Baslinux mailing list

[James Miller <jamtat AT mailsnare.net>]

On Thu, 12 May 2005, Constant Brouerius van Nidek wrote:

> Well the package says Nat firewall.

NAT means "network address translation." It is needed because the 
modem/router gets an address on the internet from your provider, which it 
then shares with several machines on your "internal" network. You internal 
network uses its own set of addresses, usually in the 192.168.X.X range. 
The router uses NAT to translate between your local machines' addresses 
and the internet address the modem/router gets from the ISP. So, good to 
hear this device does firewalling.

> IP Routing, DHPC, DNS, DMZ, NAT Firewall, Port forwarding, VPN Passthrough.

I think IP routing is just another way of saying NAT. DHCP is dynamic host 
configuration protocol. This is how the "hosts" (i.e., computers) on your 
network get assigned their internal address so they can talk to each 
other, to the router, and through the router to the wider internet. DNS = 
domain name service. This is essentially connecting numerical internet 
addresses with humanly understandable names: to make up an example, 
202.45.231.34 might resolve to www.mydomain.com. The router can apparently 
keep a cache of name/numerical address associations. DMZ = demilitarized 
zone. You can use this to make a portion of your network--say, a dedicated 
machine that acts as an ftp server--open to the internet. It would be 
partially protected by the firewall, but with some protection removed. 
Like, port 21 (the ftp port) would be left open. And other machines on 
your network would likely be protected from that machine much like they 
are from machines outside your internal network. Port forwarding means you 
can forward a port on the router to a different port on some internal 
machine. For example, on my router/firewall I run an ssh server on port 
443. I set this up so I could get around some firewalling at a friend's 
house whose ISP blocks all traffic except http (port 80) and https (port 
443). I could then forward port 443 traffic from my router to port 22 (the 
standard ssh port) on a machine on my internal network if I wanted to 
login in there and use the shell to run programs. VPN = virtual private 
networking. This allows you to log into machines on your internal network 
securely from out on the wider internet. If you've heard of PCAnywhere 
(Windows software), it works something like that. I doubt you will want to 
tweak any of those features: probably you'll want to just leave them on 
their default settings.

> What I like is that it automatically detects of a cable is straight or
> cross-over. It seems to have a web based management but I surely are not able
> to tell if that is perhaps the URL that was used by the technicians.

Sounds like a good guess. To test it, just enter that address into your 
browser of choice. You'll likely have to provide a user name and password 
to log into the router administration program. All information about the 
router's address and the username and password you need to give should be 
the in the documentation that came with it. If the user name and password 
are set to the defaults the manufacturer put on them (they always are, 
unless you've changed them), I strongly encourage you to change one or 
both of them soon to something difficult to guess.

James