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Mattia Orfano
Mattia Orfano

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RSA host key changed for github.com

#github

As recently announced, Github replaced their RSA SSH host key used to secure Git operations for GitHub.com as a security measure.

This "small" change will affect all your future deploys and you might encounter errors like this:

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY! Someone could be eavesdropping on you right now (man-in-the-middle attack)! It is also possible that a host key has just been changed. The fingerprint for the RSA key sent by the remote host is SHA256:uNiVztksCsDhcc0u9e8BujQXVUpKZIDTMczCvj3tD2s. Please contact your system administrator. Add correct host key in /home/project/.ssh/known_hosts to get rid of this message. Offending RSA key in /home/project/.ssh/known_hosts:1 remove with: ssh-keygen -f "/home/project/.ssh/known_hosts" -R "github.com" RSA host key for github.com has changed and you have requested strict checking. Host key verification failed. fatal: Could not read from remote repository. Please make sure you have the correct access rights and the repository exists.
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Even following Github's advice I wasn't able to fix the error and I had to tweak a little bit...

First, ensure you have an updated SSH key in your project's "deploy keys". Go to Github.com, enter your repository, go to Settings>Deploy Keys and create/update the existing ones.

Then, on your local machine (as well as your remote server that serves your web application) run the following:

ssh-keygen -R github.com ssh-keyscan github.com > ~/.ssh/known_hosts
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Now, try again to deploy your code.

If you see another error like this:

The authenticity of host 'github.com (140.82.121.4)' can't be established. ECDSA key fingerprint is SHA256:p2QAMXNIC1TJYWeIOttrVc98/R1BUFWu3/LiyKgUfQM.
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Warning: the ECDSA host key for 'github.com' differs from the key for the IP address '140.82.121.4' Offending key for IP in /home/project/.ssh/known_hosts:1 Matching host key in /home/project/.ssh/known_hosts:4
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you have to remove the specified IP address from known_host. Run the following command:

ssh-keygen -R "140.82.121.4"

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