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Would it be possible to run ssh-keygen without human interaction?

I have a shell script that takes care of server deployment from start to finish, but ssh-keygen is the only remaining piece that still requires my input.

Would it be possible to feed the parameters to it? Or is there something similar to debconf-set-selections that could be used for this?

*running Debian

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3 Answers 3

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20

You can do more or less anything with command-line arguments. Is there something particular you want to do which doesn't appear in the man page?

wry@onyx:~$ ssh-keygen -t dsa -N "my passphrase" -C "test key" -f mykey
Generating public/private dsa key pair.
Your identification has been saved in mykey.
Your public key has been saved in mykey.pub.
The key fingerprint is:
2f:17:a4:5d:6f:25:d7:5a:0e:84:be:af:ee:52:8b:42 test key

(the rest snipped for brevity)

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  • 2
    Best to avoid storing this command in your history - you don't want the passphrase recorded in plaintext on your computer. (Yes, generally the history file has 600 permissions so only root could snoop, but better safe than sorry.)
    – Cascabel
    Mar 28, 2010 at 20:26
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    The point is he's going to script it anyway.
    – Joshua
    Sep 5, 2012 at 18:14
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    In your script, use a prompt (read -s) to read the password to pass on. Also beware ps may reveal process command args (which will include password). Because of that it may be best to use expect along with the normal password prompt, to send it in that way.
    – Steven Lu
    Jul 19, 2013 at 19:09
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    It will still require human interaction if the file by that name already exists.
    – Suhail Gupta
    Jan 15, 2019 at 5:39
  • Recovering passwords from ssh keys is relatively trivial. In a world where many people use their admin workstation's login password as the key password it's better to advise people to NOT put a passphrase on keys. (protect your private key, if you fail to do that at least you don't also lose your password)
    – jorfus
    Jan 22, 2021 at 21:39
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In case of server deployment:

ssh-keygen -t rsa -q -f "$HOME/.ssh/id_rsa" -N ""

In terms of communication from server installed to git repositories or other servers would be easy.

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-1 
operacao@ubuntu:~$ ssh-keygen -t dsa
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    This does ask at least where to save the key.
    – spacediver
    Jan 18, 2014 at 5:19

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