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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 '''RSPAN'''. 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>ip link set dev eth1 promisc on</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 cloud environments)
|}
* '''Proprietary & Other Protocols:'''
 
** [[audiocodes tunneling|AudioCodes Tunneling]] (uses <code>udp_port_audiocodes</code> or <code>tcp_port_audiocodes</code>)
{{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.}}
** HEP (Homer Encapsulation Protocol)
 
** IPFIX (for Oracle SBCs) (enable <code>ipfix*</code> options)
== Dedicated Sensor ==


==== HEP (Homer Encapsulation Protocol) ====
A separate Linux server runs only VoIPmonitor. '''Recommended for production environments''' as it isolates monitoring from voice platform resources.


HEP is a lightweight protocol for capturing and mirroring VoIP packets. Many SBCs and sip proxies (such as Kamailio, OpenSIPS, FreeSWITCH) support HEP to send a copy of traffic to a monitoring server.
'''When Required:'''
* Windows-based PBXs
* Limited CPU/RAM/disk I/O on PBX server
* Zero monitoring impact needed
* Centralized capture from multiple sites


'''Configuration in voipmonitor.conf:'''
= Traffic Forwarding Methods =


<pre>
When using a dedicated sensor, you must forward traffic to it using one of these methods.
# Enable HEP support
 
hep = yes
== 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>


# Port to listen for HEP packets (default: 9060)
{{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>}}
hep_bind_port = 9060


# Optional: Bind to specific IP address
=== VMware/ESXi Virtual Switch ===
# hep_bind_ip = 0.0.0.0
</pre>


When <code>hep = yes</code>, VoIPmonitor listens for HEPv3 (and compatible HEPv2) packets and extracts the original VoIP traffic from the encapsulation.
For virtualized environments, VMware provides port mirroring at the virtual switch level.


'''Use Cases:'''
'''Standard vSwitch:'''
* Remote SBCs or PBXs export traffic to a centralized VoIPmonitor server
# In vSphere Client, navigate to ESXi host
* Kamailio/FreeSWITCH <code>siptrace</code> module integration
# Select virtual switch → Properties/Edit Settings → Enable Port Mirroring
* Environments where standard tunnels (GRE/ERSPAN) are not available
# Set source (SBC VM) and destination (VoIPmonitor VM) ports


'''Note:''' There is also <code>hep_kamailio_protocol_id_fix = yes</code> for Kamailio-specific protocol ID issues.
'''Distributed vSwitch:'''
# In vSphere Web Client → Networking → Select distributed switch
# Configure tab → Port Mirroring → Create mirroring session
# Specify source/destination ports and enable


== Distributed Deployment Models ==
{{Note|1=Distributed switch mirroring can span multiple ESXi hosts within a cluster.}}
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 ===
=== Multiple VoIP Platforms ===
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/MariaDB database to write CDRs. For PCAP retrieval, the GUI typically needs network access to each sensor's management port (default <code>TCP/5029</code>).
* '''Pros:''' Simple conceptual model.
* '''Cons:''' Requires opening firewall ports to each sensor and managing database credentials on every remote machine.


==== Alternative PCAP Access: NFS/SSHFS Mounting ====
Monitor multiple platforms (e.g., Mitel + FreeSWITCH) with a single sensor by mirroring multiple source ports to one destination port.


For environments where direct TCP/5029 access to remote sensors is impractical (e.g., firewalls, VPN limitations), you can mount remote spool directories on the central GUI server using NFS or SSHFS.
'''GUI differentiation:'''
* Filter by IP address ranges
* Filter by number prefixes
* Use separate sensors with unique <code>id_sensor</code> values


'''Use Cases:'''
{{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.}}
* Firewall policies block TCP/5029 but allow SSH or NFS traffic
* Remote sensors have local databases that need to be queried separately
* You want the GUI to access PCAPs directly from mounted filesystems instead of proxying through TCP/5029


'''Configuration Steps:'''
== Software-based Tunneling ==


1. **Mount remote spools on GUI server:**
When hardware mirroring is unavailable, use software tunneling to encapsulate and forward packets.


  Using NFS:
{| class="wikitable"
  <pre>
! Protocol !! Configuration Parameter !! Notes
  # On GUI server, mount remote spool directory
|-
  sudo mount -t nfs 10.224.0.101:/var/spool/voipmonitor /mnt/voipmonitor/sensor1
| IP-in-IP, GRE, ERSPAN || Built-in (auto-detected) || No additional config needed
  sudo mount -t nfs 10.224.0.102:/var/spool/voipmonitor /mnt/voipmonitor/sensor2
|-
| TZSP (MikroTik) || <code>udp_port_tzsp = 37008</code> ||
|-
| L2TP || <code>udp_port_l2tp = 1701</code> ||
|-
| VXLAN || <code>udp_port_vxlan = 4789</code> || Common in cloud environments
|-
| AudioCodes || <code>udp_port_audiocodes = 925</code> || See [[Audiocodes_tunneling|AudioCodes Tunneling]]
|-
| IPFIX (Oracle SBCs) || <code>ipfix*</code> options || Enable ipfix options in config
|}


  # Add to /etc/fstab for persistent mounts
=== HEP (Homer Encapsulation Protocol) ===
  10.224.0.101:/var/spool/voipmonitor  /mnt/voipmonitor/sensor1  nfs  defaults  0  0
  10.224.0.102:/var/spool/voipmonitor  /mnt/voipmonitor/sensor2  nfs  defaults  0  0
  </pre>


  Using SSHFS:
Lightweight protocol for mirroring VoIP packets. Supported by Kamailio, OpenSIPS, FreeSWITCH, and many SBCs.
  <pre>
  # On GUI server, mount remote spool via SSHFS
  sshfs voipmonitor@10.224.0.101:/var/spool/voipmonitor /mnt/voipmonitor/sensor1
  sshfs voipmonitor@10.224.0.102:/var/spool/voipmonitor /mnt/voipmonitor/sensor2


  # Add to /etc/fstab for persistent mounts (with key-based auth)
<syntaxhighlight lang="ini">
  voipmonitor@10.224.0.101:/var/spool/voipmonitor  /mnt/voipmonitor/sensor1  fuse.sshfs  defaults,IdentityFile=/home/voipmonitor/.ssh/id_rsa  0  0
# /etc/voipmonitor.conf
  </pre>
hep = yes
hep_bind_port = 9060
hep_bind_udp = yes
# Optional: hep_kamailio_protocol_id_fix = yes
</syntaxhighlight>


2. **Configure PCAP spooldir path in GUI:**
'''Known Limitations:'''


  In the GUI, go to '''Settings > System Configuration > Sniffer data path''' and set it to search multiple spool directories. Each directory is separated by a colon (<code>:</code>).
{{Warning|1='''HEP Correlation ID Not Supported:''' VoIPmonitor does NOT use HEP correlation ID (captureNodeID) to correlate SIP and RTP packets. If SIP and RTP arrive from different HEP sources, they will NOT be correlated into a single CDR.


  <pre>
VoIPmonitor correlates using standard SIP Call-ID, To/From tags, and RTP SSRC fields only. Feature request VS-1703 has been logged but there is no workaround currently.}}
  Sniffer data path: /var/spool/voipmonitor:/mnt/voipmonitor/sensor1:/mnt/voipmonitor/sensor2
  </pre>


  The GUI will search these paths in order when looking for PCAP files.
'''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.


3. **Register remote sensors in GUI:**
'''HEP3 with Port 0:''' Not captured by default. Add port 0 to sipport:


  Go to '''Settings > Sensors''' and register each remote sensor:
<syntaxhighlight lang="ini">
  * '''Sensor ID:''' Must match <code>id_sensor</code> in each remote's <code>voipmonitor.conf</code>
sipport = 0,5060
  * '''Name:''' Descriptive name (e.g., "Site 1 - London")
</syntaxhighlight>
  * '''Manager IP, Port:''' Optional with NFS/SSHFS mount (leave empty if mounting spools directly)


'''Important Notes:'''
== Cloud Packet Mirroring ==
* Each remote sensor must have a unique <code>id_sensor</code> configured in <code>voipmonitor.conf</code>
* Remote sensors write directly to their local MySQL database (or possibly to a central database)
* Filter calls by site using the <code>id_sensor</code> column in the CDR view
* Ensure mounted directories are writable by the GUI user for PCAP uploads
* For better performance, use NFS with async or SSHFS with caching options


'''Filtering and Site Identification:'''
Cloud providers offer native mirroring services using VXLAN or GRE encapsulation.
* In the CDR view, use the '''Sensor''' dropdown filter to select specific sites
* Alternatively, filter by IP address ranges using CDR columns
* The <code>id_sensor</code> column in the database uniquely identifies which sensor captured each call
* Sensor names can be customized in '''Settings > Sensors''' for easier identification


'''Comparison: TCP/5029 vs NFS/SSHFS'''
{| class="wikitable"
{| class="wikitable"
! Approach
! Provider !! Service Name
! Network Traffic
! Firewall Requirements
! Performance
! Use Case
|-
|-
| TCP/5029 Proxy (Standard)
| Google Cloud || Packet Mirroring
| On-demand fetch per request
| TCP/5029 outbound from GUI to sensors
| Better (no continuous mount overhead)
| Most deployments
|-
|-
| NFS Mount
| AWS || Traffic Mirroring
| Continuous (filesystem access)
| NFS ports (usually 2049) bidirectional
| Excellent (local filesystem speed)
| Local networks, high-throughput
|-
|-
| SSHFS Mount
| Azure || Virtual Network TAP
| Continuous (encrypted filesystem)
| SSH (TCP/22) outbound from GUI
| Good (some encryption overhead)
| Remote sites, cloud/VPN
|}
|}


=== Modern Mode: Client/Server Architecture (v20+) — Recommended ===
'''Configuration Steps:'''
This model uses a secure, encrypted TCP channel between remote sensors (clients) and a central sensor instance (server). The GUI communicates with the central server only, which significantly simplifies networking and security.
 
# 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:


This architecture supports two primary modes:
<syntaxhighlight lang="ini">
# '''Local Processing:''' Remote sensors process packets locally and send only lightweight CDR data over the encrypted channel. PCAPs remain on the remote sensor. On-demand PCAP fetch is proxied via the central server (to the sensor's <code>TCP/5029</code>).
udp_port_vxlan = 4789
# '''Packet Mirroring:''' Remote sensors forward the entire raw packet stream to the central server, which performs all processing and storage. Ideal for low-resource remote sites.
interface = eth0
sipport = 5060
</syntaxhighlight>


==== Architecture Diagrams (PlantUML) ====
{{Warning|1=Capturing only ingress or only egress results in incomplete CDRs and broken call data.}}


<kroki lang="plantuml">
'''Best Practices:'''
  @startuml
* Filter at source to forward only SIP/RTP ports
  skinparam shadowing false
* Monitor NIC bandwidth limits
  skinparam defaultFontName Arial
* Account for VXLAN overhead (~50 bytes) - may need jumbo frames
  skinparam rectangle {
* Ensure NTP sync across all VMs
    BorderColor #4A90E2
    BackgroundColor #FFFFFF
    stereotypeFontColor #333333
  }
  skinparam packageBorderColor #B0BEC5
  skinparam packageBackgroundColor #F7F9FC


  title Client/Server Architecture — Local Processing Mode
'''Alternative:''' Consider [[Sniffer_distributed_architecture|Client/Server architecture]] with on-host sensors instead of cloud mirroring for better performance.


  package "Remote Site" {
== Pre-Deployment Verification ==
    [Remote Probe/Sensor] as Remote
    database "Local Storage (PCAP)" as RemotePCAP
  }


  package "Central Site" {
For complex setups (RSPAN, ERSPAN, proprietary SBCs), verify compatibility before production deployment:
    [Central VoIPmonitor Server] as Central
    database "Central MySQL/MariaDB" as CentralDB
    [Web GUI] as GUI
  }


  Remote -[#2F6CB0]-> Central : Encrypted TCP/60024\nCDRs only
# Configure test mirroring with a subset of traffic
  Remote --> RemotePCAP : Stores PCAP locally
# Capture test calls with tcpdump: <code>sudo tcpdump -i eth0 -s0 port 5060 -w /tmp/test.pcap</code>
  Central --> CentralDB : Writes CDRs
# Verify pcap contains SIP and RTP: <code>tshark -r /tmp/test.pcap -Y "sip || rtp"</code>
  GUI -[#2F6CB0]-> Central : Queries data & requests PCAPs
# Submit pcap to VoIPmonitor support with hardware/configuration details
  Central -[#2F6CB0]-> RemotePCAP : Fetches PCAPs on demand (TCP/5029)
  @enduml
  </kroki>


<kroki lang="plantuml">
= Distributed Architectures =
  @startuml
  skinparam shadowing false
  skinparam defaultFontName Arial
  skinparam rectangle {
    BorderColor #4A90E2
    BackgroundColor #FFFFFF
    stereotypeFontColor #333333
  }
  skinparam packageBorderColor #B0BEC5
  skinparam packageBackgroundColor #F7F9FC


  title Client/Server Architecture — Packet Mirroring Mode
For multi-site monitoring, sensors can be deployed in various configurations.


  package "Remote Site" {
== Classic Mode: Standalone Sensors ==
    [Remote Probe/Sensor\n(Low Resource)] as Remote
  }


  package "Central Site" {
Each sensor operates independently:
    [Central VoIPmonitor Server] as Central
* Processes packets and stores PCAPs locally
    database "Central MySQL/MariaDB" as CentralDB
* Connects directly to central MySQL to write CDRs
    database "Central Storage (PCAP)" as CentralPCAP
* GUI needs network access to each sensor's <code>TCP/5029</code> for PCAP retrieval
    [Web GUI] as GUI
  }


  Remote -[#2F6CB0]-> Central : Encrypted TCP/60024\nRaw packet stream
'''Alternative: NFS/SSHFS Mounting'''
  Central --> CentralDB : Writes CDRs
  Central --> CentralPCAP : Processes & stores PCAPs
  GUI -[#2F6CB0]-> Central : Queries data & downloads PCAPs
  @enduml
  </kroki>


==== Step-by-Step Configuration Guide ====
If TCP/5029 access is blocked, mount remote spool directories on the GUI server:


; Prerequisites
<syntaxhighlight lang="bash">
* VoIPmonitor v20+ on all sensors.
# NFS mount
* Central database reachable from the central server instance.
sudo mount -t nfs 10.224.0.101:/var/spool/voipmonitor /mnt/voipmonitor/sensor1
* Unique <code>id_sensor</code> per sensor (< 65536).
* NTP running everywhere (see '''Time Synchronization''' below).


; Scenario A — Local Processing (default, low WAN usage)
# SSHFS mount
<pre>
sshfs voipmonitor@10.224.0.101:/var/spool/voipmonitor /mnt/voipmonitor/sensor1
# /etc/voipmonitor.conf on the REMOTE sensor (LOCAL PROCESSING)
</syntaxhighlight>


id_sensor              = 2          # unique per sensor (< 65536)
Configure GUI: '''Settings > System Configuration > Sniffer data path:'''
server_destination      = 10.224.0.250
<code>/var/spool/voipmonitor:/mnt/voipmonitor/sensor1:/mnt/voipmonitor/sensor2</code>
server_destination_port = 60024
server_password        = your_strong_password


packetbuffer_sender    = no        # local analysis; sends only CDRs
{{Tip|For NFS, use <code>hard,nofail,tcp</code> mount options for reliability.}}
interface              = eth0      # or: interface = any
sipport                = 5060      # example; add your usual sniffer options


# No MySQL credentials here — remote sensor does NOT write to DB directly.
== Modern Mode: Client/Server (v20+) — Recommended ==
</pre>


<pre>
Secure encrypted TCP channel between remote sensors and central server. GUI communicates only with central server.
# /etc/voipmonitor.conf on the CENTRAL server (LOCAL PROCESSING network)


server_bind            = 0.0.0.0
<kroki lang="mermaid">
server_bind_port        = 60024
%%{init: {'flowchart': {'nodeSpacing': 10, 'rankSpacing': 25}}}%%
server_password         = your_strong_password
flowchart LR
    subgraph "Local Processing"
        R1[Remote Sensor] -->|CDRs only| C1[Central Server]
         R1 -.->|PCAP on demand| C1
    end


mysqlhost              = 10.224.0.201
    subgraph "Packet Mirroring"
mysqldb                = voipmonitor
        R2[Remote Sensor] -->|Raw packets| C2[Central Server]
mysqluser              = voipmonitor
    end
mysqlpassword          = db_password
</kroki>


cdr_partition          = yes        # partitions for CDR tables
{| class="wikitable"
mysqlloadconfig        = yes       # allows DB-driven config if used
! 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
|}


interface              =            # leave empty to avoid local sniffing
For detailed configuration, see [[Sniffer_distributed_architecture|Distributed Architecture: Client-Server Mode]].
# The central server will proxy on-demand PCAP fetches to sensors (TCP/5029).
</pre>


; Scenario B — Packet Mirroring (centralized processing/storage)
'''Quick Start - Remote Sensor (Local Processing):'''
<pre>
# /etc/voipmonitor.conf on the REMOTE sensor (PACKET MIRRORING)


id_sensor              = 3
<syntaxhighlight lang="ini">
id_sensor              = 2
server_destination      = 10.224.0.250
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>


packetbuffer_sender    = yes        # send RAW packet stream to central
'''Quick Start - Central Server:'''
interface              = eth0      # capture source; no DB settings needed
</pre>
 
<pre>
# /etc/voipmonitor.conf on the CENTRAL server (PACKET MIRRORING)


<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
mysqlhost              = 10.224.0.201
mysqldb                = voipmonitor
mysqldb                = voipmonitor
mysqluser              = voipmonitor
mysqluser              = voipmonitor
mysqlpassword          = db_password
mysqlpassword          = db_password
cdr_partition          = yes
interface              =  # Leave empty - don't sniff locally
</syntaxhighlight>
== 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>
|}


cdr_partition          = yes
== Time Synchronization ==
mysqlloadconfig        = yes


# As this server does all analysis, configure as if sniffing locally:
{{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).}}
sipport                = 5060
# ... add your usual sniffer/storage options (pcap directories, limits, etc.)
</pre>


==== Firewall Checklist (Quick Reference) ====
== First Startup ==
* '''Modern Client/Server (v20+):'''
** '''Central Server:''' Allow inbound <code>TCP/60024</code> from remote sensors. Allow inbound <code>TCP/5029</code> from GUI (management/API to central sensor).
** '''Remote Sensors (Local Processing only):''' Allow inbound <code>TCP/5029</code> from the central server (for on-demand PCAP fetch via proxy). Outbound <code>TCP/60024</code> to the central server.
* '''Cloud Mode:'''
** '''Remote Sensors:''' Allow outbound <code>TCP/60023</code> to <code>cloud.voipmonitor.org</code>.


== Configuration & Checklists ==
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


=== Parameter Notes (clarifications) ===
If you see <code>Table 'cdr_next_1' doesn't exist</code> errors, check DB connectivity and privileges.
* '''<code>id_sensor</code>''' — Mandatory in any distributed deployment (Classic or Client/Server). Must be unique per sensor (< 65536). The value is written to the database and used by the GUI to identify where a call was captured.
* '''<code>cdr_partition</code>''' — In Client/Server, enable on the central server instance that writes to the database. It can be disabled on remote "client" sensors that only mirror packets.
* '''<code>mysqlloadconfig</code>''' — When enabled, the sensor can load additional parameters dynamically from the <code>sensor_config</code> table in the database. Typically enabled on the central server sensor that writes to DB; keep disabled on remote clients which do not access DB directly.
* '''<code>interface</code>''' — Use a specific NIC (e.g., <code>eth0</code>) or <code>any</code> to capture from multiple NICs. For <code>any</code> ensure promiscuous mode on each NIC.


=== Initial Service Start & Database Initialization ===
= Deployment Comparison =
After installation, the '''first startup''' against a new/empty database is critical.
# Start the service: <code>systemctl start voipmonitor</code>
# Follow logs to ensure schema/partition creation completes:
#* <code>journalctl -u voipmonitor -f</code>
#* or <code>tail -f /var/log/syslog | grep voipmonitor</code>


You should see creation of functions and partitions shortly after start. If you see errors like <code>Table 'cdr_next_1' doesn't exist</code>, the sensor is failing to initialize the schema — usually due to insufficient DB privileges or connectivity. Fix DB access and restart the sensor so it can finish initialization.
{| 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'''
|}


=== Time Synchronization ===
= Troubleshooting =
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 (e.g., <code>chrony</code> or <code>ntpdate</code>) to keep clocks in sync.
 
== NFS/SSHFS Connectivity ==
 
Missing data for specific time periods usually indicates storage server connectivity issues.


== Comparison of Remote Deployment Modes ==
{| class="wikitable"
{| class="wikitable"
! Deployment Model
! Symptom !! Likely Cause !! Solution
! Packet Processing Location
! PCAP Storage Location
! Network Traffic to Central Server
! GUI Connectivity
|-
|-
| Classic Standalone
| Data gap in time period || NFS/SSHFS server unreachable || Check logs for "not responding, timed out"
| Remote
| Remote
| Minimal (MySQL CDRs)
| GUI ↔ each Sensor (management port)
|-
|-
| '''Modern Client/Server (Local Processing)'''
| Stale file handle || Server rebooted or export changed || Remount NFS share
| Remote
| Remote
| Minimal (Encrypted CDRs)
| '''GUI ↔ Central Server only''' (central proxies PCAP fetch)
|-
|-
| '''Modern Client/Server (Packet Mirroring)'''
| Connection resets || Network interruption || Check network stability
| '''Central'''
|-
| '''Central'''
| GUI shows "File not found" || Mount point dismounted || Verify mount with <code>mount | grep nfs</code>
| High (Encrypted full packets)
| '''GUI ↔ Central Server only'''
|}
|}


== FAQ & Common Pitfalls ==
<syntaxhighlight lang="bash">
* '''Do remote sensors need DB credentials in Client/Server?''' No. Only the central server instance writes to DB.
# Check for NFS errors
* '''Why is <code>id_sensor</code> required everywhere?''' The GUI uses it to tag and filter calls by capture source.
grep "nfs: server.*not responding" /var/log/syslog
* '''Local Processing still fetches PCAPs from remote — who connects to whom?''' The GUI requests via the central server; the central server then connects to the remote sensor's <code>TCP/5029</code> to retrieve the PCAP.
grep "nfs.*timed out" /var/log/syslog
== 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, AudioCodes, IPFIX). 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, PCAPs remain remote with central-proxied fetch) and packet mirroring (sending full, raw packets for central processing), which is ideal for low-resource endpoints. The article also explains an alternative approach for classic remote sensors: mounting PCAP spools via NFS or SSHFS when TCP/5029 access to sensors is blocked by firewalls. The guide concludes with step-by-step configuration, firewall rules, critical parameter notes, and the importance of NTP plus first-start DB initialization.
# 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 =
 
'''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, architecture, topology, on-host, dedicated sensor, port mirroring, SPAN, RSPAN, traffic mirroring, tunneling, GRE, TZSP, VXLAN, HEP, AudioCodes, IPFIX, remote sensor, multi-site, client server mode, packet mirroring, local processing, firewall rules, NTP, time synchronization, cloud mode, NFS, SSHFS, spooldir mounting
'''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:'''
'''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 (<code>packetbuffer_sender</code>) 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?
* How can I access PCAP files from remote sensors if TCP/5029 is blocked?
* How do I configure HEP (Homer Encapsulation Protocol)?
* How do I configure NFS or SSHFS to mount remote PCAP spools?
* Does VoIPmonitor use HEP correlation ID to correlate SIP and RTP?
* How do I configure the GUI sniffer data path for multiple mounted spools?
* Why are SIP and RTP from different HEP sources not correlated?
* Can I run the sensor on the same machine as my Asterisk/FreeSWITCH server?
* How do I capture HEP3 packets with port 0?
* What is a SPAN port and how is it used with VoIPmonitor?
* How do I configure cloud packet mirroring (GCP/AWS/Azure)?
* Why is NTP important for a distributed VoIPmonitor setup?
* Why do I get incomplete CDRs with cloud mirroring?
* What is HEP and how do I configure VoIPmonitor to receive HEP packets?
* What is the difference between classic and client/server deployment?
* How do I configure GRE, ERSPAN, and VXLAN tunneling for VoIPmonitor?
* 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 16:49, 8 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

Known Limitations:

⚠️ Warning: HEP Correlation ID Not Supported: VoIPmonitor does NOT use HEP correlation ID (captureNodeID) to correlate SIP and RTP packets. If SIP and RTP arrive from different HEP sources, they will NOT be correlated into a single CDR.

VoIPmonitor correlates using standard SIP Call-ID, To/From tags, and RTP SSRC fields only. Feature request VS-1703 has been logged but there is no workaround currently.

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

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

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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