Configuring Packet Filtering and NAT Scenario: You are consulting for a small co

Question

Configuring Packet Filtering and NAT Scenario: You are consulting for a small company that has seven computers connected to an all-in-one SOHO router (also known as a multifunction network device). The owner is concerned whether data passed through the device is being inspected and/or filtered properly. The owner is also not sure how the internal IP addresses of his computers are being protected from the Internet properly. Your tasks are to make sure packet filtering is functioning, and explain to the owner how NAT works on this device. Consider your options when it comes to packet filtering for a device such as this. Make a recommendation based on today's SOHO routers. If the owner wanted to take packet filtering further, what could you suggest? In your own words, explain to the owner (as if you were actually speaking to the person) how NAT functions within a SOHO router.

Explanation / Answer

Packet Filtering:

Because packet filtering is older technology and lacks the capability to differentiate between types of network traffic, you might be wondering why we are discussing it. What could be the possible use for this technology in a world that is filled with hi-tech firewalls that can track protocols using knowledge of the way they work to intelligently differentiate between incoming and outgoing traffic streams? Good question! Why use a PC when we have supercomputers? Sometimes a lighter-weight, less expensive means to get things done is a major advantage. Because packet filters don't go to great depth in their analysis of traffic streams, they are faster than other firewall technologies. This is partially due to the speed at which the header information can be checked and partially due to the fact that packets don't have to be "decoded" to the application level for a decision to be made on them. Complex decisions are not necessary, simply a comparison of bits in a packet to bits in an ACL.

SOHO ROUTERS:

SOHO stands for small office/home office. SOHOs usually consist of businesses that are privately owned or individuals who are self-employed, so the term usually refers to both a small office space as well as a small number of employees.

Since the workload for these types of businesses are often primarily on the internet, they require a local area network (LAN), which means their network hardware is structured specifically for that purpose.

A SOHO network can be a mixed network of wired and wireless computers just like other local networks. Since these types of networks are meant for businesses, they also tend to include printers and sometimes voice over IP (VoIP) and fax over IP technology.

A SOHO router is a model of broadband router built and marketed for use by such organizations. These are often the same routers used for standard home networking.

While home networks shifted to predominantly Wi-Fi configurations years ago, SOHO routers continued to feature wired Ethernet. In fact, many SOHO routers did not support Wi-Fi at all.

Typical examples of Ethernet SOHO routers were common such as the TP-Link TL-R402M (4-port), TL-R460 (4-port), and TL-R860 (8-port).

Another common feature of older routers was ISDN internet support.

Small businesses relied on ISDN for internet connectivity as a faster alternative to dial-up networking.

Modern SOHO routers require most all the same functions as home broadband routers, and in fact small businesses use the same models. Some vendors also sell routers with more advanced security and manageability features added, like the ZyXEL P-661HNU-Fx Security Gateway, a DSL broadband router with SNMP support.

Another example of a popular SOHO router is the Cisco SOHO 90 Series, which is meant for up to 5 employees and includes firewall protection and VPN encryption.

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