Want to get down and dirty and find out what kind of traffic is on your network? Well, a packet sniffer is a great tool for this, and OS X has a copy of tcpdump, the open-source packet sniffer program, pre-installed.
Please note three things about tcpdump:
- It's a command line tool so you'll have to use the Terminal. (See the manual (man tcpdump) pages for options.)
- You have to be root to use it (or use sudo)
- It can be used for good or evil. Please make the right choice.
As a networking teacher, it's a great way to show students how insecure their network traffic really is (especially stuff like telnet and ftp).
Mac OS X Hints
http://hints.macworld.com/article.php?story=20010406124043420