IPQ is the old way to process iptables packets. It replaces the inline version available in pre-2.9 versions built with this:
./configure --enable-inline / -DGIDS
Start the IPQ DAQ as follows:
./snort --daq ipq \ [--daq-var device=<dev>] \ [--daq-var proto=<proto>] \ <dev> ::= ip | eth0, etc; default is IP injection <proto> ::= ip4 | ip6; default is ip4