h the peer.
(When operating as server, in listen mode, this is more often required
by the peer, while client certificates only are mandated in certain
setups.)
</p>
</dd>
<dt>&lsquo;<samp>key_file, key=<var>filename</var></samp>&rsquo;</dt>
<dd><p>A file containing the private key for the certificate.
</p>
</dd>
<dt>&lsquo;<samp>listen=<var>1|0</var></samp>&rsquo;</dt>
<dd><p>If enabled, listen for connections on the provided port, and assume
the server role in the handshake instead of the client role.
</p>