Linux and Windows Command Line Tools for Troubleshooting

See SIP traces for information on how to obtain PCAP SIP traces on Linux-based phone systems. Most Asterisk and FreeSWITCH systems run on Linux.

See NAT and firewall settings for guidance on what ports are required to be open on your firewall. Static NAT entries (port forwarding) is only required if you run your own phone system on your network.

Testing Network Connectivity


Ctrl+C to stop

Checks host is up and reachable. Note that some servers may be configured to ignore ICMP Echo requests (pings).

Also useful for determining latency. Should be under 150ms


Checks route taken to the SureVoIP website. Useful for identifying which gateways the data takes to reach the target.

Send the output of this to SureVoIP Support if requested.


MTR is a combination of traceroute and ping. You can press P to pause the test to enable you to copy and paste the output.

For Windows you will need to download WinMTR

For Linux you may need to install the MTR package (apt-get install mtr or yum install mtr)

Analysing Traffic

Sometimes it may be necessary to analyse SIP or other network data.

See SIP traces support guide for further guidance.

Ensure ngrep is installed on the server. Also install Wireshark on your desktop.

For all traffic on the SERVER run:

tcpdump -i eth0 -s 1500 -w trafficCapture.pcap

Leave for 5 to 10 minutes, or make a test call. Then press Ctrl+C to stop capture.

For pure SIP run:

### capture all SIP packets on 5060 on all interfaces
ngrep -W byline -td any . port 5060
### capture all SIP packets containing 'username' on port 5060 on all interfaces
ngrep -W byline -tqd any username port 5060

If Wireshark is on a different computer than the server, tar -czf FILENAME.tgz FILENAME.cap to compress it.

Transfer the file via rsync or scp or another method to the Wireshark computer (you may want to take md5sum or sha1sum).

rsync -avh --progress FILENAME.tgz user@DESKTOP:~
scp FILENAME.tgz user@DESKTOP:~

Note the above rsync/scp commands may not work as expected if you are behind a NAT.

  • using_command_line_tools_on_windows_and_gnu_linux.txt
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