Port scanners.

Hope you have read the previous article on TCP/IP. If not, I would advise you to do it now as the fundamentals explained them will help you to understand better what I am going to talk henceforth. Today, I want to take up the topic on Port Scanners.

In Internet security, no hacking tool is more celebrated than the scanner. It is said that a good TCP port scanner is worth a thousand user passwords. Before I treat the subject of scanners in depth, I want to familiarise you with scanners.

What Is a Scanner?

A scanner is a program that automatically detects security weaknesses in a remote or local host. By deploying a scanner, a user in Los Angeles can uncover security weaknesses on a server in Japan without ever leaving his or her living room.

How Do Scanners Work?

True scanners are TCP port scanners, which are programs that attack TCP/IP ports and services (Telnet or FTP, for example) and record the response from the target. In this way, they glean valuable information about the target host (for instance, can an anonymous user log in?). Other so-called scanners are merely UNIX network utilities. These are commonly used to discern whether certain services are working correctly on a remote machine. These are not true scanners, but might also be used to collect information about a target host.

What Will a Scanner Tell Me?

A scanner might reveal certain inherent weaknesses within the target host. These might be key factors in implementing an actual compromise of the target's security. In order to reap this benefit, however, you must know how to recognize the hole. Most scanners do not come with extensive manuals or instructions. Interpretation of data is very important.

What Won't a Scanner Tell Me?

A scanner won't tell you the following:

• A step-by-step method of breaking in.
• The degree to which your scanning activity has been logged.

Why Are Scanners Important to Internet Security?

Scanners are important to Internet security because they reveal weaknesses in the network. Whether this information is used by hackers or crackers is immaterial. If used by system administrators, scanners help strengthen security in the immediate sense. If employed by crackers, scanners also help strengthen security. This is because once a hole has been exploited, that exploitation will ultimately

Go To Page: 1 2