From the tcpcat README: Tcpcat is a simple program that is like `cat' but it works over TCP streams to allow you to cat from one host to another. The host common way to use this program whould be something like this: on host a: $ tcpcat -l 93255 | gzip -dc | tar xvf - on host b: $ tcpcat -h hosta:93255 file.tar.gz Another good use for this program is debugging network stuff. When debugging a newtork client or server you can pipe the output of tcpcat to a hex dump (I recomend xxd which comes with vim). Also it can act as a crude telnet server when invoded with --listen, --input, and --output, this mode is quite useful for network program debugging as well.