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I'd like to audit the authorized_keys file on a number of servers and match them with known AWS key fingerprints.

Is there a one-liner which incorporates ssh-keygen -lf which will output the fingerprint of every key in an authorized_keys file in a nice list with line breaks?

2 Answers 2

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From serverfault:

You can easily make it a function in your .bashrc:

function fingerprints() {
  local file="$1"
  while read l; do
    [[ -n $l && ${l###} = $l ]] && ssh-keygen -l -f /dev/stdin <<<$l
  done < $file
}

and then do:

$ fingerprints .ssh/authorized_keys
2

Here you go:

    find /path/to/keys/directory -type f -name "*.pub" -exec ssh-keygen -lf {} \; | awk '{print $2}'

Edit: Whops, ok. get it now.

here you go:

    while read line; do ssh-keygen -lf "$line"; done < <(cat authorised_keys_file)

(if this file have one key per line)

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  • thanks. I want to operate on the authorised_keys file, though, not individual .pub files
    – codecowboy
    Apr 17, 2014 at 10:54
  • Ok, check if edited answer is the one liner you have been looking for.
    – tommy
    Apr 17, 2014 at 11:04
  • thanks. please format your answer with any code, commands etc using the '{}' icon in the text editor
    – codecowboy
    Apr 17, 2014 at 11:21
  • That doesn't work, -f expects a file name (and that file has to be a regular file as ssh-keygen opens and reads the file several times) Apr 17, 2014 at 13:22
  • Use instead: while read line; do echo "$line" > key.pub; ssh-keygen -lf key.pub ; rm key.pub; done < <(cat authorised_keys)
    – tommy
    Apr 17, 2014 at 13:44

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