Re: netfilter_queue reinjecting packets

[aton <aton@packetdropped.org>]

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On Sun, 12 Mar 2006 15:44:18 +0100
Patrick McHardy <kaber@trash.net> wrote:

> aton wrote:
> > has anyone used netfilter_queue and successfully re-injected packets into the net?
> > 
> > i want to write sort of a userspace routing application. 
> > 
> > host A is my workstation, it has host B as default gateway.
> > 
> > on host B my routing application runs. 
> > it receives packets from netfilter_queue using libnetfilter_queue.
> > this works very well and i can display the whole packets.
> > 
> > now i just want to send them back into the net, so that they reach their destination.
> > 
> > i modified the main loop in the source of nfqnl_test.c in the libnetfilter_queue package:
> > 
> > 	while ((rv=recv(fd, buf, sizeof(buf), 0)) >= 0)
> > 	{
> > 		printf("pkt received:\n");
> > 		
> > 		printf("sending packet back\n");
> > 		
> > 		if ((sv=send(fd, buf, sizeof(buf), 0))==-1)
> > 		{
> > 			perror("send");
> > 			exit(EXIT_FAILURE);
> > 		}
> > 		printf("done\n");
> > 	}
> > 
> > this should send every packet back to... where? 
> > it seems the packets are just sent into nirvana, i cannot sniff them, and i dont get an error from send().
> 
> nfnql_test already reinjects packets by the call to nfq_issue_verdict.
> It seems you need to read the documentation ..
> 
> 

sorry, but i cannot find any call to nfq_issue_verdict in this file.
perhaps you mean nfq_set_verdict(qh, id, NF_ACCEPT, 0, NULL); ?

i thought nfq_set_verdict was used to specify a handling routine for the packets... in the case of nfq_test.c set the handling routine for packets to the print_pkt() function.
am i wrong?

what documentation? i would _love_ to read some documentation about libnetfilter_queue. 
i have looked through http://netfilter.org/documentation/index.html#documentation-howto but i cannot find anything specific about libnetfilter_queue...

greetings, aton

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