from the vbulletin forum tutorial:
Session IP Octet Length Check
Select the subnet mask that reflects the level of checking you want to run against IP addresses when a session is being fetched.
This is useful if you have a large number of users who are behind transparent proxies (for example, AOL) and have an IP address that can change randomly between requests.
The more the level is decreased the greater the security risk from session hijacking.
what does this mean
so If i have a session in the database do i have to check against ip
arent sessions saved with php
please do not just send me a general tutorial about sessions