I use this ssh config: ControlPath /home/tedu/.ssh/ctrl-%r@%h:%p ControlPersist 10 ControlMaster auto
It seems if my IP changes while a connection is active, the control master never exits. Here's what happened: 1. login. 2. change IP. 3. notice connection is hung. 4. ~. to disconnect. 5. wait 10 seconds for master to die. 6. it doesn't. 7. wait more. finally kill it by hand. There were no other clients connected. I expect the master to disconnect (forcefully) after ten seconds. There are no more clients, there's no need for a graceful session close or whatever it's waiting on.
