Monogame and cross platform multiplayer

Any data being transmitted only needs to be interpreted on both sides, at the end of the day it's just ones and zeros in a particular protocol. As long as they both understand the messages it's not an issue if they are windows, linux or on a potato.

If you are asking for a specific library to use, just google it; there are many.

Actually, MonoGame does use Lidgren and it is required to include with the framework.

A really good cross platform networking library (with a very simple API design) that I recommend is Enet. http://enet.bespin.org/

It works on Windows, MacOSX, and Linux of all forms. It uses a very reliable and stable UDP based network and is more reliable than TCP (from what I hear). It's also open source and the licence is pretty reasonable.

Shogun.

Was looking to port an XNA game over to Monogame to run on Linux / Mac as well. One issue though ... how to do cross platform multiplayer? Currently using Lidgren Network Library but I guess that won't work off Windows. Is there a good way to do cross platform networking?

You can use System.Net.Sockets. That namespace is implemented on both Mono and .NET.

Sure, it may take a bit longer to develop than using a networking library, but it will be helpful in learning networking, and to be honest its not really that hard once you know how TCP/UDP works and know about the several techniques you can apply to each.

System.Net.Sockets even has a slightly higher level socket class for UDP/TCP (TcpClient/UdpClient).