Nast is a packet sniffer and a LAN analyzer based on Libnet and Libpcap.
As analyzer tool, it has many features like:

              * Build LAN hosts list
              * Follow a TCP-DATA stream
              * Find LAN internet gateways
              * Discorver promiscous nodes
              * Reset an established connection
              * Perform a single half-open portscanner
              * Perform a multi half-open portscanner
              * Find link type (hub or switch)
              * Catch daemon banner of LAN nodes
              * Control arp answers to discover possible arp-spoofings
              * Byte couting with an optional filter
              * Write reports logging

It also provides a ncurses menu.

WWW: http://nast.berlios.de