Tethereal is a network protocol analyzer. It lets you capture packet
data from a live network, or read packets from a previously saved
capture file, either printing a decoded form of those packets to the
standard output or writing the packets to a file. Tethereal's native
capture file format is libpcap format, which is also the format used
by tcpdump and various other tools.

-rwxr-xr-x    1 root    root           121208 oct 11 08:00 /usr/bin/tethereal
-rw-r--r--    1 root    root            12697 oct 11 08:00 /usr/share/man/man1/tethereal.1.bz2