ipchains help

["Gregory T. Norris" <haphazard@socket.net>]

I'm trying to setup some firewalling rules, now that my Linux box has a
full-time ADSL connection to the Internet.  I'm currently running kernel
2.2.7 (under potato), so I'm using ipchains in my (apparently feeble
<g>) attempts to do this.

Ever since the ADSL connection was configured, I've noticed the
following in my logs every 10 minutes or so...

    Apr 30 21:25:23 glitch nmbd[10603]: connect from 10.0.0.153
    Apr 30 21:25:23 glitch inetd[166]: /usr/sbin/tcpd: exit status 0x1
       [above lines repeated 2-3 dozen times, IP's and PID's vary]
    Apr 30 21:25:23 glitch inetd[166]: netbios-ns/udp server failing
      (looping), service terminated

After seeing this I thought that blocking netbios broadcasts would be a
good, or at least easily verified, place to start.  After consulting
with the ipchains HOWTO, I entered the following:

   ipchains -A input -p udp -s 0.0.0.0/24 netbios-ns -l -j DENY
   ipchains -A input -p tcp -s 0.0.0.0/24 netbios-ns -l -j DENY

After doing this, however, my logfiles are showing the exact same
behaviour.  Presumably I'm missing something... any pointers as to what?

Thanx!