3.2 Firewall Types

Question 1

The universal security control

Answer 1

• Standard issue– Home, office, and in your operating system
• Control the flow of network traffic– Everything passes through the firewall
• Corporate control of outbound and inbound data– Sensitive materials
• Control of inappropriate content– Not safe for work, parental controls
• Protection against evil– Anti-virus, anti-malware

Question 2

Network-based firewalls

Answer 2

• Filter traffic by port number or application– OSI layer 4 vs. OSI layer 7– Traditional vs. NGFW firewalls
• Encrypt traffic– VPN between sites
• Most firewalls can be layer 3 devices (routers)– Often sits on the ingress/egress of the network– Network Address Translation (NAT) functionality– Authenticate dynamic routing communication

Question 3

UTM / All-in-one security appliance

Answer 3

• Unified Threat Management (UTM) /– Web security gateway
• URL filter / Content inspection– Malware inspection
• Spam filter– CSU/DSU
• Router, Switch – Firewall
• IDS/IPS– Bandwidth shaper– VPN endpoint

Question 4

Next-generation firewall (NGFW)

Answer 4

The OSI Application Layer– All data in every packet
* Can be called different names– Application layer gateway– Stateful multilayer inspection– Deep packet inspection
* Requires some advanced decodes– Every packet must be analyzed and categorized
before a security decision is determined

Question 5

NGFWs

Answer 5

• Network-based Firewalls– Control traffic flows based on the application– Microsoft SQL Server, Twitter, YouTube
• Intrusion Prevention Systems– Identify the application– Apply application-specific vulnerability signatures to
  the traffic
• Content filtering– URL filters– Control website traffic by category

Question 6

Web application firewall (WAF)

Answer 6

• Not like a “normal” firewall– Applies rules to HTTP/HTTPS conversations
• Allow or deny based on expected input– Unexpected input is a common method of exploiting
  an application
• SQL injection– Add your own commands to an application’s SQL query
• A major focus of Payment Card Industry Data Security
  Standard (PCI DSS)