Firewalls

Firewalls

1. Static Packet Filtering

2. Dynamic Packet Filtering

3. NAT

4. PAT

5. Filtering : Incoming packets subject to inspection against list of low level rules. Packets no adhering to these rules will be dropped. Packets that are not dropped propagated to other destinations if needed, or if not, sent to other protocol levels

   • Static Filtering Pros & Cons
     • Pros
       • Fast, Little overhead, implemented in hardware, single rule can protect a network
     • Cons
       • Isn't aware of application level protocols
         • Stateless
           • Less Secure

6. Dynamic Filetering allows for a number of rules to be added to the pre-existing set of rules by monitoring state information. SYN_RCVD enables a ESTABLISHED connection flag for legimate traffic