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compare single ip to ip range

Posted on 2009-02-12
Medium Priority
Last Modified: 2012-08-13
I want to allow access to a certain folder based on IP address. I can get the IP address from user and check it and all that good stuff.
The problem is I have a table that holds 2 values, starting IP and ending IP, the majority of these are ranges, not single IP's.   How can I check the single IP I get programatically against the table of IP ranges to authenticate a user?
Question by:flukester
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LVL 11

Accepted Solution

jmwheeler earned 2000 total points
ID: 23622708
I think you can do a simple string comparison (it sounded too simple but I couldn't come up with a reason why it wouldn't work).


if (ipLow.CompareTo(userIP) <= 0 And ipHigh.CompareTo(userIP) >= 0) then ....

Author Comment

ID: 23626078
Thanks jmw, seems to be working so far. Can you enlighten me to what the CompareTo() method is actually doing? How is it finding an IP if it's in a range.
LVL 11

Expert Comment

ID: 23626452
CompareTo is a comparison method for objects that implement IComparable.  It returns less than zero if the instance is less than the passed obj, 0 if they are the same and greater than zero if the instance is greater than the passed obj.


Author Comment

ID: 23626484
Thanks a lot!

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