lay back and relax

netcat6 is an IPv6-enabled clone of the original netcat utility.

From the netcat README:

"Netcat is a simple Unix utility which reads and writes data across
network connections. It is designed to be a reliable "back-end" tool
that can be used directly or easily driven by other programs and
scripts. At the same time, it is a feature-rich network debugging and
exploration tool, since it can create almost any kind of connection you
would need and has several interesting built-in capabilities. Netcat,
or "nc" as the actual program is named, should have been supplied long
ago as another one of those cryptic but standard Unix tools."

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 or hexadecimal
expressions to match against data payloads of packets. It currently recognizes IPv4/6, TCP,
UDP, ICMPv4/6, IGMP and Raw across Ethernet, PPP, SLIP, FDDI, Token Ring and null interfaces,
and understands BPF filter logic in the same fashion as more common packet sniffing tools,
such as tcpdump and snoop.