 Hello, my name is Ken Mayer and I'll be your instructor here for this Linux Plus course. Now in the past 37 years, I've been working on a variety of different platforms, operating systems, networks, servers, and everything else you can think of. And that's because in that time frame, stuff has changed. I started originally punching cards on a machine to make Fortran code. I remember when Unix systems first came into our universities and I was like, well, this is really annoying. I don't like it. And I thought, you know, I'll never see Unix again when I get through with this stuff. Then I went into this Novell world and the Microsoft world. And all during this time, what happens? Linux comes out. And we started hearing more and more about Linux and suddenly it becomes a part of Novell. And I see it as the foundation for many of the networking devices that I use for routing and switching. And it's just everywhere. And then of course, as I got really big into security, I fell back in love with Linux. So anyway, I've had, we would say, on and off again, love and hate for this operating system. My goal is to make sure that I can take all of my experience using it as a platform for network devices, using it as a hacker, using it in large institutions, and all of the different ways in which you can use. And I have utilized Linux. I hope all of that experience will be able to help you understand how you can use it to give you the commands and the information that you need to be able to make it work well for you. And of course, make it secure. All right. So we're going to start off by talking about installation. Now, I know a lot of you are going to say, really? Installation? I mean, come on. Was that thrown in a CD-ROM drive? Well, yeah, it is. But it's going to be a little bit more than that. We're going to talk about what Linux does, kind of give you an introduction. Talk about its role in the world of networking. We'll talk about ways in which you can download Linux, create an installation disk, and then talk about your options that you have about installing and doing the basic configuration of Linux. So even though it does sound pretty rudimentary, there are some things you should know, some options that you have, and some really kind of cool ways that you can get Linux up and running on your operating system, and whether it's permanent or whether it's temporary. So let's go ahead and take a look at what it means to say installation. All right. So we're going to start off in this unit by our first topic, which is just, as I said before, an introduction into Linux. Now, let me just say something right ahead of time. There are so many people that are so crazy about Linux that they have their own language, their own terms, their own way of pronouncing things. And then there are people who pronounce things differently, but it's the same word. For instance, Linux. I've heard Linux. I've heard Linux. Now, the reason I'm saying this now is I want to get out of the way. If I pronounce something differently than you've heard, it doesn't mean I'm wrong. It just means it's not the one you heard. If you don't like it, I apologize ahead of time, but it's just the world we live in today with whenever we deal with Linux. So I'm warning you ahead of time. I mean, I've heard it all along, like is it Gen2 or Gen2 for one of the distributions? All of these things are little minor pieces that I'm not going to dwell on throughout this course. So I thought that would be a great way of saying, let's have our introduction to Linux. I'm going to call it Linux. If you like calling it Linux, go ahead. Just pretend in your mind. That's what I said. Okay, so we're going to start off right now and talk about it as an introduction. All right. So as an example, we can talk about different varieties of Linux and there are. First of all, it's Unix-like. Now, it's I think important that we say Unix-like because it's not Unix. Unix, of course, is its own operating system, but much of what we use with Linux looks like Unix. It was developed by Linus Torvalds in 1991 while he was a student in Helsinki. He left it as an open source program, meaning that, you know, you could take it, you could change it, you could reverse engineer it, you can alter it, but you could not charge for it. It was something that was freely available to the open source world. As an operating system, it did what operating systems needed to do. It handles your common operating system needs, your file management, user accounts, the input and output with a variety of different types of hardware devices, including, of course, the rudimentary, keyboard, video, printer and those types of things. Since then, we have a lot of different distributions that are available for us in the world of Linux. You'll hear different types of names for the different options that you have. Of course, one of the big sellers is Red Hat. Now, suddenly somebody looks at me and they said, wait a second, seller? Yes, Red Hat does sell this operating system, but we'll talk a little bit about that in the licensing. But remember, they're selling other things like service and education and other features that they've added on. There's a large amount of readily available software that you can use in this operating system. Need a web browser? You can use Firefox. Need to have a Word document? Well, you don't use Word, you use Open Office and create your own documents that are like Word, your own spreadsheets, your own presentations. I mean, literally, you'll find almost a replacement for every Windows program already available for you in the Linux operating system. And again, almost always for free. I like that for free. It sounds really good. Maybe I should say it more and more again. Now, having said that, I'm not saying it's better or worse. Please, I'm not getting into that game. As a hacker, I can tell you that I can give you the pluses and the minuses on both sides of this in the world of security. As a person who deals with businesses, I can give you pluses and minuses for going in either direction in the support of your business. It is a tool that may or may not meet your business needs. It may be something you personally like to work with better than other options, whatever the case may be. But there is yet to be a perfect operating system. Now, once I make that perfect operating system, I'll release it all to you and I'll become the next billionaire. But right at now, there isn't one. So again, just like I said before, where we have this variety of ways of pronouncing the different terms and the different acronyms, there's also going to be a huge debate over which is better to use. I'm not here to take a part of that debate and I'm not here to favor one over the other. I want to make sure if you choose to use Linux that it works well for you. And that's why we say, even the world of Linux, there's a variety of different types of distributions. There are different, well, let's call it versions of Linux that you can use. And it's important that you pick one that has the features that you like. Now, as I said, when it comes to the Linux platform, Linux was designed to be able to run well on servers to give you an enterprise class computing environment. Now, one of the big proponents of that is Red Hat. Red Hat has an enterprise solution. What it means by having an enterprise solution means that they have actually tuned their version of Linux along with all of the other middleware that you would like to be able to give you a fully ready server-wide solution at a very inexpensive price. A lot of what you're paying for is not actually the Linux code or the Linux kernel itself, but for all the add-ons that they've given you, the support that they have if you call on the phone and have issues. We also see Linux-like or Unix-like operating systems running on different types of network devices. You might see them on your Juniper routers or your Cisco routers and switches. It's a very popular operating system. We see it in the use of Novell in the current releases of Novell for your network operating systems. You're finding a lot of underlying Linux, Unix or Unix-like solutions. Now, I'm also saying Unix-like a lot because some of these versions use BSD, which is not Linux. It's not Unix. It's Unix-like. It's kind of a sticky point that we want to make sure we're not saying it's Linux or it's Unix, but we're saying it's like them. Just like when we said Linux is Unix-like. I know you're wondering why am I jumping around all of these semantics. You'll see in just a few more minutes as we talk about licensing why I'm doing that. I'm just doing it now. I won't keep doing it all the way through. Okay. Linux also comes in availability for your desktop and end user computers, including your handheld phones or your PDAs. For the longest time, I had a PDA made by Sharp. It was called a Zorus and it had a Linux shell or a Linux kernel loaded on it. I would utilize a lot of the Linux platforms to be able to do things like war walking, looking for Wi-Fi, capturing the packets and doing all of those really cool things that I could do very easily in the Linux environment. We also see it embedded as I said into non-computer devices. Again, going back to routers switches, even a router based on Linux that is made by a company called Viata, which is trying to compete in that realm of small enterprise routing against Cisco and Juniper and all of those companies by offering, again, a device that is running a Linux or Linux-like environment and running their software and running these devices off of that platform. We see Linux, let's say, everywhere. It's there very prevalently, but not with the average user because the average user is still seeing Windows desktops when they log in and not very many of them actually get into these end devices and see them on their phones and their PDAs and the routers and switches and the firewalls and all of these other solutions. It's popular. It's everywhere. As I just said, you can see that it has a wide use from the home user, the small device to the enterprise class server. Now, there are many different distributions that we often call distros. There are many popular ones. Here we go with the fun of trying to figure out how to pronounce this. One is Ubuntu or Ubuntu, currently one of the most popular end versions or end user versions we have. The reason people like it is because it's easy to use. It supports multiple languages, which are the goals or at least two of the biggest goals for developers. Many developers don't want to fight against the operating system to be able to develop their code. In fact, some people would argue that's one of the popular points of Windows, is that it's very easy to create programs for Windows because it's going to be universally the same everywhere. In other words, their program they create on this system will run on this one and this one and this one and they don't have to worry about dealing with different hardware platforms or anything else. They just work it with Windows. So one of the reasons why it's popular. Red Hat Enterprise, again, designed for your servers and your desktops. They also provide you a lot of middleware, support, education. In fact, I'd say Red Hat's done a lot to help push forward the use of Linux and the knowledge and people wanting to get certifications and understand what it does. Fedora would be Red Hat's end user distribution or Linux distribution. SUSA, which is now I think owned by the Novell Corporation, is again their version of Linux. Now, having just said this and all of these different distributions or distros, as I'd like to call it, all of them can be downloaded for you. With the exception I said of Red Hat, for the Red Hat Enterprise, you actually pay a price for the licensing of all of the things they give you. Most of the rest of them you can download for free and you have to decide why do I want Fedora over SUSA over any other or Gen2 or Gen2 or any of the rest. Why would I choose that? Well, I'm going to try to hit that as I talk about some of these other popular distributions. Okay, Debian is another one. It's again a platform or a distribution community developed managed by a consortium of open source, let's call them members, who can contribute and continue to develop and improve the version. It's considered to be very customizable, a very powerful distribution. Slackware, one of your oldest distros that are out there, still active. It has active development being used now for power users. And here's where I can wrap up all of this. Why do I want one over the other? By talking about two others that are very popular, Backtrack and Helix. Now, Backtrack and Helix are examples of distributions of Linux that have a very specific use. And what I mean by specific is simply this. Backtrack is known as a hackers toolkit. What happens you see with Backtrack is when you install it, it installs with all, and I mean like all of the greatest or latest and greatest tools that a hacker would ever want to be able to do a penetration test against a network. I mean, it has all sorts of from every phase from the scanning, the enumeration, the tracing, the hacking into the buffer overflows. I mean, it's got it all. It's all ready to go. You don't have to install these tools. Helix was a great distribution to use for doing forensic investigations on other machines because again, it has all of the tools, a lot of PS tools, a lot of software to be able to basically do your own file carving, your own analyzing, your own copying or duplication of drives. Everything's there. So one of the things that I use Backtrack and Helix for are my examples to say, why would you choose one distribution over another? And the answer is, what are your goals? What are you trying to solve as a solution with your choice of Linux? Because some of these come with the tools already prepared, already installed, ready to run, where others may have none of them, but be the foundation for which you can build your own. And maybe that's what you want. If you're the power user, you're going to say, you know, there's a lot of stuff on Backtrack. I'll never use. I don't want it. I want to build my own from this foundation. And by the way, from what I've just told you, there are many, many other versions out there. I would almost venture to say I could, without bragging or without exaggerating too much saying that there are hundreds of different distributions that are available to you and lots of websites that you can go to and actually search for the different types of Linux that are out there and all of them, as I said before, you can download and install. Now, one of the big things that people think about with Linux right off the bat is the licensing because people say, hey, it's free. It's free. It's free. Okay, so let's talk about software licensing. There is, of course, the idea of the closed source license, which is similar to most of the operating systems that you see. That means you buy the software, not downloaded illegally off of BitTorrent. You buy it and they give you the right to use it, but you can't distribute it. You can't modify or reverse engineer the software. Now, modify does not mean adding new programs to the operating system, but modify actually means changing the kernel or how the operating system behaves. An open source license means it's free to use, modify, and you can distribute it as long as you stay within the terms of the license or what they call the GNU public license or some people call it the new public license. I say the GNU so you can hear the guh, the G, GNU, part of this. But anyway, the GPL is the abbreviation for that whole thing for the public license and that might have some types of rules of things you can't do to violate an open source. For example, if you add some sort of closed source application to an open source program, that might violate the GPL because you can't really distribute something that's open source that's relying on a closed source program. So those are things you have to deal with when you're looking at the GPL. Now there is the LGPL, which is kind of a middle man, if you would, of the open source and the closed source. That's what we'd say it sits somewhere between the GPL and the more restrictive or permissive license models as I just described. But it's one way we can use as a method to mix different types of licensing, especially when it comes to our trying to distribute software. And that's a big deal. As an example of, I saw as one example, if you were to write a program that helps draw a box on the screen and that's licensed to you and you want people to pay for it, can I really include it in my distribution, in my open source distribution of its closed source? Well, we can alter our work with the licensing to be able to say, yes, I can distribute this to a point, but it doesn't, I guess the big thing is, is the open source can't be dependent on the closed source for its functionality, because if it was, then you're violating the closed source license. So somewhere in between there, with all this one of illegal jargon, sits this LGPL to deal with, with those licenses. There's also other types of licenses, the MIT, Apache and many others. Generally, they're permissive licenses, depending on the product. For example, Apache services is, you know, is not really a part of Linux. Everybody says, ooh, Apache web server, that's Linux. Well, yeah, Apache can run on Windows too. It is a web services that is generally free to distribute, free to download, free to use. So that would be something we would call the Apache licenses. Now, behind the scenes, there have been a variety of different lawsuits over what Linux really is, and especially in the term of trying to call it Unix. Because Unix is a licensed software, it's not free for you to download. And so that's why we're so careful to say that Linux is like Unix, but it's not Unix, because Unix falls under a different licensing. The issue of BSD has the same, same type of a problem in that we don't say it is Unix, but we also don't say that it's Linux, but we say it's Linux like or Unix like because of the legal issues about the licensing. And we're trying to describe that it's similar in how to use, but it's not the same. And that's why you heard me doing all that kind of semantic fencing earlier in this unit, because of the issues with licensing. Now that I'm done with that, I'm not going to deal with it anymore, because sometimes it still is confusing. What you need to know is, is it in your corporation free to use, or do you have to pay for a license? You want to research what you're using for the very purpose of, if you're audited and you are found to have been violating license restrictions, then your company could potentially pay a lot of money and fines, and you might find yourself looking for a new job. You want to make sure you're following the proper licensing models that were assigned with each of the software or operating systems you install. And that's where I'll leave this whole issue about software licensing. Now, there are some other terms that go with the non-licensing group. The non-licensing, all right, that means all that discussion about licensing is now gone. We're not going to talk about it anymore. So one of the most common things we hear about all the time is freeware and shareware. In fact, there are websites like shareware.com where you go there to download stuff for free. It's not a licensing model, it's often just giving you trial software. Trial software means that what you have will work, maybe the full version will work for a limited time, or you'll have a limited version of the full model. And if you liked the little piece that you saw and you want to open up the rest of it, then you pay for the software. You might also hear about the creative commons. That's a non-licensing term for the documentations or books and things that deal with the types of issues about non-software but actual tangible things that I can touch, not a bunch of magnetically stored ones and zeros. You also might hear about the public domain, which is the opposite of a copyright. So if you think about it, a song generally is not open to public domain unless somebody allows it to be. It is a copyrighted type of a file, really a series of words that are sung in musical format, lyrics if you would. And as a copyright, it can't be duplicated without permission or without paying for it. If I put it in the public domain, that's the opposite of a copyright. That means that now that everybody can have it, it's basically owned by the people. And we could sometimes say that even of Linux, that it is not copyrighted, it is not protected, it is available for the people to use, to reverse engineer, to basically improve upon. So that's where we call it that open source community. And that would be part of that public domain.