- ENVIRONMENT VARIABLES
- SCRIPT HISTORY
connect-tunnel - Create CONNECT tunnels through HTTP proxies
connect-tunnel [ -Lv ] [ -A user:pass ] [ -P proxy:port ] [ -C controlport ] [ -T port:host:hostport ]
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).
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::UserAgentare supported (we use an
LWP::UserAgentinternally 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
- -v, --verbose
This option can be used several times for more verbose output.
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.
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.
Philippe "BooK" Bruhat,
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.
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
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 2003-2007, Philippe Bruhat. All rights reserved.
This module is free software; you can redistribute it or modify it under the same terms as Perl itself.