network gateway with a foreign IP address

[Claude Jones]

On Sat April 12 2008, John Cornelius wrote:
> I gather that it's simply a case of you moving from direct connection to
> the Internet to a connection that's behind your Cisco router. I further
> presume that the (nominal) 70.x.x.120 address belongs to the Cisco. In
> that case you probably don't want to do what you propose.
>

Thanks for your thoughts, and yes, your surmising is correct

> Your box should be set up on the internal LAN subnet in the normal way.
> All of the interesting configuration should be done on the Cisco router
> by setting up source and destination NAT so that internet traffic on
> specific ports addressed to the Cisco are routed to your box and
> responses are automatically routed back through the Cisco to their
> destination.
>

I viscerally believe you're correct, here - else why is this the way this is 
universally done, but I sure could use some better technically grounded 
expertise in the whys and wherefores

> Trying to deal with this issue from inside the LAN rather than in the
> router will most likely lead to frustration since whatever you do will
> be fragile and probably break often if it works at all.

This is where I need better argumentation...if you can help, it would be 
appreciated. Specific examples of why it's a bad idea, security problems that 
could occur, other issues...unfortunately, this configuration has been handed 
to me, it's not my idea, so I need to understand what's wrong with it and be 
able to offer sound arguments for the more conventional approach, if there's 
is a really sound technical reason for not doing it this way. 

I'm also dealing with the fact that another Linux box, a mail server, has been 
moved on to this new FIOS lan and configured using the hack that I cited in 
my original post, and is working quite nicely - unfortunately, I don't 
clearly understand how to implement that hack on Fedora, but, I'm getting 
the "if Jack could do this with his Debian box, why can't you with your 
Fedora?"....

-- 
Claude Jones
Brunswick, MD, USA