IOS commands
Cisco IOS organizes configuration into a hierarchy of modes. Privileged EXEC mode (indicated by #) is the entry point for viewing device state and entering configuration. Running configure terminal drops you into global configuration mode, where device-wide settings like hostname and routing protocols live. From global config, you enter sub-modes to configure specific resources. Interface configuration mode controls physical and logical ports, where you set properties like speed, IP addresses, and shutdown state. Line configuration mode controls the access lines used to connect to the device, including the console port, VTY (SSH/Telnet), and AUX port. Use exit to move up one level and end to return directly to privileged EXEC.
- Privileged EXEC (
#): view and manage device state, enter configuration - Global configuration (
(config)#): device-wide settings: hostname, routing, AAA, VLANs - Interface configuration (
(config-if)#): per-port settings: IP, speed, shutdown state - Line configuration (
(config-line)#): console, VTY, and AUX access settings - Router configuration (
(config-router)#): routing protocol settings: OSPF, EIGRP, BGP
Configuration commands
| Command | Mode | Description |
|---|---|---|
line console 0 | Global config | Enters line config mode for the physical console port |
login | Line config | Requires password authentication on the line |
password password | Line config | Sets the plain-text password for the line |
interface type port-number | Global config | Enters interface config mode for the specified port |
speed value | Interface config | Hard-sets interface speed; disables autonegotiation |
hostname name | Global config | Sets the device hostname |
exit | Any | Moves up one level in the config hierarchy |
end | Any | Returns directly to privileged EXEC from any config mode |
Ctrl+Z | Any | Returns directly to privileged EXEC from any config mode |
EXEC commands
EXEC mode is the command-line layer above configuration. User EXEC mode (indicated by >) provides limited read-only access and is the first mode you reach after connecting. Running enable elevates you to Privileged EXEC mode (indicated by #), where you can view device state, manage configuration files, reload the device, and control the session. Unlike configuration commands, EXEC commands do not modify the running configuration.
| Command | Mode | Description |
|---|---|---|
no debug all | Privileged EXEC | Disables all active debug sessions |
undebug all | Privileged EXEC | Alias for no debug all |
reload | Privileged EXEC | Reboots the device |
copy running-config startup-config | Privileged EXEC | Saves running config to NVRAM |
copy startup-config running-config | Privileged EXEC | Loads startup config into running config |
show running-config | Privileged EXEC | Displays the current running configuration |
write erase | Privileged EXEC | Erases the startup configuration from NVRAM |
erase startup-config | Privileged EXEC | Alias for write erase |
erase nvram: | Privileged EXEC | Erases all NVRAM contents |
quit | Any EXEC | Closes the current session |
show startup-config | Privileged EXEC | Displays the saved startup configuration |
enable | User EXEC | Enters Privileged EXEC mode |
disable | Privileged EXEC | Returns to User EXEC mode |
configure terminal | Privileged EXEC | Enters global configuration mode |
show mac address-table | Privileged EXEC | Displays the MAC address table (switches only) |