ACL

How it is used

Spelled out letter by letter. Engineers write ACLs, apply them to interfaces in the inbound or outbound direction and keep them up to date. Rules are checked from top to bottom and the first match wins; on many devices an invisible 'deny all' rule sits at the end, so anything not explicitly allowed is dropped.

Example sentences

1. The new ACL blocks traffic from the guest VLAN to the server subnet.

2. Monitoring stopped working after the change because the ACL didn't permit SNMP.

Common collocations

• apply an ACL
• inbound ACL
• ACL entry
• permit and deny rules
• implicit deny

Related terms

• firewallA hardware device or piece of software that checks network traffic and allows or blocks it according to a set of security rules.
• VLANShort for virtual LAN: a separate logical network created on a switch, so that devices plugged into the same hardware, for example staff PCs, guests and cameras, can be kept apart.
• portEither a physical socket on a device where a network cable is plugged in, or a number from 0 to 65535 that identifies a particular service on a host, such as 443 for HTTPS.
• routerA device that connects different networks and decides, packet by packet, the best path for data to reach its destination, usually based on IP addresses.
• DMZShort for demilitarised zone: a separate network segment between the internet and the internal network, where public-facing servers such as web or mail servers are placed.

This word in other fields

The same English word can have a different meaning in another field:

• ACL · Networking & Telecommunications
• ACL · Sports & Fitness

More terms: APIs, Networking and Security

• API
• endpoint
• REST
• JSON
• status code
• payload
• authentication
• third-party
• SDK
• breaking change
• request
• response