Registering for only Specific Packets from Net-Filter!!!!

HI Guys, I'm a Newbie to Linux Kernel Development. Need some Clarification in understanding Net-Filter Hooks. Can I register only for the Necessary Packets [Ex: IPSEC etc...] from the Net-Filters?? AFAIK ; Net-Filter Module send the Packets to the Corresponding Module based on pre-defined HOOKS. Let us say; there are Many Packets reaching that Hooks; and if I am Interested only in some Packets from Net-Filter module; can I do that ??? Any Help is Really Appreciated !! -Thnks, VKS