Category Archives: Computer

The importance of staying with linux built-in package management…

I just upgraded my Fedora server from 20 to 22.  (I know that I have procrastinated..)  A couple issues were encountered.  The first of which was fairly catastrophic.  After the usual fedup (FEDora UPgrade, which by the way was rather short-lived, from FC18 until FC21, being replaced along with yum by ‘dnc’) stuff, upon reboot, the server hung when it was trying to load the Gnome Desktop Manager.  I really think that was probably a problem with Gnome 3 and my hardware (since I could log in fine using ssh), so I got around this by the following:

# sudo dnf install lightdm lightdm-gtk

# sudo sustemctl disable gdm

# sudo systemctl enable lightdm

(If you haven’t set up sudo, you really should)  After those steps, a simple reboot, and presto!  Finished booting just fine.

The next problem encountered was one that fully illustrates the importance of staying within a modern Linux distribution’s built-in package management system….

Modern Linux Distributions use package managers, a partial list follows:

RPM: Used by RHEL, Fedora, CentOS, Yellow Dog, OpenSUSE….

DEB: Used by Debian and Ubuntu, Mint, SteamOS, Trisquel….

(Those were the ‘big two’, encompassing many different distributions, but there are many more….

Most people know that my server handles an icecast/ices streaming server.  However, ices 0.4 refused to start, giving the following error:

/usr/local/icecast/bin/ices: error while loading shared libraries: libperl.so.5.18: cannot open shared object file: No such file or directory

As part of the upgrade, perl was upgraded from perl 5.18 to 5.20, and libperl.so now points to libperl.so.5.20.  The problem arose from the fact that ices 2 is the version in the package repository.  However, it has no mp3 support, instead streams ogg.  So, for that reason, I had compiled by hand ices 0.4.

So, the only way to fix this libperl issue was to re-compile ices. (A good reason to keep the src of programs that you compile in your /home dir).

So, I jumped to the ices0.4 subdirectory and did the following:

# ./configure    (so that ices would pick up the new perl library)

# make

# sudo make install

After that, everything is fine, but, as I’ve always said, in a modern Linux distribution, try to minimize hand compiled programs.  Not always possible, but definitely preferred.

😎

prune (shear) command

Well, I successfully managed to get the one line command I wrote to successfully delete all security camera entries older than 100 days.  The directory had grown to about 300GB, encompassing 14 months, so it was time to weed things out a bit.

The command I wrote into an executable file in my personal path was:  find $1 -mtime +100 -exec rm -R {} \;

I saved it in my path and called it prune.  The syntax it was to expect was:  prune <directory to prune with trailing />  I was then to remove all files and directories older than 100 days.

However, it didn’t work.  I scratched my head for awhile, discovered it worked if I manually typed in the find string.  Sometimes I can be such a dumb ass.  I didn’t realize that there already was a prune command in /usr/bin/ for some kind of graphing functions.  So, I renamed MY prune command to shear, and everything works as expected.

Oh, the 300GB of security camera video was reduced to 60GB.  My next step will be to put it in a cron, so that it’s automatic….  Too  bad that I’ll never get that 45 minutes back, LOL.

CRAB server firewall.iptables now fixed, so it will restart without a reboot.

For those of you familiar with my Linux server, y’all know that I run many custom BASH, Perl, and Python scripts.  We are going to discuss today my iptables firewall script, or actually the fact that I took the time to repair it.   Since upgrading the server to Fedora 20 in September 2014, my firewall script would start fine, but would choke on restarting, reloading, or running it over itself.  The end result would be that the server would sever all ports with the outside, effectively taking it down, needing a reboot to get it back online.  This was a real PITA, since I couldn’t really make any changes to the firewall without reboot.  I thought it was an end result of the OS changing from SysV init scripts to a systemd system.  How wrong I was….  The cause was simply a typo that I made while adding a feature, and a ‘done’ without a ‘while’ and a ‘fi’ without an ‘if’ stopped the script from accepting the restart and reload argument.  Most of the iptables rulesets were created before this typo, so it gave the ‘appearance’ that it was working properly.  Debugging a script of this size is a fairly daunting task, as the main firewall script is a healthy 50 pages, and its configuration file (one of a half dozen helper files) is about 7 pages long.  Since I’ve had a few questions about this firewall, I’ll share it with everybody…..

Download links are only viewable to logged in users.  All the other helper files, as well as these are all available upon request.  If you are a logged in user, and downloading these files, remove the .txt extension from the config and main files….

This is the screen information if the VERBOSE variable is set to 1 (Select the pop-out gadget to see this properly formatted)

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This is the configuration file that allows for easy firewall config.     (Select the pop-out gadget to see this properly formatted)

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This is the MAIN iptables firewall script that should be run at start.  (Select the pop-out gadget to see this properly formatted)

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All in all, it was a fairly productive week off.  I have a few other minor syntax errors to chase down, but the firewall is operating within normal parameters…..

 

Security Camera BASH script to merge Zoneminder events into mp4 videos

The following script is a BASH (Bourne Again Shell) script that will take zoneminder camera events and merge them into mp4 videos that can easily be archived, or viewed.  The script will also ftp the resultant videos to a remote ftp server.

Zoneminder is a bit cumbersome to locate a particular event or time using the mysql events, or the ZM timeline, but this script streamlines that a bit, allowing you to use VLC or whatever and speed it up to ‘scan’ your day’s or week’s events…..

Very easy to configure as everything is set up using variables.  The script will create a directory name of the current date that it’s run under your home directory, or wherever you choose.

I have it set to run as a cron event daily, but you can set it to run weekly or how often you choose by changing the mtime value, and configuring the cron event to match.

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So as not to fill up the FTP server, I wrote a prune command that will delete those videos older than 60 days.  Also set to run as a cron event on the FTP server.  It will accept the following syntax:

/path.to.prune/prune </directory.path.containing.video.directories/

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Download

You will need to strip the .txt from both scripts and set them to chmod 700 and run them under the cron of the proper user.