The tcpsound(1) utility will play sounds in response to network traffic permitting a user to literally listen to a network. Specifically tcpsound forks a pseudo terminal in which to run tcpdump(8), parses that output, and plays a wide variety of user configuable sounds. Interpreting the output of tcpdump in a pty permits tcpsound to first ssh(1) to a remote host if desired.
Requirements
To install tcpsound you will need tcpdump(8) on the machine on which you will be capturing packets. On the local machine (where you will be playing the sounds of those packets) the libsdl sound library and unless you're using the OSX binary package libmba-0.9.1 or later is required. Libsdl is fairly standard on Linux machines but you may need to install development packages (specifially SDL-devel and SDL_mixer-devel for my RH 7.3 machine). For OSX I built the source package from libsdl.org.
Running
Provided the above requirements have been met, the sound is working properly on the local machine, and the user has root access on both the target machine (to capture packets in promiscuous mode) and local machine (to access the sound device), a typical commandline for tcpsound is:
# tcpsound -r myserver.com ! port ssh
This will forkpty(3), ssh to myserver.com, run tcpdump -nn ! port ssh (note the ! port ssh filter is important so you're not listening to yourself) and interpret the output playing sounds defined in the /root/.tcpsound config. Adjust the configuration file to associate different WAV files with incoming or outgoing traffic on specific ports. See the tcpsound(1) man page for details.
Mac OSX Binary
A binary package for Mac OSX has also been prepared. This package does not need libmba but it does need libSDL. Install libSDL first. Then to install tcpsound and run as follows:
$ tar -xvzf tcpsound-0.3.1.darwin.bin.tar.gz
$ cd tcpsound-0.3.1
$ sudo make -f Makefile.darwin install
$ sudo tcpsound -r myserver ! port ssh