Re: re. too long mac address for --mac-source netfilter option

From: jpinpg@home.com
Date: Sat Feb 17 2001 - 17:11:49 EST

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    James L. wrote -
    > Hello All,
    >
    > On Sat, 17 Feb 2001 jbinpg@home.com wrote:
    > > Stefan Hanse writes -
    > > >Umm.. An ethernet MAC address is 48bit long, ie AA:BB:CC:DD:EE:FF, 6
    > >groups, not 14. Is this really an ethernet
    > > >interface? (If it really has 14 groups).
    > >
    > >> Good question. I have determined by scanning my firewall logs that the
    > >"invalid" mac addresses are all coming from cable modem routers. And my
    > >linux kernel is recognizing them as being MAC addresses. Would it be
    > >better to write another module looking for these long "MAC" rather than
    > >tamper with the mac module?
    > >
    > >> To illustrate, here is a cut from my system log showing a portscan from
    > >my cable modem provider (a routine part of their service contract since
    > >you are not allowed to run client-side servers). SRC and DST have been
    > >x'ed out:
    > >
    > >> Feb 17 08:49:42 nonesuch kernel: IN=eth0 OUT=
    > >MAC=00:01:02:69:49:4f:00:00:77:93:83:d2:08:00 SRC=xx.xx.xx.xx
    > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    > This appears to be an ATM NSAP address . Hth , JimL

    OK, thanks Jim. The question then becomes: could a netfilter module for recognizing ATM addresses be developed? Are all ATM addresses 14 groups?

    Jack Bowling
    mailto: jbinpg@home.com
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