[ale] Linux box as a router w/DHCP

[James Sumners]

The P2 machine I use, I got off eBay for $25.

The "problem" with the IP address being assigned from the ISP via DHCP
lies in the way the firewall scripts have to be written. If the ISP
is... silly, and assigns a new IP address every lease renewal, or even
every day (whatever), then they scripts have to be able to handle
that. If you have a static IP from your ISP, then you can reference
the same external IP in your firewall rules without care. If you have
a dynamic IP, you have to get a little crafty and retrieve the current
external IP every time the script is run.

If you're using a third party script like the sentryCD system you are
using, then you don't really have to worry about it. Such scripts are
written to be generic and take such a scenario into account. If you
are writing your own scripts, as I assume Mr. Kruger is, then you have
to do it yourself.

On 1/22/07, Charles Shapiro <hooterpincher at gmail.com> wrote:
> Ooh, I have exactly this setup, using sentryCD  (
> http://www.linux.com/howtos/Sentry-Firewall-CD-HOWTO-1.shtml
> ) on a machine with 2 NICs, a floppy drive, and no hard drive.  I think it
> has, like, 128 mb on a PII or so motherboard. You don't need a lot of power
> to run one of these things -- betcha you could pick up a machine capable of
> doing it for $80 or so at MicroSeconds.. I really likes SentryCD. It is a
> bootable CD distro which uses a floppy to store configuration files and
> scripts. I also have it running my caching local name server.  Before I got
> broadband I had it running diald ( http://diald.sourceforge.net/ ) to go
> through the phone lines without a problem (well, besides how s l o w it
> was).
>
>  I just changed the link between the router and the modem/router supplied by
> my ISP to be static, not DHCP. Using the DHCP server on the modem/router
> means that it has to come up before the linux box in the event of a power
> failure for things to work properly. So your wife is always after you to fix
> the darn thing after a storm.
>
>  I don't quite get why dhcp to your isp would be a problemo.  As long as
> you're using it and it's up, it should know what IP address it has. If it
> reboots, it'll contact the dhcp server on the far end automatically when it
> runs its client, right?
>
>  -- CHS

-- 
James Sumners
http://james.roomfullofmirrors.com/

"All governments suffer a recurring problem: Power attracts
pathological personalities. It is not that power corrupts but that it
is magnetic to the corruptible. Such people have a tendency to become
drunk on violence, a condition to which they are quickly addicted."

Missionaria Protectiva, Text QIV (decto)
CH:D 59