CCNA Security Lab C (Optional), Configuring a Remote Access VPN Server and Client

CCNA Security Lab C (Optional), Configuring a Remote Access VPN Server and Client

Topology

ccna-security-lab-c-optional-configuring-remote-access-vpn-server-client-top

IP Addressing Table

Device Interface          IP Address Subnet Mask Default Gateway Switch Port
R1 FA0/1                  192.168.1.1 255.255.255.0 N/A S1 FA0/5
S0/0/0 (DCE)      10.1.1.1 255.255.255.252 N/A N/A
R2 S0/0/0                  10.1.1.2 255.255.255.252 N/A N/A
S0/0/1 (DCE)      10.2.2.2 255.255.255.252 N/A N/A
Loopback 0         192.168.2.1 255.255.255.0 N/A N/A
R3 FA0/1                  192.168.3.1 255.255.255.0 N/A S3 FA0/5
S0/0/1                  10.2.2.1 255.255.255.252 N/A N/A
PC-A NIC                     192.168.1.3 255.255.255.0 192.168.1.1 S1 FA0/6
PC-C NIC                     192.168.3.3 255.255.255.0 192.168.3.1 S3 FA0/18

Objectives

Part 1: Basic Router Configuration

  • Configure host names, interface IP addresses, and access passwords.
  • Configure the EIGRP dynamic routing protocol on R2 and R3.

Part 2: Configuring a Remote Access VPN

  • Configure a router to support an Easy VPN server using SDM.
  • Configure the Cisco VPN client on PC-A and connect to R2.
  • Verify the configuration.
  • Test VPN functionality.

Background
VPNs can provide a secure method of transmitting data over a public network, such as the Internet. A common VPN implementation is used for remote access to a corporate office from a telecommuter location such as a small office or home office (SOHO).
In this lab, you build a multirouter network and configure the routers and hosts. You configure a remote access IPsec VPN between a client computer and a simulated corporate network. You use SDM to configure a Cisco Easy VPN server on the corporate edge gateway router and configure the Cisco VPN client on a host. You then connect to the corporate network through a simulated ISP router.

The Cisco VPN client allows organizations to establish end-to-end, encrypted (IPsec) VPN tunnels for secure connectivity for mobile employees or teleworkers. It supports Cisco Easy VPN, which allows the client to receive security policies upon a VPN tunnel connection from the central site VPN device (Cisco Easy VPN Server), minimizing configuration requirements at the remote location. This is a scalable solution for remote access deployments where it is impractical to individually configure policies for multiple remote PCs.

Note: The router commands and output in this lab are from a Cisco 1841 with Cisco IOS Release 12.4(20)T (Advanced IP image). Other routers and Cisco IOS versions can be used. See the Router Interface Summary table at the end of the lab to determine which interface identifiers to use based on the equipment in the lab. Depending on the router model and Cisco IOS version, the commands available and output produced might vary from what is shown in this lab.

Note: Make sure that the routers and the switches have been erased and have no startup configurations.

Instructor Note: Instructions for erasing switches and routers are provided in the Lab Manual, located on Academy Connection in the Tools section.

Required Resources

  • 3 routers with SDM 2.5 installed (Cisco 1841 with Cisco IOS Release 12.4(20)T1 or comparable)

Note: This lab requires that R2 have a comparable IOS and hardware characteristics to R1 and R2 in order for it to play the role of the VPN server.

  • 2 switches (Cisco 2960 or comparable)
  • PC-A (Windows XP or Vista, with Cisco VPN Client)
  • PC-C (Windows XP or Vista)
  • Serial and Ethernet cables as shown in the topology
  • Rollover cables to configure the routers via the console

Instructor Notes:
Host PC-A is connected to R1, which simulates an ISP router. R1 is connected to R2, the corporate edge gateway router. Router R2 connects to R3 to represent a multirouter internal corporate network. Routers R2 and R3 are configured with EIGRP. The ISP router, R1, does not participate in the EIGRP process. PC-A is used to connect to R2 through R1 to configure R2 as a VPN server.

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

The version of the Cisco VPN Client used in this lab is 4.8.02.0010 for use with Windows XP. You must have a valid CCO account and service contract to download the file.

The basic running configs for all three routers are captured after Part 2 of the lab is completed. All configs are found at the end of the lab.

Part 1: Basic Router Configuration

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

Note: Perform all tasks on routers 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 shown in the topology diagram, and cable as necessary.

Step 2: Configure basic settings for each router.
a. Configure host names as shown in the topology.

b. Configure the physical interface IP addresses as shown in the IP addressing table.

c. Configure the logical loopback 0 interface on R2. This simulates the network from which the remote access clients receive addresses (192.168.2.0/24). It is not necessary to use the no shutdown command because loopback interfaces are up by default.

d. Configure a clock rate for the serial router interfaces with a DCE serial cable attached.

Step 3: Disable DNS lookup.
To prevent the router from attempting to translate incorrectly entered commands, disable DNS lookup.

Step 4: Configure the EIGRP routing protocol on R2 and R3.

Note: R2 and R3 exchange routes in EIGRP AS 101. R1 is acting as an ISP router and does not participate in the EIGRP routing process.

a. On R2, use the following commands.

b. On R3, use the following commands.

Step 5: Configure a static default route on R2.
Router R1 represents a connection to the Internet. A default route is configured on R2 for all traffic whose destination network does not exist in the R2 routing table.

Note: Without the default route configured on R2, R2 cannot respond to the SDM HTTP connection from PC-A later in the lab. Because R1 is not part of the EIGRP domain and is not advertising the PC-A LAN, R2 does not know about the 192.168.1.0/24 network.

a. Configure a static default route on R2 that points to the R1 S0/0/0 interface IP address.

Step 6: 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 7: Verify basic network connectivity.
a. Ping from PC-A to the R2 S0/0/0 interface at IP address 10.1.1.2. Are the results successful?
Yes If the pings are not successful, troubleshoot the basic device configurations before continuing.

Note: PC-A should be able to ping external R2 interface S0/0/0 but is not able to ping any of the internal EIGRP network IP addresses on R2 and R3.

b. Ping from R2 to PC-C on the R3 LAN. Are the results successful?
Yes. If the pings are not successful, troubleshoot the basic device configurations before continuing.

Note: If you can ping from R2 to PC-C, you have demonstrated that the EIGRP 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 protocol-related problems.

Step 8: Configure a minimum password length.

Note: Passwords in this lab 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. Use the security passwords command to set a minimum password length of 10 characters.

Step 9: Configure the basic console and vty lines.

a. Configure a console password and enable login for router R1. For additional security, the exectimeout command causes the line to log out after 5 minutes of inactivity. The logging synchronous command prevents console messages from interrupting command entry.

Note: To avoid repetitive logins during this lab, the exec-timeout can be set to 0 0, which prevents it from expiring. However, this is not considered a good security practice.

b. Configure the password on the vty lines for router R1.

c. Repeat these configurations on both R2 and R3.

Step 10: Encrypt clear text passwords.
a. Use the service password-encryption command to encrypt the console, aux, and vty passwords.

b. Issue the show run command. Can you read the console, aux, and vty passwords? Why or why not?
No, the passwords are now encrypted

c. Repeat this configuration on both R2 and R3.

Step 11: Save the basic running configuration for all three routers.
Save the running configuration to the startup configuration from the privileged EXEC prompt.

Part 2: Configuring a Remote Access VPN

In Part 2 of this lab, you configure a remote access IPsec VPN. R2 is configured as an Easy VPN server using SDM, and the Cisco VPN client is configured on PC-A. The PC-A host simulates an employee connecting from home over the Internet. Router R1 simulates an Internet ISP router.

Task 1: Prepare R2 for SDM Access and Easy VPN Server Setup

Step 1: Configure the enable secret password and HTTP router access prior to starting SDM.
a. From the CLI, configure the enable secret password for use with SDM on R2.

b. Enable the HTTP server on R2.

c. Create an admin account on R2 with privilege level 15 for use with AAA.

Step 2: Access SDM and set command delivery preferences.
a. Run the SDM application or open a browser on PC-A and start SDM by entering the R2 S0/0/0 IP
address 10.1.1.2 in the address field.

b. Log in with no username and the enable secret password cisco12345.

c. In the Authentication Required dialog box, enter cisco12345 in the Password field and click Yes.

d. If the Cisco IOS IPS login dialog box displays, enter the enable secret password of cisco12345.

e. Select Edit > Preferences to configure SDM to allow you to preview the commands before sending them to the router. In the User Preferences window, check the Preview commands before delivering to router check box and click OK.

Task 2: Use the SDM VPN Wizard to Configure the Easy VPN Server

Step 1: Launch the Easy VPN server wizard and configure AAA services.
a. Click the Configure button at the top of the SDM home screen.

b. Click the VPN button under Tasks to view the VPN configuration page.

c. Select Easy VPN Server from the main VPN window, and then click Launch Easy VPN Server Wizard.

d. The Easy VPN Server wizard checks the router configuration to see if AAA is enabled. If not, the Enable AAA window displays. AAA must be enabled on the router before the Easy VPN Server configuration starts. Click Yes to continue with the configuration.

e. If prompted to deliver the configuration to the router, click Deliver.

f. In the Command Delivery Status window, click OK. When the message “AAA has been successfully enabled on the router” displays, click OK.

g. Now that AAA is enabled, you can start the Easy VPN Server wizard by clicking the Launch Easy VPN Server Wizard button. Read through the descriptions of the tasks that the wizard guides you through.
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How does the client receive the IPsec policies?
They are centrally managed and pushed to the client by the server.

How does the Easy VPN remote server configuration differ from the site-to-site?
Both configure IKE polices and IPsec transforms. The remote access server configures a virtual template interface and authentication, group policy lookup and user authentication, among others.

h. Click Next when you are finished answering the above questions.

Step 2: Configure the virtual tunnel interface and authentication
a. Select the interface on which the client connections terminate. Click the Unnumbered to radio button, and select the Serial0/0/0 interface from the pull-down menu.

b. Select Pre-shared Keys for the authentication type and click Next to continue.
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Step 3: Select the IKE proposal.
a. In the Internet Key Exchange (IKE) Proposals window, the default IKE proposal is used for R2.
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What is the encryption method used with the default IKE policy? 3DES
What is the hash algorithm used to ensure that the keys have not been tampered with? SHA_1

b. Click Next to accept the default IKE policy.

Note: Configurations on both sides of the tunnel must match exactly. However, the Cisco VPN client automatically selects the proper configuration for itself. Therefore, no IKE configuration is necessary on the client PC.

Step 4: Select the transform set.
a. In the Transform Set window, the default SDM default transform set is used. What is the ESP encryption method used with the default transform set? ESP_3DES
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b. Click Next to accept the default transform set.

Step 5: Specify group authorization and group policy lookup.
a. In the Group Authorization and Group Policy Lookup window, select the Local option because a RADIUS server is not available.

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b. Click Next to create a new AAA method list for the group policy lookup that uses the local router database.

Step 6: Configure User Authentication (XAuth)
a. In the User Authentication (XAuth) window, you can specify to store user information on an external server, such as a RADIUS server or a local database or both. Check the Enable User Authentication check box and accept the default of Local Only.

ccna-security-lab-c-optional-configuring-remote-access-vpn-server-client-7

Where does the router look for valid user account and passwords to authenticate remote VPN users when they attempt to log in? The local router user database. If the username is not locally defined on R2, user cannot log in.

b. Click the Add User Credentials button. In the User Accounts window, you can view currently defined users or add new users.

What is the name of the user currently defined, and what is the user privilege level?
admin, privilege level 15.

How was this user defined?
During the initial Cisco IOS CLI configuration

c. In the User Accounts window, click the Add button to add another user. Enter the username user01 with a password of user01pass, and select the check box for encrypting the password using the MD5 hash algorithm. Leave the privilege level at 1.

What is the range of privilege levels that can be set for a user? 0 through 15

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d. Click OK to accept the user01 entries, and then click OK to close the User Accounts window.
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e. In the User Authentication (XAuth) window, click Next to continue.

Step 7: Specify group authorization and user group policies.
a. In the Group Authorization and User Group Policies window, you must create at least one group policy for the VPN server.

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b. Click Add to create a group policy.

c. In the Add Group Policy window, enter VPN-Access as the name of this group. Enter a new preshared key of cisco12345 and then re-enter it.

d. Leave the Pool Information box checked. Enter a starting address of 192.168.2.101 , an ending address of 192.168.2.150, and a subnet mask of 255.255.255.0.

e. Enter 50 for the Maximum Connections Allowed.

f. Click OK to accept the entries.

g. An SDM warning message displays indicating that the IP addresses in the pool and the IP address of the Loopback0 interface are in the same subnet. Click Yes to confirm.

Why use an IP network for the VPN clients pool that is associated with a loopback interface?
R2 will advertise the entire loopback network 192.168.2.0/24 to other routers as one full subnet and not simply host routes for VPN clients. This significantly increases stability throughout the EIGRP routing domain. How does R3 route traffic to the VPN clients? R3 learns the subnet used by R2’s loopback interface as advertised through EIGRP. Therefore, R3 sends traffic destined for VPN clients to a next hop of R2.

h. When you return to the Group Authorization window, check the Configure Idle Timer check box and enter one hour (1 ). This disconnects idle users if there is no activity for one hour and allows others to connect. Click Next to continue.

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i. When the Cisco Tunneling Control Protocol (cTCP) window displays, do not enable cTCP. Click Next to continue.

Step 8: Review the configuration summary and deliver the commands.

a. Scroll through the commands that SDM will send to the router. Do not select the check box Test VPN connectivity. Click Finish.

b. If prompted to deliver the configuration to the router, click Deliver.
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c. In the Command Delivery Status window, click OK. How many commands were delivered? 44 with SDM 2.5

Step 9: Test the VPN server.

a. You are returned to the main VPN window with the Edit Easy VPN Server tab selected. Click the Test VPN Server button in the bottom right corner of the screen.

b. In the VPN Troubleshooting window, click the Start button.
Your screen should look similar to the one below. Click OK to close the information window. Click Close to exit the VPN Troubleshooting window.

ccna-security-lab-c-optional-configuring-remote-access-vpn-server-client-13

Task 3: Use the Cisco VPN Client to Test the Remote Access VPN
Step 1: (Optional) Install the Cisco VPN client.
If not already installed, install Cisco VPN client software on host PC-A. If you do not have the Cisco VPN client software, contact your instructor.

Instructor Notes: The version of the Cisco VPN Client used in this lab is 4.8.02.0010 for use with Windows XP. You must have a valid CCO account and service contract to download the file. Extract the .exe or .zip file and begin the installation. Accept the defaults as prompted. Click Finish when the VPN Client has been successfully installed. Click Yes to restart the computer for the configuration changes to take effect.

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Step 2: Configure PC-A as a VPN client to access the R2 VPN server.

a. Start the Cisco VPN client and select Connection Entries > New or click the New icon.

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b. Enter the following information to define the new connection entry. Click Save when you are finished. Connection Entry: VPN-R2

Note: The group authentication name and password are case-sensitive and must match the ones created on the VPN server.

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Step 3: Test access from PC-A without a VPN connection.
Open a command prompt on PC-A, and ping the PC-C IP address at 192.168.3.3 on the R3 LAN. Are the pings successful? Why or why not? The pings failed because PC-A still has an IP address (192.168.1.3) that is outside the EIGRP domain. PC-A cannot access the internal PC-C host in the EIGRP network 192.168.3.0/24 without an address within the EIGRP domain (from the VPN access group associated with the 192.168.2.0/24 network).

Note: After creating a VPN connection entry, you must activate it. Currently, the VPN tunnel is not up.

Step 4: Establish a VPN connection and login
a. Select the newly created connection VPN-R2 and click the Connect icon. You can also double-click the connection entry.

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b. Enter the username admin created previously on the VPN router, and enter the password cisco12345.

c. Click OK to continue. The VPN Client window minimizes to a lock icon in the tools tray of the taskbar. When the lock is closed, the VPN tunnel is up. When it is open, the VPN connection is down.

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Task 4: Verify the VPN Tunnel between the Client, Server, and Internal Network

Step 1: Check the VPN Client status.
Double-click the VPN lock icon to expand the VPN Client window.
What does it say about the connection status at the top of the window? Status: Connected

Step 2: Check the tunnel statistics
a. Select Status > Statistics to display the Tunnel Details tab.

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b. What is the Client IP address obtained from the VPN server? Answers will vary but can range from 192.168.2.101 through 192.168.2.150. The pool of addresses was defined in Task 2.

Note: Each time you disconnect and reconnect to the VPN server, you receive a new IP address until the limit is reached.

c. What is the VPN server address? 10.1.1.2

d. How many packets have been encrypted? Answers will vary

e. What is the encryption method being used? 168-bit 3-DES

f. What is the authentication being used? HMAC-SHA1

Step 3: Check the Cisco IOS messages on R2 when the tunnel is created.

Open the console connection for R2 and locate the message displayed indicating that the virtual interface came up when the VPN Client connection was made.

Step 4: Verify the VPN connection.

a. From the PC-A command prompt, issue the ipconfig /all command to see the network connections currently in use.

b. What is the configuration for the first local area connection?

c. What is the configuration for Local Area Connection 2?

Step 5: Test the access from the client with the VPN connection.
With the VPN connection from computer PC-A to router R2 activated, open a command prompt on PC-A and ping the PC-C IP address at 192.168.3.3 on the R3 LAN. Are the pings successful? Why or why not? The pings are now successful because PC-A has an IP address (192.168.2.104 in this case) that was assigned by the VPN server and is inside the EIGRP domain. PC-A can access the internal PC-C host in the EIGRP network 192.168.3.0/24 now because it is in the VPN access group associated with the 192.168.2.0/24 network.

Step 6: Telnet to R2 from PC-A.
a. From the PC-A command prompt, telnet to R2 at the Lo0 IP address 192.168.2.1 Log in as admin with the password cisco12345.
What is the router command prompt and why is this?
Because the user admin was defined with privilege level 15 (the highest), the prompt defaults to privileged EXEC mode (R2#).

b. Issue the show run command to view the various commands generated by SDM to configure the VPN server.

c. Issue the show users command to see the connections to router R2. What connections are present? The console connection and the vty connection from PC-A by the user admin.

d. Exit the Telnet session with the quit or exit command.

e. Right-click the VPN Client icon in the tools tray and select Disconnect, or click the VPN-R2 connection and click the Disconnect icon.

f. Open the VPN client connection again but this time log in as user01 with the password user01pass.

g. Telnet from PC-A to R2 again at the Lo0 IP address 192.168.2.1. Log in as user01 with the password user01pass. What is the router command prompt and why is this? Because user user01 was defined with privilege level 1 (the lowest), the prompt defaults to user EXEC mode (R2>).

Note: You could have telnetted to R2 from the first VPN session and logged in as user01, but this process demonstrates the VPN disconnect and connect process and verifies that user01 is set up properly.

Task 5: Reflection
Why is VPN a good option for remote users?
Answers will vary but should include: It is a flexible technology that is widely supported by equipment vendors. Service is commonly available from ISPs. A VPN server can be set up independent of the ISP if desired. VPN provides easy and secure access to internal LAN resources for remote workers and business partners. Any authorized person with an Internet connection can access internal resources as if they were on the local LAN.

Router Interface Summary Table

Router Interface Summary
Router Model Ethernet Interface
#1
Ethernet Interface
#2
Serial Interface
#1
Serial Interface
#2
1700 Fast Ethernet 0
(Fa0)
Fast Ethernet 1
(Fa1)
Serial 0 (S0) Serial 1 (S1)
1800 Fast Ethernet 0/0
(Fa0/0)
Fast Ethernet 0/1
(Fa0/1)
Serial 0/0/0
(S0/0/0)
Serial 0/0/1
(S0/0/1)
2600 Fast Ethernet 0/0
(Fa0/0)
Fast Ethernet 0/1
(Fa0/1)
Serial 0/0 (S0/0) Serial 0/1 (S0/1)
2800 Fast Ethernet 0/0
(Fa0/0)
Fast Ethernet 0/1
(Fa0/1)
Serial 0/0/0
(S0/0/0)
Serial 0/0/1
(S0/0/1)
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. Rather than list all 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 might contain one. For example, for 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

Router R1 after Part 2

Router R2 after Part 2

Router R3 after Part 2

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