Пакет ngrep: Информация

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.  It currently recognizes TCP and UDP across ethernet, ppp and
slip interfaces, and understands bpf filter logic in the same fashion
as more common packet sniffing tools, like tcpdump and snoop.