Upgrading to centos 6.4 with shorewall onboard

In case you upgrade your CentOS 6.x box to version 6.4, the shorewall service might complain. With a scary message:

ERROR: Your kernel/iptables do not include state match support.
No version of Shorewall will run on this system

This is selinux at work, and the problem can easily be solved by running:

# restorecon -Rv /sbin

Thanks shorewall-users and

Happy hacking,



Fixing jerky scrolling in Firefox

Fedora did a lovely job of updating me to the latest versionĀ (v. 20) of Firefox. One problem I found, was that scrolling on certain pages was quite jerky. Performance was worse (or more likely) on pages with a frameset, and pages which were long. Pages with many images made this problem worse.

It turns out that the workaround is to disable hardware acceleration:


After you’ve unchecked this box, restart Firefox, and scrolling is now considerably smoother.

Hopefully this helped you out. Most likely there is some driver issue or deficiency with the X drivers. I’m using an excellent Thinkpad X201. I’ve also had at least two cases of X freezing while I was manipulating a Firefox window, so perhaps this is related, and hopefully this won’t happen to me anymore.

Happy hacking,



Knowing when to release and deploy your code (…and a mini script)

Knowing when to release and deploy your code can turn into a complicated discussion. In general, In general, I tend to support releasing early and often, for some value of $early and $often. I’ve decided to keep this simple and introduce you to one metric that I use…

I think that I am fairly diligent in adding plenty of comments to my source code. I might even sometimes add too many. I create plenty of XXX, FIXME, or TODO tagged comments as reminders of things to work on.

To me, XXX represents an important problem that should get looked at or fixed; FIXME, reminds me that I should definitely look into something, and finally, TODO gives me homework or things to pursue when I’m in need of a new project.

I try to resolve most if not all XXX tagged comments before making a 0.1 release, FIXME’s to consider something very stable, and a lack of TODO’s mean something is completely done for now.

To count all these, I wrote a little tool that greps through the top-level directories in my ~/code/ folder, and displays the results in a table. Feel free to give it a try, and use it for your own projects.

While I don’t see this as a particularly game changing utility, it scratches my itch, and helps me keep up my bash skills. The code is available here. Let me know if you have any improvements, or if the source isn’t enough documentation for you.

Happy hacking,