Help connecting to a server port in C#

I'm having a problem connecting Unity to a Linux server with a C++ program running on a port.

I can telnet to the Linux server and that is doing what I told it to,

Does anyone have a good, basic walk through of how to get a block of text from an ip address/port and read it into a Unity C# string?

I've spent the last week trying things and I'm sure that after all the reading and downloading I'm now just more confused than when I started. Please, someone, point me in the right direction.

All the best

Iain