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Operations 5 min read

Router NAT and ACL Configuration for External and Internal Interfaces

This article provides a step‑by‑step configuration example for a router, detailing external and internal interface settings, NAT server and static NAT rules, outbound NAT policies, and corresponding ACLs to control traffic between multiple subnets.

Practical DevOps Architecture
Practical DevOps Architecture
Practical DevOps Architecture
Router NAT and ACL Configuration for External and Internal Interfaces
interface GigabitEthernet0/0/0
description link_to_ISP
ip address x.x.x.x   x.x.x.x
nat server protocol tcp global current-interface 8890 inside 192.168.5.10 443
nat server protocol tcp global current-interface 3333 inside 192.168.5.3 telnet
nat server protocol tcp global current-interface 8888 inside 192.168.5.2 www
nat static protocol tcp global current-interface 8000 inside 192.168.2.55 8000 netmask 255.255.255.255
nat static protocol tcp global current-interface 8003 inside 192.168.2.55 8003 netmask 255.255.255.255
nat static protocol tcp global current-interface 8010 inside 192.168.2.55 8010 netmask 255.255.255.255
nat static protocol tcp global current-interface 8880 inside 192.168.2.55 8880 netmask 255.255.255.255
nat static protocol tcp global current-interface 3389 inside 192.168.2.51 3389 netmask 255.255.255.255
nat static protocol tcp global current-interface 8081 inside 192.168.2.53 8081 netmask 255.255.255.255
nat static protocol tcp global current-interface 2700 inside 192.168.2.53 2700 netmask 255.255.255.255
nat static protocol tcp global current-interface 2600 inside 192.168.2.53 2600 netmask 255.255.255.255
nat static protocol tcp global current-interface 3390 inside 192.168.3.3 3389 netmask 255.255.255.255
nat outbound 2001
acl number 2001
rule 1 permit source 192.168.5.0 0.0.0.255
rule 2 permit source 192.168.2.0 0.0.0.255
rule 3 permit source 192.168.3.0 0.0.0.255
rule 4 permit source 192.168.4.0 0.0.0.255

---

interface GigabitEthernet0/0/1
description link_to_inside_network
ip address 192.168.5.1 255.255.255.0
nat server protocol tcp global interface GigabitEthernet0/0/0 8000 inside 192.168.2.55 8000
nat server protocol tcp global interface GigabitEthernet0/0/0 8003 inside 192.168.2.55 8003
nat server protocol tcp global interface GigabitEthernet0/0/0 8010 inside 192.168.2.55 8010
nat server protocol tcp global interface GigabitEthernet0/0/0 8880 inside 192.168.2.55 8880
nat outbound 3000
acl number 3000
rule 20 permit ip source 192.168.2.0 0.0.0.255
rule 25 permit ip source 192.168.3.0 0.0.0.255
rule 30 permit ip source 192.168.4.0 0.0.0.255
rule 35 permit ip source 192.168.5.0 0.0.0.255

quit

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RouterNATACL
Practical DevOps Architecture
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