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Man Pages


Manual Reference Pages  -  CONNECT-TUNNEL (1)

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NAME

connect-tunnel - Create CONNECT tunnels through HTTP proxies

CONTENTS

SYNOPSIS

<B>connect-tunnelB> [ <B>-LvB> ] [ <B>-AB> user:pass ] [ <B>-PB> proxy:port ]
[ <B>-CB> controlport ] [ <B>-TB> port:host:hostport ]

DESCRIPTION

<B>connect-tunnelB> sets up tunneled connections to external hosts by redirecting connections to local ports towards thoses hosts/ports through a HTTP proxy.

<B>connect-tunnelB> 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.
<B>-AB>, <B>--proxy-authenticationB> 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).

<B>-CB>, <B>--control-portB> controlport The port to which one can connect to issue control commands to <B>connect-tunnelB>.

See CONTROL CONNECTIONS for more details about the available commands.

<B>-LB>, <B>--local-onlyB> Create the tunnels so that they will only listen on localhost. Thus, only connections originating from the machine that runs <B>connect-tunnelB> will be accepted.

That was the default behaviour in <B>connect-tunnelB> version 0.02.

<B>-PB>, <B>--proxyB> proxy[:port] The proxy is required to connect the tunnels. If no port is given, 8080 is used by default.

See also ENVIRONMENT VARIABLES.

<B>-TB>, <B>--tunnelB> 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, <B>connect-tunnelB> 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 <B>connect-tunnelB>.

On Unix systems, only root can forward privileged ports.

Note that you can setup tunnels to multiple destinations, by using the <B>--tunnelB> option several times.

<B>-UB>, <B>--user-agentB> string Specify User-Agent value to send in HTTP requests. The default is to send connect-tunnel/version.
<B>-vB>, <B>--verboseB> 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 <B>connect-tunnelB>.

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



<B>connect-tunnelB> 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 <B>--local-onlyB> 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 <B>connect-tunnelB>:



 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 <B>--proxyB> option, if passed to <B>connect-tunnelB>.

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, <B>connect-tunnelB> has been cited in at least one academic works:
o 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.
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