Netcat
Computer program
netcat is a computer networking utility for reading from and writing to network connections using TCP or UDP. The command is designed to be a dependable back-end that can be used directly or easily driven by other programs and scripts. Wikipedia
Example: nc -p 31337 -w 5 host.example.com 42
Syntax: nc -46cDdFhklNnrStUuvz -C certfile -e name -H hash -I length -i interval -K keyfile -M ttl -m minttl -O length -o staplefile -P proxy_username -p source_port -R CAfile -s source -T keyword -V rtable -w timeout -X proxy_protocol -x proxy_address:port destination port
Function: Arbitrary TCP and UDP connections and listens
Developer(s): Avian Research
Initial release: October 28, 1995; 28 years ago
Operating system: Unix and Unix-like, DOS, Microsoft Windows, Windows CE