The present disclosure discloses a method and a network device for performing dynamic detection and application-based policy enforcement of proxy connections in a network. Specifically, a network device receives, from a client device, a packet in a session. The network device then determines whether the packet is transmitted to a proxy. In response to determining that the packet is associated with a different application classification or web content category during the same session, the network device re-applies network firewall policies to determine whether to allow or deny transmission of the packet to the proxy.