Firewall
Hardware or software that inspects traffic between networks against defined rules, letting permitted connections through and blocking the rest.
- 01
Why it matters
A firewall shrinks the attack surface by allowing access from the internet only to the services that are really needed. Splitting the internal network into segments also makes it harder for an attacker to spread from one device to the whole network. Rules pile up over time, so they should be reviewed regularly.
- 02
Example
A server's database port was left open to the internet. Once a firewall rule allows only the application server to connect to the database, connection attempts from outside stop entirely.
- 03
Common mistake
Forgetting to close rules opened temporarily. Access opened “for a week” can stay open for years; every rule should have a recorded owner and reason.
- 04
Related terms
Related services and guides
Let's talk about your project.
Tell us what you need; we will define the scope together.