Hi,
Thanks for reply.
There is no dhcp client on our firewall. I tried to get rid of the problem
by blocking broadcast packets with the command below,
iptables -I FORWARD -d 192.168.0.255 -j DROP
But it still remained the same. So is there any quick solutions to that?
Thanks.
Regards,
Zheng Chuanbo
>This was caused by broadcast packets sent by the bridge that arrive on
>the bridge's loopback device. A dhcp client on the bridge can cause
>this, f.e.
>Op ma, 21-03-2005 te 18:44 +0800, schreef Zheng Chuanbo:
>> Hi,
>>
>> I met a problem when using bridge with netfilter. The kernel version
>> 2.4.20, and the patch is bridge-nf-0.0.10-against-2.4.20.diff.
>>
>> Our firewall configuration is as follows,
>> eth3,eth4,eth5,eth6 configured as a bridge with an IP address 10.0.0.1.
>> The local net connect to the internet via the gateway 10.0.0.1 and SNAT
>> is applied on the firewall. It worked but sometimes there are some
>> problems. The bridge stopped resonse now and there. When checking the
>> log there were some messages as below,
>>
>> Mar 21 13:48:04 NPFW br_netfilter: Argh!! br_nf_post_routing: bad mac.raw
>> pointer.[eth6][Bridge_0]
>> Mar 21 13:48:04 NPFW br_netfilter: Argh!! br_nf_post_routing: bad mac.raw
>> pointer.[eth5][Bridge_0]
>> Mar 21 13:48:04 NPFW br_netfilter: Argh!! br_nf_post_routing: bad mac.raw
>> pointer.[eth4][Bridge_0]
>> Mar 21 13:48:04 NPFW br_netfilter: Argh!! br_nf_post_routing: bad mac.raw
>> pointer.[eth3][Bridge_0]
>>
>> I checked the code, it is caused by some certain types of packets.
>>
>> /* Be very paranoid. */
>> if (skb->mac.raw < skb->head || skb->mac.raw + ETH_HLEN > skb->data)
>> {
>> printk(KERN_CRIT "br_netfilter: Argh!! br_nf_post_routing: "
>> "bad mac.raw pointer.");
>> if (skb->dev != NULL) {
>> printk("[%s]", skb->dev->name);
>> if (has_bridge_parent(skb->dev))
>> printk("[%s]",
>> bridge_parent(skb->dev)->name);
>> }
>> printk("\n");
>> return NF_ACCEPT;
>> }
>>
>> And in the new bridge-nf version it is annouced this sould not happen
>> anymore.
>> I think I should upgrade the kernel. But I'm curious on the problem and I
>> wish
>> I could know what kind of packets caused such a problem.
>
>This was caused by broadcast packets sent by the bridge that arrive on
>the bridge's loopback device. A dhcp client on the bridge can cause
>this, f.e.
>
>cheers,
>Bart
>
>
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