*BSD News Article 76392


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From: les@MCS.COM (Leslie Mikesell)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: IP Masqerading?
Date: 19 Aug 1996 00:17:15 -0500
Organization: /usr/lib/news/organi[sz]ation
Lines: 92
Message-ID: <4v8tcr$8ei@Mercury.mcs.com>
References: <jfortes-1307951117380001@10.0.2.15> <32127AB2.21876B97@lambert.org> <4v0lsb$6uv@cronkite.cisco.com> <32151AD0.699795F7@lambert.org>
NNTP-Posting-Host: mercury.mcs.com

In article <32151AD0.699795F7@lambert.org>,
Terry Lambert  <terry@lambert.org> wrote:

>] In other words, if your application doesn't support socks, you
>] can't use it.  So, NAT is more general than Socks.
>
>This is technically true, but misleading.
>
>Typical use of NAT (at least in the Linux sense, and in the
>sense where you would require direct translation) does not
>involve a firewall.  It involves:
>
>1)	Someone who doesn't want to pay their ISP for more than
>	one address.

And doesn't want inbound connections to more than one address,
perhaps not even that.  These people would need a firewall
if they had full routing enabled.

>2)	Someone who doesn't want to pay their ISP for packet
>	forwarding.

Because they have no need for it and would have to do extra
work to prevent it if they had it.

>3)	Someone who wants to run an MS OS which is not itself
>	SOCKS aware and is too lazy to install the SOCKS aware
>	WSOCK32.DLL

The MS reference is gratituitous there.  It applies equally to
any binary distribution or embedded system where it is difficult,
impossible or at least annoying to install socks awareness.

>Basically, it's for lazy people or cheap people.

Translation: practical people.

>I have no problem with people being cheap, but they should admit
>that that's what they're doing instead of trying to cloak it in
>better robes.
>
>I have a problem with lazy people.  But, since I don't want to
>force my world view down everyone's throat (or more likely, I
>simply can't 8-)), the least they can do is, once again, admit
>it.

Let's see, we can say it's cheaper and easier and since the nat
capability typically comes with packet filtering in the same
package, safer.  Now what was the down side?

>Given that there are typically better alternatives to NAT in all
>but a few cases (*real* range translation, for instance), I will
>pretty much put all NAT usage in the category "indiscriminate use".
>8-).

Better from what viewpoint?  I thought we established that nat
was cheaper and easier.

>] |o       RFC-1256 ICMP router discovery doesn't work through a
>] |        "masquerade".
>] 
>] It doesn't work past a firewall, either, nor would you want it
>] too.  In essence, so what?
>
>Typical NAT usage is to overcome some specious economic setup,
>and is not in the context of a firewall.  If any of the RFC
>arguments don't hold water, it would be my RFC-1919 argument
>(which still holds water in the full "range translation" case).

How many places using NAT would be comfortable with a non-firewalled
internet connection if they understood the implications.

>] |o       RFC 1063 MTU discovery  doesn't work through a "masquerade";
>] 
>] Uh, and why not?  Even blind NAT will have no problem properly
>] conveying the information for this option,
>
>Use of ICMP packets.

I'd prefer to firewall ICMP if it didn't make people think the
network was broken.

>] Obviously, you have something of an axe to grind wrt. NAT
>
>My only axe is that it irks the bejesus out of my elegance
>filter.  8-).

If tcp were elegant, NAT would be too - or there would be no
need for it.

Les Mikesell
  les@mcs.com