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I used ssh -L 10002:192.168.0.30:10002 192.168.1.135 to establish port forwarding but now I need to remove it.

How do I do this?

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  • We often realize port is still being forwarded when we fire a new ssh session running same command again and getting Warning: remote port forwarding failed for listen port message.
    – GabLeRoux
    Jan 8, 2016 at 22:38

5 Answers 5

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If you are using Linux you can kill the process by:

ps aux | grep ssh

and then use

kill <id>

To kill the process.

If the kill command is not successfull you can try

kill -9 <id>
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  • 42
    No. No. No. Please, please, please do not use kill -9 until after you've tried just kill. Many processes will have signal handlers which will clean up their use of resources, cleanly close connections and other pre-shutdown tasks. If you kill with -9, the process dies immediately without doing the cleanup. Killing without -9 will work most of the time.
    – Doug Harris
    Dec 23, 2009 at 18:44
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    kill -9 without reason is like using a shotgun to kill a mosquito. :)
    – Darren Hall
    Dec 23, 2009 at 21:24
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    I usually do a one liner pgrep ssh | xargs kill. Don't use -9 for nothing indeed
    – GabLeRoux
    Jan 8, 2016 at 22:35
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    @GabLeRoux That assumes you only have a single ssh command, or that all the ssh commands you are running are fine to kill. This is hardly a good general assumption.
    – tripleee
    Apr 14, 2016 at 9:11
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    @Avamander I connect to multiple ssh instances on multiple remote servers all the time, some of them without my direct active involvement. For example, Emacs Tramp mode opens an ssh connection behind the scenes when I visit a remote buffer. Some people use userspace filesystems which do something similar. It's not at all uncommon. In fact, I would assume single user, single ssh instance to be a minority fringe use case. If it works for you, good for you, but it's not good general advice.
    – tripleee
    Oct 23, 2016 at 9:16
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When using ssh multiplexing,
killing the ssh process is often undesirable (it kills all open connections with that host),

and you cannot easily access the escape because "escape not available to multiplexed sessions".

The right way is then to run the analogue of the forwarding command that you want to cancel,
but adding -O cancel. For instance:

ssh -O cancel -L 10002:192.168.0.30:10002 192.168.1.135

This will disable this port forwarding without terminating the session.
Again, this will only work if ssh multiplexing is in use for the connection to 192.168.1.135.

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  • 6
    This is a best solution. To kill master just run ssh -O exit 192.168.1.135.
    – Tomilov Anatoliy
    Sep 28, 2017 at 9:27
  • If you are not multiplexing sessions, see exhuma's excellent answer! (Thanks a3nm for catching my typo.)
    – Alan De Smet
    Jul 17, 2018 at 20:25
  • This exactly saved my life. // the kill way really killed me.
    – yurenchen
    Mar 11 at 7:33
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How to cancel a forwarded port in an already running SSH session:

  1. Press ~+C (tilde + capital C)
  2. Type -KL 10002 (or whatever port number)
  3. Press Enter

You should see this:

ssh> -KL 10002
Canceled forwarding.
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  • Sorry for the nekro but I came across your answer when trying to do exactly this. I'm forwarding a port with ssh -N -L 9200:[address]:443 but when I run ssh -KL 9200 I get "Unknown port forwarding", I can't find anything about this in that context online, do you know if I'm making a stupid mistake?
    – Bipolarbear54
    Jul 7, 2022 at 14:15
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You can enter an interactive console by typing ~C (capital "C"). This lets you dynamically add and remove port forwardings (among a few other things).

This sequence has to come right after a carriage return/newline. So in doubt, just type Enter~C (in sequence).

If you don't see the characters appear on the console, you're doing it right :)

You should now see an ssh> prompt.

To remove the port, simply enter -KL 10002 followed by Enter (where 10002 is your forwarded port).

The inverse - adding a new forward - can be done like this (from start to finish):

Enter~C

ssh> -L 10002:192.168.0.30:10002

Enter

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    This is the right answer if you're not multiplexing connections. If you are, you'll be bounced with ~C escape not available to multiplexed sessions. If that's the case, see a3nm's excellent answer.
    – Alan De Smet
    Jul 16, 2018 at 21:20
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You could use the "escape-key" (usually ~) followed by C to get a cli to your connection. You can from there remove tunnels without taking down your connection.

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    I'd like to know the specifics of this. I know you can add tunnels after you've SSH'd in, but have yet to find out how to take one down.
    – carestad
    Nov 24, 2014 at 22:40
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    When you are in CLI mode you could do help. -KL is the oppsite of -L, -KR is the oppsite of -R and -KD is the oppsite of -D. Doing "escape-key" (~) followed by # shows your tunnels.
    – Jimmy Hedman
    Nov 28, 2014 at 11:02
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    @JimmyHedman you might want to edit your answer additionally to adding a comment. It makes everything more readable. And sometimes comments are hidden (in case there are too many).
    – exhuma
    Feb 19, 2016 at 15:51

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