Re: firewall behind router
From: Chuck (none_at_example.net)
Date: 08/28/04
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Date: 28 Aug 2004 15:56:10 -0500
On Sat, 28 Aug 2004 12:34:51 -0700, Lou <mac@qnet.com> wrote:
>Is there a need for a firewall behind a router. My home network is
>configured with private addresses (i.e. 192.168.x.x). The router ip
>address which connects to the internet via cable modem is also private
>(192.168.0.142).
>
>Reason for question is I seem to recall private addresses are not
>accessible from the internet.
>
>Lou
Lou,
A NAT router is the first layer in a good layered defense. Each layer is
necessary because no layer produces complete protection.
A NAT router "acts as a firewall" in that it passes only requested traffic back
to the computer that requested it. It won't selectively filter traffic from
hostile addresses, nor selectively filter bad protocols or programs, however.
See <http://www.firewall-software.com/firewall_faqs/what_is_a_firewall.html>
One NAT router protects your entire LAN.
The second layer is a software firewall, or a port monitor like Port Explorer
(free) from <http://www.diamondcs.com.au/portexplorer/index.php?page=home>. See
various discussions in comp.security.firewall for good advice on choosing a
firewall. A software firewall can selectively block incoming or outgoing
traffic, and a port monitor can at least let you know that it's going on.
You need a software firewall on each computer in your LAN, in case one gets
infected a software firewall on the others could save you.
The third layer is good software, also on each computer. This layer has
multiple components.
AntiVirus protection. Realtime, plus a regularly scheduled virus scan.
Regularly updated. AV protection is not all that's needed today.
Adware / spyware protection. Realtime, plus a regularly run adware / spyware
scan. Regularly updated.
Complete instructions, using Spybot S&D and HijackThis (both free) are here:
<http://forums.spywareinfo.com/index.php?showtopic=227>.
Harden your browser. There are various websites which will check for
vulnerabilities, here are three which I use.
http://www.jasons-toolbox.com/BrowserSecurity/
http://bcheck.scanit.be/bcheck/
https://testzone.secunia.com/browser_checker/
Block Internet Explorer ActiveX scripting from hostile websites (Restricted
Zone).
<https://netfiles.uiuc.edu/ehowes/www/main.htm> (IE-SpyAd)
Block known dangerous scripts from installing.
<http://www.javacoolsoftware.com/spywareblaster.html>
Block known spyware from installing.
<http://www.javacoolsoftware.com/spywareguard.html>
Make sure that the spyware detection / protection products that you use are
reliable:
http://www.spywarewarrior.com/rogue_anti-spyware.htm
Harden your operating system. Check at least monthly for security updates.
http://windowsupdate.microsoft.com/
Block possibly dangerous websites with a Hosts file. Three Hosts file sources I
use:
http://www.accs-net.com/hosts/get_hosts.html
http://www.mvps.org/winhelp2002/hosts.htm
(The third is included, and updated, with Spybot (see above)).
Maintain your Hosts file (merge / eliminate duplicate entries) with:
eDexter <http://www.accs-net.com/hosts/get_hosts.html>
Hostess <http://accs-net.com/hostess/>
Secure your operating system, and applications. Don't use, or leave activated,
any accounts with names or passwords with trivial (guessable) values. Don't use
an account with administrative authority, except when you're intentionally doing
administrative tasks.
The fourth layer is common sense. Yours. Don't install software based upon
advice from unknown sources. Don't install free software, without researching
it carefully. Don't open email unless you know who it's from, and how and why
it was sent.
The fifth layer is education. Know what the risks are. Stay informed. Read
Usenet, and various web pages that discuss security problems. Check the logs
from the other layers regularly, look for things that don't belong, and take
action when necessary.
Cheers,
Chuck
Paranoia comes from experience - and is not necessarily a bad thing.
- Next message: GTS: "Re: Multiple Networks (Dual NIC config)"
- Previous message: JohnC: "Re: File Sharing Windows 98"
- In reply to: Lou: "firewall behind router"
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