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Date:	Wed, 7 May 2003 19:27:07 PDT7
From:	Peter Skye <pskye@peterskye.com >
Reply-To:	scoug-help@scoug.com
To:	scoug-help@scoug.com
Subject:	SCOUG-Help: Re: Static IP

Content Type: text/plain

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Harry Motin wrote:
>
> attached please find the file, Firewall.txt, from
> my InJoy Firewall installation. Please do a search
> on "Port and Address Redirection" in this file. I
> think you will find that the info from InJoy in
> this document supports what I said.

Hi Harry,

First a quick note on your attachment - you encoded it, which makes it
bigger (and unreadable if somebody stores it in their TEMP directory,
which is what I first did). And it would be easier for the readers if
you just quoted the relevant section (i.e. you do the one search instead
of 100 readers doing 100 searches). :)

Here's the paragraph I think you are referring to:

The firewall's Access Control rules provide
the capability of redirection, which allows a
connection request from an external client to be
remapped to a system on the internal network.

This allows different servers (HTTP, FTP, SMTP, DNS, NTP, whatever) to
be on different machines yet all have the same external IP address (same
URL). The firewall says "this request from the outside world is for
port 80 so send it to machine 1, this request is for port 21 so send it
to machine 2," etc. Port 80 is what we carbon-based life forms call
HTTP, port 21 is what we call FTP, etc. (see your \MPTN\ETC\services
file if you want to know what's what).

*However*, you still need a static IP address on the outside if you want
people to find you.

Suppose I wanted to go to your web page on your web server. Suppose you
had emailed me that your IP address was 216.184.211.34. Then in my
browser I would type in HTTP://216.184.211.34 and press Enter, and up
would come your web page.

Now suppose you turn off your firewall. And the next day you turn it on
again. If you have a static IP address then I can still connect to you
at 216.184.211.34, but if you are on a dynamic connection (DHCP) then
you might get the same IP address or you might get a different one (your
ISP assigns you one when you connect). And that could be very
embarrassing for you, because while you have your firewall switched off
somebody else could turn on their computer and your ISP might assign
216.184.211.34 to them. And if they had some, well, quirky pictures on
their own web server then the next day when I try to get to the Harry
Chris Motin web page by going to HTTP://216.184.211.34 the page that
comes up might instead be Pamela's Private Party or something. So you
need to be careful with these things . . .

If you keep your firewall on a UPS and never turn it off then the DHCP
connection will keep renewing (run DHCPMON to see your own connection)
and the IP address "probably" won't change (your ISP can still change it
and I've heard that some do but I've never had it happen to me). And
you can hand out this IP address to people and you might even be able to
get away with registering it to your own domain name
(HarryChrisMotin.com) [lurkers - I know you *can* do this, I said "get
away with it"].

But if you go to all this trouble then you're essentially creating a
"static" IP address that never changes because you won't let the DHCP
connection die. DHCP death often means an IP change.

Bottom line: The outside world needs an IP address to get to you.
Either you need to supply them with one that never changes or figure out
a way to tell them every time it does.

- Peter

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