CCNA1 Command Line Reference

Break Keys

  • Ctrl-C: Ends configuration mode -> PrivEXEC; aborts to command prompt in setup mode.
  • Ctrl-Z: Ends configuration mode -> PrivEXEC

  • Ctrl-Shift-6: Interrupts command midstream

  • Ctrl-R: Redisplays line

Modes

enable                # Enters PrivEXEC
disable               # Exits PrivEXEC -> UserEXEC

configure terminal    # Enters Global Configuration Mode (GCM)
end                   # Exits into PrivExec
exit                  # Exits into current -> previous mode

Basic Commands

Configuration Status

show running-config   # Shows current configuration in RAM
show startup-config   # Shows configuration stored in NVRAM

Save Configuration

copy running-config startup-config
cop r s               # Shortcut

Change Hostname

hostname <device_host_name>

Clock

show clock

clock set ?
clock set hh:mm:ss dd MON yyyy

Configure Passwords

Secure Privilege Exec Mode

enable password <password>    # Password in clear text
enable secret <password>      # Uses MD5 hash encryption; overrides password above

Secure Console Line

line console 0                  # Enters first console interface
password <password>
login                                 # Enables userEXEC access

Secure VTY (Terminal) Lines

line vty 0 15
password <password>
login

Encrypt Passwords

service password-encryption     # Applies weak encryption

Configure Banner MOTD

banner motd # <message> #
  • Delimiter (# above) could be any character that is not in the message.

Switch Virtual Interface Configuration

interface vlan 1
ip address <ip-address> <subnet-mask>
no shutdown

Display Interface Information

show interfaces
show ip interface brief
show ip route

show interface serial 0/0/0
show interface GigabitEthernet 0/0

show interface s0/0/0         # shortcut
show interface g0/0           # shortcut

Configure Router Interface (Lab 6.4.3.3)

interface gigabitethernet 0/0
ip address 192.168.10.1 255.255.255.0
no shutdown

Configure an Interface Description

description <description>

Configure IPv6 Addressing on the Router

Enable router to forward IPv6 packets

ipv6 unicast-routing

Configure IPv6 addressing

ipv6 address <ipv6 address>/<prefix>
ipv6 address <ipv6 address> link-local
no shutdown

Basic Security Practices

service password-encryption
security password min-length <num chars>
login block-for <seconds> attempts <num attempts> within <seconds>
line vty 0 4
exec-timeout 10
end

Configure SSH

  • Requires hostname and domain name configured.
hostname <host_name>
ip domain-name <domain.com>
crypto key generate rsa
username <username> secret <password>
line vty 0 15
login local
transport input ssh
transport input telnet ssh        # Telnet and SSH

Remove Username

no username <username>

Miscellaneous

Disable DNS lookup

  • Prevents router from translating typos into an IP address as if they were hostnames.
no ip domain-lookup

Shutdown Multiple Interfaces at a time

interface range f0/1-4, f0/7-24, g0/1-2
shutdown
end

Show Commands

show arp
show flash
show ip route
show interfaces
show ip interface brief
show protocols
show users              # Show connected users
show version
show run | i username           # Shows list of usernames

Debugging

debug ip icmp
undebug all
terminal monitor            # Show log messages through SSH
terminal no monitor         # Disable display of log messages through SSH

Cisco Discovery Protocol CDP

show cdp neighbors
show cdp neighbors detail   # Shows IP addresses of neighbouring Cisco devices

no cdp run                  # Disables CDP function - should be disabled for user-facing devices

Backup Configuration using TFTP

copy startup-config tftp:
copy flash tftp:

Flash

show flash
copy startup-config flash

TFTP

copy startup-config tftp:
copy flash tftp:

Connecting to SSH in Cisco Packet Tracer CMD Line

ssh -l <username> <target>

Terminal Configuration Settings to Access Console

  • Bits per second: 9600
  • Data bits: 8
  • Parity: None
  • Stop bits: 1
  • Flow control: None