I participated in a podcast for the Rackspace Cloud with Robert Collazo last week. We covered some important topics including network security and convenient deployment tools.

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I kept having an issue where the shift key would become stuck regardless of the settings I set for the client or server. The halfDuplexCapsLock configuration option had no effect. After installing xkeycaps, I found that both shift keys were getting stuck if I brought the mouse back and forth between Mac and Fedora twice.

I decided to run a test. I started the client with the debug argument and moved the mouse to my Fedora box. At that point, I pressed the letter 'a' and saw:

DEBUG1: CXWindowsKeyState.cpp,195:   032 (00000000) up
DEBUG1: CXWindowsKeyState.cpp,195:   03e (00000000) up
DEBUG1: CXWindowsKeyState.cpp,195:   026 (00000000) down
DEBUG1: CXWindowsKeyState.cpp,195:   032 (00000000) down
DEBUG1: CXWindowsKeyState.cpp,195:   03e (00000000) down
DEBUG1: CXWindowsKeyState.cpp,195:   026 (00000000) up

I brought the mouse back to the Mac and then back to Fedora. I pressed 'a' again and saw:

DEBUG1: CXWindowsKeyState.cpp,195:   026 (00000000) down
DEBUG1: CXWindowsKeyState.cpp,195:   026 (00000000) up
DEBUG1: CXWindowsKeyState.cpp,195:   026 (00000000) down
DEBUG1: CXWindowsKeyState.cpp,195:   026 (00000000) up

After dumping the keyboard layout with xmodmap I found the keys that corresponded with the key numbers:

• 032 - Left shift
• 03e - Right shift
• 026 - a

If I tapped the left shift, I could clear the key press, but I couldn't clear the right shift key (it was stuck down according to Fedora's X server). When I hooked up a physical keyboard and mouse, I was able to use them normally without any keybinding problems.

The root cause: When synergy started in /etc/gdm/PreSession/Default after the gdm login, the keyboard layout wasn't set up properly. The X server was setting up the keyboard layout later in the startup process and this confusion caused the shift keys to get stuck. Fedora 12 uses evdev to probe for keyboards during X's startup and eventually settles on a default layout if none are explicitly defined.

The fix: I added the synergy startup to the GNOME startup items and it works flawlessly.

©2010 Racker Hacker. All Rights Reserved.

Many cloud providers allow you access to a private network environment where you can exchange data with other instances or other services offered by the provider. The convenience of this access comes with a price: other instances can access your instance on the private network just as easily as they could on the public interface.

Here are some security tips for your private interfaces:

Disable the private interface
This one is pretty simple. If you have only one instance or server, and you don't need to communicate privately with any other instances, just disable the interface. Remember to configure your networking scripts to leave the interface disabled after reboots.

Use packet filtering
The actual mechanism will vary based on your operating system, but filtering packets is the one of the simplest ways to secure your private interface. You can take some different approaches with them, but I find the easiest method is to allow access from your other instances and reject all other traffic.

For additional security, you can limit access based on ports as well as source IP addresses. This could prevent an attacker from having easy access to your other instances if they're able to break into one of them.

Configure your daemons to listen on the appropriate interfaces
If there are services that don't need to be listening on the private network, don't allow them to listen on your private interface. For example, MySQL might need to listen on the private interface so the web server can talk to it, but apache won't need to listen on the private interface. This reduces the profile of your instance on the private network and makes it a less likely target for attack.

Use hosts.allow and hosts.deny
Many new systems administrators forget about how handy tcpwrappers can be for limiting access. If your firewall is down in error, host.allow and hosts.deny could be an extra layer of protection. It's important to ensure that the daemons you are attempting to control are build with tcpwrappers support. Daemons like sshd support it, but apache and MySQL do not.

Encrypt all traffic on the private network
Just because it's called a "private" network doesn't mean that your traffic can traverse the network privately. You should always err on the side of caution and encrypt all traffic traversing the private network. You can use ssh tunnels, stunnel, or the built-in SSL features found in most daemons.

This also brings up an important point: you should know how your provider's private network works. Are there safeguards to prevent sniffing? Could someone else possibly ARP spoof your instance's private IP addresses? Is your private network's subnet shared among many customers?

With all of that said, it's also very important to have proper change control policies so that administrators working after you are fully aware of the security measures in place and why they are important. This will ensure that all of the administrators on your instances will understand the security of the system and they should be able to make sensible adjustments later for future functionality.

©2010 Racker Hacker. All Rights Reserved.

Almost every system administrator has found themselves in a situation where they're confronted with a server which has a problem. However, if you're not the primary administrator for the server, you may not always know what has changed recently or you may not be aware of changes in the server's environment. In these situations, if the fix isn't obvious, try going through these steps:

Localize the problem to a specific daemon or service
In the case of a problem where a website isn't loading properly, is it a problem with the web server itself? Could something other than the actual web server daemon be having an issue?

As an example, consider a ruby on rails application which runs through apache's mod_proxy_balancer and queries data from MySQL. If any of those individual puzzle pieces were not functioning correctly, you'd get a different result. A downed MySQL instance could make the application throw errors or appear to be unresponsive. If the mongrel cluster had failed, apache might be returning internal server errors. Your browser might return a connection refused if apache was down. These are all relatively easy to determine.

What if you are unable to determine which daemon is causing the problem?

If it's broken, break it a little more
Let's say that you've reviewed the process list and all of the appropriate daemons appear to be running. However, the website is still not loading properly. What do you do? Bring down a service and try again. Did something change? Did a new error appear? If not, bring that daemon back up and try taking down one of the other ones.

I've also had some good results by making small adjustments in the web server's configuration file. If you have a virtual host that isn't returning the correct data, try commenting it out temporarily. For rewrite rules, try removing them temporarily or strip them down to a more basic form. Test again, and then begin adding lines back incrementally. As much as a single period or quotation mark can derail a perfectly good set of rewrite rules.

In short - try to think outside the box when you're troubleshooting a difficult issue on an unfamiliar system. Always remember to back up your configurations before making changes and ensure your daemons will start properly if you bring them down.

©2010 Racker Hacker. All Rights Reserved.

ERROR 1206 (HY000): The total number of locks exceeds the lock table size

MySQL is trying to tell you that it doesn't have enough room to store all of the row locks that it would need to execute your query. The only way to fix it for sure is to adjust innodb_buffer_pool_size and restart MySQL. By default, this is set to only 8MB, which is too small for anyone who is using InnoDB to do anything.

If you need a temporary workaround, reduce the amount of rows you're manipulating in one query. For example, if you need to delete a million rows from a table, try to delete the records in chunks of 50,000 or 100,000 rows. If you're inserting many rows, try to insert portions of the data at a single time.

Further reading:

• MySQL Bug #15667 - The total number of locks exceeds the lock table size
• MySQL Error 1206 » Mike R's Blog

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However, when you load up quite a few plugins or a heavy theme, the performance will dip due to the increased number of stylesheets, javascript files, and images. You can compress and combine the stylesheets and javascript to decrease load times, but this may not get the performance to a level you like.

I was in this situation and I found a great solution: the W3 Total Cache plugin and the MaxCDN service.

To get started, visit MaxCDN's site and set up an account. Their current promotion gives you 1TB of CDN bandwidth for one year for $10 (regularly $99). Once you sign up, do the following:

• Click Manage Zones
• Click Create pull zone

At this point, you'll see a list of form fields to complete:

• Enter an alias for the pull zone name
• The origin server URL is the URL that's normally used to access your site (i.e. rackerhacker.com)
• The custom CDN domain is the URL you want to use for your CDN (i.e. cdn.rackerhacker.com)
• The label can be anything you'd like to use to remember which zone is which
• Enabling compression is generally a good idea

Once you save the zone, MaxCDN will give you a new domain name. You'll want to create a CNAME record that points from your CDN URL (for me, that's cdn.rackerhacker.com) to the really long URL that MaxCDN provides.

STOP HERE: Ensure that all of your DNS servers are replying with the CNAME record before you continue with the W3 Total Cache installation and CDN setup. If you proceed without waiting for that, some of your blog's visitors will get errors when they try to load content via your CDN domain.

You're ready for W3 Total Cache now. Install the plugin within your Wordpress installation and activate it. Hop into the settings for the plugin and make these adjustments:

• Enable Page Caching and set it to Disk (enhanced)
• Enable Minify and set it to Disk
• Enable Database Caching and set it to Disk
• Leave the CDN disabled for now, but flip the CDN Type to Origin Pull (Mirror)
• Press Save changes

Click CDN Settings at the top of the page and configure the CDN:

• Enter your CDN domain (for me, it's cdn.rackerhacker.com) in the top form field
• Leave the other options as they are by default and click Save changes

W3 Total Cache should prompt you to clear out your page cache, and that would be recommended at this step. If you fully reload your blog's main page in your browser (may require you to hold SHIFT while you click reload/refresh) and check the page source, you should see your CDN URL appear for some of the javascript or CSS files.

You may discover that some CSS files, stylesheets, or images aren't being loaded via the CDN automatically. Luckily, that's an easy fix. Under the Minify Settings section of the W3 Total Cache plugin settings, scroll to the very bottom. Add in your javascript or CSS files via the form fields at the bottom and the plugin should handle the minifying (is that even a word?) and the CDN URL rewriting for you.

Further reading:

• MaxCDN Wordpress Integration Overview
• W3 Total Cache plugin page at wordpress.org
• W3 Total Cache main site

©2010 Racker Hacker. All Rights Reserved.

ERROR 1206 (HY000): The total number of locks exceeds the lock table size

InnoDB stores its lock tables in the main buffer pool. This means that the number of locks you can have at the same time is limited by the innodb_buffer_pool_size variable that was set when MySQL was started. By default, MySQL leaves this at 8MB, which is pretty useless if you're doing anything with InnoDB on your server.

Luckily, the fix for this issue is very easy: adjust innodb_buffer_pool_size to a more reasonable value. However, that fix does require a restart of the MySQL daemon. There's simply no way to adjust this variable on the fly (with the current stable MySQL versions as of this post's writing).

Before you adjust the variable, make sure that your server can handle the additional memory usage. The innodb_buffer_pool_size variable is a server wide variable, not a per-thread variable, so it's shared between all of the connections to the MySQL server (like the query cache). If you set it to something like 1GB, MySQL won't use all of that up front. As MySQL finds more things to put in the buffer, the memory usage will gradually increase until it reaches 1GB. At that point, the oldest and least used data begins to get pruned when new data needs to be present.

So, you need a workaround without a MySQL restart?

If you're in a pinch, and you need a workaround, break up your statements into chunks. If you need to delete a million rows, try deleting 5-10% of those rows per transaction. This may allow you to sneak under the lock table size limitations and clear out some data without restarting MySQL.

To learn more about InnoDB's parameters, visit the MySQL documentation.

©2010 Racker Hacker. All Rights Reserved.

Once I started using irssi in screen, I found that the visual bell in screen didn't get my attention quickly. Luckily, someone in the #slicehost channel let me know about screen's audible bell. You can flip between the visual and audible bell with CTRL-A and then CTRL-G. If you keep repeating that key combination, you'll switch back and forth between the two (with a status update at the bottom left).

You can also set up your visual bell configuration in your .screenrc via some configuration parameters:

vbell [on|off]
vbell_msg [message]
vbellwait sec

©2010 Racker Hacker. All Rights Reserved.

You may be wondering: "Why not just use ssh in a for loop?" Sure, you could do something like this in bash:

for i in`cat ~/myhosts.txt`; do ssh $i 'uptime'; done

But dsh allows you to do this:

dsh -g myhosts 'uptime'

In addition, dsh allows you to run the commands concurrently (-c) or one after the other (-w). You can tell it to prepend each line with the machine's name (-M) or it can omit the machine name from the output (-H). If you need to pass extra options, such as which ssh key to use, or an alternative port, you can do that as well (-o). All of these command line options can be tossed into a configuration file if you have a default set of options you prefer.

Another thing that makes dsh more powerful is the groups feature. Let's say you have three groups of servers - some are in California, others in Texas, and still others in New York. You could make three files for the groups:

• ~/.dsh/group/california
• ~/.dsh/group/texas
• ~/.dsh/group/newyork

Inside each file, you just need to list the hosts one after the other. Here's the ~/.dsh/group/texas group file:

db1.tx.mydomain.com
db2.tx.mydomain.com
web1.tx.mydomain.com
web2.tx.mydomain.com
#web3.tx.mydomain.com

As you can see, dsh handles comments in the hosts file. In the above example, the web3 server will be skipped since it's prepended with a comment. Let's say you want to check the uptime on all of the Texas servers as fast as possible:

dsh -c -g texas 'uptime'

That will run the uptime command on all of the servers in the Texas group concurrently. If you need to run it on two groups at once, just pass another group (eg. -g texas -g california) as an argument. You can also run the commands against all of your groups (-a).

The dsh command can really help you if you need to gather information or run simple commands on many remote servers. If you find yourself using it often for systems management, you may want to consider something like puppet.

©2010 Racker Hacker. All Rights Reserved.

Detaching from a screen session is done by pressing CTRL-A and then d (for detach). However, when I'm on my Mac, CTRL-A and CTRL-E send my cursor to the beginning and end of lines, respectively. Once I launch screen, I lose the CTRL-A functionality because screen thinks I'm trying to send it a command.

Luckily, this can be changed in your ~/.screenrc:

escape ^Ww

With this change, you can press CTRL-W, then press d, and you'll detach from the screen session. For all of the screen options, run man screen on your local machine or review the man page online.

©2010 Racker Hacker. All Rights Reserved.

How do I become a better systems administrator?

The best way to become a better systems administrator is to fully understand the theory of what's happening in your server's environment.

What do I mean by that? Learn why things aren't happening as you expected and think about all of the factors that could possibly be involved. Instead of thinking purely about cause and effect, you'll find it much easier and rewarding to consider everything inside and outside your environment before you make any changes.

This still may be a little difficult to fully understand, so he's an example. Let's say you're handling an issue where a customer can't reach a website hosted on their server. When you ask them for more details, they might give you the dreaded reply: "It's not coming up." Start by making a mental list of the problems that are easiest to check:

• Is the web server daemon running?
• If a database server is being used, is it running and accessible?
• Is there a software/hardware firewall blocking port 80?
• Is a script stuck on the server tying up resources?
• Could there be a DNS resolution problem?
• Is the server up?
• Did a switch fail?
• Is the server's hard disk out of space?
• Can the customer reach other websites like Google or Yahoo?
• If SELinux is involved, have the appropriate contexts been set?
• Could the site be a target of a denial of service attack?
• Has the server reached its connection tracking limit?

Of course, this is a relatively short list, but these are all easy to check. If you're thinking about cause and effect, you might only consider the web server daemon and some basic network issues. By considering all of the other factors that may be related, you've ensured that all of the basics are covered before you consider more complex problems.

Most systems administrators have taken an error message and tossed it in en masse into Google before. Occasionally, no results will appear for the search. If you find yourself in this situation, try to understand the individual parts of the error message. Work outward from what you know already. You should know which daemon said it, and you may have an idea of what the application was doing when the error occurred. Take time to consider what the daemon is trying to tell you within the context of what it was doing at the time.

One of the easiest ways to force yourself to be immersed into this way of thinking is to host applications for non-technical people. You'll find that many customers want things done differently, and they're all at different levels of technical aptitude. Some may find it a frustrating experience at first, but you'll think yourself later. It will force you to consider all aspects of how a server operates since you might not always know what's happening within a customer's application.

As always, if you find yourself stumbling, remember to ask your peers and colleagues. Even if they haven't seen the particular issue, they will probably be able to guide you closer to the solution you seek.

©2010 Racker Hacker. All Rights Reserved.

Parameter 1 to update_comment_type_cache() expected to be a reference, 
value given in wp-includes/plugin.php on line 166

The problem wasn't in a plugin, actually. It was within my theme's (R755-light) functions.php:

function update_comment_type_cache(&$queried_posts) {

The temporary fix is to remove the & from that line so it looks like this:

function update_comment_type_cache($queried_posts) {

After clearing out the WP Super Cache, the page was loading properly again. It turns out that the function actually calculates how many comments are available for a given post, so that functionality is working properly right now. A few theme authors are already releasing new versions to fix this bug, but my theme's author has not.

The credit for the fix goes to someone in the Wordpress forums.

©2010 Racker Hacker. All Rights Reserved.

The automatic upgrade via the admin interface actually worked just fine for me. Of course, I backed up my database and files first, just to be sure.

©2010 Racker Hacker. All Rights Reserved.

wget --quiet -O - http://www.kernel.org/pub/linux/kernel/v2.6/ChangeLog-2.6.31.8 | grep -A 4 ^commit | grep -B 1 "^--" | grep -v "^--"

It should give you some output like this:

    Linux 2.6.31.8
    ext4: Fix potential fiemap deadlock (mmap_sem vs. i_data_sem)
    signal: Fix alternate signal stack check
    SCSI: scsi_lib_dma: fix bug with dma maps on nested scsi objects
    SCSI: osd_protocol.h: Add missing #include
    SCSI: megaraid_sas: fix 64 bit sense pointer truncation
    ..

©2010 Racker Hacker. All Rights Reserved.

To reduce the total data downloaded, I'd recommend installing the yum-presto package first. It downloads delta RPM's and builds them on the fly, which allows you to upgrade packages without having to download the entire RPM's.

yum install yum-presto

Now, upgrade your current system to the latest packages and clean up yum's metadata:

yum upgrade
yum clean all

Get the latest fedora-release package and install it (replace x86_64 with x86 if you're using a 32-bit system):

wget ftp://download.fedora.redhat.com/pub/fedora/linux/releases/12/Fedora/x86_64/os/Packages/fedora-release-*.noarch.rpm
rpm -Uvh fedora-release-*.rpm

Now, upgrade your system to Fedora 12:

yum upgrade

For detailed documentation on the entire process, refer to Fedora using yum on the FedoraProject Wiki.

©2010 Racker Hacker. All Rights Reserved.

I recently picked up a Magic Mouse and discovered that I like almost all of its features. The biggest headache is the funky mouse acceleration curve that it applies by default. When you make small movements, they barely even register on the screen. When you make big movements and slow down a little mid-move, the pointer slows down much too rapidly.

A quick Google search revealed a support discussion post where users were discussing possible solutions. Someone suggested running this in the terminal:

defaults write -g com.apple.mouse.scaling -1

That improved things a little for me, but it's not perfect. If you adjust the tracking speed in System Preferences after running this command, the acceleration curve will be reset to the default.

Update: After some tinkering (and further Googling), I found that 0 or .1 seemed to work better for me than -1.

©2010 Racker Hacker. All Rights Reserved.

First, get your iptables rules set up the way you like them. Once you've verified that everything works, save the rules:

iptables-save > /etc/firewall.conf

Next, open up /etc/network/if-up.d/iptables in your favorite text editor and add the following:

#!/bin/sh
iptables-restore < /etc/firewall.conf

Once you save it, make it executable:

chmod +x /etc/network/if-up.d/iptables

Now, the rules will be restored each time your networking scripts start (or restart). If you need to save changes to your rules in the future, you can manually edit /etc/firewall.conf or you can adjust your rules live and run:

iptables-save > /etc/firewall.conf

Thanks to Ant for this handy tip.

©2010 Racker Hacker. All Rights Reserved.

Also, I've dropped the Adsimple theme I was using, and I'm now using a slightly modified Dojo theme. It's a little easier on the eyes, but it's still lightweight enough to be fast on mobile broadband connections.

Let me know what you think!

©2010 Racker Hacker. All Rights Reserved.

/load perl
/script exec $ENV{'TZ'}='(nameofyourtimezone)';

For example, I'm in Central Time, so I'd use:

/script exec $ENV{'TZ'}='CST6CDT';

To update the time in your status bar, simply /whois yourself and you should see the updated time zone. If you want more handy irssi tips, look no further than irssi's documentation.

©2010 Racker Hacker. All Rights Reserved.

This is not the usual type of post I'd make on this blog, but I'm trying to find a home for a lost dog that my wife found in New Braunfels, TX. More details are on my Posterous blog.

©2010 Racker Hacker. All Rights Reserved.

You could always pick up Boxcar [iTunes Link] from iTunes and use it's plug-and-play setup routine to begin receiving notifications of direct messages. The downside of the app is that the notifications are fairly delayed (sometimes 5-10 minutes late in my experience) and you're paying $2.99 for an app that can only handle one Twitter account. Also, the app only handles Twitter direct messages and replies - nothing else.

Here's where Prowl [iTunes Link] comes in. You can toss anything at the Prowl API and it comes up on your phone within seconds. The app is $2.99, but you can sent up to 1,000 notifications per hour through the API at no additional cost. Seriously - would you ever need 1,000 notifications per hour?

First, you'll need two ruby gems for this project. The first of which is the prowl gem by August Lilleaas, and the second is tmail. If you haven't installed gems from github before, you'll need to run this first:

gem sources -a http://gems.github.com

Install the gems:

gem install prowl tmail

Once they're installed, you can toss this script into /usr/local/bin/twitterdm-prowl.rb:

#!/usr/bin/env ruby
require 'rubygems'
require 'tmail'
require 'prowl'
 
message = $stdin.read
mail = TMail::Mail.parse(message)
 
prowlevent = mail.subject.gsub(/Direct message from /,'').strip
prowlbody = mail.parts[0].body.split(/\n\n/)[0].strip
 
Prowl.add('your-prowl-api-key-goes-here', {
  :application => "TWITDM",
  :event => prowlevent,
  :description => prowlbody,
  :priority => 0,
})

At the beginning of the script, we rope in rubygems, tmail and prowl. We're going to read a message in from standard input (I'll show you how that works in a moment) and then parse it with tmail. The subject and body are stripped down to make it easier to display on your iPhone's screen. Finally, we wrap up by sending the data to the Prowl API with a normal priority.

As far as customizations go, you'll obviously need to input your Prowl API key for the script to work. You can adjust the regular expressions to include different parts of the e-mail if you need them. Also, feel free to adjust the application name ("TWITDM") in the script to something else. The priority can run from 2 (OMG emergency) to -2 (I don't care). I chose 0 (normal) for my script.

Now, make sure the script is executable:

chmod 0755 /usr/local/bin/twitterdm-prowl.rb

We'll need to set up an alias in /etc/aliases to feed in this e-mails to our script:

twitterdm:	 "|/usr/bin/ruby /usr/local/bin/twitterdm-prowl.rb"

Run newaliases to ensure that your alias ends up in the hashed aliases table.

At this point, you'll need to ensure that your emails actually make it into the alias you set up. You'll need something that can filter your e-mails and forward them based on the filter. If you want a strictly Linux solution, you could use procmail for that. If you're e-mail provider has server-side filters that can forward e-mails (as mine does), that's the easiest method. Twitter provides some great e-mail headers that you can use for filtering:

X-Twittercreatedat: Sat Sep 19 17:26:31 +0000 2009
X-Twitterrecipientid: 14453057
X-Twitterrecipientscreenname: RackerHacker
X-Twitteremailtype: direct_message
X-Twitterdirectmessageid: 383469494
X-Twittersenderid: 25000734
X-Twittersendername: Major Hayden
X-Twittersenderscreenname: rkrhkr
X-Twitterrecipientname: Major Hayden

I use X-Twitteremailtype: direct_message to filter and forward, but it's up to you on how you do it.

Twitter direct message notification via Prowl

Now, use another account to send yourself a direct message and you should get a notification pretty quickly (see the image on the right). If you didn't get a notification, try going to the Prowl site and send yourself a test notification. If the test notification fails, then you may have an issue with Prowl itself (this hasn't ever happened to me).

If the test notification works, but your Twitter notifications don't, check your mail logs. Your filters may not be sending the direct message e-mails to your alias, your alias may not be configured properly, or the permissions on the ruby script you made may be incorrect.

If you want to keep testing without sending yourself a ton of direct messages, just send yourself one direct message. Once you receive the e-mail notification from Twitter, open it up and view the source of the message in your e-mail client (command-option-U in Apple Mail). Copy the entire source of the message to your clipboard, paste it into your favorite text editor on your server, and save it. You can call your script with the e-mail just like your mail server would with the following:

cat "twitterdmmessage.txt" | /usr/local/bin/twitterdm-prowl.rb

By going that route, you be testing the script itself, and your e-mail server will be removed from the equation.

If you're still having trouble, let me know and I'll be glad to help!

©2010 Racker Hacker. All Rights Reserved.

If you're using Snow Leopard, you'll find that the current version of MacFusion refuses to complete a connection to a remote server. You can fix this in two steps:

First, quit MacFusion.

Second, open System Preferences and then open the MacFUSE pane. Check the "Show Beta Versions" box and click "Check For Updates". Go ahead and update MacFUSE.

Third, open up a terminal and do the following:

rm /Applications/Macfusion.app/Contents/PlugIns/sshfs.mfplugin/Contents/Resources/sshnodelay.so

Your MacFusion installation should now be working on Snow Leopard. I've tested SSH and FTP connectivity so far, and they both appear to be working. Thanks again to Geoff for the fix!

©2010 Racker Hacker. All Rights Reserved.

[root@f11 ~]# /etc/init.d/httpd start
Starting httpd: [Fri Aug 14 17:05:24 2009] [crit] (22)Invalid argument: alloc_listener: failed to get a socket for (null)
Syntax error on line 134 of /etc/httpd/conf/httpd.conf:
Listen setup failed
                                                           [FAILED]

The issue is related to three kernel calls that are used in apr-1.3.8-1: accept4(), dup3() and epoll_create1(). Without these calls, apache is unable to start.

Update on August 17, 2009: the Fedora team has pushed apr-1.3.8-2 into the stable repositories for Fedora 11, which eliminates the need for the temporary fix shown below.

Deprecated solution: There is a bug open with the Fedora team, and there is a temporary fix available:

yum --enablerepo=updates-testing update apr

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# yum -y install mysql-devel

I'll assume that you already installed the rubygems package. You can install the mysql gem like this:

# gem install mysql -- --with-mysql-config=/usr/bin/mysql_config
Building native extensions.  This could take a while...
Successfully installed mysql-2.7
1 gem installed
Installing ri documentation for mysql-2.7...
Installing RDoc documentation for mysql-2.7...

©2010 Racker Hacker. All Rights Reserved.

If you haven't checked out bgplay, it's pretty handy.

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