This is the master list of some of the many Cisco IOS Commands that go with the CCNA track. This list also talks about what each command does in brief detail. You may also find that some commands may or may not be used for a CCNA level but offer some important information. If you don’t know what a command does or understand it, I would look at Cisco documentation.
Since this is a pretty big list of commands you can see the links to move to the different sections within this page. Enjoy!
Set a password for console access
Set a Password for virtual terminal (telnet) access
Set a password for auxiliary (modem) access
Setting up the Router
Processes and Statistics
This command “enable”will get you in privileged mode in the router or switch.
This command “disable” will put you back to the user mode in the router or switch.
Router(config)#enable password knowing
This will put a unencrypted password on the privileged mode (in this example the password would be “knowing”)
Router(config)#enable secret knowing
This command will put an encrypted password on the privileged mode (in this example the password would be “knowing”)
Router(config)#line console 0 Router(config-line)#login % Login disabled on line 0, until 'password' is set Router(config-line)#password allknowing
This sets the password as “allknowing” when accessed by the consolde line in a router or switch.
Router(config)#line vty 0 4 Router(config-line)#login % Login disabled on line 66, until 'password' is set % Login disabled on line 67, until 'password' is set % Login disabled on line 68, until 'password' is set % Login disabled on line 69, until 'password' is set % Login disabled on line 70, until 'password' is set Router(config-line)#password knowingall
Remember you must have a password on telnet to access the router or switch with a telnet session otherwise the router or switch will close the session immediately. This sets the password as “knowingall”
Router(config)#line aux 0 Router(config-line)#login Router(config-line)#password all
This sets the password as “all” when accessed via the auxiliary port.
Router#show running-config Building configuration... <output omitted="">
This command “show running-config” shows the details of the running configuration file in RAM.
This command “show startup-config” shows the details of the startup configuration file in NVRAM (If there is one saved)
Router#setup --- System Configuration Dialog --- Continue with configuration dialog? [yes/no]:
This command will start the automatic setup process, (The same as when you first boot the router)
This command “configure terminal” is used to execute configuration commands from the terminal.
This command “configure memory” is used to execute configuration commands stored in NVRAM.
This command “configure network” is used to retrieve configuration from a TFTP server.
Router#copy startup-config running-config
This command “copy startup-config running-config” will copy the startup configuration file to the running configuration file.
Router#copy running-config startup-config
This command “copy running-config startup-config” will copy the running configuration fiel to the startup configuration file.
Router(config)#boot system flash
This command “boot system flash” will tell the router which IOS file in flash to boot from.
Router(config)#boot system tftp
This command “boot system tftp” will tell the router which IOS file on the TFTP server to boot from.
Router(config)#boot system rom
This command “boot system rom” will tell the router to boot from ROM at next boot.
Router#copy flash tftp:
This command “copy flash tftp:” will copy the flash to a TFTP server.
Router#copy tftp flash:
This command “copy tftp flash:” will restore flash from a TFTP server.
Router#copy running-config tftp
This command “copy running-config tftp” will copy the current running configuration file to a TFTP server.
Router#copy tftp running-config
This command “copy tftp running-config” will restore the running configuration file from a TFTP server.
The command “no shutdown” will enable the interfaces on the router
The command “reload” will restart the router.
The command “show version” displays the Cisco IOS version, uptime, of the router, how the router started, where the system was loaded from, along with the configuration register.
The command “show clock” will display the date and time.
The command “show history” will display the past commands that you entered earlier.
This command “show debug” will show all debugging that is currently enabled.
Router#no debug all
The command “no debug all” turns off all possible debugging.
This command “show users” will show users that are connected to the router
This command “show protocols” displays which protocols are configured.
Router(config)#banner motd # Enter TEXT message.End with the character '#'.
The command “banner motd” will set or change the banner. (The “#” symbol at the end is a custom symbol the user uses)
The command “hostname” is used to configure the hostname of the router (for this example the router’s hostname is “R1”)
The command “clear counters” will clear the connection counters.
The command “show processes” shows the active processes running on the router.
Router#show processes cpu
The command “show processes cpu” shows CPU statistics.
The command “show memory” shows memory statistics.
The command “show flash” describes the flash memory and displays the size of the files and the amount of free flash memory.
The command “show buffers” displays the stats for the router buffer pools.
The command “show stacks” shows the reason for last reboot, and monitors the stack use of the processes and interrupts routines.
Router#show cdp neighbors
Shows directly connected neighbors.
Router#show cdp neighbors
Shows and displays more information about the neighbor device.
Router#show cdp interface
Shows which interfaces are running CDP.
Router#show cdp interface fastEthernet 0/1 Vlan1 is administratively down, line protocol is down Sending CDP packets every 60 seconds Holdtime is 180 seconds FastEthernet0/0 is up, line protocol is down Sending CDP packets every 60 seconds Holdtime is 180 seconds FastEthernet0/1 is administratively down, line protocol is down Sending CDP packets every 60 seconds Holdtime is 180 seconds
Shows CDP information on a specific interface.
FastEthernet0/1 is administratively down, line protocol is down Sending CDP packets every 60 seconds Holdtime is 180 seconds
Router#show cdp entry ? * all CDP neighbor entries WORD Name of CDP neighbor entry
Shows CDP neighbor detail based on the name of that device and or all CDP entries.
Router(config)#cdp timer 160
Change how often CDP information is sent. (updates) (This example is 160 seconds this can be any number the default is 60)
Router(config)#cdp holdtime 240
Change how long to wait before removing CDP information. (neighbor) (This example is 240 seconds this can be any number the default is 180)
Router(config-if)#no cdp enable
Turns off CDP on a specific interface.
Turns on CDP on a specific interface.
Turns on CDP globally. (On by default)
Router(config)#no cdp run
Turns off CDP globally.
R1#show controllers ? Async Async UART internal info Async Async interface E1 E1 controller internal state FastEthernet FastEthernet IEEE 802.3 J1 J1 controller internal state Serial Serial T1 T1 controller internal state T3 T3 controller internal state XTagATM Extended Tag ATM interface vsi VSI information | Output modifiers <cr>
To find out if the connected serial interface is DCE or DTE?
R1#show controllers serial 0/1 Interface Serial0/1 Hardware is GT96K DCE 530, clock rate 2000000 idb at 0x65F84D48, driver data structure at 0x65F8C454 wic_info 0x65F8CA80 Physical Port 0, SCC Num 0 <Output Omitted>
To configure the clock rate on serial interfaces
R1#config t Enter configuration commands, one per line. End with CNTL/Z. R1(config)#interface serial 0/1 R1(config-if)#clock rate 64000
To set the bandwidth (This is not the physical bandwidth, mainly for routing protocol calculation)
That’s the list! Like before these are the most common and are usually used in the CCNA area when troubleshooting. If you want to find more information check out Cisco documentation and like always I hope this was informative and if you have an idea on the next topic that deals with ICND1 or ICND2 let me know.
- Configure IPS (Intrusion Prevention System) via SDM (ciscoskills.net)
- Configuring SSH (ciscoskills.net)
- Cisco IOS Routers: Auto Secure (systemstechblog.wordpress.com)
- Which sequence does a router follow during startup (wiki.answers.com)
- Configure Cisco SDM (ciscoskills.net)
- Configuring Zone Based Firewalls via SDM (ciscoskills.net)