Access network is the portion of a public switched network (PSTN) that connects access nodes to individual subscribers, which is predominantly passive twisted-pair copper wiring. Access network also refers to the data network that connects individual users with the edge network of the Service Provide. Twisted-pair copper, optical fiber and wireless technologies are all used for this purpose.

In the computer network world, a DeMilitarized Zone (DMZ) is a part of a network separated from other systems by a Firewall which allows only certain types of network traffic to enter or leave. For example, a company will protect its internal networks from the Internet with a Firewall, but will have a separate network, or DMZ, to which the public can gain limited access. Public web servers might be placed in such a DMZ. With the DMZ approach, large companies with complex e-commerce Internet and extranet applications may have a two-tiered approach to firewall security.

In this article, we assume the SOHO office has multiple PCs networked in LAN as shown in the Figure 1. We also assume that you aren't hosting a Web site and that you aren't supporting VPN connections. If you are, you'll need to extend the techniques in this article to properly secure Web access, VPN connections, and other customer services you provide.

Network vulnerabilities are present in every system. Network technology advances so rapidly that it can be very difficult to eradicate vulnerabilities altogether; the best one can hope for, in many cases, is simply to minimize them. Networks are vulnerable to slowdowns due to both internal and external factors. Internally, networks can be affected by overextension and bottlenecks, external threats, DoS/DDoS attacks, and network data interception. The execution of arbitrary commands can lead to system malfunction, slowed performance, and even failure.

Network protocol analysis is a process for a program or a device to decode network protocol headers and trailers to understand the data and information inside the packet encapsulated by the protocol.To conduct protocol analysis, packets must be captured in real time for line speed analysis or later analysis. Such a program or device is called a Protocol Analyzer.

Network performance problems are one of the plagues of the modern age. People have come to depend on wired and wireless LAN networks at home and in the workplace. These networks have improved productivity for many businesses and employees, but they have become so integrated into many business structures that network slowdown often constitutes a company-wide crisis. Three of the most common network performance problems are exhaustion of bandwidth, bottlenecks and hacking (causing DoS or DDoS).

While the wireless LAN provides many conveniences in today’s communication world, it also introduces unique security challenges, compare with the traditional wired network.  The early version of the Wi-Fi technology, IEEE 802.11b, tried to overcome the security issue by devising a user authentication and data encryption system known as Wired Equivalent Privacy, or WEP. Unfortunately, some compromises that were made in developing WEP have resulted in it being much less secure than intended.

Network management is critical in today's business to ensure high network availability, secure communication, easy-to-use of the network and related technologies, effectively manage network devices and support users. There are many network management architectures and models proposed by various standard organizations and vendors. Some of them are widely implemented in the real world while others maybe only concepts for considerations.

The Ethernet LAN has many security weaknesses when facing attacks externally and internally. Security measures must be taken to ensure an secured environment for communications ever the Etehrnet LAN. The following are some key risks in an Ethernet LAN:

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