title: .ssh/config: "Bad configuration option: UseKeychain" on Mac OS Sierra 10.12.6
body: <p>I am trying to set up my ssh config on the Mac (Mac OS Sierra 10.12.6) in such a way that it stores the passphrase for my ssh key in the keychain. Previously I could do that with</p>
  
  <pre><code>ssh-add -K ~/.ssh/id_rsa
  </code></pre>
  
  <p>But recently this doesn't seem to work anymore. Following <a href="https://developer.apple.com/library/content/technotes/tn2449/_index.html" rel="noreferrer">this article</a> there seems to be a change in the behaviour of the ssh config in Mac OS > 10.12.2 and the recommended way to fix this issue is to add <code>UseKeychain yes</code> to your ssh config. So here's my <code>.ssh/config</code> section the <code>Host *</code>:</p>
  
  <pre><code>Host *
    Port 22
    ServerAliveInterval 60
    ForwardAgent yes
    IdentityFile ~/.ssh/id_rsa
    AddKeysToAgent yes
    UseKeychain yes
  </code></pre>
  
  <p>When trying to ssh to a foreign host, I get the following error message:</p>
  
  <pre><code>$ ssh my-host
  /Users/USER/.ssh/config: line 16: Bad configuration option: usekeychain
  </code></pre>
  
  <p>Any ideas why this happens and how I can fix it? Thanks!</p>