Stateless packet filtering firewall technology
➢The most basic firewall filtering method
➢ Filter based on L3 / L4 information
· Source and destination IP
·protocol
· ICMP messages and types
· TCP / UDP source and destination ports
➢ Fast processing speed
➢ Unable to stop the application layer ***
➢ Complex deployment and large maintenance
➢Deployment method
· As the first line of defense of the Internet border
· Implicit rejection, showing permission
➢Example
· Use ACL filtering router
Stateful packet filtering firewall technology
➢ Perform similar operations with stateless packet filtering firewall
➢ Keep track of connection status, status table
· No need to open high port access rights
· Access not belonging to an existing session will be denied
➢ Check more advanced information
·TCPFlag、TCPSeq.
· More DoS protection
· Specific application layer protocol detection
➢ Can't stop the application layer ***
➢System overhead caused by state table
➢Deployment method
· As the main defensive measure
· Requires stricter control