In article <8431e966.0411280619.e6e81ff@posting.google.com> ,
danicamps81@yahoo.com (Daniel Camps) writes:

> Hello, I have a small LAN and an ADSL connection to the Internet, I
> would like to install Linux (I am thinking in Fedora Core 3) in the
> machine where I have the ADSL connection, and make the other PC's
> connect to the Internet htrough this machine. I think I need to
> install and configure in that machine, DHCP and NAT, I don't know
> if I would need something else, like some Firewall capabilities.
> I am a new linux user so I basically would like to know about a
> good tutorial about how to configure this stuff, or good tools or
> programs to do it, and of course advise about which are the possible
> alternatives to do it.

You'll need DHCP and NAT on the ADSL connection: DHCP because your
ISP uses it, and NAT so that your ISP will think there's only one
machine connected. On the LAN side of the machine it doesn't matter;
my LAN uses static addresses (192.168.0.x) and lets the gateway box
figure things out if I'm talking to the outside world.

But you _definitely_ need firewall capabilities. This is _not_ an
option; there are a lot of nasties out there who are trying hard to
break into your network. I'm using a dedicated box running OpenBSD's
packet filter (pf), but there are Linux equivalents you can use.
I'm blocking probes every few of minutes from all over the world,
usually on ports 135 and 445 but I've got everything locked down
pretty tightly. I made the mistake of connecting my wife's Win98
laptop directly to the ADSL modem - she was infected in 10 minutes.
Linux boxes aren't nearly as vulnerable, but you still don't want
to take chances.

_Don't_ connect your LAN to the Internet without a firewall.

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