View source for Creating, using and managing SSH keys

== Create a new key for your machine ==

<syntaxhighlight lang="bash">
ssh-keygen -t rsa
</syntaxhighlight>

<span style="background-color:yellow;">CHOOSE A STRONG PASSPHRASE, EMPTY PASSPHRASE == BAD</span>

If someone has access to your machine via social engineering or tech exploit, your key can be stolen and used to login in all the machines and services without password.

== Install your key on the machines where you need to log in ==
=== Handy function to put in your shell config ===
In your shell resource file (<code>~/.zhrc, ~/.bashrc,...</code>) add the following function:

<syntaxhighlight lang="bash">
ssh-install-key() {
    cat ~/.ssh/id_rsa.pub | ssh ${1} "cat - >> ~/.ssh/authorized_keys"
}
</syntaxhighlight>

Now you can install your '''main''' key, <code>id_rsa.pub</code>, directly to a target machine:

<syntaxhighlight lang="bash">
ssh-install-key username@super.server.nl
</syntaxhighlight>

== Using your keys ==

=== With keychain ===
Keychain is a software that will keep track of which keys are available in your system and will only ask your passphrase once per session instead. It is a front-end to ssh-add and ssh-agent. 

Add the following in your shell resource file:
<syntaxhighlight lang="bash">
if [ -e ~/.ssh/id_rsa ]
then
    keychain --quiet --nogui ~/.ssh/id_rsa
    . ~/.keychain/${HOSTNAME}-sh
fi
</syntaxhighlight>

Now restart your session and you will be prompted, once for your passphrase. After that you can directly ssh/scp to the machines where your installed your key and you will not be prompted for any passwords!

<syntaxhighlight lang="bash">
ssh username@super.server.nl
</syntaxhighlight>

== Using aliases for your SSH connections ==
To make your life even easier you can edit (create if non existent) the <code>~/.ssh/config</code> file to create Host SSH aliases for the machines you need to connect to. You can also pass all the SSH options you might want to add, for instance:

<syntaxhighlight lang="bash" line>
Host super
    User username
    Hostname super.server.nl

Host super2
    User anotherusername
    Hostname super.serverl.nl
    Port 12345
    ForwardAgent yes
</syntaxhighlight>

Now when you want to <code>ssh</code>/<code>scp</code> to your server you can just do the following:

<syntaxhighlight lang="bash">
ssh super
</syntaxhighlight>

[[Category:Cookbook]]
[[Category:SSH]]