Mar
29

Installing and Configuring NTP on Linux

Posted by Aaron West at 12:03 PM in Linux

Many of us navigate life each day with a smartphone. And on that smartphone is an atomic clock of sorts. No it isn't a "real" atomic clock but given a smartphone is typically connected to cell towers and/or a wi-fi network the time and day on a smartphone is generally correct. I'd be willing to bet many of you use your smartphone as your daily watch. We've pretty much come to expect we will always have the correct time (within a few seconds) available at a quick glance.

Servers should be no different. During the past four years I've been responsible for leading the technology team at Dataium. We have a fair number of servers which make up our instrastructure, from basic CentOS virtual machines to clusters of database servers running open and closed source database packages. One thing we figured out early on was just how important it was to ensure our various machines have the proper day, time, and time zone configured. There are so many different reasons why this is important and we've been bitten several times when we deployed a new machine and forgot to ensure time synching was set up.

In this short post I cover how to install NTP (Network Time Protocol) a daemon which runs on a Linux box and keeps the system clock up to date. I also cover a few things I've run into over time in installing and using NTP. This post, like so many of my others, is geared specifically to CentOS but the principles can be applied to other Linux distributions such as Ubuntu.

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Feb
21

The Verge ran a story earlier about Canonical creating a docking station that provided Ubuntu desktop access for your smartphone.

I called this at least two years ago. Not the specific instance of Canonical releasing a desktop dock for Android device plug-in, but the idea of how this will change computing. If you discount some of the newest quad-core and 8-core systems out there, the latest mobile phones aren't too far behind laptops in their power. Certainly they don't have the graphics horsepower but I don't see that as an issue.

I imagine a new computing setup where your main - and perhaps only - device is your mobile device. Think Galaxy Note here. You're at the office and instead of using a desktop computer or laptop you use your mobile device alongside a docking station with dedicated horsepower and graphical capability. You essentially "side load" additional processors, RAM, and even disk storage (or you access cloud storage such as DropBox, Amazon S3/Cloud, or the newer Bitcasa). When connected to this system you're able to do most normal things you would do on your computer. And when you're done you disconnect, grab your device and head home.

The thing I haven't worked out is the software aspect. What if you're a huge Adobe Photoshop user. Are you going to have a version of this on Android or does your connection to the docking station bring about connections to typically laptop/desktop-only software? I think this will be worked out in the next 2-3 years and in 5 years we may all be using a setup like this.

Mar
1

For the past few months I've been planning on writing a post about the services that make this site possible. I've read these sorts of posts on other sites and they seem very marketing heavy. They're often titled "sponsor post" or something equivalent. This post is different. I'm genuinely a fan (and customer) of all of these services and in most cases I pay for them monthly. After the break I discuss each service/app I rely on to power this site. I put each service within category blocks such as: the server, the app, backups, uptime, etc.

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Feb
7

This post is a followup to my previous guide to installing ColdFusion 9 on Ubuntu. While that post was all about the specifics to getting ColdFusion up and running on Ubuntu, this post is all about CentOS. The overall process is the same and I'm covering all the same steps, but the commands in this post are specific to the CentOS operating system. So why I'm writing this?

Overall, installing ColdFusion isn't that big of a deal. But I've yet to see a guide or blog post that outlines all the other topics related to getting a decent ColdFusion server on CentOS up and running. That's why I wrote this super guide, to outline what I believe is important to know about installing ColdFusion. Of course, I'm not covering every single possible detail, but I believe I've hit on all the major topics. Along the way I sprinkle in my own ideas, thoughts, and what I believe are best practices. After you read this post and walk through all the instructions you should have a very solid ColdFusion / Apache set up on CentOS Linux.

There are two important things to note, so please read on.

Everything you will read, all paths, and every setup aspect is written specifically for CentOS. I've tested these instructions on CentOS 5.5, but they should be applicable to other recent versions. If you need instructions for Ubuntu, please read that guide here.

Secondly, and this is extremely important, all commands throughout this post are assumed to be run as root. Some of the commands can be run without root, but most of them cannot. So please, log into your CentOS server using the root account, put sudo in front of every command, or run the su - root command (under a non-root account) before walking through the instructions.

Before we get going, here's a list of what I'll be covering:

  1. Creating a Linux user for ColdFusion
  2. Disabling SSH and FTP login for the coldfusion user account
  3. Installing the required libstdc++.so.5 C++ Library
  4. Running the ColdFusion installer
  5. Starting ColdFusion for the first time
  6. Installing the ColdFusion 9.0.1 updater
  7. Verifying the installation of 9.0.1
  8. Creating a new ColdFusion instance for general use
  9. Tweaking the JVM memory settings
  10. Hooking Apache and ColdFusion together
  11. Getting the Apache Connector running with selinux
  12. Locking down Apache
  13. Configuring ColdFusion to start on system boot

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Jan
24

As I was finishing this guide on installing ColdFusion 9 on Ubuntu Linux I tweeted how many words made up the text (over 6,000). Several people commented on Twitter and Facebook saying things like: "[the length] seems a bit excessive," and "is it that complicated?" The thing is, I'm covering much more than simply installing ColdFusion. Overall, just installing ColdFusion isn't that big of a deal. But I've yet to see a guide or blog post that outlines all the other topics related to getting a decent ColdFusion server on Ubuntu up and running. That's why I wrote this super guide, to outline what I believe is important to know about installing ColdFusion. Of course, I'm not covering every single possible detail, but I believe I've hit on all the major topics. Along the way I sprinkle in my own ideas, thoughts, and what I believe are best practices. After you read this post and walk through all the instructions you should have a very solid ColdFusion / Apache set up on Ubuntu Linux.

There are two important things to note, so please read on.

First, this post is all about Ubuntu. Everything you will read, all paths, and every setup aspect is written specifically for Ubuntu. I've tested these instructions on Ubuntu 10.04 (Lucid Lynx), but they should be accurate from 9.04 (Jaunty Jackalope) on. If you're disappointed this was written for Ubuntu, don't be. I have a CentOS post right here that covers all the same topics.

Secondly, and this is extremely important, all commands throughout this post are assumed to be run as root. Some of the commands can be run without root, but most of them cannot. So please, log into your Ubuntu server using the root account, put sudo in front of every command, or run the su - root command (under a non-root account) before walking through the instructions.

Before we get going, here's a list of what I'll be covering:

  1. Creating a Linux user for ColdFusion
  2. Disabling SSH and FTP login for the coldfusion user account
  3. Installing the required libstdc++.so.5 C++ Library
  4. Running the ColdFusion installer
  5. Starting ColdFusion for the first time
  6. Installing the ColdFusion 9.0.1 updater
  7. Verifying the installation of 9.0.1
  8. Creating a new ColdFusion instance for general use
  9. Tweaking the JVM memory settings
  10. Hooking Apache and ColdFusion together
  11. Locking down Apache
  12. Configuring ColdFusion to start on system boot

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Oct
4

Web application security is a difficult topic and can't be covered completely in a single blog post. After the break I discuss one quick way to block ColdFusion Administrator requests in Apache. I also list other resources that will help you understand ColdFusion security and how to apply practical security constructs on your ColdFusion servers.

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Jul
4

Tab Key Trick in OS X and Linux

Posted by Aaron West at 10:56 AM in Hacks, Linux, Mac

I recently stumbled upon a little tab key trick in Mac OS X. I already knew you could press the tab key to autocomplete directory names, but I didn't know you could press the tab key additional times to resolve directory name ambiguity. How does it work? When you are typing directory names and paths, which you do with the change directory (cd) command, you can press the tab key to autocomplete the directory names. If two directories have similar names OS X and Linux will complete what you type up to the point one or more additional directory names match. If you continue to press the tab key a list of all possible directory names will display. This lets you determine what you are looking for and continue typing a directory name to resolve the ambiguity.

I'm stunned I didn't know about this neat feature of OS X and Linux, the two platforms I tested.

Check out the quick video demo below to see exactly what I'm talking about.

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Dec
7

Managing RSA Keys on Linux and OS X

Posted by Aaron West at 9:46 AM in ColdFusion, Linux, Mac

My Web sites have been hosted on Linux since 2002. About a year ago I moved some sites to a Linux virtual private server at Viviotech and have recently created setting up a new Linux server over at Linode. Linode is a Linux virtual server platform powered by Xen (Wikipedia) and was started by a friend (and past co-worker) of mine. If you're in need of Linux hosting I highly recommend Linode!

I began setting up my Linode with CentOS 4 since I was already familiar with it. But after having conversations with Chris at Linode I decided to nuke the CentOS distro and install Ubuntu. After doing this I ran into an issue the first time I attempted to connect to the server using ssh. Here's an example of what I saw when connecting.

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