- Overview
- Firewall Review
- Static Firewall
- Stateful Firewall
- The Internet Connection Firewall
- Enabling & Disabling the ICF
- Services Options
- Adding a Service
- Programs Options
- Security Logging Options
- Setting up Security Logging
- ICMP Options
- Adjusting the ICMP Options
- Understanding the ICMP options
- Issues to clarify before enabling Internet Connection Sharing
- Enabling / Adjusting / Disabling Internet Connection Sharing
- Summary of the ICF
This chapter is from the book
This chapter is from the book
This chapter is from the book
Firewall Review
Firewalls come in one of two basic forms: hardware or software. The average home or small business user often utilizes the software version because it is less expensive and is easier to set up and install. Regardless of the type of firewall, they are analogous in that both types inspect data transfer through a network. However, that is where the similarities end.
There are two main methods of inspection, which are stateful and static. The differences between the two are found in what is known as the OSI Reference Model. Every packet entering a network comes in via wires or some other form of hardware. This is the Physical layer. The data then enters the Data Link layer, and continues on up the model until it reaches its destination at the application layer. Each layer is responsible for certain parts of the delivery of information. The higher up the model, the closer the computer is to the actual data carried in the packet.
This model is important when examining firewalls because every firewall will use this model to perform its filtering. The following segments will describe briefly the key components of the static and the stateful firewall as well as the advantages and/or the disadvantages of each.