|[Home] [Credit Search] [Category Browser] [Staff Roll Call]||The LINUX.COM Article Archive|
|Originally Published: Thursday, 7 June 2001||Author: Matt Michie|
|Published to: enchance_articles_security/Basic Security Articles||Page: 1/5 - [Printable]|
Linux.com Security: Introduction to Port Scanning
Unfortunately nobody can be told which path to take, you must see it for yourself, so choose wisely. Ripped from today's headlines, the writers and editors of Linux.com are proud to present this security-minded introduction to protecting your system. Read on, and know yourself.
|Page 1 of 5 >>|
"Hence the saying: If you know the enemy and know yourself, you need not fear the result of a hundred battles. If you know yourself but not the enemy, for every victory gained you will also suffer a defeat. If you know neither the enemy nor yourself, you will succumb in every battle." -- Sun Tzu, The Art of War
What is Port Scanning?
Port scanning is a computer security technique that tests a system for open TCP/IP "ports". In layman's terms, if one compares an IP address to a telephone number, then a port would be the equivalent of a telephone extension.
For instance, if I wanted to speak to Linus Torvalds at his workplace, I would first dial the phone number to Transmeta, and then connect to his specific extension. In this way, more than one person can use the same phone number. Likewise, TCP/IP ports allow one IP address to have many different servers connect to it.
Standard TCP/IP stacks allow access to up to 65,535 different ports, 1 - 65535. In Linux, ports less than 1024 require root access for a program to bind to them.
Some of the more common ports are:
A more canonical list of standard ports can be found in
|Page 1 of 5 >>|