ngrep: ngrep (network grep)
ngrep:
ngrep: ngrep strives to provide most of GNU grep's common features,
ngrep: applying them to the network layer. ngrep is a pcap-aware tool that
ngrep: will allow you to specify extended regular or hexadecimal expressions
ngrep: to match against data payloads of packets. It currently recognizes
ngrep: IPv4/6, TCP, UDP, ICMPv4/6, IGMP and Raw across Ethernet, PPP, SLIP,
ngrep: FDDI, Token Ring and null interfaces, and understands BPF filter
ngrep: logic in the same fashion as more common packet sniffing tools,
ngrep: such as tcpdump and snoop.
ngrep: