> | Lab 4.4.2 Remote telnet access Estimated time: 30 min. Objectives: Use the telnet command to remotely access other routers. Verify that the application layer between source and destination is working properly. Retrieve information about remote routers using router show commands. Retrieve CDP information from routers not directly connected to you. Background: In this lab you will work with the telnet (remote terminal) utility to access routers remotely. You will telnet from your “local” router into another “remote” router in order to simulate being at the console on the remote router. This procedure will use your router’s Telnet client software and the remote router’s Telnet server software. You can also “telnet” from your workstation as a client into any router connected to your network. In addition, you can telnet into Cisco Ethernet Switches. You can not, however, telnet from a router or a workstation into another Windows client or server since the Windows operating system does not support the Telnet server daemon. A daemon (pronounced demon) is a UNIX term that refers to a program running on a server that accepts requests for services. You can decide whether to allow others to telnet into your router or you may require a password for incoming Telnet sessions. Telnet connections are referred to as line VTY 0 4 in the router configuration file. The router can support up to 5 simultaneous incoming Telnet sessions (0 thru 4). Telnet is a good troubleshooting tool since it can be used to access remote routers to gather information when there are problems or when configuration changes are necessary. It also tests from the OSI Application layer of the source host down through its Physical layer and then across the network and back up the protocol stack of the destination router. This allows you to verify the Application layer software between source and destination hosts. You will use telnet to access a remote router and use show cdp neighbors to gather information from routers that are not directly connected to you. Tools / Preparation: Prior to starting the lab you will need to connect a PC w/ HyperTerminal to a router using the router’s console Interface with a roll-over cable. Work individually or in teams. Before beginning this lab you may want to read the Networking Academy First Year Companion Guide, Chapter 13. You should also review On-line Chapter 4. Be familiar with the following commands: telnet ? telnet router-name or IP show CDP neighbors show interface show protocols enable show running-config show startup-config Resources Required: PC with Windows operating system and HyperTerminal installed Router connected to the PC with a console roll-over cable At least 3 routers interconnected via Ethernet or WAN simulation cables Websites Sites Resources: Routing basics General information on routers 2500 series routers 1600 series routers Terms and acronyms IP routing protocol IOS command summary Beginning IP for new users Notes: Step 1 - Log on to the router. Task: Connect to the router and login. Enter the password cisco if prompted. 1. What prompt did the router display? Step 2 - Enter the help facility. Task: Enter telnet ? at the router prompt Explanation: The router will respond with help with the telnet command. 2. What did the router reply with? Step 3 - Telnet from router to router. Task: Enter telnet router-name or IP address at the router prompt to connect to a remote router. Explanation: The router will prompt you for User Access Verification of the router you remotely access. Enter the password cisco 3. What prompt did the router display? Step 4 - Show interfaces. Task: Enter show interface at the router prompt. Explanation: The router will respond with information about its interfaces. 4. List the interfaces, their IP address and subnet mask.
> Interface | IP Address | Subnet mask
> Step 5 - Show protocol. Task: Enter show protocols at the router prompt. Explanation: This command shows the global and interface-specific status of any configured layer 3 protocols. 5. Fill in the table below with the information that was generated by the router you are remotely accessing.
> Interface | Is there a Carrier Detect signal | Are the keepalive messages being received?
Step 6 - Enter privileged mode while connected to the remote router with telnet. Task: a. Enter enable at the command prompt. b. Enter the password of class Explanation: You use the enable command to enter privileged EXEC mode 6. What prompt did the router display? What mode are you in? Step 7 - Show information about the active configuration file of the remote router. Task: Enter show running-config at the remote router prompt. Explanation: The remote router will display information on how it is currently configured. 7. What file are you viewing on the remote router? Where is this file stored? Step 8 - Show information about the backup configuration file of the remote router. Task: Enter show startup-config at the router prompt. Explanation: The remote router will display information on the backup configuration file stored in NVRAM. 8. What file are you viewing on the remote router? Where is this file stored? 9. What information do you see concerning the line VTY connections? Step 9 - Display the CDP updates received on the local router. Task: Enter show cdp neighbors command at the router prompt. Explanation: The router will respond with information about its neighbors that have CDP enabled. 10. List all device IDs that are connected to the remote router you have a Telnet session with.