Synapse works with Linux too. I made wrap up class to Next3D game engine, at least michalis said it compiled under Linux.
http://www.pascalgamedevelopment.com...p?topic=6218.0
There is demo too of TCP and UDP server, sending and receiving different packets.

I know its possible to directly use Synapse but i'm not so keen on doing the complicated multi-threading stuff again every time for network projects

It doesn't rely on any visual component so it should work even without Lazarus.