Utility for testing TCP/UDP Connectivity

I needed a utility to test connectivity between two machines for several tcp/udp ports.
The requirements for this utility was that it should be simple and wont need the .net runtime.

I found PCATTCP  a command-line sockets-based benchmarking tool for measuring TCP and UDP performance between two systems. It was originally developed for the BSD operating system starting in 1984 and was ported to use windows sockets.

Its great its small (65k) and it really helped me !