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  • How to capture large or permanent PCAP traces

If PCAP traces bigger than 500 KB are needed, the internal PCAP trace functionality of the Snom deskphone cannot be used due to its storage space limitation.

There are two ways to capture large PCAP traces: on a PC or a USB mass storage device.

PCAP trace on a PC within the same network

You will need to make sure all packets to and from the phone also reach the PC, which can be achieved by:

  • Either using a managed switch which supports port mirroring and mirror all packets to the PC
  • Or connecting both the PC and the phone to a hub
You can find more information about Ethernet capture setup on the Wireshark wiki page.

Once you have all packets reaching the PC, you can capture them in one the following ways, depending on whether you are using Windows, Linux or Mac OSX:

Windows or Mac OS:

  1. Install Wireshark (
  2. Start Wireshark
  3. Start capturing: click the Capture menu, choose Options, press 'Start' for the appropriate interface
  4. After the test is over, stop capturing by clicking Capture -> Stop
  5. Save the capture by clicking File -> Save


Install tcpdump and run as root using command:

# tcpdump -s0 -w dump.pcap -i eth0

Where dump.pcap is the saved PCAP trace and eth0 is the network interface.

PCAP trace on USB mass storage device

Alternatively you can store the PCAP trace on a USB thumb drive. The duration of the trace depends on the storage size of the USB thumb drive.

You can find the instructions for this method here: How to store a PCAP trace into an USB mass-storage device

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