ngrep strives to provide most of GNU grep's common features,applying them to the network layer. ngrep is a pcap-aware tool that will allow you to specify extended regular expressions to match against data payloads of packets.
SUPPORT/REPORTING BUGS: please use https://github.com/jpr5/ngrep/issues Thank you!
This tool is one of the main tools I use for my work. If you haven't tried it, and you tend to use tcpdump and grep, this is your salvation.