[PLUG] help required for Kernel (2.6) Network filter module compilation

[Gaurav Raval]

Hi PLUGies,

I want to perform packet filtering for

   - Session Initiation Protocol (kind of clear text messages) in
   - kernel(2.6.28) based on
   - regular expression.

Can any one help me building dynamic module to do so?
Had any one previously tried to filter (kind of firewall) @ kernel layer
earlier?
Any book/url/tutor?

Regards,

Gaurav Raval