Routing for Dummies ?

[David P. Schwartz]

I've got standard Qwest DSL line (DHCP, etc) with a Cisco 675 modem/router
plugged into a hub with a few PCs hooked into it as well.  (FWIW, I just
installed the latest firmware patch to deal with CodeRed.)

I want to have one of the machines run a small web server that I can play
with to get some experience writing CGI apps in Delphi.  I want to use a
dynamic DNS server to link a public domain name to it.

The manual that comes with the 675 describes the CBOS commands, but not how
to use them -- ie., the theory behind them.

What I'd like to understand, in principle, is how to set things up in the
675 and in my computers so that I can use the dynamic DNS server to point
to a machine acting as a web server, and have my other computers also
working fine on the network.

Someone helped me do this around December with another machine that I never
ended up using much (it quickly got moved elsewhere) and I lost the notes.
I can tell you that the common ports (http, ssh, mail, etc) are all mapped
to internal IP 10.0.0.2 in the NAT table.  Also, all of my local machines
are being allocated dynamic IPs (via the 675 DHCP server) starting at
10.0.0.100.

With the server machine allocated to, say, 10.0.0.101, I CAN reach the
server by entering that IP into my browser.  I can also access the FTP port
that way.  I cannot, however, get anything to respond when I try to go
through the domain name at the dynamic DNS host; I get a response timeout
from the dynamic DNS host.  I'm fairly sure the requests are getting to my
router, they're just not getting routed to anything on the internal
network.

What I'm unsure of is:

(1) do the server machine(s) need to have a fixed (static) internal IP?

(2) What do I need to do in the router to point requests coming in from
ports at internal IP 10.0.0.2 at the server machine?

Maybe there's a page somewhere on the web like, "Routing for dummies" ;-))

Thanks
-David Schwartz