+Keys can be exported to a subset of machines by prepending
+<b>allowed_hosts=$fqdn,$fqdn2</b> to the specific key. The allowed machines
+must only be separated by a comma.
+
+<i>Example:</i>
+<pre>
+# cat .ssh/debian-machines.pub
+allowed_hosts=ravel.debian.org,gluck.debian.org ssh-rsa AAAAB3Nz..mOX/JQ== user@machine
+ssh-rsa AAAAB3Nz..uD0khQ== user@machine
+</pre>
+