D-link dsl-504 cant block ports

Discussion in 'Computer Security' started by rello, Jun 17, 2004.

  1. rello

    rello Guest

    hi we have a network of two sharing a dsl connection
    port scans from grc and sygate both reveal many ports open..in fact
    only about 6 are stealthed.......the strange thing is if we install a
    software firewall,,,[tried kerio and zonealarm] we get exactly the
    same result...i have used kerio b4 on a small network with no hardware
    and found it to be pretty excellent...i can only assume the the router
    is to blame....it is supposed to have a firewall that obviously is not
    working properly...
    any advice on securing this network gratefully received
    relloman
    rello, Jun 17, 2004
    #1
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  2. rello

    Todd Shillam Guest

    Rello,

    Some (not all) routers do have built-in firewalls; however, you don't want to close the ports to any 'active' applications. If you're running applications that require certain ports, those ports must be open; otherwise, the program will not work correctly.

    When you use ZoneAlarm, you authorize a program to communicate with the Internet. When you authorize a program to access the Internet, ZoneAlarm configures (opens) the necessary ports for that application.

    Like you mentioned, the router may also have some open ports. Check your 'port-forwarding' settings if available. If your router doesn't have a built-in firewall, then you may be exposed to Internet instrusions. By the way...what are you using to scan your ports? Are you scanning the router, or your machine(s)?

    Best regards,

    Todd Shillam
    Information Technology Consultant
    Shillam Technology
    WWW: http://shillamtechnology.point2this.com

    "rello" <> wrote in message news:40d0cfe7.1187497@news-server...
    hi we have a network of two sharing a dsl connection
    port scans from grc and sygate both reveal many ports open..in fact
    only about 6 are stealthed.......the strange thing is if we install a
    software firewall,,,[tried kerio and zonealarm] we get exactly the
    same result...i have used kerio b4 on a small network with no hardware
    and found it to be pretty excellent...i can only assume the the router
    is to blame....it is supposed to have a firewall that obviously is not
    working properly...
    any advice on securing this network gratefully received
    relloman
    Todd Shillam, Jun 17, 2004
    #2
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  3. rello

    Andrew Guest

    6/16/2004 7:03:16 PM

    rello <> wrote in message

    <40d0cfe7.1187497@news-server>



    > hi we have a network of two sharing a dsl connection


    > port scans from grc and sygate both reveal many ports open..in fact


    > only about 6 are stealthed.......the strange thing is if we install

    a

    > software firewall,,,[tried kerio and zonealarm] we get exactly the


    > same result...i have used kerio b4 on a small network with no

    hardware

    > and found it to be pretty excellent...i can only assume the the

    router

    > is to blame....it is supposed to have a firewall that obviously is

    not

    > working properly...


    > any advice on securing this network gratefully received


    > relloman




    As Todd pointed out, any port forwarding or servers/share programs
    running (that would show up as open on the software firewall)? ZA is
    set to what security level? What do the scanners say if you leave
    your SW firewall in place and remove your router (or is that what you
    meant above, I presumed in line with router and FW)?

    Big one... Have you updated the firmaware? My linky use to have a
    similar issue, and it was tied to that version of the firmware....
    --
    Composed with Newz Crawler 1.7 http://www.newzcrawler.com/
    Andrew, Jun 17, 2004
    #3
  4. rello wrote:

    > hi we have a network of two sharing a dsl connection
    > port scans from grc and sygate both reveal many ports open.


    which ones are open?
    Have you enabled NAT, DHCP, etc on the router?
    What else did you configure or did not configure on this DSL router?


    ..in fact
    > only about 6 are stealthed.


    Don't know what you mean by "stealthed" :-/.

    .......the strange thing is if we install a
    > software firewall,,,[tried kerio and zonealarm] we get exactly the
    > same result...


    It is understandable since the router sits in front of your machines,
    thus putting firewall software on the machines does not change the equation.

    i have used kerio b4 on a small network with no hardware
    > and found it to be pretty excellent...i can only assume the the router
    > is to blame....


    Yup.

    it is supposed to have a firewall that obviously is not
    > working properly...
    > any advice on securing this network gratefully received
    > relloman


    The result of portscan will tell you what is your next step. If you
    follow the basic configure on these devices, then normally NAT is
    enabled, so is dhcp and of course simple routing.
    The outbound traffic should have no problem returning in this
    configuration and no access from outside should be provided to the machine.

    Regards,
    Patrick Soltani.
    patricksoltani, Jun 17, 2004
    #4
  5. "rello" <> wrote in message
    news:40d0cfe7.1187497@news-server...
    > hi we have a network of two sharing a dsl connection
    > port scans from grc and sygate both reveal many ports open..in fact
    > only about 6 are stealthed.......the strange thing is if we install a
    > software firewall,,,[tried kerio and zonealarm] we get exactly the
    > same result...i have used kerio b4 on a small network with no hardware
    > and found it to be pretty excellent...i can only assume the the router
    > is to blame....it is supposed to have a firewall that obviously is not
    > working properly...
    > any advice on securing this network gratefully received


    1. Turn off the DMZ function (note - this is just a Wild Ass Guess)

    2. See if there is more up-to-date firmware available

    HTH

    --

    Hairy One Kenobi

    Disclaimer: the opinions expressed in this opinion do not necessarily
    reflect the opinions of the highly-opinionated person expressing the opinion
    in the first place. So there!
    Hairy One Kenobi, Jun 17, 2004
    #5
  6. rello

    rello Guest

    On Thu, 17 Jun 2004 10:23:31 +0100, "Hairy One Kenobi"
    <abuse@[127.0.0.1]> wrote:

    >"rello" <> wrote in message
    >news:40d0cfe7.1187497@news-server...
    >> hi we have a network of two sharing a dsl connection
    >> port scans from grc and sygate both reveal many ports open..in fact
    >> only about 6 are stealthed.......the strange thing is if we install a
    >> software firewall,,,[tried kerio and zonealarm] we get exactly the
    >> same result...i have used kerio b4 on a small network with no hardware
    >> and found it to be pretty excellent...i can only assume the the router
    >> is to blame....it is supposed to have a firewall that obviously is not
    >> working properly...
    >> any advice on securing this network gratefully received

    >
    >1. Turn off the DMZ function (note - this is just a Wild Ass Guess)
    >
    >2. See if there is more up-to-date firmware available
    >
    >HTH

    thanks all,
    i tried the sw firewalls behind the router
    will look at the firmware upgrade and the settings suggested
    tnx
    relloman
    rello, Jun 17, 2004
    #6
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