HP StorageWorks 1606 Brocade Fabric OS Administrator's Guide v6.3.0 (53-100133 - Page 192

7 Management interface security Endpoint-to-Gateway Tunnel In this scenario, a protected endpoint (typically a portable computer) connects back to its corporate network through an IPsec-protected tunnel. It might use this tunnel only to access information on the corporate network, or it might tunnel all of its traffic back through the corporate network in order to take advantage of protection provided by a corporate firewall against Internet-based attacks. In either case, the protected endpoint will want an IP address associated with the security gateway so that packets returned to it will go to the security gateway and be tunneled back. FIGURE 13 Endpoint to gateway tunnel configuration RoadWarrior configuration In endpoint-to-endpoint security, packets are encrypted and decrypted by the host which produces or consumes the traffic. In the gateway-to-gateway example, a router on the network encrypts and decrypts the packets on behalf of the hosts on a protected network. A combination of the two is referred to as a RoadWarrior configuration where a host on the internet requires access to a network through a security gateway that is protecting the network. IPsec protocols IPsec uses two different protocols, Authentication Header (AH) and Encapsulating Security Payload (ESP), to ensure the authentication, integrity and confidentiality of the communication. To protect the integrity of the IP datagram, the IPsec protocols use hash message authentication codes (HMAC). To derive this HMAC, the IPsec protocols use hash algorithms like MD5 and SHA to calculate a hash based on a secret key and the contents of the IP datagram. This HMAC is then included in the IPsec protocol header and the receiver of the packet can check the HMAC if it has access to the secret key. To protect against denial of service attacks, the IPsec protocols use a sliding window. Each packet gets assigned a sequence number and is only accepted if the packet's number is within the window or newer. Older packets are immediately discarded. This protects against replay attacks where the attacker records the original packets and replays them later. 150 Fabric OS Administrator's Guide 53-1001336-01