I just started high school, and there's an unencrypted, Internet-enabled 802.11b network in our science building. However, there isn't a DHCP server automatically allocating me an IP and gateway IP, or the server just doesn't like my MAC address.

Does anybody know of any utility for Mac OS X that could do some sort of packet sniffing to get the "from/to" addresses from packets sent to and from clients to the server?

Thanks for all your help in advance.