yes</code>=full, <code>header</code>=metadata only (no audio), <code>no</code>=disabled
|-
| <code>savertp_video</code> || no || Video RTP. '''Limitation:''' Only ONE video stream per call saved to PCAP.
|-
| <code>saveudptl</code> || no || T.38 fax packets
|-
| <code>savegraph</code> || yes || Call graph data
|}


:'''Warning:''' Enabling this option significantly increases database write load and storage size, especially in high-traffic environments. Only enable it if you need to store and search non-call SIP requests.
'''Disable audio recording:'''
<syntaxhighlight lang="ini">
savertp = header  # NOT 'no' - keeps RTP analysis tool working
saveaudio = no
</syntaxhighlight>


:'''Example usage for PUBLISH packets:'''
== Spool Cleaning ==
:* By default, SIP PUBLISH packets are captured but not stored in the database or indexed for GUI filtering
:* To make PUBLISH and other non-call requests searchable, set <code>save_sip_history = requests</code>
:* After processing new calls, the GUI "SIP requests" filter will show all observed request types
:* Restart the voipmonitor service to apply changes


=== CDR Processing ===
{| class="wikitable"
;<code>nocdr = no</code>
! Parameter !! Default !! Description
:(Default: no) Disable saving CDRs to MySQL.
|-
;<code>cdronlyanswered = no</code>
| <code>cleanspool</code> || yes || Enable automatic spool cleaning
:(Default: no) Only save answered calls.
|-
;<code>cdronlyrtp = no</code>
| <code>maxpoolsize</code> || 102400 || Size limit in MB
:(Default: no) Only save calls with RTP.
|-
;<code>cdr_check_exists_callid = no</code>
| <code>maxpooldays</code> || unset || Age limit in days
:(Default: no) Check for existing CDR with same Call-ID and update it instead of creating a duplicate row. Use this when multiple probes or sniffer processes capture the same call packets and write CDRs to a shared database. The MySQL user must have UPDATE privileges on the cdr table. Side effect: the final CDR will only be associated with the id_sensor of the sniffer that last processed the call.
|-
;<code>cdr_ignore_response = 302,303,4</code>
| <code>autocleanspoolminpercent</code> || 1 || Emergency cleaning trigger (% free)
:Ignore CDRs based on SIP response codes. Use '0' or '000' to filter unreplied INVITE requests (calls with no response). This setting must be applied on the sniffer that analyzes and stores the packets. It will not work on a mirroring sniffer or probe where <code>packetbuffer_sender=yes</code> is set.
|}
;<code>cdr_sip_response_number_max_length = 3</code>
:Limit phone number length in SIP response text.
;<code>cdr_sip_response_normalisation = yes</code>
:(Default: yes) Normalize SIP response text.
;<code>cdr_reason_string_enable = yes</code>
:(Default: yes) Store reasons in cdr_reason table.
;<code>cdr_reason_normalisation = yes</code>
:(Default: yes) Normalize reason text.
;<code>cdr_ua_enable = yes</code>
:(Default: yes) Store user agent in cdr.a_ua and cdr.b_ua.
;<code>cdr_ua_normalisation = yes</code>
:(Default: yes) Normalize user agent strings.
;<code>cdr_stat = both</code>
:Enable aggregated CDR statistics. Options: both, src, dst.
;<code>cdr_stat_interval = 15</code>
:(Default: 15) Statistics interval in minutes.
;<code>vlan_siprtpsame = no</code>
:(Default: no) Filter RTP by VLAN tag from SIP packet.
;<code>dscp = yes</code>
:(Default: yes) Store DSCP values in cdr.dscp.


=== Custom Headers ===
== Audio File Generation ==
;<code>custom_headers = Referred-By, Diversion, X-Custom-Header</code>
:(Default: unset) Specifies custom SIP headers to capture and store in the database. Multiple headers are separated by commas. After adding headers to this directive and restarting the sniffer, corresponding database columns are automatically created in the `cdr_next_X` tables. You can then configure the display and filtering behavior in the GUI under [[Settings#CDR_Custom_Headers|Settings > CDR Custom Headers]]. Common use cases include capturing headers like <code>Referred-By</code>, <code>Diversion</code>, or custom correlation identifiers for call tracing.


; <code>custom_headers_last_value = yes</code>
{| class="wikitable"
:(Default: yes) Use last occurrence of custom header. If set to <code>no</code>, the first occurrence in the SIP message is stored instead.
! Parameter !! Default !! Description
; <code>custom_headers_max_size = 1024</code>
|-
:(Default: 1024) Maximum custom header size in bytes. Headers longer than this value will be truncated.
| <code>saveaudio</code> || no || Generate audio files: <code>wav</code>, <code>ogg</code>, <code>mp3</code>, or <code>yes</code>
; <code>allow_missing_header = no</code>
|-
:(Default: no) Write empty value if header is missing in the first SIP packet of the call.
| <code>saveaudio_singlefolder</code> || unset || Dedicated directory for audio files
|-
| <code>saveaudio_stereo</code> || yes || Caller=left, called=right channel
|}


=== Call Recording Control ===
= Call Processing =
;<code>pauserecordingdtmf = *9</code>
:(Default: unset) If set, RTP recording will be paused when this DTMF sequence is detected in a call.
;<code>pauserecordingdtmf_timeout = 4</code>
:(Default: 4) Timeout between DTMF digits in seconds.
;<code>pauserecordingheader = MyCustomPauseHeader</code>
:(Default: unset) Pauses/unpauses recording based on the presence of a specific SIP header and its value (e.g., `pause` or `unpause`).
;<code>norecord-header = yes</code>
:(Default: no) If any SIP packet in a call contains the `X-VoipMonitor-norecord` header, the entire call record (PCAP and CDR) will be discarded.
;<code>norecord-dtmf = yes</code>
:(Default: no) Delete recording if DTMF sequence "*0" is detected.
;<code>182queuedpauserecording = no</code>
:(Default: no) Pause on "182 Queued avaya-cm-data".


=== Audio Analysis ===
== Timeouts ==
;<code>dtmf2db = no</code>
:(Default: no) Store DTMF to database (SIP INFO and RTP RFC).
;<code>inbanddtmf = no</code>
:(Default: no) Enable in-band DTMF detection. G711 only. CPU intensive.
;<code>silencedetect = no</code>
:(Default: no) Enable silence detection. G711 only. CPU intensive.
;<code>silencethreshold = 512</code>
:(Default: 512) Silence detection threshold.
;<code>clippingdetect = no</code>
:(Default: no) Enable clipping detection. G711 only.
;<code>fasdetect = no</code>
:(Default: no) FAS (False Answer Supervision) detection based on ring detection after 200 OK.
;<code>save-energylevels = no</code>
:(Default: no) Store average 16-bit energy levels for each RTP packet in `cdr_rtp_energylevels` table.
;<code>energylevelheader = X-energlvl</code>
:Only save energy levels for calls with this header.
;<code>sipalg_detect = no</code>
:(Default: no) Detect SIP-ALG usage on routers/firewalls.


=== MOS Scoring ===
{| class="wikitable"
;<code>mos_g729 = no</code>
! Parameter !! Default !! Description
:(Default: no) Enable G.729 specific MOS scoring. Max MOS 3.92 for perfect G.729 calls.
|-
;<code>ignorertcpjitter = 0</code>
| <code>absolute_timeout</code> || 14400 || Force-end calls longer than this (seconds). Sets <code>cdr.bye = 102</code>.
:(Default: 0) Ignore RTCP jitter values higher than this.
|-
;<code>ignore_mos_degradation_for_contiguous_packet_loss_greater_than = 1024</code>
| <code>rtptimeout</code> || 300 || Close call if no RTP/RTCP for this duration
:(Default: 1024) Don't count consecutive packet loss above this threshold.
|-
;<code>ignore_mos_degradation_in_rtp_pause_without_seq_gap = 1000</code>
| <code>sipwithoutrtptimeout</code> || 3600 || Close SIP call without RTP
:(Default: 1000) Don't lower MOS for RTP gaps without sequence gaps.
|-
;<code>plcdisable = no</code>
| <code>onewaytimeout</code> || 15 || End call if no reply from other side
:(Default: no) Disable Packet Loss Concealment.
|}


=== PESQ MOS ===
== Call Merging ==
;<code>mos_lqo = no</code>
:(Default: no) Enable ITU-T P.862 PESQ scoring. Requires licensed pesq binary.
;<code>mos_lqo_bin = pesq</code>
:Path to PESQ binary.
;<code>mos_lqo_ref = /path/to/reference.wav</code>
:Reference audio file for PESQ.


=== Other Protocols ===
{| class="wikitable"
;<code>skinny = yes</code>
! Parameter !! Default !! Description
:(Default: no) Enables parsing for Cisco Skinny Call Control Protocol (SCCP).
|-
;<code>skinny_port = 2000</code>
| <code>matchheader</code> || unset || SIP header to link call legs in GUI
:(Default: 2000) Skinny port(s).
|-
;<code>skinny_ignore_rtpip = 10.1.1.1</code>
| <code>callidmerge_header</code> || unset || Header containing parent Call-ID for CDR merging
:Ignore RTP from Cisco Call Manager IP.
|-
;<code>mgcp = yes</code>
| <code>call_id_alternative</code> || unset || Alternative identifiers (e.g., <code>Session-ID,Join</code> for CUCM)
:(Default: no) Enables parsing for MGCP.
|}
;<code>tcp_port_mgcp_gateway = 2427</code>
;<code>udp_port_mgcp_gateway = 2427</code>
;<code>tcp_port_mgcp_callagent = 2727</code>
;<code>udp_port_mgcp_callagent = 2727</code>
;<code>ss7 = yes</code>
:(Default: no) Enables parsing for SS7-over-IP (SIGTRAN).
;<code>ss7_rudp_port = 7000</code>
:SS7 RUDP port.
;<code>ss7_use_sam_subsequent_number = yes</code>
:Use SAM subsequent number.
;<code>diameter = no</code>
:(Default: no) Enables parsing for the Diameter protocol.
;<code>diameter_tcp_ports = 3868</code>
;<code>diameter_udp_ports = 3868</code>
;<code>diameter_time_overlap = 10</code>
:(Default: 10) Allow Diameter packets up to 10 seconds before SIP sessions.
;<code>diameter_ignore_domain = no</code>
:(Default: no) Skip domain match between SIP and Diameter.
;<code>diameter_ignore_prefix = no</code>
:(Default: no) Allow 'sip:' to match 'tel:' prefix.
;<code>ipv6 = yes</code>
:(Default: no) Enable IPv6 support. Database must be created with IPv6 columns.


== IPFIX Support ==
See [[Merging_or_correlating_multiple_call_legs]] for detailed documentation.


IPFIX (IP Flow Information Export) allows receiving RTP QoS data from Oracle/ACME SBCs and other exporters.
== Recording Control ==


;<code>ipfix = yes</code>
{| class="wikitable"
:(Default: no) Enable IPFIX collector.
! Parameter !! Default !! Description
|-
| <code>pauserecordingdtmf</code> || unset || DTMF sequence to pause recording (e.g., <code>*9</code>)
|-
| <code>pauserecordingdtmf_timeout</code> || 4 || Timeout between DTMF digits (seconds)
|-
| <code>norecord-dtmf</code> || no || Delete recording if <code>*0</code> is detected
|-
| <code>norecord-header</code> || no || Discard call if <code>X-VoipMonitor-norecord</code> header present
|}


;<code>ipfix_bind_ip = 0.0.0.0</code>
== Custom Headers ==
:(Default: 0.0.0.0) Address to bind IPFIX UDP collector.


;<code>ipfix_bind_port = 12345</code>
<syntaxhighlight lang="ini">
:UDP port to listen for IPFIX.
custom_headers = Referred-By, Diversion, X-Custom-Header
custom_headers_last_value = yes
custom_headers_max_size = 1024
</syntaxhighlight>


;<code>ipfix_qos_fill_rtp_streams = yes</code>
After adding headers, configure display in GUI: '''Settings > CDR Custom Headers'''.
:(Default: no) Save all observed RTP streams into `cdr_rtp`.


;<code>ipfix_qos_fill_codec = yes</code>
== SIP History ==
:(Default: no) Persist exporter-provided codec value.


;<code>ipfix_qos_fill_jitter = yes</code>
;<code>save_sip_history</code>
:(Default: no) Persist RTP/RTCP jitter values.
:(Default: no) Store SIP signaling for GUI filtering.
* <code>requests</code> - All SIP methods (PUBLISH, INFO, UPDATE, PRACK, REFER) in "SIP requests" filter
* <code>responses</code> - Full response text for searching (not just codes)
* <code>all</code> - Both requests and responses


'''Important: Monitoring SIPS/SRTP Calls'''
{{Warning|1=Enabling SIP history significantly increases database load and storage.}}
When using IPFIX to monitor call quality for encrypted SIP (SIPS) and RTP (SRTP) traffic, ensure the TLS port is included in the <code>sipport</code> configuration. For example:


<pre>
# Include both UDP and TLS SIP ports
sipport = 5060,5061
</pre>


This allows VoIPmonitor to properly associate IPFIX QoS data with SIPS endpoints.


'''Data written to CDR:'''
=== GUI Filters for SIP Response Searching ===
* a_saddr / b_saddr: RTP source IPs
* a_received / b_received: Total RTP packets
* a_lost / b_lost: Lost RTP packets
* a_mos_f2_mult10 / b_mos_f2_mult10: MOS values (multiplied by 10)


== SIPREC Support ==
There are two distinct SIP response filters in the CDR view. Understanding their differences prevents confusion:


SIPREC enables VoIPmonitor to act as a recording server for SIP proxies like OpenSIPS.
{| class="wikitable"
! Filter !! What it searches !! Accepts !! Requires Configuration
|-
| '''Last SIP Response Code''' || Final response code in <code>cdr.lastSIPresponse</code> || Numeric codes (<code>404</code>, <code>503</code>), wildcards (<code>4%</code>, <code>5%</code>), '''and text''' (<code>%OK</code>, <code>%Busy%</code>) || '''None''' - always available
|-
| '''SIP responses''' || Full text of ALL SIP responses during the call || Full text search, any string || <code>save_sip_history = responses</code> or <code>save_sip_responses = yes</code>
|}


;<code>siprec_bind = 0.0.0.0</code>
'''Key differences:'''
:IP address to bind SIPREC server. Required to enable SIPREC.


;<code>siprec_bind_port = 5099</code>
* '''Last SIP Response Code''' searches only the '''final''' response. Examples:
:Port to listen for SIPREC connections. Required to enable SIPREC.
** <code>200</code> - exact numeric match
** <code>4%</code> - all 4xx errors
** <code>%OK</code> - responses ending with "OK"
** <code>%Busy%</code> - responses containing "Busy"


;<code>siprec_rtp_min = 10000</code>
* '''SIP responses''' searches '''all''' SIP responses (180 Ringing, 183, provisional, etc.). Use for:
:(Default: 10000) Lower bound of RTP port range.
** Intermediate responses (e.g., 491 Request Pending mid-dialog)
** Custom SBC error messages
** Any response text, not just the final one


;<code>siprec_rtp_max = 20000</code>
'''Example:''' A call completes with 200 OK but had a 503 from one provider during serial forking. "Last SIP Response Code = 503" won't find it, but "SIP responses = %503%" will.
:(Default: 20000) Upper bound of RTP port range.


;<code>siprec_rtp_stream_timeout_s = 300</code>
=== save_sip_history vs save_sip_responses ===
:(Default: 300) RTP stream timeout in seconds.


;<code>siprec_rtp_streams_max_threads = 2</code>
These two parameters achieve the '''same result''' - storing SIP response text for the "SIP responses" filter. '''Do not enable both simultaneously''':
:(Default: 2) Maximum RTP reception threads.


;<code>siprec_rtp_streams_max_per_thread = 100</code>
{| class="wikitable"
:(Default: 100) Maximum streams per thread.
! Parameter !! Notes
|-
| <code>save_sip_history = responses</code> || Part of the multi-value <code>save_sip_history</code> option. Can combine with <code>requests</code> or use <code>all</code>.
|-
| <code>save_sip_responses = yes</code> || Standalone parameter for same functionality. Simpler if you only need response text.
|}
== RTP Processing ==


== HEP Support ==
{| class="wikitable"
! Parameter !! Default !! Description
|-
| <code>jitterbuffer_f1</code> || yes || 50ms fixed jitterbuffer simulation
|-
| <code>jitterbuffer_f2</code> || yes || 200ms fixed jitterbuffer simulation
|-
| <code>jitterbuffer_adapt</code> || yes || Adaptive jitterbuffer (up to 500ms)
|-
| <code>allow-zerossrc</code> || no || Accept RTP with zero SSRC (some legacy gateways)
|}


HEP (Homer Encapsulation Protocol) allows receiving SIP traffic mirrored from Kamailio, OpenSIPS, Asterisk, and other SIP proxies.
'''CPU optimization (saves ~30%):'''
<syntaxhighlight lang="ini">
mosf1 = no
mos_adapt = no
mosf2 = yes  # Keep only f2 for stable MOS metric
</syntaxhighlight>


;<code>receiver_mode = yes</code>
== Audio Analysis ==
:(Default: no) Required to enable the HEP receiver. This directive must be set to <code>yes</code> in the <code>[general]</code> section before the HEP collector will bind to the configured port and accept HEP packets. Without <code>receiver_mode = yes</code>, the sensor will not listen on <code>hep_bind_port</code> even if <code>hep = yes</code> is set. After enabling, verify the port is listening with <code>netstat -an | grep hep_bind_port</code>.


;<code>hep = yes</code>
{| class="wikitable"
:(Default: no) Enable HEP collector.
! Parameter !! Default !! Description
|-
| <code>dtmf2db</code> || no || Store DTMF to database
|-
| <code>inbanddtmf</code> || no || In-band DTMF detection (G711 only, CPU intensive)
|-
| <code>silencedetect</code> || no || Silence detection (G711 only, CPU intensive)
|-
| <code>clippingdetect</code> || no || Audio clipping detection
|}


;<code>hep_bind_ip = 0.0.0.0</code>
See [[Silence_detection]] for detailed documentation.
:(Default: 0.0.0.0) Address to bind HEP UDP collector.


;<code>hep_bind_port = 9060</code>
== NAT Handling ==
:UDP port to listen for HEP packets.


;<code>hep_kamailio_protocol_id_fix = yes</code>
<syntaxhighlight lang="ini">
:(Default: yes) Workaround for Kamailio protocol ID issues. Enable this when receiving HEP from Kamailio.
natalias = 1.1.1.1 10.0.0.3  # Public to private IP mapping
sdp_reverse_ipport = no  # Reverse sniffing for NAT (use with caution)
</syntaxhighlight>


== Whisper Transcription ==
= Protocol Support =


VoIPmonitor supports audio transcription using OpenAI's Whisper model.
== SIP REGISTER/OPTIONS/SUBSCRIBE ==


;<code>audio_transcribe = yes</code>
{| class="wikitable"
:(Default: no) Enable audio transcription.
! Parameter !! Default !! Description
|-
| <code>sip-register</code> || no || Process REGISTER messages (<code>yes</code>, <code>nodb</code>, <code>no</code>)
|-
| <code>sip-options</code> || no || Process OPTIONS messages
|-
| <code>sip-subscribe</code> || no || Process SUBSCRIBE messages
|-
| <code>sip-message</code> || yes || Process MESSAGE requests
|}


;<code>whisper_rest_api_url = http://localhost:9000/asr?output=json&encode=true</code>
See [[Register]] for detailed REGISTER documentation.
:URL for Whisper REST API. If set, overrides native and python methods.


;<code>whisper_rest_api_mode = stereo</code>
== Other Protocols ==
:(Default: stereo) REST API mode: 'stereo' (one stereo WAV) or 'split' (two mono WAVs).


;<code>whisper_native = no</code>
{| class="wikitable"
:(Default: no) Use native whisper.cpp library.
! Parameter !! Default !! Description
|-
| <code>skinny</code> || no || Cisco Skinny/SCCP protocol
|-
| <code>mgcp</code> || no || MGCP protocol
|-
| <code>ss7</code> || no || SS7-over-IP (SIGTRAN)
|-
| <code>diameter</code> || no || Diameter protocol
|-
| <code>ipv6</code> || no || IPv6 support (requires IPv6 database columns)
|}


;<code>whisper_model = /path/to/ggml-base.en.bin</code>
= Advanced Protocol Support =
:Path to Whisper model file.


;<code>whisper_language = auto</code>
== IPFIX Support ==
:(Default: auto) Language for transcription. 'auto' for automatic detection.


;<code>whisper_timeout = 60</code>
IPFIX (IP Flow Information Export) is used with Oracle/ACME SBCs to receive call data.
:(Default: 0) Timeout for python script execution.


;<code>whisper_deterministic_mode = no</code>
'''IMPORTANT - PCAP Availability:''' IPFIX data is internally converted to packet format for processing. This means PCAP files CAN be downloaded from the GUI for IPFIX-sourced calls (SIP signaling is reconstructed). However, RTP streams are NOT included in the PCAP - only QoS metrics from the IPFIX data are available, not actual audio packets.
:(Default: no) Enable deterministic mode.


;<code>whisper_python = /usr/bin/python3</code>
<syntaxhighlight lang="ini">
:(Default: python3) Path to Python interpreter.
ipfix = yes
ipfix_bind_port = 12345
ipfix_qos_fill_rtp_streams = yes
# Include TLS port for SIPS/SRTP:
sipport = 5060,5061
</syntaxhighlight>


;<code>whisper_threads = 4</code>
{| class="wikitable"
:(Default: 0, auto) Number of Whisper processing threads.
! Parameter !! Default !! Description
|-
| <code>ipfix</code> || no || Enable IPFIX receiver (Oracle/ACME SBC)
|-
| <code>ipfix_bind_ip</code> || 0.0.0.0 || Bind IP address for IPFIX listener
|-
| <code>ipfix_bind_port</code> || 4739 || UDP port for IPFIX data
|-
| <code>ipfix_qos_fill_rtp_streams</code> || no || Populate RTP stream statistics from IPFIX QoS data
|}


;<code>whisper_native_lib = /usr/local/lib/libwhisper.so</code>
== SIPREC Support ==
:Path to native Whisper library.


;<code>audio_transcribe_threads = 2</code>
<syntaxhighlight lang="ini">
:(Default: 2) Number of transcription processing threads.
siprec_bind = 0.0.0.0
siprec_bind_port = 5099
siprec_rtp_min = 10000
siprec_rtp_max = 20000
</syntaxhighlight>


;<code>audio_transcribe_queue_length_max = 1000</code>
== HEP Support ==
:(Default: 1000) Maximum transcription queue length.


;<code>audio_transcribe_parallel_channel_processing = yes</code>
<syntaxhighlight lang="ini">
:(Default: yes) Process audio channels in parallel.
receiver_mode = yes # Required!
hep = yes
hep_bind_port = 9060
hep_kamailio_protocol_id_fix = yes  # For Kamailio sources
</syntaxhighlight>


== Kamailio Mirroring ==
== Kamailio Mirroring ==


Configuration for receiving SIP traffic mirrored from Kamailio's siptrace module.
;<code>receiver_mode = yes</code>
:(Default: no) Enables the receiver mode for receiving mirrored traffic. When using Kamailio mirroring or the HEP collector, this directive must be set to <code>yes</code> in the <code>[general]</code> section. Without this setting, the sensor will not bind to the configured receiver port and will not receive traffic, regardless of other configuration settings. Always verify the service is listening on the expected port after enabling this option using <code>netstat -an | grep 5888</code> or <code>ss -ulpn | grep voipmonitor</code>.
'''Kamailio configuration:'''
<syntaxhighlight lang="ini">
<syntaxhighlight lang="ini">
loadmodule "siptrace.so"
receiver_mode = yes  # Required!
modparam("siptrace", "trace_on", 1)
kamailio_port = 5888
modparam("siptrace", "duplicate_uri", "sip:10.0.0.1:5888")
modparam("siptrace", "trace_to_database", 0)
modparam("siptrace", "trace_mode", 4)
modparam("siptrace", "xheaders_write", 1)
</syntaxhighlight>
</syntaxhighlight>
;<code>kamailio_port = 5888</code>
:Port to receive Kamailio mirrored traffic.
;<code>kamailio_dstip = 10.0.0.1</code>
:VoIPmonitor host IP address.
;<code>kamailio_srcip = 10.0.0.2</code>
:Kamailio server IP address (optional).
;<code>kamailio = no</code>
:(Default: no) Enable Kamailio-style substitution on sniffed traffic.
;<code>hep_kamailio_protocol_id_fix = yes</code>
:(Default: yes) Workaround for Kamailio protocol ID issues.


== Ribbon SBC Mirroring ==
== Ribbon SBC Mirroring ==


Support for Ribbon SBC monitoring profiles.
<syntaxhighlight lang="ini">
ribbonsbc = yes
ribbonsbc_bind_ip = 0.0.0.0
ribbonsbc_bind_port = 9514
</syntaxhighlight>


=== Passive Sniffing (Mode 1) ===
== Whisper Transcription ==
;<code>ribbonsbc = yes</code>
:(Default: no) Enable Ribbon-style IP:port substitution on sniffed traffic.


;<code>ribbonsbc_port = 9514</code>
<syntaxhighlight lang="ini">
:Expected mirror port in packets (legacy filter).
audio_transcribe = yes
whisper_native = no
whisper_model = /path/to/ggml-base.bin
whisper_language = auto
</syntaxhighlight>


;<code>ribbonsbc_dstip = 10.0.0.1</code>
See [[Whisper]] for detailed transcription documentation.
:VoIPmonitor host IP (legacy filter).
{{Note|1='''Oracle/ACME SBC''' and '''Ribbon SBC''' are products from '''different vendors''' with different integration methods:
* '''Oracle SBC''' (formerly Acme Packet, acquired by Oracle in 2013) → uses '''IPFIX''' protocol
* '''Ribbon SBC''' (formed from GENBAND + Sonus Networks merger in 2017) → uses '''Monitoring Profile''' with proprietary <code>ribbonsbc</code> protocol
Do not confuse these - they require different VoIPmonitor configuration.}}
= Expert & Debugging Options =


;<code>ribbonsbc_srcip = 10.0.0.2</code>
{{Warning|1=Only change these if instructed by support or you are an expert.}}
:Ribbon SBC IP (legacy filter).


=== Active Listener (Mode 2) ===
{| class="wikitable"
;<code>ribbonsbc_bind_ip = 0.0.0.0</code>
! Parameter !! Default !! Description
:Listen address for active mode.
|-
| <code>callslimit</code> || 0 || Max concurrent calls (0=unlimited)
|-
| <code>skipdefault</code> || no || Ignore all calls unless capture rules match
|-
| <code>openfile_max</code> || 65535 || Maximum open files
|-
| <code>coredump_filter</code> || 0x7F || Memory segments in coredump
|}


;<code>ribbonsbc_bind_port = 9514</code>
== Traffic Dumper ==
:Listen port for active mode.


;<code>ribbonsbc_bind_udp = no</code>
<syntaxhighlight lang="ini">
:(Default: no) Enable UDP support. TCP recommended.
traffic_dumper_path = /var/spool/voipmonitor/traffic
 
traffic_dumper_filter_ip = 192.168.1.100, 10.0.0.0/8
;<code>ribbonsbc_size_header = yes</code>
traffic_dumper_filter_port = 5060, 5061, 10000-20000
:(Default: yes) Expect 2-byte size header before each frame.
</syntaxhighlight>
 
;<code>ribbonsbc_strict_check = no</code>
:(Default: no) Only process frames complete per size header.
 
;<code>ribbonsbc_counter_log = no</code>
:(Default: no) Log counts of incoming Ribbon frames.
 
== Traffic Dumper ==


Save captured traffic to PCAP files with optional filtering.
== DEPRECATED DO NOT USE ==


;<code>traffic_dumper_path = /var/spool/voipmonitor/traffic</code>
<!-- This is a placeholder for correct deprecated options section -->
:Path where pcap files will be saved. Setting this enables the traffic dumper.


;<code>traffic_dumper_by_interface = no</code>
:(Default: no) Create separate files per interface (yes) or per DLT type (no).


;<code>traffic_dumper_force_flush = no</code>
:(Default: no) Force flush after each packet. Impacts performance.


;<code>traffic_dumper_filter_ip = 192.168.1.100, 10.0.0.0/8</code>
:Filter by IP addresses or networks.


;<code>traffic_dumper_filter_port = 5060, 5061, 10000-20000</code>
:Filter by ports or port ranges.


== Expert & Debugging Options ==
'''Warning:''' These options should only be changed if you are an expert or instructed to do so by the support team.


;<code>database_backup_from_date = 2023-01-01</code>
:A family of options that puts the sniffer into a special database backup/migration mode, copying data from another database.
;<code>coredump_filter = 0x7F</code>
:(Default: 0x7F) Controls what memory segments are included in a coredump file if the application crashes.
;<code>abort_if_heap_full = no</code>
:A set of options that control whether the sniffer should intentionally crash under certain high-load error conditions to generate a coredump for debugging.
;<code>interrupts_counters = yes</code>
:(Default: yes) Enable interrupt statistics. Disable on Virtuozzo containers.
;<code>callslimit = 0</code>
:(Default: 0, unlimited) Maximum concurrent calls to process.
;<code>skipdefault = yes</code>
:(Default: no) Ignore all SIP calls unless capture rules are set.
;<code>openfile_max = 65535</code>
:(Default: 65535) Maximum open files.
;<code>convertchar = :</code>
:Replace characters with underscores in filenames.
;<code>fbasenameheader = X-custom-filename</code>
:Name pcap files based on custom SIP header.
;<code>pcapcommand = echo %pcap% >> /tmp/list</code>
:Command to run after pcap is closed. Warning: Resource intensive.
;<code>filtercommand = myscript '%callid%' '%dirname%'</code>
:Command for calls matching capture rules.
;<code>printinsertid = no</code>
:(Default: no) Print CDRID to stdout on every insert.


=== DPDK Configuration ===
= AI Summary for RAG =
;<code>dpdk_timer_reset_interval = 60</code>
:(Default: 60) Reset interval in seconds.
;<code>dpdk_nb_rxq = 2</code>
:(Default: 2) Number of receive queues. Increase for higher traffic.
;<code>dpdk_rxq_per_thread = no</code>
:(Default: no) Process RX queues with separate threads.
;<code>dpdk_ignore_ierrors = no</code>
:(Default: no) Ignore ierrors (packets with bad checksums).


== AI Summary for RAG ==
'''Summary:''' Comprehensive reference for <code>voipmonitor.conf</code> covering: sensor identification, database configuration (MySQL settings, partitioning, <code>mysqlloadconfig</code> for GUI vs file priority), network interface settings (BPF filters, deduplication with <code>auto_enable_use_blocks</code>), tunneling protocols (VXLAN, TZSP, HEP, AudioCodes), TLS/SRTP decryption, distributed client/server architecture (<code>packetbuffer_sender</code>), storage management (TAR archives, spool cleaning), call processing (timeouts, merging, recording control), SIP history storage, audio analysis, and protocol support (IPFIX, SIPREC, HEP, Kamailio, Ribbon SBC, Whisper). Deprecated options in v2025.09.1+ include <code>vxlan</code>, <code>packet_buffer_total_size</code>, <code>udp_reassembly</code>, <code>sipdefrag</code>.
'''Summary:''' This document is a comprehensive reference guide for the `voipmonitor.conf` sniffer configuration file. It covers General Settings (sensor ID, timezone, watchdog), Database Connection and Performance (MySQL settings, partitioning, queue tuning, cleaning, SSL/TLS, and <code>mysqlloadconfig=yes</code> for loading configuration from database including the critical manager_key from the system table; setting <code>mysqlloadconfig=no</code> prevents loading the manager_key and causes "failed read rsa key" startup errors), Network Interface and Sniffing (interface selection, BPF filters, tunneling protocols including TZSP, L2TP, VXLAN, AudioCodes, IPFIX, HEP, and '''packet deduplication''' and '''RTP association''' with options like `deduplicate`, `auto_enable_use_blocks`, and `deduplicate_ipheader`), Shared Server Optimization (voice breakage and call lag when sniffer shares PBX server, solutions: specify specific interfaces instead of `any`, disable `interfaces_optimize=no`, reduce load with `savertp=header` and `saveaudio=no`), SIP TLS/SSL Decryption (ssl, ssl_ipport, keylogger support), SRTP Configuration (srtp_rtp, ssl_dtls_boost), Caller/Called Identity (remoteparty, passertedidentity, destination_number_mode), Performance and Threading (NUMA, scheduling, buffer configuration), Distributed Architectures (client/server model and legacy mirroring including `mirror_bind_sensor_id_by_sender` for distinguishing sending probes), Storage Management (spooldir, TAR files, pcap saving, compression, and cleaning rules), Call Processing (timeouts, RTP tracking, NAT handling, custom headers, '''call recording control for privacy and opt-out scenarios including <code>pauserecordingdtmf</code> to pause recordings via DTMF sequences during calls, <code>norecord-dtmf</code> to delete recordings, <code>norecord-header</code> for SIP header-based recording suppression, and <code>pauserecordingheader</code> for pause/unpause via SIP headers''' ), '''Audio and Video Packet Saving''' (<code>savertp</code> for audio RTP payload, <code>savertp_video</code> for video RTP streams such as VP8, VP9, and H.264, <code>savertcp</code> for RTCP, <code>saveaudio</code> for audio file extraction, <code>savegraph</code> for call graphs), SIP Method Processing (REGISTER, OPTIONS, SUBSCRIBE, NOTIFY, MESSAGE, and `save_sip_history` for storing ALL SIP requests including PUBLISH, INFO, UPDATE, PRACK, REFER to enable GUI filtering), Audio Analysis (DTMF, silence detection, energy levels, MOS scoring), Protocol Support (SIP, Skinny, MGCP, SS7, Diameter), IPFIX Support, SIPREC Support, Whisper Transcription, Kamailio Mirroring, Ribbon SBC Mirroring, and Traffic Dumper.


'''Keywords:''' voipmonitor.conf, configuration, sniffer config, sensor, database, mysql, mariadb, cdr_partition, cleandatabase, interface, sniffing, promisc, bpf, filter, tunneling, DPDK, performance, threading, client/server, distributed, remote sensor, spooldir, storage, pcap, tar, maxpoolsize, saveaudio, SIP, RTP, SRTP, DTLS, ssl_dtls_boost, skinny, MGCP, SS7, diameter, NAT, natalias, call recording, watchdog, sched_pol_auto, deduplicate, auto_enable_use_blocks, deduplicate_ipheader, ip_only, packet deduplication, duplicate packets, rtp association, wrong call leg, different nic, different vlan, multiple interface, ssl, ssl_ipport, TLS decryption, IPFIX, SIPREC, whisper, transcription, Kamailio, Ribbon SBC, traffic dumper, energy levels, DTMF detection, silence detection, MOS scoring, call merging, callidmerge_header, rtp_check_both_sides_by_sdp, cdr_summary, cdr_summary_interval, cleandatabase_cdr_summary, aggregation, dashboard performance, custom_headers, custom SIP headers, Referred-By, Diversion, CDR custom headers, capture SIP headers, SIP header filtering, shared server, PBX, resource contention, voice breakage, call lag, interfaces_optimize, dedicated threads, specific interfaces, ethtool, RTP engine, save_sip_history, SIP requests filter, PUBLISH, INFO, UPDATE, PRACK, REFER, non-call SIP methods, GUI SIP requests, mysqlloadconfig, manager_key, failed read rsa key, sensor_conf table, system table, pauserecordingdtmf, norecord-dtmf, norecord-header, pauserecordingheader, privacy, opt-out, call recording control, pause recording, stop recording, DTMF control, SIP header control, video, video RTP, video codec, VP8, VP9, H.264, H264, WebRTC video, savertp_video, video capture, recording video, video packet saving
'''Keywords:''' voipmonitor.conf, sniffer configuration, id_sensor, mysqlloadconfig, manager_key, deduplicate, auto_enable_use_blocks, packetbuffer_sender, savertp, TLS decryption, SRTP, ssl_dtls_boost, distributed architecture, client-server, maxpoolsize, cleandatabase, custom_headers, save_sip_history, t2_boost, threading, scanpcapdir, deprecated options, IPFIX, SIPREC, HEP, Kamailio, Ribbon SBC, Whisper, pauserecordingdtmf


'''Key Questions:'''
'''Key Questions:'''
* What does mysqlloadconfig=no do in voipmonitor.conf?
* What are the most important settings in voipmonitor.conf?
* Why does the sniffer fail to start with "failed read rsa key" error?
* How do I configure the database connection?
* How does mysqlloadconfig affect loading of the manager_key from the database?
* Why does the sniffer fail with "failed read rsa key"?
* What are the most important settings in voipmonitor.conf for a new installation?
* How do I set up distributed client/server architecture?
* How do I configure the database connection for the sniffer?
* What is the difference between packetbuffer_sender = yes and no?
* How do I fix voice breakage and call lag when the VoIPmonitor sniffer runs on the same server as the PBX?
* How do I enable packet deduplication?
* What happens when I use interface = any versus specific interface names?
* How do I decrypt TLS/SRTP traffic?
* How does interfaces_optimize affect performance on shared servers?
* How do I disable audio recording while keeping RTP analysis?
* What should I do if moving the VoIPmonitor sensor to a separate server is not possible?
* How do I capture custom SIP headers?
* How does specifying multiple interfaces create dedicated threads?
* How do I configure IPFIX/SIPREC/HEP receivers?
* How do I set up a distributed client/server architecture?
* Which options were deprecated in v2025.09.1?
* What is the difference between `packetbuffer_sender = yes` and `no`?
* How do I fix CPU bottlenecks with t2_boost?
* How do I tune the database for high performance?
* How do I process PCAP files with scanpcapdir?
* How do I configure the sniffer to listen on multiple SIP ports?
* What are the `maxpoolsize` and `cleandatabase` options and how do they work?
* How do I enable SRTP decryption and what is ssl_dtls_boost?
* How do I configure VoIPmonitor to handle tunneled traffic from a Mikrotik router or AWS?
* How do I pause call recording during a call using DTMF sequences for opt-out scenarios?
* How do I configure pauserecordingdtmf to allow callers to pause recording by pressing a DTMF sequence?
* What is pauserecordingdtmf_timeout and how does it affect DTMF sequence recognition?
* How do I delete a recording entirely if a DTMF sequence is detected using norecord-dtmf?
* How do I suppress recording based on SIP headers using norecord-header?
* What is the difference between pauserecordingdtmf and norecord-dtmf?
* How do I enable packet deduplication for multiple sensors or interfaces?
* How do I save audio files to a single folder using saveaudio_singlefolder?
* Why are RTP packets not associated with the correct call legs when SIP and RTP are on different NICs or VLANs?
* What is `auto_enable_use_blocks` and why is it required for deduplication?
* What is the difference between `deduplicate_ipheader = yes`, `ip_only`, and `no`?
* How do I configure deduplication when packets arrive from different network paths with different TTL values?
* How do I decrypt TLS-encrypted SIP traffic?
* How do I capture and filter SIP PUBLISH, INFO, UPDATE, or other non-call SIP methods in the GUI?
* What is `save_sip_history = requests` and when should I use it?
* How do I make SIP PUBLISH packets searchable in the GUI "SIP requests" filter?
* How do I configure IPFIX to receive RTP QoS from Oracle SBC?
* How do I set up SIPREC recording?
* How do I enable Whisper audio transcription?
* How do I configure Kamailio siptrace mirroring?
* How do I set up Ribbon SBC monitoring profile mirroring?
* How do I use the traffic dumper to capture specific traffic?
* How do I enable CDR summary for faster dashboard queries?
* What is cdr_summary_interval and how does it affect aggregation?
* What is rtp_check_both_sides_by_sdp and when should I use it?
* How do I configure energy level detection for audio analysis?
* How do I configure VoIPmonitor to capture and save video RTP packets from WebRTC calls using VP8, VP9, or H.264 codecs?
* What is savertp_video and how does it differ from savertp?
* How do I enable video RTP packet saving in VoIPmonitor?
* Why are video RTP streams not being saved or captured in my PCAP files?
* How do I capture custom SIP headers like Referred-By or Diversion in the CDR?
* What is the custom_headers directive and how do I use it?
* How do I configure custom SIP headers for filtering and reporting in the CDR?
* How do I enable DTMF, silence, or clipping detection?

Latest revision as of 01:35, 11 January 2026


Comprehensive reference for `/etc/voipmonitor.conf` parameters. Additional configuration snippets can be placed in `/etc/voipmonitor/conf.d/` (without `[general]` header).

Related documentation:

General & Core Settings

Sensor Identification & Time

Parameter Default Description
id_sensor unset Unique numeric identifier (1-65535). Essential for multi-sensor deployments.
utc no Store timestamps in UTC. Recommended for multi-timezone deployments.
timezone system Override system timezone with zoneinfo path (e.g., /usr/share/zoneinfo/UTC).

Process Management

Parameter Default Description
watchdog no Auto-restart sensor on crash.
watchdog_run_command unset Custom restart command (e.g., systemctl restart voipmonitor).

Deprecated Options (v2025.09.1+)

⚠️ Warning: The following options are unsupported and ignored in sniffer version 2025.09.1+. Remove them from your configuration.

Deprecated Option Modern Replacement
vxlan, vxlan_port, vxlan_skipcrc udp_port_vxlan = 4789
packet_buffer_total_size max_buffer_mem (auto-managed)
udp_reassembly, udp_reassembly_max_size udpfrag = yes
sipdefrag, sipdefrag_maxpacket, defragment_* Auto-managed; use max_sip_packets_in_call
max_sip_size, interface_snaplen snaplen = 3200
sanity_checks, check_sip_header, ignore_sip_parsing_errors Built-in (cannot be disabled)

💡 Tip: After removing deprecated options, check logs for warnings: journalctl -u voipmonitor -f

Database Configuration

Connection Settings

Parameter Default Description
mysqlhost localhost MySQL/MariaDB server address
mysqlsocket unset Socket path for local connections (faster than TCP)
mysqlport 3306 TCP port
mysqlusername root Database username
mysqlpassword empty Database password
mysqldb voipmonitor Database name (auto-created if missing)
mysql_reconnect no Auto-reconnect on connection loss

SSL/TLS for Database

mysqlsslkey = /etc/ssl/client-key.pem
mysqlsslcert = /etc/ssl/client-cert.pem
mysqlsslcacert = /etc/ssl/ca-cert.pem

Performance & Schema

Parameter Default Description
query_cache yes Critical: Queue SQL to disk (qoq* files) to prevent data loss during DB outages.
quick_save_cdr no CDR visibility delay: no=10s, yes=3s, quick=1s. Higher values increase load.
cdr_partition yes Essential: Daily table partitioning for performance.
cdr_partition_by_hours no Hourly partitions for extreme traffic (≥15k CPS).
disable_partition_operations no Disable auto partition management (for centralized DB).
mysql_enable_set_id no Central server generates CDR IDs (high-traffic client/server).

Configuration Priority: File vs GUI

mysqlloadconfig = yes
(Default: yes) Load settings from database (sensor_config table). GUI settings take priority over file settings.

⚠️ Warning: Setting mysqlloadconfig = no prevents loading the manager_key from the database, causing "failed read rsa key" startup errors in distributed deployments.

Diagnosing conflicts: 

systemctl restart voipmonitor
grep 'Configuration valu' /var/log/syslog | grep ' / '

Resolution options:

  • Option 1: Update settings via GUI (recommended)
  • Option 2: Set mysqlloadconfig = no for file-only management
  • Option 3: Delete specific entries from sensor_config table

SQL Queue Tuning

Parameter Default Description
mysqlstore_concat_limit 400 SQL statements per batch
mysqlstore_max_threads_cdr 2 Max parallel CDR write threads

Database Cleaning

See Data_Cleaning for detailed documentation.

Parameter Default Description
cleandatabase 0 Master retention period in days (0=disabled)
cleandatabase_cdr 0 CDR/message table retention
cleandatabase_rtp_stat 2 RTP statistics retention
partition_operations_enable_fromto 1-5 Partition drop time window (e.g., 1-5 AM)

CDR Summary (Aggregation)

Pre-aggregates call data for faster dashboard queries. 

cdr_summary = yes
cdr_summary_interval = 5  # minutes

Network Interface & Sniffing

Interface Selection

Parameter Default Description
interface eth0 Interface(s) to capture. Comma-separated for multiple. any = all (no promisc).
promisc yes Promiscuous mode (doesn't work with any).
interfaces_optimize yes Auto-tune NIC settings via ethtool.
snaplen 3200 Packet capture length. Increase for large SIP packets.

BPF Filtering

filter
BPF filter (tcpdump syntax). Warning: Can accidentally exclude important traffic.
# Example: Exclude specific subnets
filter = not net 192.168.0.0/16 and not net 10.0.0.0/8
interface_ip_filter
CPU-efficient IP allow-list (no negation). Multiple lines supported.
interface_ip_filter = 192.168.0.0/24
interface_ip_filter = 10.0.0.0/8

Shared Server Optimization

When the sniffer runs on the same server as the PBX, resource contention can cause voice breakage.

Symptoms: Audio jitter, packet loss, call lag that resolves when sniffer is stopped.

Solutions: 

# Solution 1: Specify interfaces (creates dedicated threads)
interface = ens192,ens224  # NOT 'any'

# Solution 2: Disable NIC optimization
interfaces_optimize = no

# Solution 3: Reduce sniffer load
savertp = header
saveaudio = no

Long-term: Move sensor to dedicated server with SPAN/Mirror. See Sniffer_distributed_architecture.

Packet Deduplication

Required when receiving same packets from multiple sources/interfaces. 

deduplicate = yes
auto_enable_use_blocks = yes  # Required for deduplication
deduplicate_ipheader = ip_only  # Recommended for different network paths
Parameter Default Description
deduplicate no Enable checksum-based deduplication (CPU intensive)
auto_enable_use_blocks no Required for deduplication and correct RTP association across interfaces/VLANs
deduplicate_ipheader yes ip_only recommended when packets have different TTL

Tunneling Protocol Support

Parameter Default Description
udp_port_tzsp 37008 Mikrotik TZSP
udp_port_l2tp 1701 L2TP tunneling
udp_port_vxlan 4789 VXLAN (AWS/cloud)
audiocodes no AudioCodes proprietary tunnel. See Audiocodes_tunneling.
ipfix no Oracle/ACME SBC IPFIX
hep no Homer Encapsulation Protocol

Scan PCAP Directory Mode

Process PCAP files instead of live capture. Useful for Windows hosts without SPAN ports. 

scanpcapdir = /var/spool/voipmonitor/scanpcap
scanpcapmethod = newfile

Workflow:

  1. Capture on source: tcpdump -i eth0 udp -G 300 -w /path/dump.pcap
  2. Transfer to VoIPmonitor server
  3. Sensor processes files automatically

SIP Configuration

Port Settings

Parameter Default Description
sipport 5060 SIP ports. Multiple: 5060,5061,5070-5080
cdr_sipport yes Store SIP ports in database
cdr_country_code yes Country code lookup for caller/called. Set no to disable country flags.

TCP Reassembly & UDP Fragmentation

Parameter Default Description
sip_tcp_reassembly_ext yes TCP reassembly for SIP over TCP
udpfrag yes Critical: IP fragment reassembly for large SIP messages
max_sip_packets_in_call 2000 Maximum SIP packets per call

TLS/SSL & SRTP Decryption

SIP TLS Decryption

ssl = yes
ssl_ipport = 10.0.0.1:5061 /path/to/your.key
# Subnet with multiple keys:
ssl_ipport = 10.0.0.0/24:5061 /path/key1.pem,/path/key2.pem

Keylogger support (for PFS/TLS 1.3): 

ssl_sessionkey_udp = yes
ssl_sessionkey_udp_port = 1234

See Tls for complete TLS decryption documentation.

SRTP Configuration

Parameter Default Description
srtp_rtp no Decrypt and store RTP data in PCAPs
srtp_rtcp yes Decrypt RTCP streams
srtp_rtp_dtls yes DTLS decryption (requires keylogger)
ssl_dtls_boost no Meta-parameter enabling aggressive DTLS decryption options

Caller/Called Identity

Parameter Default Description
remoteparty_caller unset Update caller from Remote-Party-ID (calling/called)
passertedidentity no Use P-Asserted-Identity for caller
destination_number_mode 1 Source for called number: 1=To header, 2=INVITE URI
sipoverlap yes Update destination from subsequent INVITEs (overlap dialing)

Performance & Threading

Core Threading

Parameter Default Description
t2_boost unset Set to high_traffic for ≥1500Mbit. Fixes CPU bottlenecks where single defrag thread runs at 100%.
threading_expanded yes Modern multi-threaded engine. Set high_traffic for >5 Gbit/s.
preprocess_rtp_threads 2 Initial RTP preprocessing threads (auto-scales)
rtpthreads CPU count RTP processing threads

Buffer Configuration

Parameter Default Description
ringbuffer 50 Ringbuffer size MB. ≥500 recommended for >100 Mbit. Max 2000.
max_buffer_mem 2000 Max buffer memory MB. Increase to 10000+ for high concurrent calls.
packetbuffer_compress no Enable in distributed setups to reduce bandwidth.

Thread Priority

sched_pol_auto = prio -20  # Auto-elevate critical threads under load
sched_pol_auto_cpu_limit = 45  # CPU threshold for elevation

Distributed Operation

See Sniffer_distributed_architecture for complete documentation.

Client/Server Configuration

Central Server: 

server_bind = 0.0.0.0
server_bind_port = 60024
server_password = yourpassword
# CRITICAL: Exclude server port from sipport!
sipport = 1-60023,60025-65535

Remote Sensor: 

id_sensor = 2
server_destination = 10.0.0.1
server_destination_port = 60024
server_password = yourpassword
packetbuffer_sender = no  # or yes for packet mirroring

⚠️ Warning: When packetbuffer_sender = yes, all packets including RTP are transmitted regardless of savertp setting.

Storage & File Management

Spool Directory

Parameter Default Description
spooldir /var/spool/voipmonitor Primary storage directory
spooldir_2 unset Secondary storage for capture rules with "Store to second spooldir"
cachedir unset Temp storage (use RAM/SSD for performance)

ℹ️ Note: For GUI access to spooldir_2, configure "Sniffer second datapath" in GUI Settings > System Configuration > Basic.

TAR Storage Strategy

tar = yes  # Group PCAPs into minute-based archives (reduces I/O)
tar_compress_sip = zstd
tar_compress_graph = zstd

Saving Options

Parameter Default Description
savesip yes Save SIP packets
savertp yes yes=full, header=metadata only (no audio), no=disabled
savertp_video no Video RTP. Limitation: Only ONE video stream per call saved to PCAP.
saveudptl no T.38 fax packets
savegraph yes Call graph data

Disable audio recording: 

savertp = header  # NOT 'no' - keeps RTP analysis tool working
saveaudio = no

Spool Cleaning

Parameter Default Description
cleanspool yes Enable automatic spool cleaning
maxpoolsize 102400 Size limit in MB
maxpooldays unset Age limit in days
autocleanspoolminpercent 1 Emergency cleaning trigger (% free)

Audio File Generation

Parameter Default Description
saveaudio no Generate audio files: wav, ogg, mp3, or yes
saveaudio_singlefolder unset Dedicated directory for audio files
saveaudio_stereo yes Caller=left, called=right channel

Call Processing

Timeouts

Parameter Default Description
absolute_timeout 14400 Force-end calls longer than this (seconds). Sets cdr.bye = 102.
rtptimeout 300 Close call if no RTP/RTCP for this duration
sipwithoutrtptimeout 3600 Close SIP call without RTP
onewaytimeout 15 End call if no reply from other side

Call Merging

Parameter Default Description
matchheader unset SIP header to link call legs in GUI
callidmerge_header unset Header containing parent Call-ID for CDR merging
call_id_alternative unset Alternative identifiers (e.g., Session-ID,Join for CUCM)

See Merging_or_correlating_multiple_call_legs for detailed documentation.

Recording Control

Parameter Default Description
pauserecordingdtmf unset DTMF sequence to pause recording (e.g., *9)
pauserecordingdtmf_timeout 4 Timeout between DTMF digits (seconds)
norecord-dtmf no Delete recording if *0 is detected
norecord-header no Discard call if X-VoipMonitor-norecord header present

Custom Headers

custom_headers = Referred-By, Diversion, X-Custom-Header
custom_headers_last_value = yes
custom_headers_max_size = 1024

After adding headers, configure display in GUI: Settings > CDR Custom Headers.

SIP History

save_sip_history
(Default: no) Store SIP signaling for GUI filtering.
  • requests - All SIP methods (PUBLISH, INFO, UPDATE, PRACK, REFER) in "SIP requests" filter
  • responses - Full response text for searching (not just codes)
  • all - Both requests and responses

⚠️ Warning: Enabling SIP history significantly increases database load and storage.


GUI Filters for SIP Response Searching

There are two distinct SIP response filters in the CDR view. Understanding their differences prevents confusion:

Filter What it searches Accepts Requires Configuration
Last SIP Response Code Final response code in cdr.lastSIPresponse Numeric codes (404, 503), wildcards (4%, 5%), and text (%OK, %Busy%) None - always available
SIP responses Full text of ALL SIP responses during the call Full text search, any string save_sip_history = responses or save_sip_responses = yes

Key differences:

  • Last SIP Response Code searches only the final response. Examples:
    • 200 - exact numeric match
    • 4% - all 4xx errors
    • %OK - responses ending with "OK"
    • %Busy% - responses containing "Busy"
  • SIP responses searches all SIP responses (180 Ringing, 183, provisional, etc.). Use for:
    • Intermediate responses (e.g., 491 Request Pending mid-dialog)
    • Custom SBC error messages
    • Any response text, not just the final one

Example: A call completes with 200 OK but had a 503 from one provider during serial forking. "Last SIP Response Code = 503" won't find it, but "SIP responses = %503%" will.

save_sip_history vs save_sip_responses

These two parameters achieve the same result - storing SIP response text for the "SIP responses" filter. Do not enable both simultaneously:

Parameter Notes
save_sip_history = responses Part of the multi-value save_sip_history option. Can combine with requests or use all.
save_sip_responses = yes Standalone parameter for same functionality. Simpler if you only need response text.

RTP Processing

Parameter Default Description
jitterbuffer_f1 yes 50ms fixed jitterbuffer simulation
jitterbuffer_f2 yes 200ms fixed jitterbuffer simulation
jitterbuffer_adapt yes Adaptive jitterbuffer (up to 500ms)
allow-zerossrc no Accept RTP with zero SSRC (some legacy gateways)

CPU optimization (saves ~30%): 

mosf1 = no
mos_adapt = no
mosf2 = yes  # Keep only f2 for stable MOS metric

Audio Analysis

Parameter Default Description
dtmf2db no Store DTMF to database
inbanddtmf no In-band DTMF detection (G711 only, CPU intensive)
silencedetect no Silence detection (G711 only, CPU intensive)
clippingdetect no Audio clipping detection

See Silence_detection for detailed documentation.

NAT Handling

natalias = 1.1.1.1 10.0.0.3  # Public to private IP mapping
sdp_reverse_ipport = no  # Reverse sniffing for NAT (use with caution)

Protocol Support

SIP REGISTER/OPTIONS/SUBSCRIBE

Parameter Default Description
sip-register no Process REGISTER messages (yes, nodb, no)
sip-options no Process OPTIONS messages
sip-subscribe no Process SUBSCRIBE messages
sip-message yes Process MESSAGE requests

See Register for detailed REGISTER documentation.

Other Protocols

Parameter Default Description
skinny no Cisco Skinny/SCCP protocol
mgcp no MGCP protocol
ss7 no SS7-over-IP (SIGTRAN)
diameter no Diameter protocol
ipv6 no IPv6 support (requires IPv6 database columns)

Advanced Protocol Support

IPFIX Support

IPFIX (IP Flow Information Export) is used with Oracle/ACME SBCs to receive call data.

IMPORTANT - PCAP Availability: IPFIX data is internally converted to packet format for processing. This means PCAP files CAN be downloaded from the GUI for IPFIX-sourced calls (SIP signaling is reconstructed). However, RTP streams are NOT included in the PCAP - only QoS metrics from the IPFIX data are available, not actual audio packets. 

ipfix = yes
ipfix_bind_port = 12345
ipfix_qos_fill_rtp_streams = yes
# Include TLS port for SIPS/SRTP:
sipport = 5060,5061
Parameter Default Description
ipfix no Enable IPFIX receiver (Oracle/ACME SBC)
ipfix_bind_ip 0.0.0.0 Bind IP address for IPFIX listener
ipfix_bind_port 4739 UDP port for IPFIX data
ipfix_qos_fill_rtp_streams no Populate RTP stream statistics from IPFIX QoS data

SIPREC Support

siprec_bind = 0.0.0.0
siprec_bind_port = 5099
siprec_rtp_min = 10000
siprec_rtp_max = 20000

HEP Support

receiver_mode = yes  # Required!
hep = yes
hep_bind_port = 9060
hep_kamailio_protocol_id_fix = yes  # For Kamailio sources

Kamailio Mirroring

receiver_mode = yes  # Required!
kamailio_port = 5888

Ribbon SBC Mirroring

ribbonsbc = yes
ribbonsbc_bind_ip = 0.0.0.0
ribbonsbc_bind_port = 9514

Whisper Transcription

audio_transcribe = yes
whisper_native = no
whisper_model = /path/to/ggml-base.bin
whisper_language = auto

See Whisper for detailed transcription documentation.

ℹ️ Note: Oracle/ACME SBC and Ribbon SBC are products from different vendors with different integration methods:

  • Oracle SBC (formerly Acme Packet, acquired by Oracle in 2013) → uses IPFIX protocol
  • Ribbon SBC (formed from GENBAND + Sonus Networks merger in 2017) → uses Monitoring Profile with proprietary ribbonsbc protocol

Do not confuse these - they require different VoIPmonitor configuration.

Expert & Debugging Options

⚠️ Warning: Only change these if instructed by support or you are an expert.

Parameter Default Description
callslimit 0 Max concurrent calls (0=unlimited)
skipdefault no Ignore all calls unless capture rules match
openfile_max 65535 Maximum open files
coredump_filter 0x7F Memory segments in coredump

Traffic Dumper

traffic_dumper_path = /var/spool/voipmonitor/traffic
traffic_dumper_filter_ip = 192.168.1.100, 10.0.0.0/8
traffic_dumper_filter_port = 5060, 5061, 10000-20000

DEPRECATED DO NOT USE

AI Summary for RAG

Summary: Comprehensive reference for voipmonitor.conf covering: sensor identification, database configuration (MySQL settings, partitioning, mysqlloadconfig for GUI vs file priority), network interface settings (BPF filters, deduplication with auto_enable_use_blocks), tunneling protocols (VXLAN, TZSP, HEP, AudioCodes), TLS/SRTP decryption, distributed client/server architecture (packetbuffer_sender), storage management (TAR archives, spool cleaning), call processing (timeouts, merging, recording control), SIP history storage, audio analysis, and protocol support (IPFIX, SIPREC, HEP, Kamailio, Ribbon SBC, Whisper). Deprecated options in v2025.09.1+ include vxlan, packet_buffer_total_size, udp_reassembly, sipdefrag.

Keywords: voipmonitor.conf, sniffer configuration, id_sensor, mysqlloadconfig, manager_key, deduplicate, auto_enable_use_blocks, packetbuffer_sender, savertp, TLS decryption, SRTP, ssl_dtls_boost, distributed architecture, client-server, maxpoolsize, cleandatabase, custom_headers, save_sip_history, t2_boost, threading, scanpcapdir, deprecated options, IPFIX, SIPREC, HEP, Kamailio, Ribbon SBC, Whisper, pauserecordingdtmf

Key Questions:

  • What are the most important settings in voipmonitor.conf?
  • How do I configure the database connection?
  • Why does the sniffer fail with "failed read rsa key"?
  • How do I set up distributed client/server architecture?
  • What is the difference between packetbuffer_sender = yes and no?
  • How do I enable packet deduplication?
  • How do I decrypt TLS/SRTP traffic?
  • How do I disable audio recording while keeping RTP analysis?
  • How do I capture custom SIP headers?
  • How do I configure IPFIX/SIPREC/HEP receivers?
  • Which options were deprecated in v2025.09.1?
  • How do I fix CPU bottlenecks with t2_boost?
  • How do I process PCAP files with scanpcapdir?
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