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{{DISPLAYTITLE:VoIPmonitor Deployment & Topology Guide}}
{{DISPLAYTITLE:VoIPmonitor Deployment & Topology Guide}}


'''This guide provides a comprehensive overview of VoIPmonitor's deployment models. It covers the fundamental choice between on-host and dedicated sensors, methods for capturing traffic, and detailed configurations for scalable, multi-site architectures.'''
This guide covers VoIPmonitor deployment options: where to install the sensor, how to forward traffic, and distributed architectures for multi-site monitoring.


== Core Concept: Where to Capture Traffic ==
<kroki lang="mermaid">
The first decision in any deployment is where the VoIPmonitor sensor (sniffer) will run.
%%{init: {'flowchart': {'nodeSpacing': 15, 'rankSpacing': 30}}}%%
flowchart TB
    START[Where to deploy sensor?] --> Q1{PBX runs on Linux?}
    Q1 -->|Yes| Q2{Spare resources?}
    Q1 -->|No - Windows| DED[Dedicated Sensor]
    Q2 -->|Yes| ONHOST[On-Host Capture]
    Q2 -->|No| DED


=== 1. On-Host Capture (on the PBX/SBC) ===
    DED --> Q3{Traffic forwarding method?}
The sensor can be installed directly on the same Linux server that runs your PBX or SBC.
    Q3 --> SPAN[SPAN/RSPAN]
*'''Pros:''' Requires no extra hardware, network changes, or port mirroring. It is the simplest setup.
    Q3 --> TUNNEL[Software Tunnel]
*'''Cons:''' Adds CPU, memory, and disk I/O load to your production voice server. If these resources are critical, a dedicated sensor is the recommended approach.
    Q3 --> CLOUD[Cloud Mirroring]


=== 2. Dedicated Sensor ===
    TUNNEL --> T1[GRE/ERSPAN]
A dedicated Linux server runs only the VoIPmonitor sensor. This is the recommended approach for production environments as it isolates monitoring resources from your voice platform. To use a dedicated sensor, you must forward a copy of the network traffic to it using one of the methods below.
    TUNNEL --> T2[TZSP/VXLAN]
    TUNNEL --> T3[HEP/AudioCodes]
</kroki>


== Methods for Forwarding Traffic to a Dedicated Sensor ==
= Sensor Deployment Options =


=== A. Hardware Port Mirroring (SPAN/RSPAN) ===
== On-Host Capture ==
This is the most common and reliable method. You configure your physical network switch to copy all traffic from the switch ports connected to your PBX/SBC to the switch port connected to the VoIPmonitor sensor. This feature is commonly called '''Port Mirroring''', '''SPAN''', or '''RAP'''. Consult your switch's documentation for configuration details.


The VoIPmonitor sensor interface will be put into promiscuous mode automatically. To capture from multiple interfaces, set <code>interface = any</code> in <code>voipmonitor.conf</code> and enable promiscuous mode manually on each NIC (e.g., <code>ifconfig eth1 promisc</code>).
Install the sensor directly on the same Linux server as your PBX/SBC.


=== B. Software-based Tunnelling ===
{| class="wikitable"
When hardware mirroring is not an option, many network devices and PBXs can encapsulate VoIP packets and send them to the sensor's IP address using a tunnel. VoIPmonitor natively supports a wide range of protocols.
! Pros !! Cons
* '''Built-in Support:''' IP-in-IP, GRE, ERSPAN
|-
* '''UDP-based Tunnels:''' Configure the corresponding port in <code>voipmonitor.conf</code>:
| No extra hardware, network changes, or port mirroring required || Adds CPU, memory, and disk I/O load to production voice server
** <code>udp_port_tzsp = 37008</code> (for Mikrotik's TZSP)
|-
** <code>udp_port_l2tp = 1701</code>
| Simplest setup || Not suitable if resources are critical
** <code>udp_port_vxlan = 4789</code> (Common in AWS environments)
|}
* '''Proprietary & Other Protocols:'''
** [[audiocodes tunneling|AudioCodes Tunneling]] (uses <code>udp_port_audiocodes</code> or <code>tcp_port_audiocodes</code>)
** HEP (v3+) (enable <code>hep*</code> options)
** IPFIX (for Oracle SBCs) (enable <code>ipfix*</code> options)


== Distributed Deployment Models ==
{{Note|1=VoIPmonitor sensor runs '''exclusively on Linux'''. For Windows-based PBXs (e.g., 3CX Windows edition), you must use a dedicated Linux sensor with traffic mirroring.}}
For monitoring multiple remote offices or a large infrastructure, a distributed model is essential. This involves a central GUI/Database server collecting data from multiple remote sensors.


=== Classic Mode: Standalone Remote Sensors ===
== Dedicated Sensor ==
In this traditional model, each remote sensor is a fully independent entity.
*'''How it works:''' The remote sensor processes packets and stores PCAPs locally. It connects directly to the central MySQL database to write CDRs. The central GUI must also have direct network access to each sensor's management port (default 5029) to fetch PCAP files.
*'''Pros:''' Simple conceptual model.
*'''Cons:''' Requires opening firewall ports to each sensor and managing database credentials on every remote machine.


=== Modern Mode: Client/Server Architecture (v20+) ===
A separate Linux server runs only VoIPmonitor. '''Recommended for production environments''' as it isolates monitoring from voice platform resources.
This is the '''recommended''' model for all new distributed deployments. It uses a secure, encrypted TCP channel between remote sensors (clients) and a central sensor instance (server). The GUI only needs to communicate with the central server.


This model supports two modes of operation:
'''When Required:'''
# '''Local Processing:''' Remote sensors process packets locally and send only the small CDR data over the encrypted channel. PCAPs remain on the remote sensor.
* Windows-based PBXs
# '''Packet Mirroring:''' Remote sensors do '''no''' processing. They forward the entire raw packet stream over the encrypted channel to the central server, which handles all processing and storage. This is ideal for low-resource remote devices.
* Limited CPU/RAM/disk I/O on PBX server
* Zero monitoring impact needed
* Centralized capture from multiple sites
 
= Traffic Forwarding Methods =
 
When using a dedicated sensor, you must forward traffic to it using one of these methods.
 
== Hardware Port Mirroring (SPAN/RSPAN) ==
 
Physical or virtual switches copy traffic from source port(s) to a monitoring port.
 
=== Physical Switch ===
 
Configure your switch to mirror traffic from PBX/SBC ports to the sensor's port. Consult your switch documentation for specific commands.
 
<syntaxhighlight lang="ini">
# /etc/voipmonitor.conf
interface = eth0
sipport = 5060
savertp = yes
</syntaxhighlight>
 
{{Tip|To capture from multiple interfaces, set <code>interface = any</code> and enable promiscuous mode on each NIC: <code>ip link set dev eth1 promisc on</code>}}
 
=== VMware/ESXi Virtual Switch ===
 
For virtualized environments, VMware provides port mirroring at the virtual switch level.
 
'''Standard vSwitch:'''
# In vSphere Client, navigate to ESXi host
# Select virtual switch → Properties/Edit Settings → Enable Port Mirroring
# Set source (SBC VM) and destination (VoIPmonitor VM) ports
 
'''Distributed vSwitch:'''
# In vSphere Web Client → Networking → Select distributed switch
# Configure tab → Port Mirroring → Create mirroring session
# Specify source/destination ports and enable
 
{{Note|1=Distributed switch mirroring can span multiple ESXi hosts within a cluster.}}
 
=== Multiple VoIP Platforms ===
 
Monitor multiple platforms (e.g., Mitel + FreeSWITCH) with a single sensor by mirroring multiple source ports to one destination port.
 
'''GUI differentiation:'''
* Filter by IP address ranges
* Filter by number prefixes
* Use separate sensors with unique <code>id_sensor</code> values
 
{{Warning|1='''Critical:''' When sniffing from multiple mirrored sources, packets may arrive as duplicates. Add <code>auto_enable_use_blocks = yes</code> to voipmonitor.conf to enable automatic deduplication. See [[Sniffer_configuration#auto_enable_use_blocks|Sniffer_configuration]] for details.}}
 
== Software-based Tunneling ==
 
When hardware mirroring is unavailable, use software tunneling to encapsulate and forward packets.


==== Comparison of Remote Deployment Modes ====
{| class="wikitable"
{| class="wikitable"
! Deployment Model
! Protocol !! Configuration Parameter !! Notes
! Packet Processing Location
|-
! PCAP Storage Location
| IP-in-IP, GRE, ERSPAN || Built-in (auto-detected) || No additional config needed
! Network Traffic to Central Server
|-
! GUI Connectivity
| TZSP (MikroTik) || <code>udp_port_tzsp = 37008</code> ||
|-
| L2TP || <code>udp_port_l2tp = 1701</code> ||
|-
|-
| Classic Standalone
| VXLAN || <code>udp_port_vxlan = 4789</code> || Common in cloud environments
| Remote
| Remote
| Minimal (MySQL CDRs)
| GUI ↔ each Sensor (management port)
|-
|-
| '''Modern Client/Server (Local Processing)'''
| AudioCodes || <code>udp_port_audiocodes = 925</code> || See [[Audiocodes_tunneling|AudioCodes Tunneling]]
| Remote
| Remote
| Minimal (Encrypted CDRs)
| '''GUI ↔ Central Server only'''
|-
|-
| '''Modern Client/Server (Packet Mirroring)'''
| IPFIX (Oracle SBCs) || <code>ipfix*</code> options || Enable ipfix options in config
| '''Central'''
| '''Central'''
| High (Encrypted full packets)
| '''GUI ↔ Central Server only'''
|}
|}


== Configuration & Checklists ==
=== HEP (Homer Encapsulation Protocol) ===
 
Lightweight protocol for mirroring VoIP packets. Supported by Kamailio, OpenSIPS, FreeSWITCH, and many SBCs.
 
<syntaxhighlight lang="ini">
# /etc/voipmonitor.conf
hep = yes
hep_bind_port = 9060
hep_bind_udp = yes
# Optional: hep_kamailio_protocol_id_fix = yes
</syntaxhighlight>
 
'''SIP and RTP Correlation from Multiple HEP Sources:'''
 
VoIPmonitor correlates calls using standard SIP Call-ID, To/From tags, and RTP streams are matched based on IP:port from SDP.
 
{{Note|1='''Multiple HEP sources to same sniffer:''' When SIP HEP (e.g., from Kamailio) and RTP HEP (e.g., from rtpproxy) are sent to the '''same sniffer instance''', they ARE correlated into unified CDRs. The sniffer processes both as regular SIP/RTP packets.
 
'''Example:''' Kamailio sends SIP via HEP → VoIPmonitor + rtpproxy sends RTP via HEP → same VoIPmonitor = Complete CDRs with SIP+RTP}}


=== Client/Server Configuration Example ===
{{Tip|1='''Client/Server mode also supported:''' A sniffer client can receive HEP packets and forward them to a central sniffer server using <code>packetbuffer_sender=yes</code>. The central server then correlates SIP and RTP from all sources. This works for HEP, IPFIX, and RibbonSBC protocols.}}
Below is a minimal configuration for the modern client/server model.


;On each ''Remote Sensor (Client)'':
'''HEP Header Fields:'''
<pre>
# /etc/voipmonitor.conf on the remote sensor


id_sensor               = 2      # MUST be unique for each sensor, < 65536
{| class="wikitable"
server_destination      = 10.0.0.1 # IP address of your central server
! HEP Field !! Present In !! Current Usage
|-
| <code>correlation_id</code> || INVITE only || Parsed but not used
|-
| <code>capture_node_id</code> || All SIP packets || Parsed but not used
|}
 
{{Note|1='''Feature Request VS-1703:''' Option to set CDR <code>id_sensor</code> from HEP <code>correlation_id</code> or <code>capture_node_id</code> headers. This would allow sensor attribution based on the originating HEP source when SIP arrives via HEP but RTP comes from different sensors. [https://jira.voipmonitor.org/browse/VS-1703 Track status]}}
 
'''HEP Timestamp:''' VoIPmonitor uses the HEP timestamp field. If the source has an unsynchronized clock, call timestamps will be incorrect. There is no option to ignore HEP timestamps.
 
'''HEP3 with Port 0:''' Not captured by default. Add port 0 to sipport:
 
<syntaxhighlight lang="ini">
sipport = 0,5060
</syntaxhighlight>
==== HEP/IPFIX Timestamp Options ====
 
'''(New in 2026.1)''' By default, VoIPmonitor uses timestamps from HEP/IPFIX packet headers. If the source has an unsynchronized clock, enable system time instead:
 
<syntaxhighlight lang="ini">
# /etc/voipmonitor.conf
hep_use_system_time = yes    # Use system arrival time instead of HEP timestamp
ipfix_use_system_time = yes  # Use system arrival time instead of IPFIX timestamp
</syntaxhighlight>
 
'''Use case:''' Debugging packet timing issues when combining HEP with PCAP replay or when HEP sources have clock drift.
== Cloud Packet Mirroring ==
 
Cloud providers offer native mirroring services using VXLAN or GRE encapsulation.
 
{| class="wikitable"
! Provider !! Service Name
|-
| Google Cloud || Packet Mirroring
|-
| AWS || Traffic Mirroring
|-
| Azure || Virtual Network TAP
|}
 
'''Configuration Steps:'''
 
# Create a VoIPmonitor sensor VM in your cloud environment
# Create mirroring policy: select source VMs/subnets, set destination to sensor VM
# '''Critical:''' Capture traffic in '''BOTH directions''' (INGRESS and EGRESS)
# Configure sensor:
 
<syntaxhighlight lang="ini">
udp_port_vxlan = 4789
interface = eth0
sipport = 5060
</syntaxhighlight>
 
{{Warning|1=Capturing only ingress or only egress results in incomplete CDRs and broken call data.}}
 
'''Best Practices:'''
* Filter at source to forward only SIP/RTP ports
* Monitor NIC bandwidth limits
* Account for VXLAN overhead (~50 bytes) - may need jumbo frames
* Ensure NTP sync across all VMs
 
'''Alternative:''' Consider [[Sniffer_distributed_architecture|Client/Server architecture]] with on-host sensors instead of cloud mirroring for better performance.
 
== Pre-Deployment Verification ==
 
For complex setups (RSPAN, ERSPAN, proprietary SBCs), verify compatibility before production deployment:
 
# Configure test mirroring with a subset of traffic
# Capture test calls with tcpdump: <code>sudo tcpdump -i eth0 -s0 port 5060 -w /tmp/test.pcap</code>
# Verify pcap contains SIP and RTP: <code>tshark -r /tmp/test.pcap -Y "sip || rtp"</code>
# Submit pcap to VoIPmonitor support with hardware/configuration details
 
= Distributed Architectures =
 
For multi-site monitoring, sensors can be deployed in various configurations.
 
== Classic Mode: Standalone Sensors ==
 
Each sensor operates independently:
* Processes packets and stores PCAPs locally
* Connects directly to central MySQL to write CDRs
* GUI needs network access to each sensor's <code>TCP/5029</code> for PCAP retrieval
 
'''Alternative: NFS/SSHFS Mounting'''
 
If TCP/5029 access is blocked, mount remote spool directories on the GUI server:
 
<syntaxhighlight lang="bash">
# NFS mount
sudo mount -t nfs 10.224.0.101:/var/spool/voipmonitor /mnt/voipmonitor/sensor1
 
# SSHFS mount
sshfs voipmonitor@10.224.0.101:/var/spool/voipmonitor /mnt/voipmonitor/sensor1
</syntaxhighlight>
 
Configure GUI: '''Settings > System Configuration > Sniffer data path:'''
<code>/var/spool/voipmonitor:/mnt/voipmonitor/sensor1:/mnt/voipmonitor/sensor2</code>
 
{{Tip|For NFS, use <code>hard,nofail,tcp</code> mount options for reliability.}}
 
== Modern Mode: Client/Server (v20+) — Recommended ==
 
Secure encrypted TCP channel between remote sensors and central server. GUI communicates only with central server.
 
<kroki lang="mermaid">
%%{init: {'flowchart': {'nodeSpacing': 10, 'rankSpacing': 25}}}%%
flowchart LR
    subgraph "Local Processing"
        R1[Remote Sensor] -->|CDRs only| C1[Central Server]
        R1 -.->|PCAP on demand| C1
    end
 
    subgraph "Packet Mirroring"
        R2[Remote Sensor] -->|Raw packets| C2[Central Server]
    end
</kroki>
 
{| class="wikitable"
! Mode !! Processing !! PCAP Storage !! WAN Traffic !! Best For
|-
| '''Local Processing''' (<code>packetbuffer_sender=no</code>) || Remote || Remote || Low (CDRs only) || Limited WAN bandwidth
|-
| '''Packet Mirroring''' (<code>packetbuffer_sender=yes</code>) || Central || Central || High (full packets) || Low-resource remote sites
|}
 
For detailed configuration, see [[Sniffer_distributed_architecture|Distributed Architecture: Client-Server Mode]].
 
'''Quick Start - Remote Sensor (Local Processing):'''
 
<syntaxhighlight lang="ini">
id_sensor              = 2
server_destination      = 10.224.0.250
server_destination_port = 60024
server_destination_port = 60024
server_password        = your_strong_password
server_password        = your_strong_password
packetbuffer_sender    = no
interface              = eth0
sipport                = 5060
# No MySQL credentials needed - central server writes to DB
</syntaxhighlight>


# Optional: Uncomment the next line to enable packet mirroring mode
'''Quick Start - Central Server:'''
# packetbuffer_sender  = yes
</pre>
 
;On the ''Central Server'':
<pre>
# /etc/voipmonitor.conf on the central server


<syntaxhighlight lang="ini">
server_bind            = 0.0.0.0
server_bind            = 0.0.0.0
server_bind_port        = 60024
server_bind_port        = 60024
server_password        = your_strong_password
server_password        = your_strong_password
 
mysqlhost              = 10.224.0.201
# Remember to configure mysql* options for the central database connection
mysqlhost              = localhost
mysqldb                = voipmonitor
mysqldb                = voipmonitor
mysqluser              = root
mysqluser              = voipmonitor
mysqlpassword          = db_password
mysqlpassword          = db_password
</pre>
cdr_partition          = yes
interface              =  # Leave empty - don't sniff locally
</syntaxhighlight>
{{Note|1='''Deduplication in Packet Mirroring mode (New in 2026.1):''' When using <code>packetbuffer_sender=yes</code> with <code>deduplicate_ipheader=ip_only</code> on the server, the server now automatically sends this parameter to clients. For older versions, set <code>deduplicate_ipheader=ip_only</code> on '''both''' server AND client to ensure consistent hash calculation.}}
== Firewall Requirements ==
 
{| class="wikitable"
! Deployment !! Port !! Direction !! Purpose
|-
| Client/Server || TCP/60024 || Remote → Central || Encrypted CDR/packet channel
|-
| Client/Server || TCP/5029 || Central → Remote || On-demand PCAP fetch (Local Processing mode)
|-
| GUI Access || TCP/5029 || GUI → Central || Management/API
|-
| Cloud Mode || TCP/60023 || Sensor → cloud.voipmonitor.org || Cloud service connection
|}
 
= Configuration Notes =
 
== Critical Parameters ==
 
{| class="wikitable"
! Parameter !! Description !! Notes
|-
| <code>id_sensor</code> || Unique sensor identifier (1-65535) || '''Mandatory''' in distributed deployments
|-
| <code>cdr_partition</code> || Enable daily CDR table partitions || Enable on server writing to DB
|-
| <code>mysqlloadconfig</code> || Load config from database || Enable on central server only
|-
| <code>interface</code> || Capture interface || Use specific NIC or <code>any</code>
|}
 
== Time Synchronization ==
 
{{Warning|1=Accurate NTP sync is '''critical''' for correlating call legs across sensors. All servers (GUI, DB, sensors) must run NTP client (chrony or ntpd).}}
 
== First Startup ==
 
On first start against empty database:
# Start service: <code>systemctl start voipmonitor</code>
# Monitor logs: <code>journalctl -u voipmonitor -f</code>
# Wait for schema/partition creation to complete
 
If you see <code>Table 'cdr_next_1' doesn't exist</code> errors, check DB connectivity and privileges.
 
= Deployment Comparison =
 
{| class="wikitable"
! Model !! Processing !! PCAP Storage !! WAN Traffic !! GUI Connectivity
|-
| Classic Standalone || Remote || Remote || Minimal (MySQL CDRs) || GUI ↔ each Sensor
|-
| '''Client/Server (Local Processing)''' || Remote || Remote || Minimal (encrypted CDRs) || '''GUI ↔ Central only'''
|-
| '''Client/Server (Packet Mirroring)''' || Central || Central || High (encrypted packets) || '''GUI ↔ Central only'''
|}
 
= Troubleshooting =
 
== NFS/SSHFS Connectivity ==
 
Missing data for specific time periods usually indicates storage server connectivity issues.
 
{| class="wikitable"
! Symptom !! Likely Cause !! Solution
|-
| Data gap in time period || NFS/SSHFS server unreachable || Check logs for "not responding, timed out"
|-
| Stale file handle || Server rebooted or export changed || Remount NFS share
|-
| Connection resets || Network interruption || Check network stability
|-
| GUI shows "File not found" || Mount point dismounted || Verify mount with <code>mount | grep nfs</code>
|}
 
<syntaxhighlight lang="bash">
# Check for NFS errors
grep "nfs: server.*not responding" /var/log/syslog
grep "nfs.*timed out" /var/log/syslog
 
# Verify mount status
mount | grep nfs
stat /mnt/voipmonitor/sensor1
</syntaxhighlight>
 
= See Also =
 
* [[Sniffer_distributed_architecture|Distributed Architecture: Client-Server Mode]] - Detailed client/server configuration
* [[Sniffer_troubleshooting|Sniffer Troubleshooting]] - Diagnostic procedures
* [[Audiocodes_tunneling|AudioCodes Tunneling]] - AudioCodes SBC integration
* [[Tls|TLS/SRTP Decryption]] - Encrypted traffic monitoring
* [[Cloud|Cloud Service Configuration]] - Cloud deployment specifics
* [[Scaling|Scaling and Performance Tuning]] - Performance optimization
 
 
 
 
= AI Summary for RAG =


=== Firewall Checklist ===
'''Summary:''' VoIPmonitor deployment guide covering sensor placement (on-host vs dedicated), traffic forwarding methods (SPAN/RSPAN, software tunneling, cloud mirroring), and distributed architectures. Key traffic forwarding options: hardware port mirroring (physical/VMware switches), software tunnels (GRE, ERSPAN, TZSP, VXLAN, HEP, AudioCodes, IPFIX), and cloud provider services (GCP Packet Mirroring, AWS Traffic Mirroring, Azure Virtual Network TAP). CRITICAL HEP LIMITATION: VoIPmonitor does NOT use HEP correlation ID (captureNodeID) - SIP and RTP from different HEP sources will NOT be correlated (feature request VS-1703, no workaround). HEP3 packets with port 0 require adding port 0 to sipport directive. Cloud mirroring requires BIDIRECTIONAL capture (ingress+egress) or CDRs will be incomplete. Distributed architectures: Classic standalone (each sensor writes to central DB, GUI connects to each sensor) vs Modern Client/Server (recommended, encrypted TCP/60024 channel, GUI connects only to central server). Client/Server modes: Local Processing (packetbuffer_sender=no, CDRs only, PCAPs remain remote) vs Packet Mirroring (packetbuffer_sender=yes, full packets sent to central). Alternative for blocked TCP/5029: mount remote spools via NFS/SSHFS, configure multiple paths in GUI Sniffer data path setting. NFS troubleshooting: check for "not responding, timed out" in logs, verify mount status, use hard,nofail,tcp mount options. Critical requirement: NTP sync across all servers.
* '''Modern Client/Server Mode (v20+):'''
** On '''Central Server:''' Allow inbound <code>TCP/60024</code> from remote sensors. Allow inbound <code>TCP/5029</code> for GUI management access.
* '''Cloud Mode:'''
** On '''Remote Sensors:''' Allow outbound <code>TCP/60023</code> to <code>cloud.voipmonitor.org</code>.


=== Time Synchronization ===
'''Keywords:''' deployment, topology, on-host, dedicated sensor, SPAN, RSPAN, port mirroring, VMware, vSwitch, dvSwitch, tunneling, GRE, ERSPAN, TZSP, VXLAN, HEP, HEP correlation ID, captureNodeID, VS-1703, HEP port 0, sipport, AudioCodes, IPFIX, cloud mirroring, GCP, AWS, Azure, Packet Mirroring, Traffic Mirroring, ingress, egress, bidirectional, client server, packetbuffer_sender, local processing, packet mirroring, TCP 60024, TCP 5029, NFS, SSHFS, sniffer data path, NTP, time synchronization, id_sensor, cdr_partition
Accurate and synchronized time is '''critical''' for correlating call legs from different sensors. All servers (GUI, DB, and all Sensors) must run an NTP client (like `chrony` or `ntpdate`) to keep their clocks in sync.


== AI Summary for RAG ==
'''Summary:''' This guide covers the deployment topologies for VoIPmonitor. It contrasts running the sensor on the same host as a PBX versus on a dedicated server. For dedicated sensors, it details methods for forwarding traffic, including hardware-based port mirroring (SPAN) and various software-based tunneling protocols (IP-in-IP, GRE, TZSP, VXLAN, HEP, etc.). The core of the article explains distributed architectures for multi-site monitoring, comparing the "classic" standalone remote sensor model with the modern, recommended "client/server" model. It details the two operational modes of the client/server architecture: local processing (sending only CDRs) and packet mirroring (sending full, raw packets for central processing), which is ideal for low-resource endpoints. The guide concludes with minimal configuration examples and firewall rules for the client/server setup and emphasizes the critical importance of time synchronization using NTP.
'''Keywords:''' deployment, architecture, topology, on-host, dedicated sensor, port mirroring, SPAN, RSPAN, traffic mirroring, tunneling, GRE, TZSP, VXLAN, HEP, remote sensor, multi-site, client server mode, packet mirroring, local processing, firewall rules, NTP, time synchronization, cloud mode
'''Key Questions:'''
'''Key Questions:'''
* How do I set up VoIPmonitor to monitor multiple remote locations?
* Should I install VoIPmonitor on my PBX or use a dedicated sensor?
* What is the difference between the classic remote sensor and the modern client/server mode?
* How do I configure port mirroring (SPAN) for VoIPmonitor?
* When should I use packet mirroring (packetbuffer_sender) instead of local processing?
* How do I configure VMware/ESXi virtual switch mirroring?
* What are the firewall requirements for the client/server deployment model?
* What software tunneling protocols does VoIPmonitor support?
* Can I run the sensor on the same machine as my Asterisk/FreeSWITCH server?
* How do I configure HEP (Homer Encapsulation Protocol)?
* What is a SPAN port and how is it used with VoIPmonitor?
* Does VoIPmonitor use HEP correlation ID to correlate SIP and RTP?
* Why is NTP important for a distributed VoIPmonitor setup?
* Why are SIP and RTP from different HEP sources not correlated?
* How do I capture HEP3 packets with port 0?
* How do I configure cloud packet mirroring (GCP/AWS/Azure)?
* Why do I get incomplete CDRs with cloud mirroring?
* What is the difference between classic and client/server deployment?
* What is the difference between local processing and packet mirroring mode?
* How do I access PCAPs if TCP/5029 is blocked?
* How do I configure NFS/SSHFS for remote spool access?
* How do I troubleshoot missing data with NFS mounts?
* What firewall ports are required for client/server mode?
* Why is NTP important for distributed VoIPmonitor?

Latest revision as of 13:02, 20 January 2026


This guide covers VoIPmonitor deployment options: where to install the sensor, how to forward traffic, and distributed architectures for multi-site monitoring.

Sensor Deployment Options

On-Host Capture

Install the sensor directly on the same Linux server as your PBX/SBC.

Pros Cons
No extra hardware, network changes, or port mirroring required Adds CPU, memory, and disk I/O load to production voice server
Simplest setup Not suitable if resources are critical

ℹ️ Note: VoIPmonitor sensor runs exclusively on Linux. For Windows-based PBXs (e.g., 3CX Windows edition), you must use a dedicated Linux sensor with traffic mirroring.

Dedicated Sensor

A separate Linux server runs only VoIPmonitor. Recommended for production environments as it isolates monitoring from voice platform resources.

When Required:

  • Windows-based PBXs
  • Limited CPU/RAM/disk I/O on PBX server
  • Zero monitoring impact needed
  • Centralized capture from multiple sites

Traffic Forwarding Methods

When using a dedicated sensor, you must forward traffic to it using one of these methods.

Hardware Port Mirroring (SPAN/RSPAN)

Physical or virtual switches copy traffic from source port(s) to a monitoring port.

Physical Switch

Configure your switch to mirror traffic from PBX/SBC ports to the sensor's port. Consult your switch documentation for specific commands. 

# /etc/voipmonitor.conf
interface = eth0
sipport = 5060
savertp = yes

💡 Tip:

VMware/ESXi Virtual Switch

For virtualized environments, VMware provides port mirroring at the virtual switch level.

Standard vSwitch:

  1. In vSphere Client, navigate to ESXi host
  2. Select virtual switch → Properties/Edit Settings → Enable Port Mirroring
  3. Set source (SBC VM) and destination (VoIPmonitor VM) ports

Distributed vSwitch:

  1. In vSphere Web Client → Networking → Select distributed switch
  2. Configure tab → Port Mirroring → Create mirroring session
  3. Specify source/destination ports and enable

ℹ️ Note: Distributed switch mirroring can span multiple ESXi hosts within a cluster.

Multiple VoIP Platforms

Monitor multiple platforms (e.g., Mitel + FreeSWITCH) with a single sensor by mirroring multiple source ports to one destination port.

GUI differentiation:

  • Filter by IP address ranges
  • Filter by number prefixes
  • Use separate sensors with unique id_sensor values

⚠️ Warning: Critical: When sniffing from multiple mirrored sources, packets may arrive as duplicates. Add auto_enable_use_blocks = yes to voipmonitor.conf to enable automatic deduplication. See Sniffer_configuration for details.

Software-based Tunneling

When hardware mirroring is unavailable, use software tunneling to encapsulate and forward packets.

Protocol Configuration Parameter Notes
IP-in-IP, GRE, ERSPAN Built-in (auto-detected) No additional config needed
TZSP (MikroTik) udp_port_tzsp = 37008
L2TP udp_port_l2tp = 1701
VXLAN udp_port_vxlan = 4789 Common in cloud environments
AudioCodes udp_port_audiocodes = 925 See AudioCodes Tunneling
IPFIX (Oracle SBCs) ipfix* options Enable ipfix options in config

HEP (Homer Encapsulation Protocol)

Lightweight protocol for mirroring VoIP packets. Supported by Kamailio, OpenSIPS, FreeSWITCH, and many SBCs. 

# /etc/voipmonitor.conf
hep = yes
hep_bind_port = 9060
hep_bind_udp = yes
# Optional: hep_kamailio_protocol_id_fix = yes

SIP and RTP Correlation from Multiple HEP Sources:

VoIPmonitor correlates calls using standard SIP Call-ID, To/From tags, and RTP streams are matched based on IP:port from SDP.

ℹ️ Note: Multiple HEP sources to same sniffer: When SIP HEP (e.g., from Kamailio) and RTP HEP (e.g., from rtpproxy) are sent to the same sniffer instance, they ARE correlated into unified CDRs. The sniffer processes both as regular SIP/RTP packets.

Example: Kamailio sends SIP via HEP → VoIPmonitor + rtpproxy sends RTP via HEP → same VoIPmonitor = Complete CDRs with SIP+RTP

💡 Tip: Client/Server mode also supported: A sniffer client can receive HEP packets and forward them to a central sniffer server using packetbuffer_sender=yes. The central server then correlates SIP and RTP from all sources. This works for HEP, IPFIX, and RibbonSBC protocols.

HEP Header Fields:

HEP Field Present In Current Usage
correlation_id INVITE only Parsed but not used
capture_node_id All SIP packets Parsed but not used

ℹ️ Note: Feature Request VS-1703: Option to set CDR id_sensor from HEP correlation_id or capture_node_id headers. This would allow sensor attribution based on the originating HEP source when SIP arrives via HEP but RTP comes from different sensors. Track status

HEP Timestamp: VoIPmonitor uses the HEP timestamp field. If the source has an unsynchronized clock, call timestamps will be incorrect. There is no option to ignore HEP timestamps.

HEP3 with Port 0: Not captured by default. Add port 0 to sipport: 

sipport = 0,5060

HEP/IPFIX Timestamp Options

(New in 2026.1) By default, VoIPmonitor uses timestamps from HEP/IPFIX packet headers. If the source has an unsynchronized clock, enable system time instead: 

# /etc/voipmonitor.conf
hep_use_system_time = yes    # Use system arrival time instead of HEP timestamp
ipfix_use_system_time = yes  # Use system arrival time instead of IPFIX timestamp

Use case: Debugging packet timing issues when combining HEP with PCAP replay or when HEP sources have clock drift.

Cloud Packet Mirroring

Cloud providers offer native mirroring services using VXLAN or GRE encapsulation.

Provider Service Name
Google Cloud Packet Mirroring
AWS Traffic Mirroring
Azure Virtual Network TAP

Configuration Steps:

  1. Create a VoIPmonitor sensor VM in your cloud environment
  2. Create mirroring policy: select source VMs/subnets, set destination to sensor VM
  3. Critical: Capture traffic in BOTH directions (INGRESS and EGRESS)
  4. Configure sensor:
udp_port_vxlan = 4789
interface = eth0
sipport = 5060

⚠️ Warning: Capturing only ingress or only egress results in incomplete CDRs and broken call data.

Best Practices:

  • Filter at source to forward only SIP/RTP ports
  • Monitor NIC bandwidth limits
  • Account for VXLAN overhead (~50 bytes) - may need jumbo frames
  • Ensure NTP sync across all VMs

Alternative: Consider Client/Server architecture with on-host sensors instead of cloud mirroring for better performance.

Pre-Deployment Verification

For complex setups (RSPAN, ERSPAN, proprietary SBCs), verify compatibility before production deployment:

  1. Configure test mirroring with a subset of traffic
  2. Capture test calls with tcpdump: sudo tcpdump -i eth0 -s0 port 5060 -w /tmp/test.pcap
  3. Verify pcap contains SIP and RTP: tshark -r /tmp/test.pcap -Y "sip || rtp"
  4. Submit pcap to VoIPmonitor support with hardware/configuration details

Distributed Architectures

For multi-site monitoring, sensors can be deployed in various configurations.

Classic Mode: Standalone Sensors

Each sensor operates independently:

  • Processes packets and stores PCAPs locally
  • Connects directly to central MySQL to write CDRs
  • GUI needs network access to each sensor's TCP/5029 for PCAP retrieval

Alternative: NFS/SSHFS Mounting

If TCP/5029 access is blocked, mount remote spool directories on the GUI server: 

# NFS mount
sudo mount -t nfs 10.224.0.101:/var/spool/voipmonitor /mnt/voipmonitor/sensor1

# SSHFS mount
sshfs voipmonitor@10.224.0.101:/var/spool/voipmonitor /mnt/voipmonitor/sensor1

Configure GUI: Settings > System Configuration > Sniffer data path: /var/spool/voipmonitor:/mnt/voipmonitor/sensor1:/mnt/voipmonitor/sensor2

💡 Tip: For NFS, use hard,nofail,tcp mount options for reliability.

Modern Mode: Client/Server (v20+) — Recommended

Secure encrypted TCP channel between remote sensors and central server. GUI communicates only with central server.

Mode Processing PCAP Storage WAN Traffic Best For
Local Processing (packetbuffer_sender=no) Remote Remote Low (CDRs only) Limited WAN bandwidth
Packet Mirroring (packetbuffer_sender=yes) Central Central High (full packets) Low-resource remote sites

For detailed configuration, see Distributed Architecture: Client-Server Mode.

Quick Start - Remote Sensor (Local Processing): 

id_sensor               = 2
server_destination      = 10.224.0.250
server_destination_port = 60024
server_password         = your_strong_password
packetbuffer_sender     = no
interface               = eth0
sipport                 = 5060
# No MySQL credentials needed - central server writes to DB

Quick Start - Central Server: 

server_bind             = 0.0.0.0
server_bind_port        = 60024
server_password         = your_strong_password
mysqlhost               = 10.224.0.201
mysqldb                 = voipmonitor
mysqluser               = voipmonitor
mysqlpassword           = db_password
cdr_partition           = yes
interface               =   # Leave empty - don't sniff locally

ℹ️ Note: Deduplication in Packet Mirroring mode (New in 2026.1): When using packetbuffer_sender=yes with deduplicate_ipheader=ip_only on the server, the server now automatically sends this parameter to clients. For older versions, set deduplicate_ipheader=ip_only on both server AND client to ensure consistent hash calculation.

Firewall Requirements

Deployment Port Direction Purpose
Client/Server TCP/60024 Remote → Central Encrypted CDR/packet channel
Client/Server TCP/5029 Central → Remote On-demand PCAP fetch (Local Processing mode)
GUI Access TCP/5029 GUI → Central Management/API
Cloud Mode TCP/60023 Sensor → cloud.voipmonitor.org Cloud service connection

Configuration Notes

Critical Parameters

Parameter Description Notes
id_sensor Unique sensor identifier (1-65535) Mandatory in distributed deployments
cdr_partition Enable daily CDR table partitions Enable on server writing to DB
mysqlloadconfig Load config from database Enable on central server only
interface Capture interface Use specific NIC or any

Time Synchronization

⚠️ Warning: Accurate NTP sync is critical for correlating call legs across sensors. All servers (GUI, DB, sensors) must run NTP client (chrony or ntpd).

First Startup

On first start against empty database:

  1. Start service: systemctl start voipmonitor
  2. Monitor logs: journalctl -u voipmonitor -f
  3. Wait for schema/partition creation to complete

If you see Table 'cdr_next_1' doesn't exist errors, check DB connectivity and privileges.

Deployment Comparison

Model Processing PCAP Storage WAN Traffic GUI Connectivity
Classic Standalone Remote Remote Minimal (MySQL CDRs) GUI ↔ each Sensor
Client/Server (Local Processing) Remote Remote Minimal (encrypted CDRs) GUI ↔ Central only
Client/Server (Packet Mirroring) Central Central High (encrypted packets) GUI ↔ Central only

Troubleshooting

NFS/SSHFS Connectivity

Missing data for specific time periods usually indicates storage server connectivity issues.

Symptom Likely Cause Solution
Data gap in time period NFS/SSHFS server unreachable Check logs for "not responding, timed out"
Stale file handle Server rebooted or export changed Remount NFS share
Connection resets Network interruption Check network stability
GUI shows "File not found" Mount point dismounted grep nfs 
# Check for NFS errors
grep "nfs: server.*not responding" /var/log/syslog
grep "nfs.*timed out" /var/log/syslog

# Verify mount status
mount | grep nfs
stat /mnt/voipmonitor/sensor1

See Also



AI Summary for RAG

Summary: VoIPmonitor deployment guide covering sensor placement (on-host vs dedicated), traffic forwarding methods (SPAN/RSPAN, software tunneling, cloud mirroring), and distributed architectures. Key traffic forwarding options: hardware port mirroring (physical/VMware switches), software tunnels (GRE, ERSPAN, TZSP, VXLAN, HEP, AudioCodes, IPFIX), and cloud provider services (GCP Packet Mirroring, AWS Traffic Mirroring, Azure Virtual Network TAP). CRITICAL HEP LIMITATION: VoIPmonitor does NOT use HEP correlation ID (captureNodeID) - SIP and RTP from different HEP sources will NOT be correlated (feature request VS-1703, no workaround). HEP3 packets with port 0 require adding port 0 to sipport directive. Cloud mirroring requires BIDIRECTIONAL capture (ingress+egress) or CDRs will be incomplete. Distributed architectures: Classic standalone (each sensor writes to central DB, GUI connects to each sensor) vs Modern Client/Server (recommended, encrypted TCP/60024 channel, GUI connects only to central server). Client/Server modes: Local Processing (packetbuffer_sender=no, CDRs only, PCAPs remain remote) vs Packet Mirroring (packetbuffer_sender=yes, full packets sent to central). Alternative for blocked TCP/5029: mount remote spools via NFS/SSHFS, configure multiple paths in GUI Sniffer data path setting. NFS troubleshooting: check for "not responding, timed out" in logs, verify mount status, use hard,nofail,tcp mount options. Critical requirement: NTP sync across all servers.

Keywords: deployment, topology, on-host, dedicated sensor, SPAN, RSPAN, port mirroring, VMware, vSwitch, dvSwitch, tunneling, GRE, ERSPAN, TZSP, VXLAN, HEP, HEP correlation ID, captureNodeID, VS-1703, HEP port 0, sipport, AudioCodes, IPFIX, cloud mirroring, GCP, AWS, Azure, Packet Mirroring, Traffic Mirroring, ingress, egress, bidirectional, client server, packetbuffer_sender, local processing, packet mirroring, TCP 60024, TCP 5029, NFS, SSHFS, sniffer data path, NTP, time synchronization, id_sensor, cdr_partition

Key Questions:

  • Should I install VoIPmonitor on my PBX or use a dedicated sensor?
  • How do I configure port mirroring (SPAN) for VoIPmonitor?
  • How do I configure VMware/ESXi virtual switch mirroring?
  • What software tunneling protocols does VoIPmonitor support?
  • How do I configure HEP (Homer Encapsulation Protocol)?
  • Does VoIPmonitor use HEP correlation ID to correlate SIP and RTP?
  • Why are SIP and RTP from different HEP sources not correlated?
  • How do I capture HEP3 packets with port 0?
  • How do I configure cloud packet mirroring (GCP/AWS/Azure)?
  • Why do I get incomplete CDRs with cloud mirroring?
  • What is the difference between classic and client/server deployment?
  • What is the difference between local processing and packet mirroring mode?
  • How do I access PCAPs if TCP/5029 is blocked?
  • How do I configure NFS/SSHFS for remote spool access?
  • How do I troubleshoot missing data with NFS mounts?
  • What firewall ports are required for client/server mode?
  • Why is NTP important for distributed VoIPmonitor?
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