The 'io/remote' plugin implements a simple binary protocol for connecting client/server radare implementation and extend the basic IO operations over the network.
An example of use would be:
(alice)$ radare listen://:9999 Listening at port 9999
(bob)$ radare connect://alice:9999/dbg:///bin/ls ...
Once bob connects to alice using the listen/connect URIs (both handled by the remote plugin) the listening one loads the nested uri and tries to load it "dbg:///bin/ls". Both radares will be working in debugger mode and all the debugger commands will be wrapped by network.
In the same way it is possible to nest multiple socket connections between radare.