SSLH(1) User Contributed Perl Documentation SSLH(1)NAMEsslh - Switch incoming connection between SSH and SSL/HTTPS servers
SYNOPSISsslh [ -v ] [ -p [host:]port ] [ -t timeout ]
[ --ssh [host:]port ] [ --ssl [host:]port ]
DESCRIPTIONsslh is a simple script that lets you switch an incoming connection on
a single port between distinct SSH and SSL/HTTPS servers.
sslh listens for connections on a port and is able to redirect them
either to an HTTPS web server or a SSH server.
This lets one setup both a HTTPS web server and a SSH server and access
them through the same host+port.
OPTIONS
The program follows the usual GNU command line syntax, with long
options starting with two dashes.
-p, --port [host:]port
The port the proxy will listen to. If no port is given, 443 is
used by default. If no host is given, "localhost" is used by
default.
-s, --ssh [host:]port
The SSH server which the SSH connections must be forwarded to. If
omitted, the default is localhost:22.
-l, --ssl, --https [host:]port
The HTTPS server which the HTTPS connections must be forwarded to.
If omitted, the default is localhost:443.
-t, --timeout delay
Timeout in seconds before a silent incoming connection is
considered as a SSH connection. The number can be fractional.
The default is 2seconds.
-v, --verbose
Verbose output. This option can be used several times for more
verbose output.
EXAMPLE OF USE
Is this tool actually useful? Yes.
For example one can use it to access both a SSH server and a secure web
server via a corporate proxy that only accepts to relay connections to
port 443. Creating a tunnel that passes SSH connection through a
CONNECT-enabled web proxy is easy with connect-tunnel (also included in
the "Net::Proxy" distribution).
The proxy will let both SSH and HTTPS connections out (since they all
point to port 443), and the home server will connect those incoming
connections to the appropriate server. This only requires to run the
HTTPS server on a non standard port (not 443).
TECHNICAL NOTE
How can this proxy find out what kind of protocol is using a TCP
connection to port 443, without being connected (yet) to the server?
We actually rely on a slight difference between the SSL and SSH
protocols (found thanks to ethereal):
SSH Once the TCP connection is established, the server speaks first,
presenting itself by saying something like:
SSH-2.0-OpenSSH_3.6.1p2 Debian 1:3.6.1p2-1
SSL With SSL, it's always the client that speaks first.
This means that sslh can be used with any pair of protocols/services
that share this property (the client speaks first for one and the
server speaks first for the other).
AUTHORS
Original idea and C version
Frederic Ple "<frederic.ple+sslh@gmail.com>".
Perl versions
Philippe 'BooK' Bruhat "<book@cpan.org>".
SCRIPT HISTORY
Version 0.01 of the script was a quick hack designed in 2003 as a proof
of concept.
Version 0.02 (and higher) are based on "Net::Proxy", and included with
the "Net::Proxy" distribution. Version 0.02 didn't work, though.
Version 0.03 correctly initialised the "in" connector.
Version 0.04 lets the proxy listen on any address (instead of
"localhost", which is still the default). Thanks to Dieter Voegtli for
spotting this.
SEE ALSO
Net::Proxy, Net::Proxy::Connector::dual.
COPYRIGHT
Copyright 2003-2008, Philippe Bruhat. All rights reserved.
LICENSE
This module is free software; you can redistribute it or modify it
under the same terms as Perl itself.
perl v5.20.2 2014-11-02 SSLH(1)
