From LedHed's Wiki
Cisco uses a proprietary OS called 'IOS'
Contents
Logging In
In order to make changes to the IOS configurations you need to login as an Enabled user, to do this type:
enable
You will then be prompted for a password (assuming a password has been set for this account).
Basic Commands
Show the currently running configuration
show running-config
or in IOS Shorthand
sh run
Configure an interface
config term interface fa0/1
Delete a line from a config
Prepend 'no' to a line to delete it. Example: To delete
switchport mode access
issue this command
no switchport mode access
Save a config
Copy running config to startup config (RAM) to (NVRAM)
copy run start
Reset a port
config term int fa0/1 shutdown no shutdown exit
Show MAC Table
show mac-address-table
or
sh mac-address-table
CCNA Cheat Sheet
http://www.cb-net.co.uk/networking-articles/26-cisco-articles/56-ccna-ciso-router-cram-sheet