Lysergid

I got a similar issue for regular minecraft to minecraft connection (in such case Internal server runs). I run one of minecraft (server side) in debug mode and set "onlineMode" filed to false and release debugging it solved my problem. It's really annoying to do it such way. I tried to edit bytecode of InternalServer to run it simply from launcher but i met a problem that forge jar is signed and any modifications inside jar become a reason of security exception.