Cisco RV042 Administration Guide - Page 135

VPN Setting Up a Gateway to Gateway (Site to Site) VPN 9 • Required fields for IKE with Preshared Key Enter the settings for Phase 1 and Phase 2. Phase 1 establishes the preshared keys to create a secure authenticated communication channel. In Phase 2, the IKE peers use the secure channel to negotiate Security Associations on behalf of other services such as IPsec. Be sure to enter the same settings when configuring other router for this tunnel. - Phase 1 / Phase 2 DH Group: DH (Diffie-Hellman) is a key exchange protocol. There are three groups of different prime key lengths: Group 1 - 768 bits, Group 2 - 1,024 bits, and Group 5 - 1,536 bits. For faster speed but lower security, choose Group 1. For slower speed but higher security, choose Group 5. Group 1 is selected by default. - Phase 1 / Phase 2 Encryption: Select a method of encryption for this phase: DES, 3DES, AES-128, AES-192, or AES-256. The method determines the length of the key used to encrypt or decrypt ESP packets. AES-256 is recommended because it is more secure. - Phase 1 / Phase 2 Authentication: Select a method of authentication for this phase: MD5 or SHA1. The authentication method determines how the ESP (Encapsulating Security Payload Protocol) header packets are validated. MD5 is a one-way hashing algorithm that produces a 128-bit digest. SHA1 is a one-way hashing algorithm that produces a 160-bit digest. SHA1 is recommended because it is more secure. Make sure that both ends of the VPN tunnel use the same authentication method. - Phase 1 / Phase 2 SA Life Time: Configure the length of time a VPN tunnel is active in this phase. The default value for Phase 1 is 28800 seconds. The default value for Phase 2 is 3600 seconds. - Perfect Forward Secrecy: If the Perfect Forward Secrecy (PFS) feature is enabled, IKE Phase 2 negotiation will generate new key material for IP traffic encryption and authentication, so hackers using brute force to break encryption keys will not be able to obtain future IPSec keys. Check the box to enable this feature, or uncheck the box to disable this feature. This feature is recommended. - Preshared Key: Enter a pre-shared key to use to authenticate the remote IKE peer. You can enter up to 30 keyboard characters and hexadecimal values, such as My_@123 or 4d795f40313233. Both ends of the VPN tunnel must use the same Preshared Key. It is strongly recommended that you change the Preshared Key periodically to maximize VPN security. Cisco Small Business RV0xx Series Routers Administration Guide 135