* RE: Mangling problem
2003-05-21 11:49 ` Mangling problem Regina Reine
@ 2003-05-21 13:26 ` Chris Hoeschen
2003-05-21 14:02 ` Scott MacKay
2003-05-21 23:33 ` Arnt Karlsen
1 sibling, 1 reply; 5+ messages in thread
From: Chris Hoeschen @ 2003-05-21 13:26 UTC (permalink / raw)
To: 'Regina Reine'; +Cc: netfilter
I maybe wrong but I don't believe netfilter will process any packets not
intended for that box. TCPDump will see it as in a hubbed environment
all nodes receive all packets but only those that are destined for that
box will netfilter process.
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-----Original Message-----
From: netfilter-admin@lists.netfilter.org
[mailto:netfilter-admin@lists.netfilter.org] On Behalf Of Regina Reine
Sent: Wednesday, May 21, 2003 6:50 AM
To: netfilter@lists.netfilter.org
Subject: Mangling problem
Hi,
I am doing an experiment with iptables. I use a hub to connect two
computers. Computer A captures the video packet (or any packets) and
computer B runs iptables and my code in Red Hat 8. Basically, with hub,
computer B will be able to see the packets coming to computer A. I would
like computer B to preroute this packet and put these packets in
userspace where I run my code.
I uses :
** Iptables -t mangle -I PREROUTING -p udp -I eth0 -j QUEUE
However, seems like I only be able to capture broadcast packets. (But
TCPDUMP could see the udp packets). I have checked my code (just a
simple code that scan what kind of packets and it worked with udp
generator such as iperf or hping).
I have tried a few other similar ways but still only could capture
broadcast packets. Does anybody spots my mistake or could give me advice
for better solution? Thank you
Best regards,
Regina Reine
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Mangling problem
2003-05-21 11:49 ` Mangling problem Regina Reine
2003-05-21 13:26 ` Chris Hoeschen
@ 2003-05-21 23:33 ` Arnt Karlsen
1 sibling, 0 replies; 5+ messages in thread
From: Arnt Karlsen @ 2003-05-21 23:33 UTC (permalink / raw)
To: netfilter
On Wed, 21 May 2003 12:49:54 +0100,
"Regina Reine" <regina@erg.abdn.ac.uk> wrote in message
<000001c31f8f$1866f1d0$88cc858b@TOSHIBAFIRE>:
>
> Hi,
> I am doing an experiment with iptables. I use a hub to connect two
..hub? And being visible wont hurt your experiment?
> computers. Computer A captures the video packet (or any packets) and
> computer B runs iptables and my code in Red Hat 8. Basically, with
> hub, computer B will be able to see the packets coming to computer A.
> I would like computer B to preroute this packet and put these packets
> in userspace where I run my code.
>
> I uses :
>
> ** Iptables -t mangle -I PREROUTING -p udp -I eth0 -j QUEUE
>
> However, seems like I only be able to capture broadcast packets. (But
> TCPDUMP could see the udp packets). I have checked my code (just a
> simple code that scan what kind of packets and it worked with udp
> generator such as iperf or hping).
> I have tried a few other similar ways but still only could capture
> broadcast packets. Does anybody spots my mistake or could give me
> advice for better solution? Thank you
>
> Best regards,
> Regina Reine
>
..you want tcpdump running in promiscous mode, 'info tcpdump'
for the gory details, it is also possible to pipe it.
..you could also set up an ip-less sniff bridge, it works nicely
for bandwidth throttling too. ;-)
--
..med vennlig hilsen = with Kind Regards from Arnt... ;-)
...with a number of polar bear hunters in his ancestry...
Scenarios always come in sets of three:
best case, worst case, and just in case.
^ permalink raw reply [flat|nested] 5+ messages in thread