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)

Interfaces:

show interfaces
show interface trunk
show interfaces switchport. To display the administrative and operational status of a switching (nonrouting) port

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

show ip
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 logging
no shutdown. Enables an interface (brings it up).

ip route-cache
no ip route-cache

ip ssh pubkey-chain

include, similar to grep linux command

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

aaa new model

show ip route or show ip ro

show ip arp
show ip ssh
show privilege

username Create and delete users
show users

write

show crypto ca certificates

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

HTTP Server

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

Configuration Guides

Activities

Read wikipedia article about Cisco Internetwork Operating System
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
Read Cisco IOS Cheat Sheet: https://www.netwrix.com/cisco_commands_cheat_sheet.html
Configure a user with public key access Configure public RSA key authentication
Associate a user with default higher privileges using username command