Firewall technology
### Definition:
effect:
limitation:
Technology and Classification:
—Packet filtering firewall technology
1. Simple packet filtering
Logical location:
Two strategies:
Advantages and disadvantages:
2. State inspection packet filtering
principle:
Logical location:
Advantages and disadvantages:
—Proxy service firewall technology
1. Circuit-level gateway
The proxy makes a TCP connection
working principle:
Advantages and disadvantages:
2. Application-level gateway
The agent receives the packet
Advantages and disadvantages:
3. Adaptive proxy
Architecture:
1. Dual-host firewall
Structural components
Bastion host + dual network cards
Work characteristics:
Prohibit direct communication between internal and external networks
2. Shield the host firewall
Structure and components:
Packet filtering router + bastion host
3. Shield the subnet
working principle:
Advantages and disadvantages:
