Cisco IOS Software

Connection to a router, boot-up an various options including basic IOS commands, modes (user mode / privilege mode) etc

Informational

• Console cable is a "roll over" cable. The pin-outs are 'rolled over'

  • Pin 1 --> Pin 8

  • Pin 2 --> Pin 7

  • Pin 3 --> Pin 6

  • Pin 4 --> Pin 5

  • Pin 5 --> Pin 4

  • Pin 6 --> Pin 3

  • Pin 7 --> Pin 2

  • Pin 8 --> Pin 1

• Terminal Emulation

  • Hyper-terminal - Limited (Comes with Windows)

  • Putty - only runs on Windows

  • Terra Term - Free

  • SecureCRT - Windows and MacOS

  • iTerm

  • Royal TSX

Modes

• User Mode: Router>

  • view only mode

  • limited set of commands

  • basic monitoring commands

• Privilege Mode (Enable Mode): Router#

  • allows a lot more show commands

  • allow debugging

  • used to configure the device

• Global Config Mode: Router#(config)

  • change global parameters

  • MOTD (message of the day) - should be a legal entity. You can use any delimiter like hash (#) , a letter like 'c' etc and have to end with the same delimiter.

• Line Mode - remember to use the 'login' parameter to use the password feature

  • console (console)

  • vty 0 4 (Used for telnet and ssh access)

    • login

    • password cisco

    • input transport telnet ssh

Useful Shortcuts

• Other useful commands

  • Ctrl-U = deletes an entire line

  • Ctrl-C = cancels the command

  • Ctrl+Shift 6 x = breaks a command (like issue with domain lookup - arrgghhhhhhhhh)

Managing Cisco IOS Configuration

• Running Config and Startup Config

  • copy run start (from RAM to NVRAM - overwrites the NVRAM config)

  • copy start run (merges the NVRAM with the RAM config)

• show start run | b vty ---- b = begin

  • line vty 0 4

  • login

  • !

  • end

• #config replace nvram:startup (replaces the config)

• #erase startup-config

• #copy run tftp://192.168.1.1/<config_name>

  • copy run tftp to copy start tftp = override or replacement

  • copy tftp to running config = merge

  • copy tftp replace = will replace the configuration file

Storing Files in Flash

• show flash

  • copy running-config flash:/run1.cfg

    • more flash:run1.cfg will show the contents of the config file

Terminal Length & No IP Domain Lookup

When you do a show run, by default the config is restricted to a certain amount of lines (24) and it will then give out the --more-- command and then press spacebar and the next 24 lines will show etc etc

A tip is to use the command # terminal length 0, which shows the ENTIRE config in one go (good if you have long configurations etc)

Another tip is to use #no ip domain lookup when the router takes a long time to time out after trying to resolve a mistake you typed into a domain name!!

Basic Device Security

• (config)#service password encryption

  • not very secure as it encrypts enable password with a type 7

• (config)#enable secret CISCO

  • will see a 5 (md5) in front of encrypted password.

If you have both "enable password" and "enable secret" configured - the IOS will only use the "enable secret" password and ignore the other

LAB

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