Command syntax

Convention	Description
`boldface`	Boldface text indicates commands and keywords that you enter literally as shown.
`italics`	Italic text indicates arguments for which you supply values.
`[x]`	Square brackets indicate an optional element (keyword or argument).
`{x}`	Braces indicate a required element (keyword or argument).
`[x { y \\| z }]`	Braces and vertical lines within square brackets indicate a required choice within an optional element. Spaces are used to clearly delineate parts of the command.

Hotkeys and shortcuts

Keystroke	Description
`Tab`	Completes a partial command name entry.
`Backspace`	Erases the character to the left of the cursor.
`Ctrl+D`	Erases the character at the cursor.
`Ctrl+K`	Erases all characters from the cursor to the end of the command line.
`Esc D`	Erases all characters from the cursor to the end of the word.
`Ctrl+U` or `Ctrl+X`	Erases all characters from the cursor back to the beginning of the command line.
`Ctrl+W`	Erases the word to the left of the cursor.
`Ctrl+A`	Moves the cursor to the beginning of the line.
`Left Arrow` or `Ctrl+B`	Moves the cursor one character to the left.
`Esc B`	Moves the cursor back one word to the left.
`Esc F`	Moves the cursor forward one word to the right.
`Right Arrow` or `Ctrl+F`	Moves the cursor one character to the right.
`Ctrl+E`	Moves the cursor to the end of command line.
`Up Arrow` or `Ctrl+P`	Recalls the previous command in the history buffer, beginning with the most recent command.
`Down Arrow` or `Ctrl+N`	Goes to the next line in the history buffer.
`Ctrl+R` or `Ctrl+I` or `Ctrl+L`	Redisplays the system prompt and command line after a console message is received.

Note: While the Delete key typically deletes the character to the right of the prompt, the IOS command structure does not recognize the Delete key.

--More-- mode prompt.

Keystroke	Description
`Enter`	Displays the next line.
`Space` or `y`	Displays the next screen.
Any other key	Ends the display string, returning to previous prompt.

Commands used to exit from an operation.

Keystroke	Description
`Ctrl-C`	When in any configuration mode, ends the configuration mode and returns to privileged EXEC mode. When in setup mode, aborts back to the command prompt.
`Ctrl-Z`	When in any configuration mode, ends the configuration mode and returns to privileged EXEC mode.
`Ctrl-Shift-6`	All-purpose break sequence used to abort DNS lookups, traceroutes, pings, and to interrupt an IOS process.

Show

Command	Used to
`show running-config`	Verify the current configuration and settings.
`show interfaces`	Verify the interface status and see if there are any error messages.
`show ip interface`	Verify the Layer 3 information of an interface.
`show arp`	Verify the list of known hosts on the local Ethernet LANs.
`show ip route`	Verify the Layer 3 routing information.
`show protocols`	Verify which protocols are operational.
`show version`	Verify the memory, interfaces, and licenses of the device.

Basic configuration

Hostname.

Router(config)# hostname hostname

Secure privileged EXEC mode.

Router(config)# enable secret password
Switch(config)# enable secret class

Secure user EXEC mode over console (serial).

Router(config)# line console 0
Router(config-line)# password password
Router(config-line)# login

Secure remote Telnet / SSH access.

Router(config-line)# line vty 0 4
Router(config-line)# password password
Router(config-line)# login
Router(config-line)# transport input {ssh | telnet | none | all}
Router(config-line)# transport input ssh telnet

Configure SSH.

Switch# show ip ssh
Switch# configure terminal
Switch(config)# ip domain-name cisco.com
Switch(config)# crypto key generate rsa
Switch(config)# username admin secret ccna
Switch(config-line)# line vty 0 15
Switch(config-line)# transport input ssh
Switch(config-line)# login local
Switch(config-line)# exit
Switch(config)# ip ssh version 2
Switch(config)# exit

Secure all passwords in the config file.

Router(config-line)# exit
Router(config)# service password-encryption

Provide legal notification.

Router(config)# banner motd delimiter message delimiter
Router(config)# banner motd # Legal message here #
Router(config)# banner motd #
Enter TEXT message. End with a new line and the # ***********************************************  WARNING: Unauthorized access is prohibited! *********************************************** #
Router(config)#

Save the configuration.

Router(config)# copy running-config startup-config

Management IP address for a switch.

Switch# configure terminal
Switch(config)# interface vlan 1
Switch(config-if)# ip address 192.168.1.20 255.255.255.0
Switch(config-if)# no shutdown
Switch(config-if)# exit
Switch(config)# ip default-gateway 192.168.1.1

Connect over serial console

Using picocom. You can find the name of the TTY with journalctl.

picocom -b 115200 /dev/ttyUSB3

Exit with ctrl-a ctrl-x.

Upload a file in ROMMON

Example using an AP.

Requirements:

TFTP server IP address 192.168.0.2
IOS image ap3g2-k9w8-mx.153-3.JD.tar
Serial console connection

The easiest way is to connect the computer to the device via POE inyector.

Create a TFTP server to upload files

Using tftp-hpa.

Leave the files at /srv/tftp/
Start the service systemctl start tftpd
Allow TFTP through the firewall. TBD

Delete corrupt images

ap: del /force /recursive ap3g2-k9w8-mx.153-3.JD

Upload file

Configure the AP:

ap: set IP_ADDR 192.168.0.3
ap: set NETMASK 255.255.255.0
ap: set DEFAULT_ROUTER 192.168.0.1
ap: tftp_init
ap: ether_init

Download the file from the TFTP server to the AP and extract it to flash.

ap: tar -xtract tftp://192.168.0.2/ap3g2-k9w8-tar.153-3.JD.tar flash:

You can check for connections with tcpdump -ennqi enp2s0 port 69.

And you can check connectivity with arping 192.168.0.3 -I enp2s0.

Remove the variables (optional)

ap: unset IP_ADDR
ap: unset NETMASK
ap: unset DEFAULT_ROUTER

Boot

ap: boot

You can also set the boot image if there are others:

set BOOT flash:ap3g2-k9w8-mx.153-3.JD/ap3g2-k9w8-xx.153-3.JD