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.
Dropbear SSH Server and Client - Dropbear is a relatively small SSH 2 server and client.
Debookee - Debookee is the simplest & most powerful network traffic analyzer for macOS.
OpenSSH - OpenSSH is a free version of the SSH connectivity tools that technical users rely on.
SmartSniff - SmartSniff is a packet sniffer that capture TCP/IP packets and display them as sequence of conversations between clients and servers.
Ethereal - Ethereal® is used by network professionals around the world for troubleshooting, analysis...