> For the complete documentation index, see [llms.txt](https://chloe-codes1.gitbook.io/til/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://chloe-codes1.gitbook.io/til/aws/practical-aws/07_network_acls.md).
# Network ACLs
> A deep dive into Network ACL - Practical ver.
\
### Before getting started
Things that can control the network besides firewalls
* Routing Table
* Controls where to send packets
* Network ACL
* Transmits or blocks packets based on rules
\
### What are Network ACLs?
* Rules that determine whether to block or allow certain packets
* Configured rules apply to all resources, so you can't set too many
* They apply to all resources in the subnet
* Therefore, Network ACLs must be well designed
* Why? Even if the firewall (SG) is properly configured, access may be blocked due to a **Deny Rule** in the `Network ACL`
* The more `Network ACL` rules there are, the more confusing firewall configuration becomes, so it's best to keep `Network ACL` rules as concise as possible
* If firewall settings are done properly, you don't need to configure `Network ACLs` separately!
\
### Rule number in Network ACLs
* Network ACL rules have priorities
* They are applied in order of highest priority (Rule number)!
\
### Network ACLs and Well Known Ports
* The reason why `1024 - 65535` is allowed in the **Port Range** of Network Inbound rules
* \== Because they are `Well Known Ports`!
* [Learn about well known ports](https://chloe-codes1.gitbook.io/til/network/11_tcp_and_udp#1-layer-4-protocol-tcp-udp-and-service-port)
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