Wireshark - Wireshark is a network protocol analyzer for Unix and Windows. It lets you capture and interactively browse the traffic running on a computer network.
netcat - Netcat is a featured networking utility which reads and writes data across network connections...
NetworkMiner - NetworkMiner is a Network Forensic Analysis Tool (NFAT) for Windows.
SmartSniff - SmartSniff is a packet sniffer that capture TCP/IP packets and display them as sequence of conversations between clients and servers.
PCAPdroid - PCAPdroid is an android app to capture the phone traffic and analyze it remotely (e.g. via Wireshark). The traffic can be easily downloaded from a remote device thanks to the integrated HTTP server, or streamed to a remote UDP receiver.
tcpdump - tcpdump is a common packet analyzer that runs under the command line.