ACLs and firewalls both filter traffic, but they differ in capabilities:
ACLs:
- Built into routers
- Stateless (each packet judged independently)
- Simple permit/deny rules
- No application awareness
Firewalls:
- Dedicated security devices
- Stateful (track connection state)
- Advanced filtering options
- Application layer inspection
- Logging and reporting
Use ACLs for basic filtering. Use firewalls for perimeter security and complex policies.