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Multiple HTTP requests from different IPs - IIS

blocking HTTP requests from different IPs IIS ASP flood control mitigation

     
10:46 am on Oct 15, 2008 (gmt 0)

New User

10+ Year Member

joined:Sept 17, 2008
posts: 11
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Hello,

I have multiple HTTP requests (20 to 50 within 1 sec) from a bot flooding an IIS server, running ASP websites. This flood of HTTP requests is crashing the IIS Application Pool, so legit users get 500 errors and broken pages and it is costing us greatly.

The attacker(s) change IP addresses after a couple of requests, so just blocking the IP has not been effective. From the log files I can see a lot of 400 responses because they are requesting pages that do not exist.

How can I block this flood of HTTP requests coming from multiple IPs?

Does anybody have a script (in ASP would be great!) that can block multiple requests when they are done within a short period of time?

Thanks,

KH

7:01 pm on Oct 17, 2008 (gmt 0)

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10+ Year Member

joined:Jan 31, 2008
posts:114
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I had a similar problem. It was when a user comes to my site (and has AVG toolbar installed) it gets stuck in a loop and continues to try to request files.

Are the requests always for the same file?

I ended up returning a 404 for the requests and that solved my problem