Category Archives: How To

Basics of securing a Linux server

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One of the most important jobs that someone who calls themselves a “System Administrator” has is securing their servers. Whether it’s a personal server you are tinkering with, or a production server at work somewhere, keeping a server secure is paramount for many reasons, not just keeping your data safe. If your server were to get compromised, depending on what happened, it could be used as a zombie to target other machines in a massive DDoS attack. It might be used to send yet more spam out to the users of the world, or it could even be setup as a platform to launch more viruses and attacks against unsuspecting users all over the Internet.

The point is that there are a great many reasons to keep your server secure, and I don’t think there is anyone out there who would disagree. That being said, I have written up some basic steps that I go through to begin the process of securing my Linux boxes, thus hoping you can use it to help you secure yours. I decided to start with Linux because many people are testing and playing with it since it is very powerful and free. These are guidelines, as well as examples of how I do it. It’s too simple to say that there are better or worse ways of doing things. Read what I have below here and apply it to your situation, lots of things in this article can even be applied to Windows, as they are good practices regardless of the OS. Let’s get started shall we?

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Solaris and CD ROMs

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Here’s a quick tip for anyone who is tinkering with a Solaris box, and it stems from a question I get from folk who are new to Solaris, and that is “How do I mount a CD ROM?”. The short answer is to use the mount command, but there is a little more to it. You need to know what device your CD drive is, and the easiest way to find out if you don’t already know, is to use the iostat command, specifically running it with -En so that the (iostat -En) results look like this:

c0t0d0 Soft Errors: 0 Hard Errors: 0 Transport Errors: 0
Model: ST3120026A Revision: 8.01 Serial No: 4JT0S129
Size: 120.03GB <120034123776 bytes>
Media Error: 0 Device Not Ready: 0 No Device: 0 Recoverable: 0
Illegal Request: 0
c0t2d0 Soft Errors: 4 Hard Errors: 0 Transport Errors: 0
Vendor: TSSTcorp Product: CDW/DVD TS-H492C Revision: SI00 Serial No:
Size: 0.00GB <0 bytes>
Media Error: 0 Device Not Ready: 0 No Device: 0 Recoverable: 0
Illegal Request: 4 Predictive Failure Analysis: 0

From the output you can see that one drive is a hard drive by the line Model: ST3120026A and Size: 120.03GB, and the other drive is the CD ROM then because it says Vendor: TSSTcorp Product: CDW/DVD. There you go, find the one that says it’s a CD ROM and we know the device we need to mount is c0t2d0.

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iTunes, QuickTime, and Errors

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Let me start this article by saying that I finally broke down last year and bought myself an mp3 player, specifically an iPod. I didn’t choose the iPod because it was trendy or hip or whatever, I chose it because for what it could do and the space it had, for the price, it was the best deal. Now, with an iPod you need to use iTunes (I realize there are other 3rd party tools out there, but call me a purist, I want to use it the way it was intended). In many ways, iTunes rocks, and in many ways, iTunes sucks. Whether you love it or hate it, you are pretty much stuck with it.

That being said, let me share with you a couple of errors I received recently, and what I did (finally) to make them go away. In my dealings with these errors, my searching on the Internet didn’t find any solution to the problem, although some information pointed me in the right direction. Ultimately, I spent enough time troubleshooting and testing (a.k.a banging my head against the wall) that I got the problem resolved, so I thought I would share, just in case anyone else runs across this issue. Judging from the number of posts I saw about it, lots of folk other than myself have had this come up too.

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Backing up your MailWasher settings

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For any of you that use MailWasher, have you gotten tired of manually re-entering all of your email account data every time you re-install, re-build or switch computers? I know I have. If you don’t have to do that very often, or if you don’t have more than one or two email accounts, it’s not that bad. But still, there is all of the data in your Friends list and Black list that you might not want to re-create. If you don’t know what MailWasher is, it’s a great email management and anti-spam tool that we featured as a Cool Tool awhile back, check it out.

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Sending mail via telnet

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Sending mail via telnet through your SMTP server

There have been many times over the course of my time working with computers that I have had to manually test email functionality. Email is one of those things that everyone has to have for various reasons. It’s great for getting status info and results from scripts for example. However, it’s also one of those ornery things that is affected by everything from network settings and firewall rules to spam filters and DNS problems.

The point is that sometimes you need to be on the machine that is sending the message, and verify that it can in fact send a message. This article will help you not only test connectivity, but walk you through sending an email message via a telnet connection, going through the SMTP commands much like your mail client uses.

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Labeling disks in Linux

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There’s a new article up that discusses Linux, and how it uses labels to mount disks in many cases, instead of the device paths of yesteryear. In the article I explain what this is and why we do it, as well as how to manage the labels of your disks. This is one of the things that when I first saw it, blew me away. I didn’t realize what it was, and once I learned more about it, I was blown away again by just how cool this is. All in all, I think the idea of mounting disks via a label so that it just doesn’t matter what the device name or path is, is an awesome idea. I hope I put together an article that is helpful, and can shed some light on it for you.