Enhanced Firewall System Design

Dhs Cyber Security Dmz Diagram

The second firewall system design is shown in Figure 2-29. As you can see, it has more components and rectifies some of the security deficiencies in the simple firewall system design. I examine the perimeter router component first. As in the last example, the perimeter router packet-filtering firewall is performing basic filtering of traffic as it comes into the Internet. Nothing is different in this example except for what the bottom-right IDS device is doing monitoring both the external...

Examining TCP Control Bits

The second approach is to examine transport layer information about the connection to determine whether it is part of an existing connection and, if so, allow the returning traffic back to 200.1.1.1. With TCP, this can be done by examining the control flags in the TCP segment header. These are shown in Table 2-4 and are defined in RFC 793. Note that multiple codes, commonly calleflags, can be sent in the same segment header, such as SYN and ACK (SYN ACK), or FIN and ACK (FIN ACK). Initiates a...