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

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 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

show ip

• show ip route or sh ip ro

• show ip arp
• show ip ssh
• show privilege

• username Create and delete users
• show users

• write

• show crypto ca certificates

• aaa new model

Access List

Configuring IP Access Lists: https://www.cisco.com/c/en/us/support/docs/security/ios-firewall/23602-confaccesslists.html#acltypes

Types of ACLs: Standard ACLs, Extended ACLs, Lock and Key (Dynamic ACLs), IP Named ACLs, Reflexive ACLs, Time-Based ACLs Using Time Ranges, Commented IP ACL Entries, Context-Based Access Control, Authentication Proxy, Turbo ACLs, Distributed Time-Based ACLs, Receive ACLs, Infrastructure Protection ACLs, Transit ACLs.

• show access-list
• show ip access-list
• router(config)#access-list 101 deny icmp any any
• router(config)#access-list 101 permit ip any any

• router(config)#ip access-list extended test
• router(config-ext-nacl)#permit ip host 2.2.2.2 host 3.3.3.3
• router(config-ext-nacl)#permit tcp host 1.1.1.1 host 5.5.5.5 eq www
• router(config-ext-nacl)#permit icmp any any
• router(config-ext-nacl)#permit udp host 6.6.6.6 10.10.10.0 0.0.0.255 eq domain

• ip access-group

• copy running-config startup-config

HTTP Server

• sh ip http server all

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

Configuration Guides

• Cisco IOS DHCP Server configuration
• Configure public RSA key authentication: ip ssh pubkey-chain

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

See also

• Networking: bandwidth, latency, Jitter, Ethernet, UPnP, MPLS, Frame Relay, ATM, TCP/IP, ARP, WiFi, BGP, Networking timeline, Router, Proxy ARP, Services & Networking, Traffic shapper
• 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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