Determining the Likelihood of Traffic Being Legitimately Received At a Proxy Server in a Cloud-Based Proxy Service

An apparatus, comprising:

• a plurality of proxy servers that are anycasted to a same IP address, wherein each of the plurality of proxy servers is configured to perform the following:
• receive packets at the same IP address as a result of one or more domains resolving to the same IP address, wherein this proxy server receives the packets at the same IP address as a result of an anycast protocol implementation selecting this one of the plurality of proxy servers as the closest in terms of routing protocol metric used to route traffic to the plurality of proxy servers;
• transmit one or more messages to a central server that indicate source IP addresses of the received packets;
• and
• receive, from the central server, a message that indicate source IP addresses of packets that are not likely to be legitimately received at that proxy server;
• and
• install, based on the received message, one or more rules to rate limit packets that are received having a source IP address that is not likely to be legitimately received at that proxy server;
• and
• the central server coupled with the plurality of proxy servers, wherein the remote server is configured to perform the following:
• receive, from each of the plurality of proxy servers, the one or more messages that indicate source IP addresses of the received packets;
• determine, based on the one or more messages received from the plurality of proxy servers, a likelihood of a packet having a particular source IP address being legitimately received at each of the proxy servers;
• and
• transmit, to each of the proxy servers, the message that indicates which source IP addresses of packets are not likely to be legitimately received at that proxy server.

A non-transitory computer-readable storage medium that provides instructions that, if executed by a processor, will cause said processor to perform operations for determining a likelihood of a packet having a particular source address being received at a particular one of a plurality of proxy servers that are anycasted to a same IP address, wherein the proxy servers are part of a cloud-based proxy service and are situated between a plurality of client computing devices accessing network resources and a plurality of origin servers that serve network resources, the operations comprising:

• receiving, from each of the plurality of proxy servers, one or more messages that indicate source IP addresses of packets received at that proxy server that are directed to the same IP address, wherein the proxy servers receive traffic at the same IP address as a result of one or more domains resolving to the same IP address;
• and wherein a particular one of the proxy servers receives packets directed to the same IP address as a result of an anycast protocol implementation selecting that particular one of the proxy servers as the closest in terms of routing protocol metric used to route traffic to the proxy servers;
• determining, based on the one or more messages from each of the plurality of proxy servers, a likelihood of a packet having a particular source IP address being legitimately received at each of the proxy servers;
• transmitting, to each of the proxy servers, a message that indicates which source IP addresses of packets are not likely to be legitimately received at that proxy server.