ssh -L (error: bind: Address already in use)

Pretty simple, I know that this has happened to me before. Couldn't find a good answer on AU.

I was running an ssh session with ports bound:

ssh -L 3000:<server_name>:22

I just lost my connection. When I try to reconnect using the same command, I get the following error:

bind: Address already in use
channel_setup_fwd_listener: cannot listen to port: 3000

How do I reset ssh on my machine to allow the port to be bound again? Resetting the local machine works.

Solution 1:

Couldn't you just kill whatever is using that port?

 lsof -ti:5901 | xargs kill -9

lsof -ti:5901 to find whatever is using port 5901.

Pass the whole thing to kill -9 to kill whatever was using port 5901.

Replace with the port you want to open up again.

Solution 2:

I suppose you have still something connected to local port 3000.

You can find it with

netstat -tulpn | grep 3000 

and then dispose of it. For example in my machine:

[:~] % netstat -tulpn | grep 5900
(Not all processes could be identified, non-owned process info
 will not be shown, you would have to be root to see it all.)
tcp        0      0 0.0.0.0:5900            0.0.0.0:*               LISTEN      2547/vino-server
tcp6       0      0 :::5900                 :::*                    LISTEN      2547/vino-server

correctly identifies the process waiting and connected on port 5900 (vnc server).

Another useful command is

fuser 3000/tcp 

...all of them may need to be run with sudo if you do not own the process which is opening the port.

Solution 3:

I was able to recreate and fix it by doing the following:

• Open up something that will list your processes (ps -ae)
• Kill the process called sh (kill <proc_number>)

Then reopen the ssh connection

Alternatively, I have had success with:

killall ssh

In the terminal on the local machine