Systemd for voipmonitor service management

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Revision as of 19:34, 7 January 2026 by Admin (talk | contribs) (Add troubleshooting for multiple VoIPmonitor instances (init.d vs systemd conflict causing duplicate packets and corrupted RRD))


This guide provides the recommended method for managing the VoIPmonitor sensor service using systemd on modern Linux distributions.

Overview

Modern Linux distributions (Debian, Ubuntu, CentOS, RHEL, AlmaLinux) use systemd as the primary service manager. The recommended approach is to create a systemd unit file that wraps the reliable /etc/init.d/voipmonitor script, ensuring compatibility across various distributions.

⚠️ Warning: Always use systemctl commands to manage the service. Do not use the legacy service command (e.g., service voipmonitor start) as systemd may lose track of the process state.

Unit File Configuration

Create file /etc/systemd/system/voipmonitor.service: 

[Unit]
Description=VoIPmonitor sniffer
After=syslog.target
After=network.target
After=mysql.service

[Service]
Type=forking
Restart=no
TimeoutSec=5min
IgnoreSIGPIPE=no
KillMode=process
GuessMainPID=no
RemainAfterExit=yes
SuccessExitStatus=5 6
ExecStart=/etc/init.d/voipmonitor start
ExecStop=/etc/init.d/voipmonitor stop
PrivateTmp=false

[Install]
WantedBy=multi-user.target

Dependency Customization

MySQL/MariaDB

The line After=mysql.service is only required if the database is installed locally on the same server. If your database runs on a remote server, you can remove this line.

Napatech Cards

If you use Napatech hardware acceleration cards, add the following lines to the [Unit] section to ensure drivers load before VoIPmonitor starts: 

Before=network-pre.target
Wants=network-pre.target
After=ntservice.service
Requires=ntservice.service

Activation and Management

Reload systemd after changes

systemctl daemon-reload

Enable start on boot

systemctl enable voipmonitor

Standard management commands

# Start the service
systemctl start voipmonitor

# Stop the service
systemctl stop voipmonitor

# Restart the service
systemctl restart voipmonitor

# Check status and view recent logs
systemctl status voipmonitor

Troubleshooting

Service Not Starting vs Connection Failures

Before troubleshooting systemd issues, identify whether the problem is with the systemd service OR with network connectivity:

Problem Type Symptoms Solution
Service fails to start systemctl start voipmonitor returns error, service shows failed status Continue with this guide
Service starts but cannot connect Service shows active (running) but logs show "cannot connect to server" See Distributed Architecture Troubleshooting

Unit File Syntax Errors

If you encounter errors like: 

Error: Assignment outside of section. Ignoring.
Job for voipmonitor.service failed because the control process exited with error code.

This indicates syntax errors in the unit file. To bypass and fix: 

# 1. Identify existing processes
ps aux | grep voipmonitor

# 2. Kill the watchdog process first (find its PID from ps output)
kill <PID_WATCHDOG>

# 3. Kill the main voipmonitor process
kill -9 <PID_VOIPMONITOR>

# 4. Stop using init.d script
/etc/init.d/voipmonitor stop

# 5. Start using init.d script (bypasses broken systemd unit)
/etc/init.d/voipmonitor start

Common Unit File Errors

  • Missing [Unit], [Service], or [Install] section headers
  • Assignments placed outside of their proper sections
  • Typos in directive names (e.g., ExecStar instead of ExecStart)
  • Missing equals (=) signs between directive and value

After fixing the unit file: 

systemctl daemon-reload
systemctl start voipmonitor

Multiple VoIPmonitor Processes Running

If you see multiple voipmonitor processes running simultaneously, or if the GUI shows duplicate SIP packets and corrupted RRD (Round-Robin Database) statistics, you may have a service manager conflict. This commonly occurs when both the legacy init.d script and the systemd service attempt to start VoIPmonitor at the same time.

⚠️ Warning: Multiple VoIPmonitor instances writing to the same RRD files simultaneously will immediately corrupt the statistics data. Do not ignore this problem until RRD graphs display correctly.

Symptoms

  • Duplicate SIP packets appearing in the GUI for the same call
  • RRD graphs showing errors or missing data
  • Multiple voipmonitor processes in ps aux | grep voipmonitor
  • GUI may show higher-than-expected call counts or inconsistent statistics

Root Cause

On modern systems (Ubuntu 20.04+, Debian 10+), systemd is the default init system. However, systemd automatically generates services for existing /etc/init.d scripts. If both a native systemd unit file (/etc/systemd/system/voipmonitor.service) and the init.d wrapper service are enabled, both attempt to start VoIPmonitor simultaneously.

Step 1: Stop All Running Processes

First, stop all voipmonitor processes to prevent ongoing RRD corruption: 

# Force-kill all voipmonitor processes
sudo killall -9 voipmonitor

# Verify no processes remain
ps aux | grep voipmonitor

Step 2: Identify Conflicting Services

Determine which services are enabled and conflicting: 

# Check for systemd unit files
systemctl list-unit-files | grep voipmonitor

# Check for init.d script existence
ls -l /etc/init.d/voipmonitor

# Check enabled systemd services
systemctl is-enabled voipmonitor.service

Step 3: Disable the Redundant init.d Wrapper

The recommended approach is to use the native systemd unit file (documented above). To prevent the init.d wrapper from starting VoIPmonitor automatically while keeping the script available for manual use, remove the execute permission: 

# Remove execute permission from init.d script (prevents systemd from auto-starting it)
sudo chmod -x /etc/init.d/voipmonitor

# Verify permissions are now removed
ls -l /etc/init.d/voipmonitor

ℹ️ Note: This disables the SysV compatibility service generated by systemd from the /etc/init.d/voipmonitor script. The script remains available for manual execution if needed, but systemd will no longer attempt to start it automatically.

Step 4: Corrupted RRD Files

Multiple instances writing to the same RRD files simultaneously cause immediate corruption. The corrupted RRD files must be deleted so the single, correctly-running instance can regenerate them with clean data.

See RRD Graph Errors Troubleshooting for complete instructions. The short version: 

# Stop the service first if it's still running
systemctl stop voipmonitor

# Delete all corrupted RRD files (safe operation - files will be regenerated)
sudo rm -f /var/spool/voipmonitor/rrd/*

# Restart the service
systemctl start voipmonitor

Step 5: Restart with systemd

Now start the service using the correct systemd method: 

# Enable systemd service (ensures it starts on boot)
sudo systemctl enable voipmonitor

# Start the service
sudo systemctl start voipmonitor

# Verify it's running correctly
sudo systemctl status voipmonitor

Step 6: Verify Single Instance

# Check that only one main process is running (ignore grep output and threads)
ps aux | grep "[v]oipmonitor"

You should see only a single main process (possibly with multiple threads/worker processes), not multiple independent instances.

💡 Tip: After fixing the service conflict, always use systemctl commands (start, stop, restart, status) to manage VoIPmonitor. Do not use the legacy service voipmonitor start or direct /etc/init.d/voipmonitor start commands, as this may cause systemd to lose track of the process and create conflicts.

Verification Steps

1. Make a test SIP call and verify only ONE CDR record appears in the GUI 2. Navigate to Settings > Sensor and confirm status shows "Active (running)" with green indicator 3. Check RRD graphs after a few minutes - data should be displaying without errors 4. Monitor process count with ps aux | grep "[v]oipmonitor" to ensure only one instance persists

Internal Watchdog and SystemD

When using SystemD to manage the VoIPmonitor service, there is a potential issue if the internal watchdog restarts the VoIPmonitor process. By default, the internal watchdog may attempt to restart the binary directly. When this happens, the main process ID (PID) tracked by SystemD exits, causing SystemD to mark the service as "failed" or "dead," even though a new process has been spawned.

⚠️ Warning: If the internal watchdog is enabled but not configured to use SystemD for restarts, the SystemD service status will incorrectly show the service as failed after a watchdog-triggered restart.

Configuring the Watchdog to Use SystemD

To ensure that SystemD correctly tracks the service status after a watchdog-triggered restart, edit the /etc/voipmonitor.conf file:

  1. Enable the watchdog (if not already enabled): 
    watchdog = yes
  2. Add the following line to make the watchdog use SystemD for restarts: 
    watchdog_run_command = systemctl restart voipmonitor

Why This Works

Setting watchdog_run_command forces the watchdog to hand over the restart process to SystemD via systemctl restart. This ensures that SystemD manages the entire stop/start cycle, keeps its internal state tracking consistent, and correctly reports the service as active (running) after a watchdog-triggered restart.

Verification

After configuration, you can verify that SystemD correctly tracks the service: 

# Check service status
systemctl status voipmonitor

# Service should show "active (running)" not "failed" or "dead"

AI Summary for RAG

Summary: Guide for managing VoIPmonitor sensor with systemd by wrapping the init.d script in a unit file. Configuration uses Type=forking with RemainAfterExit=yes. Key dependencies: After=mysql.service for local DB, After=ntservice.service with Requires=ntservice.service for Napatech. Always use systemctl commands (not legacy service) for reliable process tracking. For watchdog integration, set watchdog_run_command = systemctl restart voipmonitor to prevent systemd from incorrectly reporting failed status after watchdog-triggered restarts. For multiple instance conflicts (duplicate packets, corrupted RRD), remove execute permission from /etc/init.d/voipmonitor (chmod -x) to prevent systemd from auto-starting the init.d wrapper, then delete corrupted RRD files and restart with systemctl start voipmonitor.

Keywords: systemd, systemctl, voipmonitor.service, init.d wrapper, unit file, Type=forking, RemainAfterExit, After=mysql.service, Napatech, daemon-reload, watchdog, watchdog_run_command, service management, multiple instances, duplicate packets, corrupted RRD

Key Questions:

  • What is the recommended systemd unit file for VoIPmonitor?
  • Why should I use systemctl instead of the service command?
  • How do I configure systemd dependencies for MySQL and Napatech?
  • How do I make VoIPmonitor start automatically on boot?
  • How do I bypass a broken systemd unit file?
  • What causes "Assignment outside of section" error in systemd?
  • Why does systemd show service as failed after watchdog restart?
  • What should I set watchdog_run_command to when using systemd?
  • Multiple voipmonitor processes running - how to fix duplicate packets and corrupted RRD?
  • How do I stop init.d and systemd from conflicting and starting multiple VoIPmonitor instances?
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