Reply To: Redirect after filter on packets

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After some struggling with the redirect of the packets (and it works) I am certain now I need to parse the DNS and modify the record to redirect the user. This because filtering (and redirecting) on IP adres is not failsafe. A domainname can have more ip-addresses …..

I’ve succeeded in getting to the DNS request structure from the send packet.

I’m not so lucky in altering the packet; this is logical because the redirect packet is greater in size than the original. This is where i get stuck.

I think I need to create a totally new packet with the correct DNS data. When I filter a packet which has to be redirected I copy the packet (except for the DNS), modify the etherheader size, ip-size and recalc the IP-,TCP- and UDP checksums …

Is that the correct way ? and … if you could please assist me do you have some example code to create a new packet ?

Many thanks