Shared memory ?

[Rémy Sanchez]

Hi,
I'm coding a module to somehow replace/complement mod_security (it's 
more a proof of concept than a real project for now). The first thing 
that I'd like to have is a DNSBL, so that detected intruders are 
instantly banned when added to the blacklist. Because doing a DNS query 
for each HTTP request might be a bit heavy, I'd like to keep the results 
in cache.

I guess that if I create something from the config pool, it will be 
duplicated between processes. But another security I want is to check 
URL against regexps commonly used by botnets/script kiddies. Then, if an 
IP is blacklisted, I want its state to be changed instantly in all 
caches. Which, if data is duplicated, is not possible. Would there be a 
simple way to achieve this ? Or would it be more clever to move to 
another solution, like using a common redis datastore for 
blacklist/whitelist/rules lookup ?

Thanks,
Rémy