CODEWITHSUNDEEP
udpsipnetcat
fedd
fedd

Reputation: 941

Testing the SIP basics with netcat udp

I'm writing my own simple soft phone, but I fail to understand the basics of how SIP works, so I wanted to see on a low level how a server responds to messages like the REGISTER request. I have a simple OpenWRT PBX in my router at home, and a couple of hard and Android softphones are working normally - they seem to register, perform calls both between themselves and outside too, so I'm sure it's functional. It's serving requests over UDP and port 5060.

But when I try to get a response from the server on a low level, how I used to do with tcp and telnet, just to see what's going on when a phone is working, the server doesn't seem to respond anything.

Can you please guide me how I can use netcat or some other telnet-like tool to see how the server responds over udp to any request, be them good or malformed?

Upvotes: 1

Views: 3073

Answers (2)

mail2subhajit
mail2subhajit

Reputation: 1150

Use tcpdump tool over telnet

Tcpdump Commands – A Network Sniffer Tool

check the link below.

https://www.tecmint.com/12-tcpdump-commands-a-network-sniffer-tool/

Upvotes: 1

tomrtc
tomrtc

Reputation: 555

The good tool is Wireshark very good support for SIP message flow and RTP/RTCP.

You may capture the packets from the OpenWRT PBX and from your development device in order to compare things. Good learning!

Upvotes: 0

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