Cisco IOS

Summary

Cisco IOS (Internetwork Operating System) is a proprietary network operating system developed by Cisco Systems. It runs on Cisco routers, switches, and other networking devices, providing the foundation for network operations and management. Cisco IOS offers a rich set of features for routing, switching, security, and network management, making it a cornerstone of Cisco's networking solutions.

General

ACLs

Insert into existing Standard ACL

1. # show access-list 24
2. (config)# ip access-list standard 24
3. (config-std-nacl)# 15 permit 10.1.2.0 0.0.0.255
4. (config-std-nacl)# exit
5. (config)# ip access-list resequence 24 10 10

Insert into existing Extended ACL

1. # sh access-lists vlan2-out
2. (config)# ip access-list extended vlan2-out
3. (config-ext-nacl)# 1421 permit tcp object-group VPN.CLIENTS host 10.1.49.23 eq 3389
4. (config)# ip access-list resequence vlan2-out 10 10

Packet Capture

(This example is on a Catalyst 6506-E)

1. # show monitor
2. # Show run | inc monitor session
3. (config)# no monitor session 1
4. (config)# monitor session 1 source vlan 1309
5. (config)# monitor session 1 destination interface Gi2/1/3

VPN

Some Useful Links

LAN-to-LAN IPsec Tunnel Between Two Routers Configuration Example

Cisco IOS VPN Configuration Guide

Site-to-Site IKEv2 Tunnel between ASA and Router Configuration Examples