Debug Capturing on VoIP Interfaces

You can debug capture (record) network traffic on the device's VoIP interfaces per VLAN that is configured in the Ethernet Devices table (see Configuring Underlying Ethernet Devices). You can also capture traffic on one of the device's kernel interfaces (e.g., eth0, eth1, lo, or tun0). This may be useful, for example, to capture packets on the tunneling interface used for WebSocket traffic.

You can send the captured traffic to the following:

CLI terminal screen (tcpdump format): The captured network packets are displayed in the CLI until you end the capture, by pressing the CTRL + C key combination.
Remote server (TFTP or FTP): The capture is saved as a PCAP file (suitable for Wireshark) and sent to a specified server (default is TFTP) . The generated PCAP file is in the Extensible Record Format (ERF) and is saved on the device during the capture. The maximum file size that can be saved to the device is 10 MB and as long as the capture continues, the packets are written to this 10-MB file in a cyclic manner. When you end the capture (by pressing the CTRL + C key-combination), the device sends the capture file to the server.

The following procedure describes how to configure debug capturing for a specific VLAN. For debug capturing a kernel interface, use the same commands, but instead of vlan use kernel-dev, as shown below:

# debug capture voip interface kernel-dev <Name, e.g., tun0>
To capture traffic on VoIP VLAN interface:
1. Define the VLAN ID on which you want to do the capture:
# debug capture voip interface vlan <VLAN ID>
2. Define the protocol that you want to capture (all|arp|icmp|ip|ipv6|tcp|udp):
# debug capture voip interface vlan <VLAN ID> proto <Protocol>
3. Define a source and/or destination IP address to be captured (any|ipv4_address|ipv6_address):
# debug capture voip interface vlan <VLAN ID> proto <Protocol> host < IPv4 / IPv6 Address>

At this stage, you can press Enter to output the capture to the CLI terminal window, or you can continue with the next step to configure additional commands.

4. Define a source and/or destination port number to be captured (any|[1-65535]):
# debug capture voip interface vlan <VLAN ID> proto <Protocol> host < IPv4 / IPv6 Address> port <Port>

At this stage, you can press Enter to output the capture to the CLI terminal window, or you can continue with the next step to configure additional commands.

5. Define the IP address (IPv4) of the server (TFTP or FTP) to where you want the device to send the captured file:
# debug capture voip interface vlan <VLAN ID> proto <Protocol> host <IP Address> ftp-server|tftp-server < IPv4 / IPv6 Address>
6. Press Enter to start debug capturing (and temporarily saves the capture to a file on the device).
7. Press the CTRL+C key-combination to stop the capture and send the file to the defined server.