Re: Networking on 2.4: Finding source of a masqgraded packet and source/destination MAC address

[Rusty Russell]

In message <01a001c0a1cc$22bd5e50$5f01a8c0@worm> you write:
> Hi,
> 
> I am the author of the WRR (http://wipl-wrr.dkik.dk/wrr) qdisc, an extension 
to the 2.2 kernels which is supposed to run on a router/bridge/firewall and do 
Weighted Round Robin scheduling with a class for each local machine.
> 
> Now, I want to port this scheduler to 2.4. One of the problems is that someti
mes I have an outgoing (to the world) packet which has been masqgraded. I want 
to account this packet to the local machine which has originally generated it. 
On 2.2. I used the following code to get the IP address of the local machine:
> 

If they are using masquerading, the nfct will be set.  Use
#include <linux/netfilter_ipv4/ip_conntrack.h>

enum ip_conntrack_info ctinfo;
struct ip_conntrack *ct;

ct = ip_conntrack_get(skb, &ctinfo);
if (ct) {
	/* We want the initial source. */
	ipaddr = ct->tuplehash[CTINFO2DIR(ctinfo)].tuple.src.ip;
} else {
	ipaddr = skb->nh.iph.saddr;
}

Cheers!
Rusty.
--
Premature optmztion is rt of all evl. --DK