A proxy device coupled to a network receives communications between a client and a server on the network. The proxy device operates transparently to the client and the server, while coupled to receive and process the communications from a node on the network via a network port in a one-armed configuration. The proxy device communicates packets of the communications with an external tool coupled to the proxy device via a tool port and operates transparently to the nod and the tool. In certain embodiments, the tool may be a network security device, such as a firewall.