Which socket library?

[Borneq]

Which is good C++ socket library for Linux/Windows?

[helios]

For both? Probably Boost.Asio.

[againtry]

Communication section here might be of interest?
https://en.cppreference.com/w/cpp/links/libs

[kbw]

You could consider Poco.

[Computergeek01]

SFML has a good easy socket lib as something to add to this list.