Networking (was: Re: [CS-FSLUG] Networking details #2 (slapping myself))

[Bradly McConnell]

On Tue, 07 Dec 2004 23:30:13 -0600, N. Thompson <n.thomp at sasktel.net> wrote:
> I'm a little uneducated as far as networking goes, my understanding of
> it is that two computers need to both be connected to a router or hub
> since connecting them both together directly won't work. 

Actually, you can as long as you are using a "cross-over" cable.  It's
pinned slightly different than a straight or "normal thru".  Take a
look at the 568A and 568B standards, and they should show some
examples.

http://www.zytrax.com/tech/layer_1/cables/tech_lan.htm

>Can someone
> here with more understanding of networking provide me with more
> information on how networking works and what different kinds exist and
> can be used. Also is the 192.168.0.x IP address what you would always
> use for computers in a local domain? I only seen routers use the
> 192.168.x.x range of IP addresses for computers connected to them.

The 192.168.x.x are private IP's.  They are non-routable, and should
only be used with Network Address Translation (NAT) or on an internal
network.  Usually, the router/DHCP server will issue the address to
the clients, and any packet it receives from those addresses, it will
send out under it's own IP to the rest of the internet/infrastructure.
 It is one of the ways that you can hook up more than one computer to
a broadband connection, as it is a violation of the Terms Of Service
for most providers for a residential account to have more than one IP
address (received via the same account).  It also helps shield the
client computers, as the router will typically block or redirect
packets based on the port needed.  The router could send incoming port
80 to 192.168.0.22, and inbound port 25 traffic to 192.168.0.56 (just
examples, not necessarily the case).  There may even be a DMZ where
the mail and web servers are located to where they aren't directly
exposed to the rest of the world, but also are not directly on the
local network.  There's a pretty funny video about TCP/IP
communication at http://www.warriorsofthe.net/

For other info, I would google NAT, and take a look at some of the
firewall documentation for shorewall and the others.