7.1.2.4 Packet Tracer - Configuring VPNs (Optional)

Addressing Table

ISAKMP Phase 1 Policy Parameters

Bolded parameters are defaults. Other parameters need to be explicitly configured.

IPsec Phase 2 Policy Parameters

Objectives

Part 1: Enable Security Features

Part 2: Configure IPsec Parameters on R1

Part 3: Configure IPsec Parameters on R3

Part 4: Verify the IPsec VPN

Scenario

In this activity, you will configure two routers to support a site-to-site IPsec VPN for traffic flowing from their respective LANs. The IPsec VPN traffic will pass through another router that has no knowledge of the VPN. IPsec provides secure transmission of sensitive information over unprotected networks such as the Internet. IPsec acts at the network layer, protecting and authenticating IP packets between participating IPsec devices (peers), such as Cisco routers.

Part 1:     Enable Security Features
Step 1:     Activate securityk9 module.

The Security Technology Package license must be enabled to complete this activity.

Note: Both the user EXEC and privileged EXEX pass word is cisco.

a.     Issue the show version command in the user EXEC or privileged EXEC mode to verify that the Security Technology Package license is activated.

Configuration register is 0x2102
b.    If not, activate the securityk9 module for the next boot of the router, accept the license, save the configuration, and reboot.

R1(config)# license boot module c2900 technology-package securityk9
R1(config)# end
R1# copy running-config startup-config
R1# reload
c.     After the reloading is completed, issue the show version again to verify the Security Technology Package license activation.

Technology Package License Information for Module:'c2900'

d.    Repeat Steps 1a to 1c with R3.

Part 2:     Configure IPsec Parameters on R1
Step 1:     Test connectivity.

Ping from PC-A to PC-C.

Step 2:     Identify interesting traffic on R1.

Configure ACL 110 to identify the traffic from the LAN on R1 to the LAN on R3 as interesting. This interesting traffic will trigger the IPsec VPN to be implemented whenever there is traffic between R1 to R3 LANs. All other traffic sourced from the LANs will not be encrypted. Remember that due to the implicit deny any, there is no need to add the statement to the list.

R1(config)# access-list 110 permit ip 192.168.1.0 0.0.0.255 192.168.3.0 0.0.0.255
Step 3:     Configure the ISAKMP Phase 1 properties on R1.

Configure the crypto ISAKMP policy 10 properties on R1 along with the shared crypto key cisco. Refer to the ISAKMP Phase 1 table for the specific parameters to configure. Default values do not have to be configured therefore only the encryption, key exchange method, and DH method must be configured.

R1(config)# crypto isakmp policy 10
R1(config-isakmp)# encryption aes
R1(config-isakmp)# authentication pre-share
R1(config-isakmp)# group 2
R1(config-isakmp)# exit
R1(config)# crypto isakmp key cisco address 10.2.2.2
Step 4:     Configure the ISAKMP Phase 2 properties on R1.

Create the transform-set VPN-SET to use esp-3des and esp-sha-hmac. Then create the crypto map VPN-MAP that binds all of the Phase 2 parameters together. Use sequence number 10 and identify it as an ipsec-isakmp map.

R1(config)# crypto ipsec transform-set VPN-SET esp-3des esp-sha-hmac
R1(config)# crypto map VPN-MAP 10 ipsec-isakmp
R1(config-crypto-map)# description VPN connection to R3
R1(config-crypto-map)# set peer 10.2.2.2
R1(config-crypto-map)# set transform-set VPN-SET
R1(config-crypto-map)# match address 110
R1(config-crypto-map)# exit
Step 5:     Configure the crypto map on the outgoing interface.

Finally, bind the VPN-MAP crypto map to the outgoing Serial 0/0/0 interface. Note: This is not graded.

R1(config)# interface S0/0/0
R1(config-if)# crypto map VPN-MAP
Part 3:     Configure IPsec Parameters on R3
Step 1:     Configure router R3 to support a site-to-site VPN with R1.

Now configure reciprocating parameters on R3. Configure ACL 110 identifying the traffic from the LAN on R3 to the LAN on R1 as interesting.

R3(config)# access-list 110 permit ip 192.168.3.0 0.0.0.255 192.168.1.0 0.0.0.255
Step 2:     Configure the ISAKMP Phase 1 properties on R3.

Configure the crypto ISAKMP policy 10 properties on R3 along with the shared crypto key cisco.

R3(config)# crypto isakmp policy 10
R3(config-isakmp)# encryption aes
R3(config-isakmp)# authentication pre-share
R3(config-isakmp)# group 2
R3(config-isakmp)# exit
R3(config)# crypto isakmp key cisco address 10.1.1.2
Step 3:     Configure the ISAKMP Phase 2 properties on R1.

Like you did on R1, create the transform-set VPN-SET to use esp-3des and esp-sha-hmac. Then create the crypto map VPN-MAP that binds all of the Phase 2 parameters together. Use sequence number 10 and identify it as an ipsec-isakmp map.

R3(config)# crypto ipsec transform-set VPN-SET esp-3des esp-sha-hmac
R3(config)# crypto map VPN-MAP 10 ipsec-isakmp
R3(config-crypto-map)# description VPN connection to R1
R3(config-crypto-map)# set peer 10.1.1.2
R3(config-crypto-map)# set transform-set VPN-SET
R3(config-crypto-map)# match address 110
R3(config-crypto-map)# exit
Step 4:     Configure the crypto map on the outgoing interface.

Finally, bind the VPN-MAP crypto map to the outgoing Serial 0/0/1 interface. Note: This is not graded.

R3(config)# interface S0/0/1
R3(config-if)# crypto map VPN-MAP
Part 4:     Verify the IPsec VPN
Step 1:     Verify the tunnel prior to interesting traffic.

Issue the show crypto ipsec sa command on R1. Notice that the number of packets encapsulated, encrypted, decapsulated and decrypted are all set to 0.

R1# show crypto ipsec sa

interface: Serial0/0/0
    Crypto map tag: VPN-MAP, local addr 10.1.1.2

   protected vrf: (none)
   local  ident (addr/mask/prot/port): (192.168.1.0/255.255.255.0/0/0)
   remote  ident (addr/mask/prot/port): (192.168.3.0/255.255.255.0/0/0)
   current_peer 10.2.2.2 port 500
    PERMIT, flags={origin_is_acl,}
   #pkts encaps: 0, #pkts encrypt: 0, #pkts digest: 0
   #pkts decaps: 0, #pkts decrypt: 0, #pkts verify: 0
   #pkts compressed: 0, #pkts decompressed: 0
   #pkts not compressed: 0, #pkts compr. failed: 0
   #pkts not decompressed: 0, #pkts decompress failed: 0
   #send errors 0, #recv errors 0

     local crypto endpt.: 10.1.1.2, remote crypto endpt.:10.2.2.2
     path mtu 1500, ip mtu 1500, ip mtu idb Serial0/0/0
     current outbound spi: 0x0(0)
<output omitted>

Step 2:     Create interesting traffic.

Ping PC-C from PC-A.

Step 3:     Verify the tunnel after interesting traffic.

On R1, re-issue the show crypto ipsec sa command. Now notice that the number of packets is more than 0 indicating that the IPsec VPN tunnel is working.

R1# show crypto ipsec sa

interface: Serial0/0/0
    Crypto map tag: VPN-MAP, local addr 10.1.1.2

   protected vrf: (none)
   local  ident (addr/mask/prot/port): (192.168.1.0/255.255.255.0/0/0)
   remote  ident (addr/mask/prot/port): (192.168.3.0/255.255.255.0/0/0)
   current_peer 10.2.2.2 port 500
    PERMIT, flags={origin_is_acl,}
   #pkts encaps: 3, #pkts encrypt: 3, #pkts digest: 0
   #pkts decaps: 3, #pkts decrypt: 3, #pkts verify: 0
   #pkts compressed: 0, #pkts decompressed: 0
   #pkts not compressed: 0, #pkts compr. failed: 0
   #pkts not decompressed: 0, #pkts decompress failed: 0
   #send errors 1, #recv errors 0

     local crypto endpt.: 10.1.1.2, remote crypto endpt.:10.2.2.2
     path mtu 1500, ip mtu 1500, ip mtu idb Serial0/0/0
     current outbound spi: 0x0A496941(172583233)
<output omitted>
Step 4:     Create uninteresting traffic.

Ping PC-B from PC-A.

Step 5:     Verify the tunnel.

On R1, re-issue the show crypto ipsec sa command. Finally, notice that the number of packets has not changed verifying that uninteresting traffic is not encrypted.