Remote use of XDMCP

[James Knott]

Robert Brockway wrote:
> On Sun, 19 Mar 2006, James Knott wrote:
> 
>> I currently have XDMCP running well on my local network, in that
>> computers on my home network can use it to access other computers.
>> However, when I try to connect via WiFi & VPN, one computer that works
> 
> So you are using the VPN at all times when connected locally?

No, only when using WiFi or connecting from elsewhere.
> 
> What sort of VPN are we talking about here btw?

OpenVPN

> 
> Is there some reason you don't want to use the WiFi without the VPN?  If
> it is security, there is a lot to be said for WPA.

I have my WiFi (with WEP) on the outside of my firewall.  To reach my
home network, I have to use either SSH or the VPN.

> 
>> well on the local lan, cannot connect.  I've used ethereal to see what's
> 
> I don't suppose you could connect it via a wire to test xdmcp with
> wireless right out of the equation?  I'd say you would have already done
> this if you could.

It works fine with both computers on the local lan.

> 
>> happening.  In the list below, the letters A & B indicate the source of
>> the packets.  "A" (10.x.x.x address) is a notebood connected via WiFi &
>> VPN and "B" (192.168.x.x) is my main desktop system. Both systems are
>> SUSE 10.0.  Ethereal, running on both the notebook and desktop shows the
>> following.
>>
>> A XDMCD Query
>> B XDMCP Willing
>> A XDMCP Request
>> B XDMCP Accept
>> A XDMCP Manage (repeats 7 times)
>> B XDMCP Failed.
>>
>> So, it's obvious the two systems are communicating, but unable to run an
>> X session.  Is there something that prevents a routed connection from
>> working?  Perhaps an address range issue?  Other ideas?
> 
> Probably not related to the address range based on the info you relate
> from ethereal.  You can check the relevant Xaccess file to make sure.
> 
> Similarly it does seem that udp/177 is getting through.  Use netcat to
> be sure.
> 
> It's unlikely to be WiFi related unless your getting abysmal performance.
> I've used xdmcp over (WEP & WPA encrypted) links plenty of times with
> few problems.
> 
> Could it be an MTU or packat fragmentation problem passing over the VPN?
> 
> Rob
> 

It turns out that I can run X, if I use the X -from option.  However,
this means I cannot use the remote login feature of KDE, which works
well on the local network.  Apparently the problem is caused by the dual
interfaces on my notebook computer, when using a VPN.  Right now, I'm
trying to see if there's some option somewhere, that will affect this.


tnx jk


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