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USPS Tracking Site hitting Infinite Loop Block rule

Users trying to track packages on USPS website are hitting the "X-MWG-Via: Prevent Proxy Loop" protection block rule. How do we verify this is a valid block without potentially causing problems to the system by just allowing it? If it's valid do we just inform the users we have to leave it in place because it could destabilize the system or is there something else we can do to safely allow it?
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McAfee Employee
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Re: USPS Tracking Site hitting Infinite Loop Block rule



Hope you are doing well.


Benefits to having a Via Header is that it can help prevent Proxy Loops.


A proxy loop can happen when a proxy forwards a request either to itself or receives a request “back” from another proxy . The proxy keeps trying to serve the request and the process is repeated causing a loop.  You want to avoid proxy loops as the request that keeps looping will cause a large resource spike on your proxy which can lead to performance problems such as the proxy failing to pass traffic. When the Via header is added to the request, the proxy (MWG) will be able to identify and end the loop.


Please refer below link for more information:-



We would need data to look further into this like connection traces.


You can remove Via header for this traffic if required.



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Alok Sarda

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