1. Router Configuration PJC CCNA Semester 2 Ver. 3.0 by William Kelly

2. Command Modes • The router has two main modes: user exec mode for monitoring and user privileged exec mode for monitoring and changing the configuration • Enter the privileged mode with the enable command • Enter the global configuration mode with the configure command • To configure from the terminal use “terminal” • Enter the specific mode • Typing exit leaves a specific config mode and the Ctl-Z key combination leaves the global config mode entirely and returns to the privileged mode prompt Note: Understand how the prompts change at each level

3. Router Startup Modes • ROM Monitor Mode – used for password recovery or system failure recovery • Setup – used for initial setup • RXBoot – limited set of commands to enable a new IOS to be loaded from a tftp server

4. Router Configuration Commands • configure terminal • configure memory • copy tftp running-config • show running-config • copy running-config startup-config • copy running-config tftp • show startup-config • erase startup-config

5. Configuring the Router Name • Router(config)# hostname moscow moscow(config)#

6. Protecting Router Passwords • The enable secret uses md5 one way strong encryption (This method can’t currently be unencrypted) • Weak encryption can be used with the following command: Router(config)# service password encryption

7. Information from show Commands • Be aware of the information each show command gives you if you needed to choose the correct output from a list

8. Configuring Serial and Ethernet Interfaces • Serial Interface Router(config)# interface serial 1/0Router(config-if)# 192.168.1.3 255.255.255.0Router(config-if)# clockrate 56000 Router(config-if)# no shutdown • Ethernet Interface Router(config)# interface ethernet 1/0 Router(config-if)# 192.168.0.1 255.255.255.0 Router(config-if)# no shutdown

9. Executing Router Changes • Interfaces are powered on by the “no shutdown” command • A “no” in front of a command usually reverses the command • Contents of NVRAM are managed by the erase start, copy run start, and show start commands

10. Configuration Standards, Backup, and Documentation • Organization wide standards aids in maintaining configurations • Standards help reduce complexity, downtime, and exposure to unusual events that impact the network • Router configurations should be backed up to disk or remote servers (tftp servers)

11. Interface Descriptions • Setting an Interface Description Router(config)# interface ethernet 0 Router(config-if)# description crystal peak secure LAN Router(config-if)# exit

12. Login Banners • Login banners display messages at login • Anyone can see a login banner so unwanted visitors should be warned that it is illegal to attempt to access the system Router(config)# banner login # You are attempting to access SKYNET. This connection is being traced and attempts at unauthorized entry will be referred to our HK Investigation Division!#

13. Message of the Day (MOTD) • MOTD can only been seen by users who have successfully logged in Router(config)# banner motd # You are logged into SKYNET. Have a nice day!#

14. Host Name Resolution • A host table allows names to be translated to ip addresses • Host names are only meaningful on the router on which they are configured (they are not the same as DNS) Router(config)# ip host moscow 172.16.0.4 Router(config)# ip host perm 142.16.1.5

15. Password Recovery • The technique varies from router to router but the general points are as follows: • The config-register is recorded is possible from the show version command • The normal boot prompt is interrupted (Ctrl-break) • The configuration register is changed perhaps from 0x2102 to 0x42 using o/r 0x42 after interrupted the boot • The router is rebooted using i • The password is bypassed • A new password is entered • The config register is reset with config-register 0x2102 at global config • The router is rebooted to test the password change