1 U32 allows you to extract quantities of up to 4 bytes from a packet,
2 AND them with specified masks, shift them by specified amounts and
3 test whether the results are in any of a set of specified ranges.
4 The specification of what to extract is general enough to skip over
5 headers with lengths stored in the packet, as in IP or TCP header
8 Details and examples are in the kernel module source.
git://git.onelab.eu / iptables.git / blob