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Re: cups relaying remote broadcasts to a local subnet



On Thu, 2006-05-25 at 00:12 -0700, Thomas Taylor wrote:
> On Wednesday 24 May 2006 09:35, Gregory P. Ennis wrote:
> >>>>> snip <<<<<
> > >
> > > This sounds like an application that could use a vpn (virtual private
> > > network) over the internet.  I haven't done this yet but have seen it
> > > used at one company.  You should be able to get information from the LPD
> > > howto's on vpn or try googling for vpn.
> > >
> > > HTH,
> > > Tom
> > >
> > > --
> > > Tom Taylor
> > > Linux user #263467
> > > Federal Way, WA
> >
> > Tom,
> >
> > I have not set up a VPN yet either and had wondered the same thing.
> > Does this mean you believe that cups is not designed to perform in the
> > way I the network designed?
> >
> > I thought cups was a little more robust than that!!!
> >
> > Greg
> 
> To the best of my knowledge, cups has no way of communicating with a remote 
> network without using a vpn.  
> 
> The 10.x.x.x series of IP addresses is set aside as private address space.  
> Probably millions of people use it in their internal networks.  How is cups 
> to know which 10.x.x.x to communicate with over the internet?  It can 
> communicate with any allowed private address including subnets within as long 
> as their is a direct physical or wireless connection.  It can't go out over 
> the internet to find a private address space without a "tunnel" through the 
> internet (between two internet portals)
> 
> If this doesn't make sense, think about how you would control a "remote" 
> computer.  You would need to send a control signal (hopefully encoded) 
> through your portal (your gateway to your ISP).  That signal would have to 
> know how to find the portal for the remote you wanted to control.  Then you 
> would have to connect to the internal network on the remote whose IP you can 
> supply to cups.  What cups doesn't know is how to make a connection between 
> the portals.  That's where the vpn (the tunnel) comes in.  It makes a 
> connection between the internal network at one site and the internal network 
> at another remote site and carries the communication over it.
> 
> I suspect that if you ask about how to set up the vpn like this on the list, 
> you will get some better responses than I have given.
> 
> Tom
> 
> -- 
> Tom Taylor
> Linux user #263467
> Federal Way, WA
> 

Tom,

Thank you for taking the time to help me.  I have wanted to set up a VPN
for awhile anyway, so now would he a good time to start the study
process.

In regards to your comments about cups, I understand what you are
saying, but my thought was that the documentation of cups seems to
support the feature of local broadcasting from a gateway.  This
certainly works for one of my units (the one with only one ethernet
card), but as per your comments above it is placed on the same subnet as
the network and would be expected to work.

There is still a lot of magic in the way tcp/ip communication occurs for
me, but I was hopeful that cups would work in the same manner as httpd
behind the gateway which allows communication to a desktop behind the
firewall.  

I will take your VPN challenge, but do some studying before I post
laughable questions.   

Thanks again for your help!!!!

Greg


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