Re: TCPReplay problem

> Can we direct tcpreplay to send packets to another machine?

Yes.

> If so what is the command for that.

You can use tcpreplay to send packets to another machine. You have to do a bit of work, though. First, you can change the source and destination IP addresses for all packets with the '-e' flag. So calling

./tcpreplay -i eth0 -e 1.1.1.1:2.2.2.2 test.pcap

will send all packets in 'test.pcap' through interface 'eth0', rewriting the source IP for all packets to '1.1.1.1' and the destination IP to '2.2.2.2'. However, you should also change the layer 2 source and destination MAC, which can be done with the '-I' and '-k' flags.

./tcpreplay -i eth0 -e 1.1.1.1:2.2.2.2 test.pcap -I 11:11:11:11:11:11 -k 22:22:22:22:22:22

This rewrites the source MAC to '22:22:22:22:22:22' and the destination MAC to '11:11:11:11:11:11'. Of course, if the destination computer is in your subnet, the dest MAC should be its MAC, otherwise, it should be the MAC of your gateway. The source MAC should be your compy's, but this shouldn't really be necessary.

So, to recap, get the IP of the machine you want to send to, then the MAC of that machine (if it's in your subnet) or your gateway (if it's not), then place that info into the tcpreplay call, and you should be able to resend captured packet data to another computer.

--Graeme Connell


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