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Configuring a site-to-site IPsec VPN with NAT on Cisco devices involves several steps. Here's a high-level outline to guide you through the process:
1. Configure ISAKMP (IKE) Phase 1
• Define ISAKMP Policy: Set encryption, hash, authentication, group, and lifetime parameters.
crypto isakmp policy 10
encr aes
hash sha
authentication pre-share
group 2
lifetime 86400
• Set Pre-shared Key: Define the pre-shared key for authentication.
crypto isakmp key YOUR_KEY address PEER_IP
2. Configure IPsec (IKE) Phase 2
• Define Transform Set: Specify the encryption and hash algorithms.
crypto ipsec transform-set MY_TRANSFORM_SET esp-aes esp-sha-hmac
• Create Crypto Map: Bind the transform set to a crypto map and define the peer.
crypto map MY_CRYPTO_MAP 10 ipsec-isakmp
set peer PEER_IP
set transform-set MY_TRANSFORM_SET
match address VPN_ACL
3. Configure Access Control List (ACL)
• Define Traffic to Encrypt: Specify which traffic should be encrypted.
access-list VPN_ACL permit ip 10.10.10.0 0.0.0.255 20.20.20.0 0.0.0.255
4. Configure NAT
• Define NAT Rules: Configure NAT to translate internal IP addresses.
ip nat inside source list NAT_ACL interface OUTSIDE_INTERFACE overload
access-list NAT_ACL permit ip 10.10.10.0 0.0.0.255 any
5. Apply Crypto Map to Interface
• Bind Crypto Map to Interface: Apply the crypto map to the outgoing interface.
interface OUTSIDE_INTERFACE
crypto map MY_CRYPTO_MAP
6. Verify Configuration
• Check ISAKMP and IPsec Status: Use commands to verify the tunnel status.
show crypto isakmp sa
show crypto ipsec sa
If you have any specific questions or need further details on any step, feel free to ask in our experts forum!