Using Security Tools Tutorials
General Utilities / Secure Shell (ssh)
Subtitles of the Movie (Using Security Tools / General Utilities / Secure Shell (ssh))
One of the first tools we're going to cover is Secure Shell or ssh. ssh is a fundamental tool that all security professionals should know how to use. What it is is a secure replacement for several older, unencrypted protocols and tools such as Telnet, old FTP and the R Services that come with UNIX. Now, these tools have been around for a long time and they've been used traditionally to offer remote administration capabilities to systems and file copy. Now, ssh offers an encrypted remote administration sessions and secure copy and secure FTP in addition to port forwarding and tunneling, whereas these other protocols, these older protocols that I just mentioned don't offer any kind of encryption at all and sometimes not even any authentication. ssh offers encryption and authentication between systems. You definitely need to learn how to use this if you're going to be a security professional. Now the platforms that ssh is available for are pretty much any platform you can think of; Windows, Linux, BSD. Now, in Windows you would have to install a third-party ssh client such as PuTTY; that's probably the most popular one out there or any other ssh-enabled program for Windows. Now, in Linux, ssh is usually installed by default. Most Linux distributions come with it unless you make an effort to not install it. It's usually installed so you really don't have to install it in Linux. Now, you need to have the SSHD which is the ssh daemon, the server portion running and you also have to have a client. So if you're going to ssh into a computer, it must be running the daemon, the server itself and you don't have to be running that on the client that you have and Windows can be a client, Linux can be a client, whatever. And let's go ahead and look at a demonstration of using ssh between two Linux boxes; two open SUSE boxes. OK, we're in our openSUSE Desktop and what we're going to do first is ssh over to another computer. Where at Computer A, which is 172.16.30.20 and we're going to ssh to Computer B to do some remote administration tasks. So the first thing we need to do is connect to the system and it's just a matter of simply typing in ssh and you want to use a user name that is located on the other system and you can use the host name or the IP address. If you're using DNS or have the host file populated, then you can use Computer Name. If you're not using DNS or host file, then you must use the IP address. You can use that IP address any time and that might be the simpler way to do it. So you're sshing, you're giving a user name and the computer's destination. That's the very basic ssh command. So we're going to press Enter. We're going to get prompted for a password. Now, this command will get you basic remote administration capabilities provided you have an account on that other system. Now, notice that I have ssh'd into it and I'm not at Computer B. I have a prompt, a terminal prompt on Computer B but I'm not logged in as a privileged user and this is normally recommended for ssh. You normally do not want to login as a privileged user across ssh. It's just not something you want to do, especially with the root account so what you might do as soon as you login across using ssh, then you might want to sudo and run privilege-level commands using the sudo command and we'll talk about sudo a little bit later in the course but it allows you to be a normal user and run privileged commands so you protect the root account. So once we're in here we can do various things. We can perform administration, run remote commands and such on the remote system. We can do whatever our user is allowed to do unless we sudo to another user account; say to root for example and to exit out of ssh all I basically have to do is type Exit and we're back at our Desktop for the computer we started. So that's essentially ssh. Now, there are other commands that use similar syntax that you probably need to learn. SCP is another ssh command. It's part of the ssh suite and it's been used essentially the same way except you specify files that you want to copy or entire directories and you specify a destination. It's actually very, very easy to use. So get familiar with ssh, learn how it works, learn the syntax. I've just showed you the basic syntax. You can see it's a very easy command to use and use that in, get in the habit of using that for your daily remote administration and file copy operations between computers on the secure network because if you use some of the older protocols that we talked about; Telnet, R Services, FTP and so forth, those are unencrypted sessions and a user, a malicious user or hacker could intercept those communications. So that's how to use ssh.
Tutorial Information
| Course: | Using Security Tools |
| Author: | Bobby Rogers |
| SKU: | 34068 |
| ISBN: | 1-935320-88-2 |
| Release Date: | 2009-12-04 |
| Duration: | 9 hrs / 91 lessons |
| Captions: | No |
| Compatibility: |
Vista/XP/2000, OS X, Linux QuickTime 7, Flash 8 |
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