May 2015
Beginner to intermediate
118 pages
2h 29m
English
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Port scanning
Nmap is a port scanner, but we haven't yet covered what a port actually is. As the name somewhat implies, a port is a way to access a networked service on a computer. Each computer has 65,535 ports that can be either open, or closed at any time. Some services such as HTTP (that serves web pages) or FTP (that allows file transfer) have ports that are associated with them by default. HTTP runs on port 80, FTP runs on port 21, and so on. There are huge lists of commonly used ports that we can reference later—fortunately for us, Nmap has these lists included with its distribution package.
One way to conceptualize a port is to think about an apartment building. In this analogy, one apartment building would be an IP address—each apartment ...
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.