Provided by: sslh_1.20-1_amd64 bug


        sslh - protocol demultiplexer


       sslh [-Fconfig file] [-t num] [--transparent] [-p listening address [-p listening address
       ...] [--ssl target address for SSL] [--tls target address for TLS] [--ssh target address
       for SSH] [--openvpn target address for OpenVPN] [--http target address for HTTP] [--xmpp
       target address for XMPP] [--tinc target address for TINC] [--anyprot default target
       address] [--on-timeout protocol name] [-u username] [-C chroot] [-P pidfile] [-v] [-i]
       [-V] [-f] [-n]


       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.

   Libwrap support
       One drawback of sslh is that the servers do not see the original IP address of the client
       anymore, as the connection is forwarded through sslh.

       For this reason, sslh can be compiled with libwrap to check accesses defined in
       /etc/hosts.allow and /etc/hosts.deny.  Libwrap services can be defined using the
       configuration file.

   Configuration file
       A configuration file can be supplied to sslh. Command line arguments override file
       settings. sslh uses libconfig to parse the configuration file, so the general file format
       is indicated in <>.  Please refer
       to the example configuration file provided with sslh for the specific format (Options have
       the same names as on the command line, except for the list of listen ports and the list of

       The configuration file makes it possible to specify protocols using regular expressions: a
       list of regular expressions is given as the regex_patterns parameter, and if the first
       packet received from the client matches any of these expressions, sslh connects to that

   Probing protocols
       When receiving an incoming connection, sslh will read the first bytes sent by the
       connecting client. It will then probe for the protocol in the order specified on the
       command line (or the configuration file). Therefore --anyprot should alway be used last,
       as it always succeeds and further protocols will never be tried.

       If no data is sent by the client, sslh will eventually time out and connect to the
       protocol specified with --on-timeout, or ssh if none is specified.

       As a security/authorization program, sslh logs to the LOG_AUTH facility, with priority
       LOG_INFO for normal connections and LOG_ERR for failures.


       -Ffilename, --config filename
           Uses filename as configuration file. If other command-line options are specified, they
           will override the configuration file's settings.

           When using the shorthand version, make sure there should be no space between -F and
           the filename.

       -t num, --timeout num
           Timeout before forwarding the connection to the timeout protocol (which should usually
           be SSH). Default is 2s.

       --on-timeout protocol name
           Name of the protocol to connect to after the timeout period is over. Default is to
           forward to the first specified protocol. It usually makes sense to specify 'ssh' as
           the timeout protocol, as the SSH specification does not tell who is supposed to speak
           first and a large number of SSH clients wait for the server to send its banner.

           Makes sslh behave as a transparent proxy, i.e. the receiving service sees the original
           client's IP address.  This works on Linux only and involves iptables settings.  Refer
           to the README for more information.

       -p listening address, --listen listening address
           Interface and port on which to listen, e.g. foobar:443, where foobar is the name of an
           interface (typically the IP address on which the Internet connection ends up).

           This can be specified several times to bind sslh to several addresses.

       --ssl target address
       --tls target address
           Interface and port on which to forward SSL connection, typically localhost:443.

           Note that you can set sslh to listen on ext_ip:443 and httpd to listen on
           localhost:443: this allows clients inside your network to just connect directly to

           Also, sslh probes for SSLv3 (or TLSv1) handshake and will reject connections from
           clients requesting SSLv2. This is compliant with RFC6176 which prohibits the usage of
           SSLv2. If you wish to accept SSLv2, use --default instead.

       --ssh target address
           Interface and port on which to forward SSH connections, typically localhost:22.

       --openvpn target address
           Interface and port on which to forward OpenVPN connections, typically localhost:1194.

       --xmpp target address
           Interface and port on which to forward XMPP connections, typically localhost:5222.

       --http target address
           Interface and port on which to forward HTTP connections, typically localhost:80.

       --tinc target address
           Interface and port on which to forward tinc connections, typically localhost:655.

           This is experimental. If you use this feature, please report the results (even if it

       --anyprot target address
           Interface and port on which to forward if no other protocol has been found. Because
           sslh tries protocols in the order specified on the command line, this should be
           specified last. If no default is specified, sslh will forward unknown protocols to the
           first protocol specified.

       -v, --verbose
           Increase verboseness.

       -n, --numeric
           Do not attempt to resolve hostnames: logs will contain IP addresses. This is mostly
           useful if the system's DNS is slow and running the sslh-select variant, as DNS
           requests will hang all connections.

       -V  Prints sslh version.

       -u username, --user username
           Requires to run under the specified username.

       -C chroot, --chroot chroot
           Requires to run under the specified chroot.

       -P pidfile, --pidfile pidfile
           Specifies a file in which to write the PID of the main server.

       -i, --inetd
           Runs as an inetd server. Options -P (PID file), -p (listen address), -u (user) are

       -f, --foreground
           Runs in foreground. The server will not fork and will remain connected to the
           terminal. Messages normally sent to syslog will also be sent to stderr.

           Runs in background. This overrides foreground if set in the configuration file (or on
           the command line, but there is no point setting both on the command line unless you
           have a personality disorder).


           Start-up script. The standard actions start, stop and restart are supported.

           Server configuration. These are environment variables loaded by the start-up script
           and passed to sslh as command-line arguments. Refer to the OPTIONS section for a
           detailed explanation of the variables used by sslh.


       The latest version is available from <>, and can be
       tracked from <>.


       Written by Yves Rutschle.