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Troubleshooting Linux
with Unix tools

Darren Kressin has been in computers since taking a basic programming course in college in 1986. Presently he is the Network Administrator for the Alamo Area Council of Governments while maintaining a separate computer/networking consulting business.


With the evolution of the personal computer, we are seeing the changes in networking grow exponentially. A network enables the user to share files and devices like printers, external zip or other drives with other computers on the network. As more people acquire computers, the need to have the computers communicate with one another is growing rapidly. Networking used to be beyond the price range for the average person. With the change in technology and drop in cost, most everyone has two or more computers and can now have their own network. The network can range from Ethernet to token ring to wireless. The most common as of this writing is Ethernet. 

With the reasonable priced, High speed Internet connections that are available, the inexperienced user now has a new set of hazards that must be addressed. 

The first priority after connecting to a High speed Internet connection should be a firewall to protect the computers that are always on and connected to the Internet. Firewalls protect the computers from hackers. This can be accomplished with a hardware firewall device or software that is loaded on the computer. 

The second dilemma is connecting all the computers, in the building or house, to a network system that allows the computers to access the same Internet connection. The newly created network brings its own additional problems that require attention. The remaining sections of this article address those concerns.

I would like to discuss the advantages of using networking tools designed for Unix that will run on the Linux operating system. These tools will make it possible for a User to trouble shoot network problems and carry out an overall review of computer security. 

When networking computers together, you have additional layers of potential problems that could and will occur. One has to either hire someone to come in and troubleshoot the network or else the user develops the necessary skills and troubleshoots the problems themselves. Although Windows provide tools to address the troubleshooting process, there are more powerful tools available elsewhere on the Internet to help a user analyze what the problem is. This is where the basis of the matter appears. 

Most networking tools for the Unix platform are freeware or shareware. However, the freeware or shareware tools that can be used on a Windows system are becoming readily available on the Internet, but still lag behind most of the Unix tools in versatility and robustness. 

Unix tools have not been ported to the Windows environment. I am specifically speaking of tools that assist a user to pinpoint a problem within a network or security system or on a specific computer. I am also referring to tools that are freeware or shareware. There are tools for the Windows environment that the user could purchase, but most are rather expensive. The tools that I have come across seem to be more specific in nature and not multifunctional and this singularity adds to the purchase cost. 

Unix OS dates back to the late sixties. Some of the first networking tools developed were for Unix platforms. The only way to take advantage of these tools is to run Unix. This is where Linux comes in. With the development and release of Linux, this enables the non-Unix user to employ these very powerful tools since Linux is based on Unix. 

As Linux grows, the operating system is becoming friendlier to the average user. It is fast approaching to the point of being a system that the average user can load and start using with very little training or reading. The Linux community is achieving great progress in the development of the operating system. They are working hard to make the system more user friendly. This is going to allow the operating system to grow and become more easily accepted. The system engineers are working to integrate Linux within a Windows network environment, and are exceeding very well. 

Since Linux OS is an open source code system, all the tools I have found are either freeware or shareware. To locate the tools on the Internet, open a search engine and type in the type of tool that you need.  That is the easy part.  The hard part is determining where to trouble shoot your problems. 

You will need to have a basic knowledge of networking and understand the flow. Both Linux and Windows have available the basic tools to get you started in troubling shooting your network. If your problem is not a basic TCP/IP related or related driver then you will require tools to help you in defining the problem and the method to fix it. 

One of the most difficult problems is pinpointing a bad network card. The card from hell is the one that demonstrates connectivity but doesn’t function as it was designed. Locate the tool that can look at packets and the flow of packets. Also having a program that can measure TCP/IP throughput is also quite useful. Ideally, you want a program that does both. Qcheck is such a program that will work on the Windows operating system and does both. There is talk about porting it to the Linux platform. This is the foundation to trouble shooting your TCP/IP connections.

Security is the other shoe that I am going to drop. One could be reminded of the saying, fight fire with fire in describing the following advice. Keep in mind that most of the hackers in the world are using some version of the Unix operating system. Hacker sites are the best places to obtain additional necessary tools and to keep up with the cyber-criminals.  Be aware that when you go to a hacking Web site you are entering the devil’s den. I would suggest using a computer that has no important information on it and will not hurt you if it is crashed by the hacker. I realize this is a big risk, and this is something you will have to consider. If tugging the devil’s beard is not your cup of tea, then the software security industry has something just for you.

A software tool with an attitude is called SATAN.  It was written by Dan Farmer and Weitse Venema. It is designed to scan hosts on an IP network and report about well-known security vulnerabilities. It is one of the most helpful tools that a system administrator can use in securing their systems. 

I have touched on just one area a user is going to have to face when upgrading to a high speed Internet connection. Nevertheless, one of the best defenses that a user can do is to “network” or reach out to other users. Employ all the resources that you have available to you. One place is the Alamo PC Organization. Avail yourself of the talent concentrated there and don’t hesitate to ask questions. By speaking with other club members you may discover ways to avoid mistakes that others have made.


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