3

In a wireless Ad-Hoc network, I have two computers which communicates in UDP together from 192.168.1.3 to 192.168.1.5

I have a third computer (192.168.1.6) which wants to listen to the packets which are not addressed to it. I can see the packets with tcpdump (which sets the wireless card in promiscuous mode).

To redirect the packets, I am using :

iptables -t nat -I PREROUTING -s 192.168.1.3 -j DNAT --to-destination 192.168.1.5

Is it the only rule I need to use? Why isn't it working? Did I miss other requirements?

  • Something looks strange here. In a wireless network, why are you re-transmitting through iptables? The destination is receiving multiple copies of the same packets. If all you are doing is sniffing, you do not need to route. – schroeder Jun 5 '13 at 17:02
  • I don't want to re-transmitting packets. I would like to catch the packet which are not destinated to computer .5 – Vladimir Leiv Jun 5 '13 at 17:29
  • But you are 'redirecting' the packets ... What did you intend iptables to do? – schroeder Jun 5 '13 at 17:37
7

Why are you using iptables rather than using good old Wireshark which is specifically made for this? Wireshark is a free and open-source packet analyzer and the ideal tool for performing these types of analysis.

EDIT

If you need to reinject the packets I would have a look at scapy in python.

  • I am reusing the packets caught by my filter. Is there anyway to reemit Wireshark caught packets ? – Vladimir Leiv Jun 5 '13 at 15:07
  • 2
    I would have a look at scapy – Lucas Kauffman Jun 5 '13 at 15:15

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