Patent ID: 7475420

Claim:
A method for detecting proxies, comprising: analyzing network transmission data to detect symmetric relationships between network data transmissions, wherein a symmetric relationship is detected with respect to a first network data transmission sent by a first node to a second node if the second node is observed to send or have sent to a third node a second network data transmission that satisfies a prescribed first criterion that it is anticipated the second network data transmission would satisfy if it were used to forward to the third node at least part of the data comprising the first network data transmission; and for each symmetric relationship found, performing further analysis to determine if the second node is configured to serve as a proxy; wherein the further analysis comprises determining whether a third network data transmission is or was sent from the third node to the second node in response to the second network data transmission and, if so, determining whether a fourth network data transmission having a symmetric relationship with the third network data transmission is or was sent by the second node to the first node.