CIDR Lookup?

[eluser]Eric Brown[/eluser]
I'm trying to take a user's X-Forwarded-For header and do an IP lookup from a table of values I have for CIDR ranges. I did a search but did not find anything on this forum.

Has anyone done anything like this with CI? or can you point me to the right forum post if addressed under another topic?

Thanks. I look forward to learning and contributing as I get up to speed with this framework.