Re: ssh tunneling to bypass web proxy rules

[Sagiko <sagiko () gmail com>]

hi,

There are a number of ways to do it. Assume this guy has full control
over an external server and your firewall or filtering mechanism does
not stop him from access to that server through SSH (outbound port
22).

What he will do is port forwarding the webtraffic (port 80) using SSH
(check the -L or -R option in the man manual) from his pc (inside your
network) to his external server.  At his external server, the SSH
daemon will pick up this traffic and redirect it back to normal web
traffic. What you can do to stop this is to filter or at least limit
unnecessory outbound SSH traffics. Or you can get a firewall which
have the feature to check tunneled traffics and protocols.

Also he can choose to use an external proxy server to by pass your
local proxy restrictions as long as your local proxy allow him to
connect to that external proxy. (although that's not really a SSH
tunneling).

regards,
Rick Zhong Liming 

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On 8/21/05, Juan B <juanbabi () yahoo com> wrote:
> Hi,
>
> Someone told me one can pass web proxy restrictions by
> tunnling throw ssh to restricted web sites like web
> mail sites in our corporate network.I really whant to
> know how he is doing that but I dont know where and
> how to test it, and he of course doesnt tell.
>
> I need to close this hole in the network.
>
> can someone give me a hand please.
>
> Juan.
>
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