future – UK 1

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Posted from UK:

Comments for future:you have 4 comments

me
whatever

24 Jan 2007
zzz
2. Users who access your website from behind proxy banks.As a security measure (to protect their users) many large ISPs (like AOL) and corporations use Proxy Web Access Servers. When they have thousands of users going through them, they have to use banks of proxy servers to handle the load. Users who are behind these banks of proxy servers can potentially have a different ip address with every single page request. Since Joomla authenticates its sessions by ip address, these users look like first time page requests every time their ip address changes.With Joomla creating a new session for every page request that does not have a valid session (as authenticated by this ip address), this can dramatically increase the number of sessions Joomla creates for that user. If they request 16 pages and thier ip address changes with each page request, you end up with 16 sessions in your database even though there is only one user.You may have noticed that some AOL users cannot stay logged into your Joomla website unless they select the remember me option when logging in. This is why. Joomla cannot authenticate them because their IP address has changed. If they do select the remember me option in order to stay logged in, you end up with an inflated logged in user count and way too many sessions.
What can be done”Fixing these problems is relatively straightforward, requiring that we find some way to test for cookies in a users request, and if we want to accomodate proxy bank users, modifying our authentication methodology.Testing for cookies is relatively easy. Instead of setting up a session automatically, we need to test first. So instead of setting up a session for page’s requested without a cookie, we need to simply set a test cookie instead. Then on subsequent page loads if that cookie exists, we proceed with setting up a session. This way if we never get our test cookie back (a page reader like a search engine, or a user who does not allow cookies) we never set up a session.Fixing the problem for proxy bank users is a little more complex, but not a lot. First understand the reason for authenticating sessions based on IP address. By authenticating a user’s ip address before allowing them to access an existing session, we lower the ease with which a session cracker can steal a session. We simply don’t allow them access unless they are coming from the same IP address that they set the session up from. Although not foolproof, its a pretty good way of ensuring that someone halfway across the world cannot access a users session just because they found a key (remember your cookie holds the key, and it is sent with each page request).We can fix this problem by modifying our session authentication very slightely, in a way that allows a small IP range to be authenticated instead of using a singular IP address. For thos who do not understand IP addresses, a typical ip address consists of four value ranges seperated by decimal points, ie: 192.168.2.1 . The allowed range for each value in this ip address is 0-256. The total number of IP addresses addressable by the internet protocal is around 2 billion, but that does not account for reserved address space, internet netwrok segment addressing, or space used by networks that are only transitional.We don’t want to allow our sessions to be aquired by any of billions of internet users, so we need a good compromise. By authenticating only the first three value units of an IP address, we force the requesting user to be in a very narrow range of 256 different IP addresses, that will typically be concentrated to a singular bandwidth provider thus localizing the range of allowable IP addresses. This is a substantially reduced range of IP addresses and represents for most of us an acceptable risk in exchange for access for users of proxy banks (the same risk that has to be mediatad by your bank or any other extremely secure website that cannot afford to exclude AOL users).So, we need an option that allows us to authenticate based on a small range of ip addresses, which means authenticating only the first three value units of the requestors ip address, ie 192.168.2 instead of 192.168.2.1 .

24 Jan 2007
well
well

21 Jan 2007
me
hi

21 Jan 2007
18 Oct 2011 – start of travelblog

posted Monday May 2006

cachet