Cisco IOS IPSec L2L VPN with AES PSK Encryption

Example of Cisco IOS IPSec LAN2LAN VPN with local on device AES (type 6) encryption of PSK's to protect them. WARNING - This will encrypt your PSK with non-reversible encryption. MAKE SURE YOU HAVE A SECURE BACKUP OF IT. Notes: - xauth is disabled for the peer - AES 256 with PFS using group 5 for phase 1 ISAKMP. - AES 256 with SHA HMAC for phase 2 ESP. - Ingress ACL filter used to immediately filter traffic received over VPN. - DF bit is cleared on applied interface. - Reverse route injection used to add a specific route to table

February 16, 2012

key config-key password-encrypt %{PSK_ENCRYPTION_KEY}%
password encryption aes
ip access-list extended %{CRYPTO_ACL_NAME}%
ip access-list extended %{INGRESS_ACL_NAME}%
 deny ip any any log-input
crypto isakmp key %{PSK_KEY}% address %{PEER_ADDRESS}% no-xauth
crypto isakmp policy %{ISAKMP_POLICY_SEQ}%
 encr aes 256
 authentication pre-share
 group 5
crypto ipsec transform-set ESP-AES256-SHA-HMAC esp-aes 256 esp-sha-hmac
crypto map %{CRYPTO_MAP_NAME}% %{CRYPTO_MAP_SEQ}% ipsec-isakmp
 description <<< %{USEFUL_DESCRIPTION}% >>>
 set peer %{PEER_ADDRESS}%
 set ip access-group %{INGRESS_ACL_NAME}% in
 set transform-set ESP-AES256-SHA-HMAC
 match address %{CRYPTO_ACL_NAME}%
interface GigabitEthernet0/1
 crypto map %{CRYPTO_MAP_NAME}%
 crypto ipsec df-bit clear