April 2010
To start Screen for multi-user mode, the executable must be suid root and the WD has to have permission 755:
chmod +s $(which screen)
chmod 755 /var/lib/screen
To have a session together:
user1@host$ screen -s MySession
Ctrl A:multiuser on
Ctrl A:acladd user2
user2@host$ screen -x user1/MySession