A policy server correlates information from several messages associated with a client device to implement an identity-based network access policy. A network element connected to the client device obtains an authentication message including a first network address from the client device. The network element provides the authentication device to an identity server via a Network Address Translation (NAT) device, which translates the first network address to a second network address. The network element also provides a first message including the first network address to the policy server to request an identity-based policy for network communications of the client device. The network element implements the identity-based policy authorized by the policy server.