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Andrew
Asked: 2013-12-05 17:07:51 +0800 CST

How to add SSH known host in a bash script?

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I am creating a bash script to provision a new server that I can deploy a web application to. One thing I always have to do is as GitHub as a known host using ssh [email protected]. How can I automate this process in a bash script, and do it in an idempotent way?

ssh

3 Answers

  1. Best Answer

    The simple way to go would be to do something like this.

    ssh-keyscan remote_server >>~/.ssh/known_hosts

    If this box is brand new you might also need to create the ~/.ssh directory before you run ssh-keyscan.

    Keep in mind that ssh-keyscan can take an arbitrary number of hostnames. It will get all the keys it can.

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  2. Are you trying to automate accepting the new key? If so, you could use -oStrictHostKeyChecking=no.
    Doing so is a very bad idea as you're now completely wide open to man-in-the-middle attacks.

    A better option would be just to manage a known_hosts file and reuse that file when you provision new servers. Stick it on github and write a simple script to download that file before sshing into github.

    The strict host key checking is a good thing.

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  3. I'm not sure i understand the question, but i think you want to ignore the known_host prompt or avoid it entirely, in which case:

    ssh -o StrictHostKeyChecking=no

    or other suggestions at: http://www.joedog.org/2012/07/ssh-disable-known_hosts-prompt/

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