Linux


Why doesn't it look different? 14
Here’s the scenario: you’ve set up Dynamically Allocated Storage for the hard drive on your Guest VM in VirtualBox and you’ve run out of space — even though your Actual Size is smaller than the Virtual Size (this happened to me recently when my Virtual Size was 10 GB, and […]

Resize a Fedora, CentOS, or Windows Dynamic Guest Virtual Disk ...


Linux Uptime 6
CentOS 7 was released recently, and so I fired up my build VM so I could attempt to build the OpenDKIM package for submission to EPEL. But the compile barfs on strlcat/strlcopy, because RHEL/CentOS doesn’t have libbsd available (yet?). The libbsd package was a requirement for the package to work […]

Rant: Why is there no libbsd for CentOS 7?


Rasmus Lerdorf's opcache-status script 2
When I upgraded to PHP 5.5, I also said goodbye to my beloved APC cache (which never let me down) in favor of Zend OPcache, because it’s already part of the PHP package. Back when I used APC, one of my favorite tools was the apc.php script that showed cache status and allowed me […]

My Favorite Zend OPcache Status Scripts



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If you’re trying to set up an Apache web server on CentOS  as your origin server for Google PageSpeed service, you need to take certain steps to make sure that Apache can see (and also log) the IP address of the visiting host. Otherwise, all you’ll see in your Apache log files […]

Configuring Apache on CentOS 6 for Google PageSpeed Service


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It all started about a week ago. I got an alert email from a server, complaining about a RAID array. That’s nothing terribly out of the ordinary, as I have all of my systems set to alert me if something seems out of place. However, the problem in this case […]

Rant: Google Apps’ Gmail Can’t Protect Me from Misconfigured Mailers


Linux Uptime 1
After upgrading from Nagios 4.0 to 4.0.1, I attempted to manually reschedule a check of all services on a particular host, I received the following error: Error: Could not open command file ‘/usr/local/nagios/var/rw/nagios.cmd’ for update! The source of the problem turned out to be a permissions issue with the nagios.cmd […]

How to Fix Error: Could not open command file ‘/usr/local/nagios/var/rw/nagios.cmd’ ...



Cisco/Linksys E4200 overclocked to 532 MHz 31
It’s a question asked in the DD-WRT forums all the time. It’s a question often asked in the comments of my DD-WRT posts. And it’s a question to which no “official” answer from the primary maintainers of DD-WRT exists… and therefore it will probably keep getting asked. However, based on […]

Difference between DD-WRT BrainSlayer, Eko, Fractal, and Kong Builds


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In an effort to extend my WiFi coverage outside our vacation home on a lake, I purchased a Ubiquiti NanoStation LOCO M5. My goal was to provide a strong WiFi signal a few hundred feet into the back yard, onto the beach, and all the way out to the dock. […]

Connecting iOS devices (iPhone, iPad, iPod) to Ubiquiti NanoStation M5 ...


Timeline for Shutdown and Turn Off for the PCNS server OS and the UPS 14
I decided to write this blog post after attempting to configure APC’s PowerChute Network Shutdown (PCNS) software to gracefully shut down a number of Windows and Linux computers on my network, all of which are attached to various APC SmartUPS Uninterruptible Power Supply (UPS) units with AP9617 and AP9630 Network Management Cards […]

HowTo: Configure Low Battery Duration and PCNS to Shut Down ...



Postfix 2.9 Upgrade 5
I run a number of “real” Postfix servers that live “away from home,” in a cozy server cabinet at our colo facility, but I also like to keep a Postfix server handy in the basement, running on an ancient (but rock solid) Dell PowerEdge 2450 running CentOS 5. I don’t […]

HowTo: Get Around Comcast Port 25 Block with a Postfix ...


Linux Uptime
This is one of those reference posts mainly for myself, that helps me remember commands for stuff I have to do from time to time, but not often enough that I remember it without searching for it. This post is about MySQL commands. Resetting the Root Password: http://dev.mysql.com/doc/refman/5.0/en/resetting-permissions.html What to run […]

MySQL Commands: Password Reset, Initial Setup, and more!


Cisco/Linksys E4200 overclocked to 532 MHz 42
UPDATE: Newer versions of the DD-WRT firmware now include a web-based option for selecting your overclock speed, if it’s supported on your device. You can still follow these steps to overclock (and I recommend you continue reading so you understand what you’re doing), but now you can access overlocking on the Administration/Management tab. […]

How To: Overclock a Cisco/Linksys E4200 Router running DD-WRT



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When setting up a vanilla WordPress installation on a vanilla CentOS server with a vanilla Apache install, I kept getting 404 errors on pages and posts when Permalinks was set to anything other than the default. I fixed it by editing Apache’s httpd.conf file to add the following in the […]

WordPress File Not Found with Custom Permalinks


Upgrade from Fedora 17 to 18 with FedUp 1
Fedora 18 (codename Spherical Cow) was officially released today, and there’s a mad scramble to figure out how to upgrade to this latest Linux desktop from Fedora 17. Previously, you’d have to either do a fresh install with a CD or DVD, or you could use the built-in PreUpgrade method. […]

Upgrade from Fedora 17 to Fedora 18 with FedUp


WiFi connection on iPhone 4 680
UPDATED Dec 21, 2016. This post is a reference post for those looking to squeeze maximum speed out of their Cisco Linksys E4200 v1 wireless router running DD-WRT. The DD-WRT build I currently recommend for this router is K2.6 30880 (by BrainSlayer). IMPORTANT: My testing shows that DD-WRT K2.6 builds are much faster on the […]

My Cisco Linksys E4200 DD-WRT Settings for Max Speed



Setting up multiple WLANs in DD-WRT 14
Even for the extremely ungeeky, having WiFi available throughout your house is pretty much standard these days. And while the next logical step of securing that network via encryption (WEP is for n00bs — those in the know use WPA2-AES) may not be standard, it really should be. Assuming you do […]

Use DD-WRT to Create a Guest WiFi Network and Block ...


Remote Cable Modem and Router Power Cycle 2
We’ve all been there. You try to load a web page, or check your email, or download a file, and nothing happens. “The Internet’s down!” is the cry at my house when we lose connection. It’s also the #1 reason why people call their Internet service providers’ tech support numbers, […]

How To Automatically Power Cycle Your Modem and Router on ...




Postfix 2.9 Upgrade 6
I’ve previously written a how-to for compiling Postfix from source on a CentOS 5 box. I recently tried following the same steps on a CentOS 6 box, to upgrade from Postfix 2.6.6 which is installed by default. I’m glad to report that the same instructions will work just fine to upgrade […]

Building Postfix 2.10 on RHEL6 / CentOS 6 from Source


Yahoo and Postfix 26
If you’re getting “temporarily deferred” Postfix log entries when trying to send mail to Yahoo! that look like this: host mta7.am0.yahoodns.net[66.196.118.34] refused to talk to me: 421 4.7.0 [GL01] Message from (xxx.xx.xx.xxx) temporarily deferred - 4.16.50. Please refer to http://postmaster.yahoo.com/errors/postmaster-21.html or status=deferred (host mta7.am0.yahoodns.net[66.196.118.35] said: 451 mta1336.mail.bf1.yahoo.com Resources temporarily unavailable. […]

How-To: Postfix configuration to reduce Yahoo temporary deferrals using Transport ...




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I often say there are only two types of data: data that is backed up, and data that is waiting to be lost. Even if you’re the most contentious hax0r who always backs up your data, if your backups are stored in the same physical location as the source data, […]

How to Back Up a Linux Server to Amazon S3 ...


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One recommended way to help secure your Postfix mail server is enabling TLS (Transport Layer Security) for connections to and from Postfix. You can search for more detailed descriptions of exactly how TLS works, but basically it’s a crypotgraphic protocol that allows connections between systems to remain secure. It relies on a key […]

Configure Postfix TLS with a Free StartSSL Certificate