question about iptables

question about iptables

[subramoni padmanabhan]

Hi,

   I have a question about the use of iptables. I am working on a project in 
which I have to capture packets. Does iptables allow non-obtrusive packet 
capture? For example, if there is a router between A and B and when I send a 
packet from A to B, the router is supposed to make a copy of the packet 
going through it and send that copy to another node, say C without altering 
the packet going to B. So in effect the packet becomes two at the router and 
one goes to C and the original one goes to B. Is there provision in iptables 
to do such a thing? Also, can I capture packets based on the data fields 
inside the packet rather than on the fields in the packet header? If so, 
please let me know how. Any response would be greatly appreciated. Thanks.

Subramoni Padmanabhan
G-126, 700 woodland avenue
Lexington, Kentucky 40508
Phone : 859 323 9405




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Re: question about iptables

[Arnt Karlsen]

On Thu, 27 Feb 2003 19:23:33 -0500, 
"subramoni padmanabhan" <smoni77@hotmail.com> wrote in message 
<BAY2-F97bJeQvFFleSI00046a04@hotmail.com>:

> Hi,
> 
>    I have a question about the use of iptables. I am working on a
>    project in 
> which I have to capture packets. Does iptables allow non-obtrusive
> packet capture? For example, if there is a router between A and B and
> when I send a packet from A to B, the router is supposed to make a
> copy of the packet going through it and send that copy to another
> node, say C without altering the packet going to B. So in effect the
> packet becomes two at the router and one goes to C and the original
> one goes to B. Is there provision in iptables to do such a thing?
> Also, can I capture packets based on the data fields inside the packet
> rather than on the fields in the packet header? If so, please let me
> know how. Any response would be greatly appreciated. Thanks.
> 
> Subramoni Padmanabhan
> G-126, 700 woodland avenue
> Lexington, Kentucky 40508
> Phone : 859 323 9405

..you can do this with tcpdump thru ssh, 'info tcpdump' for details.
(I assume you control the router you use to sniff traffic from.)

-- 
..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.

question about iptables

[胡磊]

Hi !
Does the iptables support port triggering?
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