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Thread: Using more than one firewall

  1. #1
    Junior Member
    Join Date
    Nov 2003

    Question Using more than one firewall

    I have a general question about firewalls. In most cases, is it alright to use more than one firewall? Can they interfere with each other, and cause security risks? Is it recommended to use only one firewall, or is it case-specific?
    I am using Sygate and ZoneAlarm on Windows 98SE, but I have been told that this is not ok. On my Linux system, I am using the firewall that came with RedHat.
    Thank you.

  2. #2
    Senior Member
    Join Date
    May 2004
    I see no point to using more than one firwall because the first one will block the incoming connection before it even gets to the second firewall ... if you have one firewall installed and have it configure _properly_ then using 2 is pointless

  3. #3
    Senior Member
    Join Date
    Jan 2002
    Using several software firewalls on the same machine is asking for trouble. They may interfere with each other, and prevent each other from updating properly etc.

    Using a software firewall combined with either a hardware firewall or a dedicated firewall device on generic hardware, is fine.

    As far as I'm aware, Linux firewalls either just use iptables to implement the filtering, or in the case of expensive commercial solutions, bypass the kernel's IP stack entirely and implement their own. Either way, you won't want to put multiple ones on, they will just wrestle for control of the kernel's iptables.


  4. #4
    Junior Member
    Join Date
    Nov 2003
    Thank you slarty, this is what I wanted to know.

  5. #5
    Regal Making Handler
    Join Date
    Jun 2002
    Just to point out that there is a school of thought that once you have a properly configuerd hardware firewall a software firewall is surplus to requirements and a waste of system reasorces. The greater the number of services running on a machine the less secure the machine becomes.
    What happens if a big asteroid hits the Earth? Judging from realistic simulations involving a sledge hammer and a common laboratory frog, we can assume it will be pretty bad. - Dave Barry

  6. #6
    Junior Member
    Join Date
    Aug 2004


    I think that good idea is to read Sygate forum:
    Can Sygate Firewall coexist with other firewalls?
    SygateŽ Personal Firewall STD
    SygateŽ Personal Firewall Pro
    Operating systems:
    All supported operating systems.

    No, SygateŽ Personal Firewall STD and SygateŽ Personal Firewall Pro will not function while another firewall are running. In order to properly run SPF you will need to uninstall any other software firewalls prior to installing SPF

    Firewall, ICF, ZoneAlarm, Norton, BlackICE, Agnitum Outpost,
    I am an atheist, thank God.
    Luois Bunuel

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