`sslh` accepts connections on specified ports, and forwards
them further based on tests performed on the first data
packet sent by the remote client.

Probes for HTTP, SSL, SSH, OpenVPN, tinc, XMPP are
implemented, and any other protocol that can be tested using
a regular expression, can be recognised. A typical use case
is to allow serving several services on port 443 (e.g. to
connect to SSH from inside a corporate firewall, which
almost never block port 443) while still serving HTTPS on
that port. 

Hence `sslh` acts as a protocol demultiplexer, or a
switchboard. Its name comes from its original function to
serve SSH and HTTPS on the same port.