I have just updated to MacOS Sierra, and found that openssh version 1 has beed disabled or removed.

ssh1 is not supported

I have to use ssh1 for some server, how can I enable ssh1?

Or can I install another openssh which support ssh1 tentatively?

  • 1
    OpenSSH 7.2p1 does not enable SSH1 protocol by default. Linux distributions created a package openssh-client-ssh1 packages for client with ssh1 support, but I am not sure if Brew/MacOS did inherit this in some way
    – Jakuje
    Oct 3, 2016 at 6:44

5 Answers 5


Here's my github repo trying to solve the problem by patching the openssh in homebrew/dupes. It's far from perfect but works.

Basically you have to:

brew tap homebrew/dupes
curl -fsSL https://github.com/boltomli/MyMacScripts/raw/master/homebrew/homebrew-dupes.openssh.diff | patch /usr/local/Homebrew/Library/Taps/homebrew/homebrew-dupes/openssh.rb
brew install openssh --with-ssh1

Please note that openssh also incorrectly displays this error when connecting to a firewalled port or a port without sshd listening.

In my case I got this error on MacOS when I mistakenly used "ssh -P5363 ..." instead of "ssh -p5356 ..."

  • Same with scp. Use scp -P <port> to specifying port number. Sep 19, 2018 at 18:27

curl/patch line from above slightly modified to run on macOS Sierra...

curl -fsSL https://github.com/boltomli/MyMacScripts/raw/master/homebrew/homebrew-dupes.openssh.diff | patch /usr/local/Library/Taps/homebrew/homebrew-dupes/openssh.rb


openSSH has been moved from 'dupes' to 'core'. boltomli has updated his GitHub repo to account for this. Here is the new command to get it working on Sierra.

curl -fsSL https://raw.githubusercontent.com/boltomli/MyMacScripts/master/homebrew/homebrew-core.openssh.diff | patch /usr/local/Homebrew/Library/Taps/homebrew/homebrew-core/Formula/openssh.rb
brew install openssh --with-ssh1
  • This doesn't work. I think the homebrew file to patch has been modified. I've opened an issue in Github at /usr/local/Library/Taps/homebrew/homebrew-dupes/openssh.rb
    – Andy Madge
    May 30, 2017 at 11:05

Given that ssh1 is absolutely ancient (v2 has been standard for 10 years now) a far better solution is upgrading the security on the server you access that is still running ssh1 only. V1 has all the usual security issues of 20 year old software, whoever is managing that particular piece of hardware is simply not doing their job.

You can probably install an alternate client that supports V1, but I would send a memo to management that they have a major issue with their legacy hardware.

  • 6
    It's very easy to assume that "someone isn't doing their job" when you encounter older protocols still in use. Older protocols may be around simply because they are on older embedded control interfaces on various equipment. For instance, I use older SSH protocols on Nortel equipment. Now that Nortel is defunct, where exactly am I going to get updated firmware to upgrade SSH to v2?
    – Allan
    Oct 3, 2016 at 14:13

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