Limiting number of calls to an ASMX Web Service

We have an asmx web service hosted in IIS6. Is there a good way to limit the number of calls to the service in a period of time for a single IP? We don't want to put a hard limit (X number of times an hour), but we want to be able to prevent a spike from a single user.

We're currently investigating to see if our firewall is capable of limiting connection attempts. In the case that our firewall is not able to limit connections, is there a good way to handle this programmatically? Rather th开发者_如何学Can trying to come up with our own custom solution and reinventing the wheel, is there an existing implementation or strategy that can be used?

---

ASMX web services have almost no extensibility. If you have any choice, you should use WCF.

You might be able to write a method to be called from each of your operations, that would look at the caller IP, check in a database, and throw a SoapFault if that IP has connected too much. That's about all there is, though. You might be able to do that from a SoapExtension, but you have to be very careful with those.