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I was trying to run a Rogue DHCP Server which should cause a MITM attack. I did the following

  • Exhaust the real DHCP Server using DHCPig (worked)
  • Run a Rogue DHCP Server using the auxiliary/server/dhcp module (runs)
  • Cause a device to send a DHCP request

I see the incoming request in wireshark but the real DHCP Server which has no more leases is sending a DHCP NACK Packet which causes the client to cancel his request instantly. This results in the client ignoring the DHCP Offer from my Rogue DHCP Server.

I can thihnk of not exhausting the DHCP Server and "just" be faster which did not work out very well when I tried it.

What is the best way to move the client to accept my DHCP offer?

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Plan A: Try using another ip range than the real DHCP server.

A DHCP server is not supposed to NACK a request for an ip outside it's IP range.

Plan B: it is a race condition, so flood the client with DHCPOFFER messages.

Plan C: use arpspoofing, it's much easier.

  • Solution A wont work becase the NACK isn't send as a response to my fake offer its send because the DHCP Server does not have any leases left but B might be possible when I start before the request is sent. – davidb Oct 6 '15 at 13:46
  • Does your client ignore your offers once the first DHCP gives its answer ? – Nate Oct 6 '15 at 13:48

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