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Re: openvpn in spite of firewalls



On Wed, Jul 18, 2007 at 10:15:32AM -0700, PETER EASTHOPE wrote:
> Folk,
> 
> I've installed openvpn on two systems and tried some
> configurations including Example 2 from the man page.

For those without access to the man page: Uses an UDP tunnel with static 
key security.

> Seems that firewalls block successfully (sarcasm). 
> Nevertheless, http, ssh, ftp and a few other protocols
> work.

I presume that you do not have control over the firewall?  If not then 
you'll have to make use of the existing holes.

The protocols you mentioned all use TCP - any holes in the firewalls for 
UDP? That's openvpn's preferred mode of operation, although a TCP hole 
can be used too...

> Is there any chance of using one of the open ports for
> the tunnel between the two machines?  

Yes :-)

> For example,
> can the tunnel between 10.4.0.1 and 10.4.0.2 use port
> 22 while ssh uses it for other connections? 
> 
> Can a proxy server solve this? 

If you run openvpn in tcp mode, then you can use a proxy server at the 
receiving end. I've written some software that just might fit the bill 
here: It allows the same port to be used for two different protocols:
    http://sourceforge.net/projects/ssh-ssl-proxy/
It should be possible to use this to switch between SSH and openvpn:
    http://ssh-ssl-proxy.svn.sourceforge.net/viewvc/ssh-ssl-proxy/tags/0.3/FAQ?view=markup

> Is there any other way to connect the tunnel in spite
> of the firewalls?

Since the firewalls allow SSH through, you can always run a PPP link 
over ssh...

Hope this helps

-- 
Karl E. Jorgensen
karl@jorgensen.org.uk  http://www.jorgensen.org.uk/
karl@jorgensen.com     http://karl.jorgensen.com
==== Today's fortune:
A girl's conscience doesn't really keep her from doing anything wrong--
it merely keeps her from enjoying it.

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