Configuring a manual mode IPsec tunnel for IPv4 packets

Network requirements

As shown in Figure 133, establish an IPsec tunnel between Router A and Router B to protect data flows between subnet 10.1.1.0/24 and subnet 10.1.2.0/24. Configure the tunnel as follows:

Figure 128: Network diagram

Configuration procedure

  1. Configure Router A:

    # Configure IP addresses for interfaces. (Details not shown.)

    # Configure an IPv4 advanced ACL to identify data flows from subnet 10.1.1.0/24 to subnet 10.1.2.0/24.

    <RouterA> system-view
    [RouterA] acl advanced 3101
    [RouterA-acl-ipv4-adv-3101] rule permit ip source 10.1.1.0 0.0.0.255 destination 10.1.2.0 0.0.0.255
    [RouterA-acl-ipv4-adv-3101] quit
    

    # Configure a static route to the subnet where Host B resides. The command uses the direct next hop address (2.2.2.3) as an example.

    [RouterA] ip route-static 10.1.2.0 255.255.255.0 gigabitethernet 2/0/2 2.2.2.3
    

    # Create an IPsec transform set named tran1.

    [RouterA] ipsec transform-set tran1
    

    # Specify the encapsulation mode as tunnel.

    [RouterA-ipsec-transform-set-tran1] encapsulation-mode tunnel
    

    # Specify the security protocol as ESP.

    [RouterA-ipsec-transform-set-tran1] protocol esp
    

    # Specify the ESP encryption and authentication algorithms.

    [RouterA-ipsec-transform-set-tran1] esp encryption-algorithm aes-cbc-128
    [RouterA-ipsec-transform-set-tran1] esp authentication-algorithm sha1
    [RouterA-ipsec-transform-set-tran1] quit
    

    # Create a manual IPsec policy entry. Specify the policy name as map1 and set the sequence number to 10.

    [RouterA] ipsec policy map1 10 manual
    

    # Apply ACL 3101.

    [RouterA-ipsec-policy-manual-map1-10] security acl 3101
    

    # Apply the IPsec transform set tran1.

    [RouterA-ipsec-policy-manual-map1-10] transform-set tran1
    

    # Specify the remote IP address of the IPsec tunnel as 2.2.3.1.

    [RouterA-ipsec-policy-manual-map1-10] remote-address 2.2.3.1
    

    # Configure inbound and outbound SPIs for ESP.

    [RouterA-ipsec-policy-manual-map1-10] sa spi outbound esp 12345
    [RouterA-ipsec-policy-manual-map1-10] sa spi inbound esp 54321
    

    # Configure the inbound and outbound SA keys for ESP.

    [RouterA-ipsec-policy-manual-map1-10] sa string-key outbound esp simple abcdefg
    [RouterA-ipsec-policy-manual-map1-10] sa string-key inbound esp simple gfedcba
    [RouterA-ipsec-policy-manual-map1-10] quit
    

    # Apply the IPsec policy map1 to interface GigabitEthernet 2/0/2.

    [RouterA] interface gigabitethernet 2/0/2
    [RouterA-GigabitEthernet2/0/2] ip address 2.2.2.1 255.255.255.0
    [RouterA-GigabitEthernet2/0/2] ipsec apply policy map1
    [RouterA-GigabitEthernet2/0/2] quit
    
  2. Configure Router B:

    # Configure IP addresses for interfaces. (Details not shown.)

    # Configure an IPv4 advanced ACL to identify data flows from subnet 10.1.2.0/24 to subnet 10.1.1.0/24.

    <RouterB> system-view
    [RouterB] acl advanced 3101
    [RouterB-acl-ipv4-adv-3101] rule permit ip source 10.1.2.0 0.0.0.255 destination 10.1.1.0 0.0.0.255
    [RouterB-acl-ipv4-adv-3101] quit
    

    # Configure a static route to Host A. The command uses the direct next hop address (2.2.3.3) as an example.

    [RouterB] ip route-static 10.1.1.0 255.255.255.0 gigabitethernet 2/0/2 2.2.3.3
    

    # Create an IPsec transform set named tran1.

    [RouterB] ipsec transform-set tran1
    

    # Specify the encapsulation mode as tunnel.

    [RouterB-ipsec-transform-set-tran1] encapsulation-mode tunnel
    

    # Specify the security protocol as ESP.

    [RouterB-ipsec-transform-set-tran1] protocol esp
    

    # Specify the ESP encryption and authentication algorithms.

    [RouterB-ipsec-transform-set-tran1] esp encryption-algorithm aes-cbc-128
    [RouterB-ipsec-transform-set-tran1] esp authentication-algorithm sha1
    [RouterB-ipsec-transform-set-tran1] quit
    

    # Create a manual IPsec policy entry. Specify the policy name as use1 and set the sequence number to 10.

    [RouterB] ipsec policy use1 10 manual
    

    # Apply ACL 3101.

    [RouterB-ipsec-policy-manual-use1-10] security acl 3101
    

    # Apply IPsec transform set tran1.

    [RouterB-ipsec-policy-manual-use1-10] transform-set tran1
    

    # Specify the remote IP address of the IPsec tunnel as 2.2.2.1.

    [RouterB-ipsec-policy-manual-use1-10] remote-address 2.2.2.1
    

    # Configure the inbound and outbound SPIs for ESP.

    [RouterB-ipsec-policy-manual-use1-10] sa spi outbound esp 54321
    [RouterB-ipsec-policy-manual-use1-10] sa spi inbound esp 12345
    

    # Configure the inbound and outbound SA keys for ESP.

    [RouterB-ipsec-policy-manual-use1-10] sa string-key outbound esp simple gfedcba
    [RouterB-ipsec-policy-manual-use1-10] sa string-key inbound esp simple abcdefg
    [RouterB-ipsec-policy-manual-use1-10] quit
    

    # Apply the IPsec policy use1 to interface GigabitEthernet 2/0/2.

    [RouterB] interface gigabitethernet 2/0/2
    [RouterB-GigabitEthernet2/0/2] ip address 2.2.3.1 255.255.255.0
    [RouterB-GigabitEthernet2/0/2] ipsec policy use1
    [RouterB-GigabitEthernet2/0/2] quit
    

Verifying the configuration

After the configuration is completed, an IPsec tunnel between Router A and Router B is established, and the traffic between subnet 10.1.1.0/24 and subnet 10.1.2.0/24 is IPsec protected. This example uses Router A to verify the configuration.

# Use the display ipsec sa command to display IPsec SAs on Router A.

[RouterA] display ipsec sa
-------------------------------
Interface: GigabitEthernet2/0/2
-------------------------------

  -----------------------------
  IPsec policy: map1
  Sequence number: 10
  Mode: Manual
  -----------------------------
    Tunnel id: 549
    Encapsulation mode: tunnel
    Path MTU: 1443
    Tunnel:
        local  address: 2.2.2.1
        remote address: 2.2.3.1
    Flow:
        as defined in ACL 3101
    [Inbound ESP SA]
      SPI: 54321 (0x0000d431)
      Connection ID: 1
      Transform set: ESP-ENCRYPT-AES-CBC-128 ESP-AUTH-SHA1
      No duration limit for this SA
    [Outbound ESP SA]
      SPI: 12345 (0x00003039)
      Connection ID: 2
      Transform set: ESP-ENCRYPT-AES-CBC-128 ESP-AUTH-SHA1
      No duration limit for this SA