The ngrep application is a cross between grep and tcpdump. It watches network ports and displays packets that match a pattern. You must have root privileges to run ngrep.
Finding packets with ngrep
Getting ready
You may not have the ngrep package installed. However, it can be installed with most package managers:
# apt-get install ngrep # yum install ngrep
How to do it...
The ngrep application accepts a pattern to watch for (such as grep), a filter string (such as tcpdump), and many command-line flags to fine-tune its behavior.
The following example watches the traffic on port 80 and reports any packets with the...