tcpdump
tcpdump is a simple command-line sniffing tool found on most router, firewall, and Linux/UNIX systems. There is also a version that runs on Windows made by micoOLAP, which can be found at http://www.microolap.com/products/network/tcpdump/. It's not free, but there is a trial version. The nice thing about this version is that it is one simple executable which can be uploaded to a system and used without installing extra drivers. It can be launched on a cracked system to which you have shell access. Your shell must have system or administrator level access to work, because NICs will not run in promiscuous mode without administrative privileges. Another packet dump tool is Windump.exe, available from http://www.winpcap.org/windump/install/ ...