Greeting Wise Ones,

I'm working on a program that captures DNS packets via an iptables queue, then I'd like to rewrite the answer portion of the packet for undesirable URL's. (Basically, advert blocking at the firewall+kernel level)

Net::DNS::Packet doesn't work. It parses the header okay, but can't find the answer.

Net::ncap and Net::pcap listen on interfaces. I get my packets from the firewall queue.

NetPacket::UDP appears to get me the binary payload. In the payload is the Question as a variable length string and one or more answers.

I have the format of the packet in a pretty picture, http://www.firewall.cx/dns-query-format.php.

DNS RFC is here: http://www.faqs.org/rfcs/rfc1035.html

I think my question is how do I unpack the payload, then turn the RR into a string?

In reply to Disassembling DNS Packet by mpapet

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