NAME¶
connect-tunnel - Create CONNECT tunnels through HTTP proxies
SYNOPSIS¶
connect-tunnel [
-Lv ]
[
-A user:pass ] [
-P proxy:port ]
[
-C controlport ]
[
-T port:host:hostport ]
DESCRIPTION¶
connect-tunnel sets up tunneled connections to external hosts by
redirecting connections to local ports towards thoses hosts/ports through a
HTTP proxy.
connect-tunnel makes use of the HTTP "CONNECT" method to ask
the proxy to create a tunnel to an outside server. Be aware that some proxies
are set up to deny outside tunnels (either to ports other than 443 or outside
a specified set of outside hosts).
OPTIONS¶
The program follows the usual GNU command line syntax, with long options
starting with two dashes.
- -A, --proxy-authentication
user:password
- Proxy authentication information.
Please note that all the authentication schemes supported by
"LWP::UserAgent" are supported (we use an
"LWP::UserAgent" internally to contact the proxy).
- -C, --control-port controlport
- The port to which one can connect to issue control commands
to connect-tunnel.
See "CONTROL CONNECTIONS" for more details about the available
commands.
- -L, --local-only
- Create the tunnels so that they will only listen on
"localhost". Thus, only connections originating from the machine
that runs connect-tunnel will be accepted.
That was the default behaviour in connect-tunnel version 0.02.
- -P, --proxy proxy[:port]
- The proxy is required to connect the tunnels. If no port is
given, 8080 is used by default.
See also "ENVIRONMENT VARIABLES".
- -T, --tunnel port:host:hostport
- Specifies that the given port on the local host is
to be forwarded to the given host and hostport on the remote
side. This works by allocating a socket to listen to port on the
local side, and whenever a connection is made to this port,
connect-tunnel forwards it to the proxy (with the credentials, if
required), which in turn forwards it to the final destination.
Note that this does not imply the use of any cryptographic system (SSL or
any other). This is a simple TCP redirection. The security if any, is the
one provided by the protocol used to connect to the destination through
connect-tunnel.
On Unix systems, only root can forward privileged ports.
Note that you can setup tunnels to multiple destinations, by using the
--tunnel option several times.
- -U, --user-agent string
- Specify User-Agent value to send in HTTP requests. The
default is to send "connect-tunnel/ version".
- -v, --verbose
- Verbose output.
This option can be used several times for more verbose output.
EXAMPLES¶
To connect to a SSH server running on "ssh.example.com", on port 443,
through the proxy "proxy.company.com", running on port 8080, use the
following command:
connect-tunnel -P proxy.company.com:8080 -T 22:ssh.example.com:443
And now point your favorite ssh client to the machine running
connect-tunnel.
You can also emulate a "standard" user-agent:
connect-tunnel -U "Mozilla/4.03 [en] (X11; I; Linux 2.1.89 i586)"
-P proxy.company.com:8080 -T 22:ssh.example.com:443
connect-tunnel can easily use your proxy credentials to connect outside:
connect-tunnel -U "Mozilla/4.03 [en] (X11; I; Linux 2.1.89 i586)"
-P proxy.company.com:8080 -T 22:ssh.example.com:443
-A book:s3kr3t
But if you don't want anybody else to connect to your tunnels and through the
proxy with
your credentials, use the
--local-only option:
connect-tunnel -U "Mozilla/4.03 [en] (X11; I; Linux 2.1.89 i586)"
-P proxy.company.com:8080 -T 22:ssh.example.com:443
-A book:s3kr3t -L
If you have several destinations, there is no need to run several instances of
connect-tunnel:
connect-tunnel -U "Mozilla/4.03 [en] (X11; I; Linux 2.1.89 i586)"
-P proxy.company.com:8080 -A book:s3kr3t -L
-T 22:ssh.example.com:443
-T 222:ssh2.example.com:443
But naturally, you will need to correctly set up the ports in your clients.
Mmm, such a long command line would perfectly fit in an alias or a
.BAT
file. ";-)"
ENVIRONMENT VARIABLES¶
The environment variable "HTTP_PROXY" can be used to provide a proxy
definition.
The environment variable is overriden by the
--proxy option, if passed to
connect-tunnel.
AUTHOR¶
Philippe "BooK" Bruhat, "<book@cpan.org>".
I seem to have re-invented a well-known wheel with that script, but at least, I
hope I have added a few interesting options to it.
SCRIPT HISTORY¶
The first version of the script was a quick hack that let me go through a
corporate proxy.
Version 0.02 and version 0.03 were released on CPAN in 2003.
Version 0.04 sits half-finished in a CVS repository at home: I couldn't decypher
the spaghetti of my data structures any more. ":-("
Version 0.05 (and higher) are based on "Net::Proxy", and included with
the "Net::Proxy" distribution.
Even though it's not rocket science,
connect-tunnel has been cited in at
least one academic works:
- •
- HTTP Tunnels Through Proxies, Daniel Alman
Available at SANS InfoSec Reading Room: Covert Channels
<http://www.sans.org/rr/whitepapers/covert/>
Direct link: <http://www.sans.org/rr/whitepapers/covert/1202.php>
COPYRIGHT¶
Copyright 2003-2007, 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.