Hello: First off, I should thank mad duck (martin krafft) and Brian
Bassett (ipmasq maintainer). I had this problem of my Motorola SB3100
cable modem, spewing forth multicast packet log details on my console
every 3 minutes after getting 'ipmasq' installed. When I stop the
ipmasq firewall daemon, everything returned to normal. It was madduck
who suggested that I had a multicast issue. I turned off IP
multicasting when compiling the kernel to stop this 'spew menace'; tho'
that was not the correct solution and even removed 'ipmasq'.
Today, I re-installed ipmasq because this is the ultimate firewall
config tool. It can setup firewalling for you on both the 2.2.x and
2.4.x kernels ie. for both IPChains and IPTables. I solved the issue by
modifying the rule-set 'I32intmcast.def' in /etc/ipmasq/rules. A
similar file 'I32intmcast.rul' was created using 'I32intmcast.def' as
the template and the following line under the netfilter section:
$IPTABLES -A INPUT -j DROP -s 192.168.100.1/27 -d 0.0.0.0/0
solved the console noise. The default rule-set in 'I32intmcast.def'
accepts the multi-casted packet instead of DROP/DENY and forwards it.
(I do not know and am a total idiot here ;-) Maybe it is required for
some other interface/service). Here is the culprit-line:
$IPTABLES -A INPUT -j ACCEPT -i ${i%%:*} -d 224.0.0.0/4 -p ! tcp
Why did it happen ? The SB3100 can also act as a DHCP server for a LAN
consisting of 32 machines (I dunno the exact figure) and the multicast
noise was generated by this DHCP server with IP 192.168.100.1. This was
happening even after I unchecked the server option via the Web interface
at this IP. (I am still clueless). The rule-set was written to accept
Internal interface/s multicast packets (I still have to learn why ?).
I am still reading the IPMasq docs and I have no words to thank this
excellent package/docs. Look no further if you want to 'firewall' your
Cable/Dial-up system. Please do visit the IPMasq site @
http://ipmasq.cjb.net/
and sorry for this longish troll.
--
ragOO, VU2RGU<->http://gnuhead.dyndns.org/<->GPG: 1024D/F1624A6E
Helping to keep the Air-Waves FREE Amateur Radio
Helping to keep your Software FREE the GNU Project
Helping to keep the W W W FREE Debian GNU/${kernel}
