19.5.6 Lab – Configure a Site-to-Site VPN Answers

19.5.6 Lab – Configure a Site-to-Site VPN Answers version

Addressing Table

Objectives

Part 1: Configure Basic Device Settings

• Configure hostnames, interface IP addresses, and access passwords.
• Configure the OSPF dynamic routing protocol.

Part 2: Configure a Site-to-Site VPN Using Cisco IOS

• Configure IPsec VPN settings on R1 and R3.
• Verify site-to-site IPsec VPN configuration.
• Test IPsec VPN operation.

Background / Scenario

VPNs can provide a secure method of transmitting data over a public network, such as the Internet. VPN connections can help reduce the costs associated with leased lines. Site-to-Site VPNs typically provide a secure (IPsec or other) tunnel between a branch office and a central office. Another common implementation of VPN technology is remote access to a corporate office from a telecommuter location, such as a small office or home office.

In this lab, you will build and configure a multi-router network, use Cisco IOS to configure a site-to-site IPsec VPN, and then test the VPN. The IPsec VPN tunnel is from R1 to R3 via R2. R2 acts as a pass-through and 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 and protecting and authenticating IP packets between participating IPsec devices (peers), such as Cisco routers.

Note: The routers used with hands-on labs are Cisco 4221 with Cisco IOS XE Release 16.9.6 (universalk9 image). The switches used in the labs are Cisco Catalyst 2960+ with Cisco IOS Release 15.2(7) (lanbasek9 image). Other routers, switches, and Cisco IOS versions can be used. Depending on the model and Cisco IOS version, the commands available and the output produced might vary from what is shown in the labs. Refer to the Router Interface Summary Table at the end of the lab for the correct interface identifiers.

Note: Before you begin, ensure that the routers and the switches have been erased and have no startup configurations.

Required Resources

• 3 Routers (Cisco 4221 with Cisco XE Release 16.9.6 universal image or comparable with a Security Technology Package license)
• 2 Switches (Cisco 2960+ with Cisco IOS Release 15.2(7) lanbasek9 image or comparable)
• 2 PCs (Windows OS with a terminal emulation program, such as PuTTY or Tera Term installed)
• Console cables to configure Cisco networking devices
• Ethernet cables as shown in the topology

Answers Notes:
This lab is divided into three parts. Each part can be administered individually or in combination with others as time permits. The main goal of this lab is to configure a site-to-site VPN between two routers using the Cisco IOS CLI. R1 and R3 are on separate networks and communicate through R2, which simulates an ISP. The routers in this lab are configured with OSPF, although it is not typical for stub networks to communicate with an ISP using an interior routing protocol. You can also use static routes for basic (non-VPN) communication between R1 and R2 and between R1 and R3 if desired.

Students can work in teams of two for router configuration. One person configures R1 and the other person configures R3.

Although switches are shown in the topology, students can omit the switches and use crossover cables between the PCs and R1 and R3.

The running configurations for all three routers are captured after Part 1 of the lab is completed. The running configurations for R1 and R3 from Part 2 are also captured. All configurations are found at the end of the lab.

Intructions

Part 1: Configure Basic Device Settings

In Part 1, you will set up the network topology and configure basic settings, such as the interface IP addresses, dynamic routing, device access, and passwords.

Note: All tasks should be performed on R1, R2, and R3. The procedure for R1 is shown here as an example.

Step 1: Cable the network as shown in the topology.

Attach the devices as shown in the topology diagram and cable as necessary.

Step 2: Configure basic settings for each router.

a. Configure hostnames, as shown in the topology.

b. Configure the interface IP addresses, as shown in the Addressing Table.

Step 3: Disable DNS lookup.

Disable DNS lookup to prevent the router from attempting to translate incorrectly entered commands.

R1(config)# no ip domain lookup

Step 4: Configure the OSPF routing protocol on R1, R2, and R3.

a. On R1, use the following commands:

R1(config)# router ospf 101
R1(config-router)# network 192.168.1.0 0.0.0.255 area 0
R1(config-router)# network 10.1.1.0 0.0.0.3 area 0=

b. On R2, use the following commands:

R2(config)# router ospf 101
R2(config-router)# network 10.1.1.0 0.0.0.3 area 0
R2(config-router)# network 10.2.2.0 0.0.0.3 area 0

c. On R3, use the following commands:

R3(config)# router ospf 101
R3(config-router)# network 192.168.3.0 0.0.0.255 area 0
R3(config-router)# network 10.2.2.0 0.0.0.3 area 0

Step 5: Configure PC host IP settings.

a. Configure a static IP address, subnet mask, and default gateway for PC-A, as shown in the IP Addressing Table.

b. Configure a static IP address, subnet mask, and default gateway for PC-C, as shown in the IP Addressing Table.

Step 6: Verify basic network connectivity.

a. Ping from R1 to the R3 G0/0/1 interface at IP address 192.168.3.1.

If the pings are unsuccessful, troubleshoot the basic device configurations before continuing.

b. Ping from PC-A on the R1 LAN to PC-C on the R3 LAN.

If the pings are unsuccessful, troubleshoot the basic device configurations before continuing.

Note: If you can ping from PC-A to PC-C, you have demonstrated that the OSPF routing protocol is configured and functioning correctly. If you cannot ping, but the device interfaces are up and IP addresses are correct, use the show run and show ip route commands to help identify routing protocolrelated problems.

Step 7: Configure and encrypt passwords.

Note: Passwords in this task are set to a minimum of 10 characters but are relatively simple for the benefit of performing the lab. More complex passwords are recommended in a production network.

Configure the same settings for R1 and R3.

a. Configure a minimum password length.

Use the security passwords command to set a minimum password length of 10 characters.

R1(config)# security passwords min-length 10

b. Configure the enable secret password on both routers with a password of cisco12345. Use the type 9 (SCRYPT) hashing algorithm.

R1(config)# enable algorithm-type scrypt secret cisco12345

c. Create a local admin01 account using admin01pass for the password. Use the type 9 (SCRYPT) hashing algorithm.

R1(config)# username admin01 algorithm-type scrypt secret admin01pass

Step 8: Configure the console line.

Configure the console to use the local database for login. For additional security, configure the line to log out after five minutes of inactivity. Issue the logging synchronous command to prevent console messages from interrupting command entry.

R1(config)# line console 0

R1(config-line)# login local

R1(config-line)# exec-timeout 5 0

R1(config-line)# logging synchronous

Step 9: Configure SSH Server.

a. Configure a domain name netsec.com.

R1(config)# ip domain-name netsec.com

b. Configure the RSA keys with 2048 for the number of modulus bits.

R1(config)# crypto key generate rsa general-keys modulus 2048

c. Issue the command to force the use of SSH version 2.

R1(config)# ip ssh version 2

d. Configure the vty lines on R1 and R3 to use the local database for login. Remote access to the routers should only be allowed using SSH. Configure the vty lines to logout after five minutes of inactivity.

R1(config)# line vty 0 4

R1(config-line)# login local

R1(config-line)# exec-timeout 5 0

R1(config-line)# transport input ssh

Step 10: Save the basic running configuration for all three routers.

Save the running configuration to the startup configuration from the privileged EXEC mode prompt on R1, R2, and R3.

R1# copy running-config startup-config

Part 2: Configure a Site-to-Site VPN with Cisco IOS

In Part 2 of this lab, you will configure an IPsec VPN tunnel between R1 and R3 that passes through R2. You will configure R1 and R3 using the Cisco IOS CLI. You will then review and test the resulting configuration.

Note: Because no tunnel is yet in place, PC-A should still be able to ping PC-C. If not, troubleshoot the basic device configurations before continuing.

Task 1: Configure IPsec VPN Settings on R1 and R3.

Step 1: Enable IKE policies on R1 and R3.

IPsec is an open framework that allows for the exchange of security protocols as new technologies, and encryption algorithms as they are developed.

There are two central configuration elements in the implementation of an IPsec VPN:

• Implement Internet Key Exchange (IKE) parameters
• Implement IPsec parameters

a. Verify that IKE is supported and enabled.

IKE Phase 1 defines the key exchange method used to pass and validate IKE policies between peers. In IKE Phase 2, the peers exchange and match IPsec policies for the authentication and encryption of data traffic.

IKE must be enabled for IPsec to function. IKE is enabled, by default, on IOS images with cryptographic feature sets. If it is disabled, you can enable it with the crypto isakmp enable command. Use this command to verify that the router IOS supports IKE and that it is enabled.

R1(config)# crypto isakmp enable

R3(config)# crypto isakmp enable

Note: If you cannot execute this command on the router, you must upgrade to the IOS image that includes the Cisco cryptographic services.

b. Establish an ISAKMP policy and view the available options.

To allow IKE Phase 1 negotiation, you must create an ISAKMP policy and configure a peer association for that ISAKMP policy. An ISAKMP policy defines the authentication and encryption algorithms and the hash function used to send control traffic between the two VPN endpoints. When an ISAKMP security association has been accepted by the IKE peers, IKE Phase 1 has been completed. IKE Phase 2 parameters will be configured later.

Issue the crypto isakmp policy number global configuration mode command on R1 for policy 10.

R1(config)# crypto isakmp policy 10

c. View the various IKE parameters available using Cisco IOS help by typing a question mark (?).

R1(config-isakmp)# ?
ISAKMP commands:
  authentication  Set authentication method for protection suite
  default         Set a command to its defaults
  encryption      Set encryption algorithm for protection suite
  exit            Exit from ISAKMP protection suite configuration mode
  group           Set the Diffie-Hellman group
  hash            Set hash algorithm for protection suite
  lifetime        Set lifetime for ISAKMP security association
  no              Negate a command or set its defaults

Step 2: Configure the IKE Phase 1 ISAKMP policy on R1 and R3.

Your choice of an encryption algorithm determines how confidential the control channel between the endpoints is. The hash algorithm controls data integrity, ensuring that the data received from a peer has not been tampered with in transit. The authentication type ensures that the packet was sent and signed by the remote peer. The Diffie-Hellman group is used to create a secret key shared by the peers that has not been sent across the network.

a. Configure an ISAKMP policy with a priority of 10. Use pre-shared key as the authentication type, aes 256 for the encryption algorithm, sha as the hash algorithm, and the Diffie-Hellman group 24 key exchange. Give the policy a lifetime of 3600 seconds (one hour).

Note: Older versions of Cisco IOS do not support AES 256 encryption and SHA as a hash algorithm. Substitute whatever encryption and hashing algorithm your router supports. Ensure that the same changes are made on R3 in order to be in sync.

R1(config)# crypto isakmp policy 10
R1(config-isakmp)# hash sha
R1(config-isakmp)# authentication pre-share
R1(config-isakmp)# group 24
R1(config-isakmp)# lifetime 3600
R1(config-isakmp)# encryption aes 256
R1(config-isakmp)# end

b. Configure the same policy on R3.

R3(config)# crypto isakmp policy 10
R3(config-isakmp)# hash sha
R3(config-isakmp)# authentication pre-share
R3(config-isakmp)# group 24
R3(config-isakmp)# lifetime 3600
R3(config-isakmp)# encryption aes 256
R3(config-isakmp)# end

c. Verify the IKE policy with the show crypto isakmp policy command.

R1# show crypto isakmp policy

Global IKE policy
Protection suite of priority 10
        encryption algorithm:   AES - Advanced Encryption Standard (256 bit keys).
        hash algorithm:         Secure Hash Standard
        authentication method:  Pre-Shared Key
        Diffie-Hellman group:   #24 (2048 bit, 256 bit subgroup)
        lifetime:               3600 seconds, no volume limit

Step 3: Configure pre-shared keys.

Because pre-shared keys are used as the authentication method in the IKE policy, a key must be configured on each router that points to the other VPN endpoint. These keys must match for authentication to be successful. The global configuration mode crypto isakmp key key-string address ip-address command is used to enter a pre-shared key. Use the IP address of the remote peer, which is the remote interface that the peer would use to route traffic to the local router.

Which IP addresses should you use to configure the IKE peers, given the topology diagram and IP addressing table?
The IP addresses should be R1 G0/0/0 IP address 10.1.1.1 and R3 G0/0/0 IP address 10.2.2.1. These are the addresses that are used to send normal traffic between R1 and R3.

a. Each IP address that is used to configure the IKE peers is also referred to as the IP address of the remote VPN endpoint. Configure the pre-shared key of cisco123 on router R1. Production networks should use a complex key. This command points to the remote peer R3 G0/0/0 IP address.

R1(config)# crypto isakmp key cisco123 address 10.2.2.1

b. Configure the pre-shared key cisco123 on router R3. The command for R3 points to the R1 S0/0/0 IP address.

R3(config)# crypto isakmp key cisco123 address 10.1.1.1

Step 4: Configure the IPsec transform set and lifetime.

a. The IPsec transform set is another crypto configuration parameter that routers negotiate to form a security association. To create an IPsec transform set, use the crypto ipsec transform-set tag command where tag is a name configured by the administrator. Use ? to see which parameters are available.

R1(config)# crypto ipsec transform-set R1-R3 ?
  ah-md5-hmac     AH-HMAC-MD5 transform
  ah-sha-hmac     AH-HMAC-SHA transform
  ah-sha256-hmac  AH-HMAC-SHA256 transform
  ah-sha384-hmac  AH-HMAC-SHA384 transform
  ah-sha512-hmac  AH-HMAC-SHA512 transform
  esp-192-aes     ESP transform using AES cipher (192 bits)
  esp-256-aes     ESP transform using AES cipher (256 bits)
  esp-3des        ESP transform using 3DES(EDE) cipher (168 bits)
  esp-aes         ESP transform using AES cipher
  esp-des         ESP transform using DES cipher (56 bits)
  esp-gcm         ESP transform using GCM cipher
  esp-gmac        ESP transform using GMAC cipher
  esp-md5-hmac    ESP transform using HMAC-MD5 auth
  esp-null        ESP transform w/o cipher
  esp-seal        ESP transform using SEAL cipher (160 bits)
  esp-sha-hmac    ESP transform using HMAC-SHA auth
  esp-sha256-hmac ESP transform using HMAC-SHA256 auth
  esp-sha384-hmac ESP transform using HMAC-SHA384 auth
  esp-sha512-hmac ESP transform using HMAC-SHA512 auth

b. On R1 and R3, create a transform set with tag R1-R3 and use an ESP transform with an AES 256 cipher with ESP and the SHA hash function. The transform sets must match on both ends of the VPN.

R1(config)# crypto ipsec transform-set 50 esp-aes 256 esp-sha-hmac
R1(cfg-crypto-trans)# exit

R3(config)# crypto ipsec transform-set 50 esp-aes 256 esp-sha-hmac
R3(cfg-crypto-trans)# exit

What is the function of the IPsec transform set?
The IPsec transform set specifies the cryptographic algorithms and functions (transforms) that a router employs on the actual data packets sent through the IPsec tunnel. These algorithms include the encryption, encapsulation, authentication, and data integrity services that IPsec can apply.

c. You can also change the IPsec security association lifetime from the default of 3600 seconds. On R1 and R3, set the IPsec security association lifetime to 30 minutes, or 1800 seconds.

R1(config)# crypto ipsec security-association lifetime seconds 1800

R3(config)# crypto ipsec security-association lifetime seconds 1800

Step 5: Define interesting traffic.

To make use of the IPsec encryption with the VPN, it is necessary to define extended access lists to tell the router which traffic to encrypt. A packet that is permitted by an access list used for defining IPsec traffic is encrypted if the IPsec session is configured correctly. A packet that is denied by the IPsec access list is not dropped. It is sent unencrypted. Also, like any other access list, there is an implicit deny at the end, which means the default action is to not encrypt traffic. If there is no IPsec security association correctly configured, no traffic is encrypted and traffic is forwarded unencrypted.

In this scenario, from the perspective of R1, the traffic you want to encrypt is traffic going from R1’s Ethernet LAN to R3’s Ethernet LAN or vice versa from the perspective of R3. These access lists are used outbound on the VPN endpoint interfaces and must mirror each other.

a. Configure the IPsec VPN interesting traffic ACL on R1.

R1(config)# access-list 101 permit ip 192.168.1.0 0.0.0.255 192.168.3.0 0.0.0.255

b. Configure the IPsec VPN interesting traffic ACL on R3.

R3(config)# access-list 101 permit ip 192.168.3.0 0.0.0.255 192.168.1.0 0.0.0.255

Does IPsec evaluate whether the access lists are mirrored as a requirement to negotiate its security association?
Yes. IPsec does evaluate whether access lists are mirrored. IPsec does not form a security association if the peers do not have mirrored access lists to select interesting traffic.

Step 6: Create and apply a crypto map.

A crypto map associates traffic that matches an access list to a peer and various IKE and IPsec settings. After the crypto map is created, it can be applied to one or more interfaces. The interfaces that it is applied to should be the ones facing the IPsec peer.

To create a crypto map, use crypto map <name> <sequence-num> <type> command in global configuration mode to enter crypto map configuration mode for that sequence number. Multiple crypto map statements can belong to the same crypto map and are evaluated in ascending numerical order. Enter crypto map configuration mode on R1. Use a type of ipsec-isakmp, which means IKE is used to establish IPsec security associations.

a. Create the crypto map on R1, name it CMAP, and use 10 as the sequence number. A message displays after the command is issued.

R1(config)# crypto map CMAP 10 ipsec-isakmp
% NOTE: This new crypto map will remain disabled until a peer
        and a valid access list have been configured.

b. Use the match address <access-list> command to specify which access list defines which traffic to encrypt.

R1(config-crypto-map)# match address 101

c. To view the list of possible set commands that you can do with a crypto map, use the help function.

R1(config-crypto-map)# set ?
  identity             Identity restriction.
  ip Interface         Internet Protocol config commands
  isakmp-profile       Specify isakmp Profile
  nat                  Set NAT translation
  peer                 Allowed Encryption/Decryption peer.
  pfs                  Specify pfs settings
  reverse-route        Reverse Route Injection.
  security-association Security association parameters
  transform-set        Specify list of transform sets in priority order

d. Setting a peer IP or hostname is required. Set it to R3’s remote VPN endpoint interface using the following command.

R1(config-crypto-map)# set peer 10.2.2.1

e. Use the set transform-set tag command to hard code the transform set to be used with this peer. Set the perfect forwarding secrecy type using the set pfs type command, and modify the default IPsec security association life time with the set security-association lifetime seconds seconds command.

R1(config-crypto-map)# set pfs group24
R1(config-crypto-map)# set transform-set R1-R3
R1(config-crypto-map)# set security-association lifetime seconds 900
R1(config-crypto-map)# exit

f. Create a mirrored matching crypto map on R3.

R3(config)# crypto map CMAP 10 ipsec-isakmp
R3(config-crypto-map)# match address 101
R3(config-crypto-map)# set peer 10.1.1.1
R3(config-crypto-map)# set pfs group24
R3(config-crypto-map)# set transform-set R1-R3
R3(config-crypto-map)# set security-association lifetime seconds 900
R3(config-crypto-map)# exit

g. Apply the crypto maps to the appropriate interfaces on R1 and R3.

Note: . The router generates a notification that crypto is now on. However, the SAs are not established until the crypto map has been activated by interesting traffic

R1(config)# interface G0/0/0
R1(config-if)# crypto map CMAP
*Jan 28 04:09:09.150: %CRYPTO-6-ISAKMP_ON_OFF: ISAKMP is ON
R1(config)# end

R3(config)# interface G0/0/1
R3(config-if)# crypto map CMAP
*Jan 28 04:10:54.138: %CRYPTO-6-ISAKMP_ON_OFF: ISAKMP is ON
R3(config)# end

Task 2: Verify the Site-to-Site IPsec VPN Configuration.

Step 7: Verify the IPsec configuration on R1 and R3.

a. Previously, you used the show crypto isakmp policy command to display the configured ISAKMP policies on the router. The show crypto ipsec transform-set command displays the configured IPsec policies in the form of the transform sets.

R1# show crypto ipsec transform-set
Transform set AES_GCM_256: { esp-gcm 256 }
   will negotiate = { Transport, },

Transform set AES_CBC_256_HMAC_SHA1: { esp-256-aes esp-sha-hmac }
   will negotiate = { Transport, },

Transform set AES_CBC_128_HMAC_SHA1: { esp-aes esp-sha-hmac }
   will negotiate = { Transport, },

Transform set default: { esp-aes esp-sha-hmac }
   will negotiate = { Transport, },

Transform set R1-R3: { esp-256-aes esp-sha-hmac }
   will negotiate = { Tunnel, },

R3# show crypto ipsec transform-set
Transform set AES_GCM_256: { esp-gcm 256 }
   will negotiate = { Transport, },

Transform set AES_CBC_256_HMAC_SHA1: { esp-256-aes esp-sha-hmac }
   will negotiate = { Transport, },

Transform set AES_CBC_128_HMAC_SHA1: { esp-aes esp-sha-hmac }
   will negotiate = { Transport, },

Transform set default: { esp-aes esp-sha-hmac }
   will negotiate = { Transport, },

Transform set R1-R3: { esp-256-aes esp-sha-hmac }
   will negotiate = { Tunnel, },

a. Use the show crypto map command to display the crypto maps that will be applied to the router.

R1# show crypto map
Crypto Map IPv4 "CMAP" 10 ipsec-isakmp
        Peer = 10.2.2.1
        Extended IP access list 101
             access-list 101 permit ip 192.168.1.0 0.0.0.255 192.168.3.0 0.0.0.255
        Current peer: 10.2.2.1
        Security association lifetime: 4608000 kilobytes/900 seconds
        Responder-Only (Y/N): N
        PFS (Y/N): Y
        DH group: group24
        Mixed-mode : Disabled
        Transform sets={
                R1-R3: { esp-256-aes esp-sha-hmac } ,
        }
        Interfaces using crypto map CMAP:
                GigabitEthernet0/0/0

R3# show crypto map
Crypto Map IPv4 "CMAP" 10 ipsec-isakmp
        Peer = 10.1.1.1
        Extended IP access list 101
            access-list 101 permit ip 192.168.3.0 0.0.0.255 192.168.1.0 0.0.0.255
        Current peer: 10.1.1.1
        Security association lifetime: 4608000 kilobytes/900 seconds
        Responder-Only (Y/N): N
        PFS (Y/N): Y
        DH group: group24
        Mixed-mode : Disabled
        Transform sets={
                R1-R3: { esp-256-aes esp-sha-hmac } ,
        }
        Interfaces using crypto map CMAP:
                GigabitEthernet0/0/0

Note: The output of these show commands does not change if interesting traffic goes across the connection. You test various types of traffic in the next task.

Task 3: Verify the IPsec VPN Operation.

Step 8: Display ISAKMP security associations.

The show crypto isakmp sa command reveals that no IKE SAs exist yet. When interesting traffic is sent, this command output will change.

R1# show crypto isakmp sa
IPv4 Crypto ISAKMP SA
dst           src          state c          onn-id status
IPv6 Crypto ISAKMP SA

Step 9: Display IPsec security associations.

The show crypto ipsec sa command shows the unused SA between R1 and R3.

Note: The number of packets sent across is zero, and there is a lack of any security associations listed toward the bottom of the output. The output for R1 is shown here.

R1# show crypto ipsec sa

interface: GigabitEthernet0/0/0
    Crypto map tag: CMAP, local addr 10.1.1.1

  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 10.2.2.1 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.: 10.1.1.1, remote crypto endpt.: 10.2.2.1
    plaintext mtu 1500, path mtu 1500, ip mtu 1500, ip mtu idb GigabitEthernet0/0/0
    current outbound spi: 0x0(0)
    PFS (Y/N): N, DH group: none

    inbound esp sas:

    inbound ah sas:

    inbound pcp sas:

    outbound esp sas:

    outbound ah sas:

    outbound pcp sas:

Why haven’t any SAs been negotiated?
IPsec has not begun to negotiate an SA over which it will encrypt traffic because no interesting traffic has been identified.

Step 10: Generate some uninteresting test traffic and observe the results.

a. Ping from R1 to the R3 G0/0/0 interface IP address 10.2.2.1. These pings should be successful.

b. Issue the show crypto isakmp sa command.

c. Ping from R1 to the R3 G0/0/1 interface IP address 192.168.3.1. These pings should be successful.

d. Issue the show crypto isakmp sa command again.

Was an SA created for these pings? Explain.
SA was not created. The source address of both pings was the R1 S0/0/0 address of 10.1.1.1. In the first case, the destination address was 10.2.2.1. In the second case, the destination address was 192.168.3.1. This is not “interesting” traffic. The ACL 101 that is associated with the crypto map for R1 defines interesting traffic as IP packets from the 192.168.1.0/24 network to the 192.168.3.0/24 network.

e. Issue the debug ip ospf hello command. You should see OSPF hello packets passing between R1 and R3.

R1# debug ip ospf hello
OSPF hello events debugging is on
R1#
*Apr 7 18:04:46.467: OSPF: Send hello to 224.0.0.5 area 0 on GigabitEthernet0/1 from
192.168.1.1
*Apr 7 18:04:50.055: OSPF: Send hello to 224.0.0.5 area 0 on Serial0/0/0 from
10.1.1.1
*Apr 7 18:04:52.463: OSPF: Rcv hello from 10.2.2.2 area 0 from Serial0/0/0 10.1.1.2
*Apr 7 18:04:52.463: OSPF: End of hello processing
*Apr 7 18:04:55.675: OSPF: Send hello to 224.0.0.5 area 0 on GigabitEthernet0/1 from
192.168.1.1
*Apr 7 18:04:59.387: OSPF: Send hello to 224.0.0.5 area 0 on Serial0/0/0 from
10.1.1.1
*Apr 7 18:05:02.431: OSPF: Rcv hello from 10.2.2.2 area 0 from Serial0/0/0 10.1.1.2
*Apr 7 18:05:02.431: OSPF: End of hello processing

f. Turn off debugging with the no debug ip ospf hello or undebug all command.

g. Re-issue the show crypto isakmp sa command.

Was an SA created between R1 and R3? Explain.
No. This is router-to-router routing protocol traffic. The source and destination of these packets is not interesting, does not initiate the SA, and is not encrypted.

Step 11: Generate some interesting test traffic and observe the results.

a. Use an extended ping from R1 to the R3 G0/1 interface IP address 192.168.3.1. Extended ping allows you to control the source address of the packets. Respond as shown in the following example. Press Enter to accept the defaults, except where a specific response is indicated.

Note: You can also ping from PC-A to PC-C to generate interesting traffic.

R1# ping 192.168.3.1 source 192.168.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.3.1, timeout is 2 seconds:
Packet sent with a source address of 192.168.1.1
..!!!
Success rate is 80 percent (4/5), round-trip min/avg/max = 1/1/2 ms

h. Re-issue the show crypto isakmp sa command.

R1# show crypto isakmp sa
IPv4 Crypto ISAKMP SA
dst         src         state         conn-id status
10.2.2.1    10.1.1.1    QM_IDLE          1001 ACTIVE
IPv6 Crypto ISAKMP SA

Why was an SA created between R1 and R3 this time?
The source was 192.168.1.1 and the destination was 192.168.3.1. This is interesting traffic based on the ACL 101 definition. An SA is established and packets travel through the tunnel as encrypted traffic.

What are the endpoints of the IPsec VPN tunnel?
Src: 10.1.1.1 (R1 G0/0/0), Dst: 10.2.2.1 (R3 G0/0/0).

i. Ping from PC-A to PC-C and then issue the show crypto ipsec sa command.

How many packets have been transformed between R1 and R3?
Answers may vary. Seven: Three of the five packets from the R1 to R3 pings, four packets from the PC-A to R3 pings, and one packet for each echo request. The number of packets may vary depending on how many pings have been issued and from where.

R1# show crypto ipsec sa

interface: GigabitEthernet0/0/0
    Crypto map tag: CMAP, local addr 10.1.1.1

 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 10.2.2.1 port 500
   PERMIT, flags={origin_is_acl,}
  #pkts encaps: 12, #pkts encrypt: 12, #pkts digest: 12
  #pkts decaps: 8, #pkts decrypt: 8, #pkts verify: 8
  #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.: 10.1.1.1, remote crypto endpt.: 10.2.2.1
   plaintext mtu 1438, path mtu 1500, ip mtu 1500, ip mtu idb GigabitEthernet0/0/0
   current outbound spi: 0x95B6C7B5(2511783861)
   PFS (Y/N): Y, DH group: group24

   inbound esp sas:
    spi: 0x1EBD4016(515719190)
      transform: esp-256-aes esp-sha-hmac ,
      in use settings ={Tunnel, }
      conn id: 2001, flow_id: ESG:1, sibling_flags FFFFFFFF80004048, crypto map:
CMAP
      sa timing: remaining key lifetime (k/sec): (4607999/671)
      IV size: 16 bytes
      replay detection support: Y
      Status: ACTIVE(ACTIVE)
      inbound ah sas:

      inbound pcp sas:

      outbound esp sas:
       spi: 0x95B6C7B5(2511783861)
         transform: esp-256-aes esp-sha-hmac ,
         in use settings ={Tunnel, }
         conn id: 2002, flow_id: ESG:2, sibling_flags FFFFFFFF80004048, crypto map:
   CMAP
         sa timing: remaining key lifetime (k/sec): (4607999/671)
         IV size: 16 bytes
         replay detection support: Y
         Status: ACTIVE(ACTIVE)

      outbound ah sas:

      outbound pcp sas:

j. The previous example used pings to generate interesting traffic.

What other types of traffic would result in an SA forming and tunnel establishment?
Any traffic initiated from R1 with a source address in the 192.168.1.0/24 network and a destination address in the 192.168.3.0/24 network. On R3, interesting traffic is any traffic with a source address in the 192.168.3.0/24 network and a destination address in the 192.168.1.0/24 network. This includes FTP, HTTP, Telnet, and others.

Reflection

Would traffic on the Gigabit Ethernet link between PC-A and the R1 G0/0 interface be encrypted by the siteto-site IPsec VPN tunnel? Explain.
No. This site-to-site VPN only encrypts from router R1 to R3. A sniffer could be used to see the traffic from PC-A to the R1 default gateway.

Router Interface Summary Table

Note: To find out how the router is configured, look at the interfaces to identify the type of router and how many interfaces the router has. There is no way to effectively list all the combinations of configurations for each router class. This table includes identifiers for the possible combinations of Ethernet and Serial interfaces in the device. The table does not include any other type of interface, even though a specific router may contain one. An example of this might be an ISDN BRI interface. The string in parenthesis is the legal abbreviation that can be used in Cisco IOS commands to represent the interface.

Router Configs

Note: ISR G2 devices have Gigabit Ethernet interfaces instead of Fast Ethernet Interfaces.

Router R1 after Part 1

R1# show run

Building configuration…

Current configuration : 1607 bytes

!

version 16.9

service timestamps debug datetime msec

service timestamps log datetime msec

platform qfp utilization monitor load 80

platform punt-keepalive disable-kernel-core

!

hostname R1

!

boot-start-marker

boot-end-marker

!

security passwords min-length 10

enable secret 9 $9$4o9XpHVevphwz.$Gk.U.BjU7ZFO9Ou516diJJSiROu3p2X5clTNOANH92w

!

no aaa new-model

!

no ip domain lookup

ip domain name netsec.com

!

!

!

login on-success log

!

subscriber templating

!

multilink bundle-name authenticated

!

license udi pid ISR4221/K9 sn FGL221693BV

license accept end user agreement

license boot level securityk9

no license smart enable

diagnostic bootup level minimal

!

spanning-tree extend system-id

!

username admin01 secret 9 $9$2EsbUlytWz4ltk$aLnkFCbMrM4OKelfQ9K41H8hmfA2ZQUX8aadeGmqINI

!

redundancy

mode none

!

interface GigabitEthernet0/0/0

ip address 10.1.1.1 255.255.255.252

negotiation auto

!

interface GigabitEthernet0/0/1

ip address 192.168.1.1 255.255.255.0

negotiation auto

!

interface Serial0/1/0

no ip address

!

interface Serial0/1/1

no ip address

!

router ospf 101

network 10.1.1.0 0.0.0.3 area 0

network 192.168.1.0 0.0.0.255 area 0

!

ip forward-protocol nd

no ip http server

ip http secure-server

!

ip ssh version 2

!

control-plane

!

line con 0

exec-timeout 5 0

logging synchronous

login local

transport input none

stopbits 1

line aux 0

stopbits 1

line vty 0 4

exec-timeout 5 0

login local

transport input ssh

!

end

R1#

Router R2 after Part 1

R2# show run

Building configuration…

Current configuration : 1159 bytes

!

version 16.9

service timestamps debug datetime msec

service timestamps log datetime msec

platform qfp utilization monitor load 80

platform punt-keepalive disable-kernel-core

!

hostname R2

!

boot-start-marker

boot-end-marker

!

no aaa new-model

!

no ip domain lookup

!

login on-success log

!

subscriber templating

!

multilink bundle-name authenticated

!

license udi pid ISR4221/K9 sn FGL221693BU

no license smart enable

diagnostic bootup level minimal

!

spanning-tree extend system-id

!

redundancy

mode none

!

interface GigabitEthernet0/0/0

ip address 10.1.1.2 255.255.255.252

negotiation auto

!

interface GigabitEthernet0/0/1

ip address 10.2.2.2 255.255.255.252

negotiation auto

!

router ospf 101

network 10.1.1.0 0.0.0.3 area 0

network 10.2.2.0 0.0.0.3 area 0

!

ip forward-protocol nd

no ip http server

ip http secure-server

!

control-plane

!

line con 0

exec-timeout 0 0

logging synchronous

transport input none

stopbits 1

line aux 0

stopbits 1

line vty 0 4

login

!

end

Router R3 after Part 1

R3# show run

Building configuration…

Current configuration : 1574 bytes

!

version 16.9

service timestamps debug datetime msec

service timestamps log datetime msec

platform qfp utilization monitor load 80

platform punt-keepalive disable-kernel-core

!

hostname R3

!

boot-start-marker

boot-end-marker

!

security passwords min-length 10

enable secret 9 $9$Zy3MkswwE/xsAG$NcWd2ELnzx7wi2etzFrTC6use71XmIR/pxNeVPfH0s2

!

no aaa new-model

!

no ip domain lookup

ip domain name netsec.com

!

login on-success log

!

subscriber templating

!

vtp domain TSHOOT

vtp mode off

!

multilink bundle-name authenticated

!

license udi pid ISR4221/K9 sn FGL221693BW

no license smart enable

diagnostic bootup level minimal

!

spanning-tree extend system-id

!

username admin01 secret 9 $9$zaeX6vFzGg7hd0$kz45j7QU1KQHsvRYsa8AxnsalMWRSVoFhJd8c8AvaQs

!

redundancy

mode none

!

interface GigabitEthernet0/0/0

ip address 10.2.2.1 255.255.255.252

negotiation auto

!

interface GigabitEthernet0/0/1

ip address 192.168.3.1 255.255.255.0

negotiation auto

!

interface Serial0/1/0

no ip address

!

interface Serial0/1/1

no ip address

!

router ospf 101

network 10.2.2.0 0.0.0.3 area 0

network 192.168.3.0 0.0.0.255 area 0

!

ip forward-protocol nd

no ip http server

ip http secure-server

!

ip ssh version 2

!

control-plane

!

line con 0

exec-timeout 5 0

logging synchronous

login local

transport input none

stopbits 1

line aux 0

stopbits 1

line vty 0 4

exec-timeout 5 0

login local

transport input ssh

!

end

R3#

Router R1 after Part 2

R1# show run

Building configuration…

Current configuration : 2153 bytes

!

version 16.9

service timestamps debug datetime msec

service timestamps log datetime msec

platform qfp utilization monitor load 80

platform punt-keepalive disable-kernel-core

!

hostname R1

!

boot-start-marker

boot-end-marker

!

security passwords min-length 10

enable secret 9 $9$4o9XpHVevphwz.$Gk.U.BjU7ZFO9Ou516diJJSiROu3p2X5clTNOANH92w

!

no aaa new-model

!

no ip domain lookup

ip domain name netsec.com

!

login on-success log

!

subscriber templating

!

multilink bundle-name authenticated

!

license udi pid ISR4221/K9 sn FGL221693BV

license accept end user agreement

license boot level securityk9

no license smart enable

diagnostic bootup level minimal

!

spanning-tree extend system-id

!

username admin01 secret 9 $9$2EsbUlytWz4ltk$aLnkFCbMrM4OKelfQ9K41H8hmfA2ZQUX8aadeGmqINI

!

redundancy

mode none

!

crypto isakmp policy 10

encr aes 256

authentication pre-share

group 24

lifetime 3600

crypto isakmp key cisco123 address 10.2.2.1

!

crypto ipsec security-association lifetime seconds 1800

!

crypto ipsec transform-set R1-R3 esp-aes 256 esp-sha-hmac

mode tunnel

!

crypto map CMAP 10 ipsec-isakmp

set peer 10.2.2.1

set security-association lifetime seconds 900

set transform-set R1-R3

set pfs group24

match address 101

!

interface GigabitEthernet0/0/0

ip address 10.1.1.1 255.255.255.252

negotiation auto

crypto map CMAP

!

interface GigabitEthernet0/0/1

ip address 192.168.1.1 255.255.255.0

negotiation auto

!

interface Serial0/1/0

no ip address

!

interface Serial0/1/1

no ip address

!

router ospf 101

network 10.1.1.0 0.0.0.3 area 0

network 192.168.1.0 0.0.0.255 area 0

!

ip forward-protocol nd

no ip http server

ip http secure-server

!

ip ssh version 2

!

ip access-list extended 101

permit ip 192.168.1.0 0.0.0.255 192.168.3.0 0.0.0.255

!

control-plane

!

!

line con 0

exec-timeout 0 0

logging synchronous

login local

transport input none

stopbits 1

line aux 0

stopbits 1

line vty 0 4

exec-timeout 5 0

login local

transport input ssh

!

end

Router R3 after Part 2

R3# show run

Building configuration…

Current configuration : 2105 bytes

!

version 16.9

service timestamps debug datetime msec

service timestamps log datetime msec

platform qfp utilization monitor load 80

platform punt-keepalive disable-kernel-core

!

hostname R3

!

boot-start-marker

boot-end-marker

!

security passwords min-length 10

enable secret 9 $9$Zy3MkswwE/xsAG$NcWd2ELnzx7wi2etzFrTC6use71XmIR/pxNeVPfH0s2

!

no aaa new-model

!

no ip domain lookup

ip domain name netsec.com

!

login on-success log

!

subscriber templating

!

vtp domain TSHOOT

vtp mode off

!

multilink bundle-name authenticated

!

license udi pid ISR4221/K9 sn FGL221693BW

no license smart enable

diagnostic bootup level minimal

!

spanning-tree extend system-id

!

username admin01 secret 9 $9$zaeX6vFzGg7hd0$kz45j7QU1KQHsvRYsa8AxnsalMWRSVoFhJd8c8AvaQs

!

redundancy

mode none

!

crypto isakmp policy 10

encr aes 256

authentication pre-share

group 24

crypto isakmp key cisco123 address 10.1.1.1

!

crypto ipsec security-association lifetime seconds 1800

!

crypto ipsec transform-set R1-R3 esp-aes 256 esp-sha-hmac

mode tunnel

!

crypto map CMAP 10 ipsec-isakmp

set peer 10.1.1.1

set security-association lifetime seconds 900

set transform-set R1-R3

set pfs group24

match address 101

!

interface GigabitEthernet0/0/0

ip address 10.2.2.1 255.255.255.252

negotiation auto

crypto map CMAP

!

interface GigabitEthernet0/0/1

ip address 192.168.3.1 255.255.255.0

negotiation auto

!

interface Serial0/1/0

no ip address

!

interface Serial0/1/1

no ip address

!

router ospf 101

network 10.2.2.0 0.0.0.3 area 0

network 192.168.3.0 0.0.0.255 area 0

!

ip forward-protocol nd

no ip http server

ip http secure-server

!

ip ssh version 2

!

ip access-list extended 101

permit ip 192.168.3.0 0.0.0.255 192.168.1.0 0.0.0.255

!

control-plane

!

line con 0

exec-timeout 0 0

logging synchronous

login local

transport input none

stopbits 1

line aux 0

stopbits 1

line vty 0 4

exec-timeout 5 0

login local

transport input ssh

!

end