Cisco IOS

Cisco Internetwork Operating System (IOS) is a family of network operating systems used on many Cisco Systems routers and current Cisco network switches

Basic commands

• show version or sh ver (includes uptime information)
• show clock

• debug
• show platform
• show cdp neighbors

Interfaces

• show interface
  • show interface Gi1/0/1
• show interface link
• show interface status (enable or disabled)
  • show interface status err
• show interface stats
• show interface summary
• show interface trunk
• show interfaces switchport. To display the administrative and operational status of a switching (nonrouting) port, including VLANs. and switchport mode

• show configuration or sh conf
• show running-config or sh run An enable mode command that displays the current configuration
• configure terminal or conf t Logs you into configuration mode

• switchport mode access|trunk

• interface Te1/0/1

• show mac address-table interface <switchport>

• show ip [OPTION]
• show ip interface
  • show ip interface brief or sh ip int br
• enable Logs into enable mode. Also known as user exec mode or privileged mode. See also: show privilege
  • enable 5 Change to level 5
  • no enable password

• show ip traffic

• show tcp brief

• show logging
  • show logging history

• show archive log config all

• no shutdown. Enables an interface (brings it up).

• show process

• ip dns
  • ip dns spoofing

• debug ip domain

• ip domain lookup
• no ip domain lookup

• ip domain-lookup
• no ip domain-lookup

• ip host HOSTNAME xx.xx.xx.xx (Similar to /etc/hosts)

• [no] ip forward-protocol nd

• ip route-cache
• no ip route-cache

• ip ssh pubkey-chain

• include, similar to grep linux command

VLAN

• show vlan [brief | id <vlan-id> | name <name> [ifindex] | <ifindex>]
  • show vlan
  • show vlan brief or sh vlan br
  • show vlan summary or sh vlan s
• show vtp status

• Create a new VLAN

show ip

• show ip route or sh ip ro

• show ip arp
• show ip ssh

Stacking

• show switch stack-ports

Users

• show privilege

• username Create and delete users
• Cisco IOS: show users

• write

• show crypto ca certificates

• aaa new model

IOS: Access List (ACLs)

HTTP Server

• sh ip http server all

• R1(config)#ip http server
• R1(config)#ip http authentication local
• R1(config)#ip http secure-server

DHCP Server

• show ip dhcp binding

Memory

• show memory
• show memory platform

Configuration Guides

• IOS: Create a VLAN
• Change vlan configuration: switchport mode access, switchport access vlan 4545
• Cisco IOS: enable an interface: conf t, int XXXXXX no shutdown
• Cisco IOS DHCP Server configuration
• Configure public RSA key authentication: ip ssh pubkey-chain
• Cisco IOS logging

Activities

1. Read Cisco IOS command reference: https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/fundamentals/command/Cisco_IOS_Configuration_Fundamentals_Command_Reference.pdf
2. Read Cisco IOS Cheat Sheet: https://www.netwrix.com/cisco_commands_cheat_sheet.html
3. Configure a user with public key access Configure public RSA key authentication
4. Associate a user with default higher privileges using username command
5. Create a new VLAN
6. Use ansible: ansible-galaxy install ansible-network.cisco_ios

Related terms

• Secure Gateway OS (SGOS)
• iOS
• Cisco NX-OS

See also

• Cisco IOS: Cisco IOS XE, Config (mode), VLANs, Cisco IOS logging, VTP, ACLs, show logging, show logging history, show interface status, debug, archive, show archive, conf t, int, ip http server, ip ssh, ip address, vty, show mac address-table, show access-list, Access-list, ip access-group, admin
• Networking: bandwidth, latency, Jitter, Ethernet, UPnP, MPLS, Frame Relay, ATM, TCP/IP, ARP, WiFi, BGP, Networking timeline, Router, Proxy ARP, Services & Networking
• Cisco IOS, PAN-OS, Junos OS, FortiOS
• OS: PAN-OS, FortiOS, SonicOS, IPFire, JunOS
• Cisco, Meraki, Cisco IOS, Cisco NX-OS, Cisco UCS, Cisco ACI, Cisco IOS XE, Cisco SD-access, AppDynamics, CCT, CCNA, CCNP, CCENT, Duo Mobile, Cisco Duo Mobile, Webex

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