[Day 10] 5. Named ACL

Named Access Control Lists (ACLs) make it easier to manage and modify router rules. They use descriptive names to identify specific rules, making it easier to troubleshoot network issues and improve network performance.

Commands:

Named ACL creation:
```
A(config)# ip access-list extended blockweb
```
- This command creates an Extended ACL named
```
blockweb
```
  .
- Extended ACLs allow filtering based on various factors like source/destination IP, protocols, port numbers, etc.
Permit rule for TCP traffic:
```
A(config-ext-nacl)# permit tcp any host 172.16.30.100 eq 80
```
- This allows TCP traffic from any source to the specific destination IP address
```
172.16.30.100
```
  on port 80 (HTTP).
Deny rule for all IP traffic:
```
A(config-ext-nacl)# deny ip any host 172.16.30.100
```
- This blocks all other IP traffic (regardless of protocol) from reaching the same destination IP
```
172.16.30.100
```
  .
Permit all remaining traffic:
```
A(config-ext-nacl)# permit ip any any
```
- This ensures that all remaining traffic is permitted after the previous deny rule. It prevents unintended traffic blocking.
Applying the ACL:
```
A(config-if)# ip access-group blockweb in
```
- The ACL
```
blockweb
```
  is applied inbound on the interface
```
g0/0
```
  , meaning it filters traffic entering the interface.
Summary: This Named ACL (
```
blockweb
```
) is designed to allow HTTP traffic (port 80) to a server at
```
172.16.30.100
```
while blocking all other traffic to that server, and permitting all other traffic. Named ACLs make it easier to manage and modify access rules by using descriptive names instead of numbers.

[Day 10] 5. Named ACL

Read Next

[Day 10] 6. Monitoring commands

[Day 10] 7. ACL for Telnetting