IOS Terminal Access Methodologies

To gain access to an EXEC session to an IOS for configuration and administration, you can use the following methods:

  • Console: Out-of-band CLI access via a rollover cable connected to the COM port of your terminal PC.
  • Auxiliary: Out-of-band CLI access via rollover cable connected to external modem for remote access.
  • Telnet: In-band CLI access to an active IP address on the device’s vty lines using the Telnet protocol. Requires configuration.
  • SSH: Secure encrypted in-band CLI access to an active IP address using the SSH pro­tocol. Requires configuration.
  • HTTP/HTTPS:In-band GUI access to an active IP address using the HTTP or HTTPS protocol. Requires configuration.

IOS Terminal

IOS Boot Processes

To solidify the startup process, the following is a recap of the stages of the bootup, any fallback procedures, and the memory locations involved:

  1. POST located in ROM tests hardware.
  2. Bootstrap located in ROM looks at boot field in configuration register to locate IOS. 0x2 100 boots to ROMmon located in ROM.
  3. 0x2 101 to 0x210F prompt bootstrap to parse startup-config in NVRAM for any boot system commands. If there are any commands, do what they say.
  4. If no boot system commands, load first file in flash. If no file in flash, TFTP boot. If no IOS file found from TFTP, go to ROMmon mode.
  5. After IOS is loaded, check configuration register. If 0x2 142, ignore startup-config in NVRAM. If 0x2 102, load startup-config in NVRAM. If no startup-config, TFTP autoinstall. If no TFTP autoinstall configuration found, enter Setup Mode.

 

 IOS Navigation Modes 
ModePromptDescription
User EXECRouter>Basic troubleshooting and verification
Privileged EXECRouter#All available commands, including delete,

clear, erase, configure, copy, andreload

Global configurationRouter(config)#Configurations that apply to the entire device
Line configurationRouter(config-line)#Configurations that apply to the terminal lines

into a device

Interface configurationRouter(config-if)#Configurations that apply to interfaces
Subinterface configurationRouter(config-subif)#Configurations that apply to logical extensions of

the physical interface

Router configurationRouter(config-router)# Configurations that apply to routing protocols
VLAN configurationSwitch(vlan)#              VLAN-specific configurations in switches

 

Terminal Editing Keys

Cisco IOS Terminal Editing Keystrokes

Keystroke                               Function

Ctrl+A                                          Moves the cursor to the beginning of the command line.

Ctrl+E                                          Moves the cursor to the end of the command line.

Ctrl+B                                          Moves the cursor back one character.

Ctrl+F                                          Moves the cursor forward one character.

Esc+B                                          Moves the cursor back one word.

Esc+F                                          Moves the cursor forward one word.

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