How To: Install Ngrep Source to Debug SIP Packets on Asterisk, Opensips, Freswitch
First you need to download ngrep with the following command
Once you have the ngrep archive on your linux system extract the source with the following command
tar -jxf ngrep-1.45.tar.bz2
Then enter the directory and start the installation commands
Now you are all done and have the ability to use ngrep as you see fit. I will have documentation on how to use ngrep for the purpose of sip debugging so come back to check it out.