Running two Firewalls

[B.W.]

I think I have read that it is not recommended to run more than one
firewall. For example Windows XP and Zone Alarm free vers. Is this true?
Can it cause conflicts?

TIA

B.W.

 

[Tom Willett]

What have you read? Where?

 

[Galen]

In B.W. had this to say:

My reply is at the bottom of your sent message:

I think I have read that it is not recommended to run more than one
firewall. For example Windows XP and Zone Alarm free vers. Is this
true? Can it cause conflicts?

TIA

B.W.

In my experiences it hasn't so much caused issues (though two AV scanners
have) so much as providing an additional point one must check when they find
they have connectivity issues. That being said I quite frequently have XP's
firewall on while I have a third party firewall running but that's mostly
'cause I'm too lazy to go turn it off and I don't always have a third party
firewall running. I'm aware that it's not the best choice and it /could/
cause me issues down the road but in all honesty I've never found any
connectivity problems because of it.

--
Galen - MS MVP - Windows (Shell/User & IE)
http://dts-l.org/
http://kgiii.info/

"At present I am, as you know, fairly busy, but I propose to devote my
declining years to the composition of a textbook which shall focus the
whole art of detection into one volume." - Sherlock Holmes

 

[longman]

I think I have read that it is not recommended to run more than one
firewall. For example Windows XP and Zone Alarm free vers. Is this true?
Can it cause conflicts?

TIA

B.W.

Yes it is true. Running 2 firewalls creates problems. When you install
Zone Alarm it shuts down the windows firewall automatically. The
windows firewall checks inbound internet traffic only. Zone alarm
checks traffic in and outbound.

 

[Shenan Stanley]

I think I have read that it is not recommended to run more than one
firewall. For example Windows XP and Zone Alarm free vers. Is
this true? Can it cause conflicts?

I wouldn't do it - as you gain nothing.
Just like you shouldn't run more than one active antivirus at a time...

And could it cause problems? Sure.
What if one is configured to allow port 3389 and the other is set to deny
port 3389?
You have to figure out who is doing the blocking because the deny will win.

The question becomes... why do you feel the need to double your effort to
get the same protection you would have with one well configured and managed
solution?

 

[Bruce Chambers]

I think I have read that it is not recommended to run more than one
firewall. For example Windows XP and Zone Alarm free vers. Is this true?
Can it cause conflicts?

TIA

B.W.

You don't _have_ to disable the built-in firewall, but it would be
a good idea.

Running two software firewalls simultaneously is unnecessary and
can sometimes cause conflicts, possibly negating the protection of both.
In any event, having two firewalls running simultaneously is an
unnecessary drain on system resources.

Control Panel > Windows Firewall > Off.


--

Bruce Chambers

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[B.W.]

Thank you everybody for your advice on this query.

B.W.

 

[Ken Blake, MVP]

I think I have read that it is not recommended to run more than one
firewall. For example Windows XP and Zone Alarm free vers. Is this
true?

Yes, it's true.

Can it cause conflicts?

Yes. It also provides no extra security.

See http://www.microsoft.com/athome/security/protect/firewall.mspx which
includes the following:

"Q. Should I use both the built-in firewall and a software firewall from a
different company on my Windows XP computer?

"A. No. Running multiple software firewalls is unnecessary for typical home
computers, home networking, and small-business networking scenarios. Using
two firewalls on the same connection could cause issues with connectivity to
the Internet or other unexpected behavior. One firewall, whether it is the
Windows XP Internet Connection Firewall or a different software firewall,
can provide substantial protection for your computer."

Also note that if you update your third-party firewall to a new version, the
update routine will probably turn it off first. If the Windows firewall
isn't running, you will temporarily be left with no running firewall, which
is very dangerous. So turn on the Windows firewall temporarily before doing
maintenance on your third-party firewall.

The Windows firewall monitors incoming traffic only. Almost any third-party
firewall will also monitor outbound traffic, stopping rogue programs trying
to call home, and is a better choice.