CGoban ("Complete Goban") provides a large set of go-related services
for Unix and X11. A list of the functions that it provides:

Play go against another player.

Edit and view SGF files. CGoban provides full functionality for
editing and viewing SGF files.

Connect to a go server over the internet. CGoban can connect to
NNGS or IGS and gives a convienent graphical user interface to the
server.

Act as a bridge to go modem protocol. Go modem protocol has become
a standard way for computer go programs to communicate.
internet go servers.