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Ready To Unplug And Find Another Conduit For Your Passion? Click On Any Picture Below! Click On Any Picture Above To Enjoy A Good Read Of Varying Length!
I actually have some stuff to write today, and was going to write it, but while I was trying to figure out an issue at work (that, strangely enough, had absolutely nothing to do with the topic of this post ;), I happened upon a great article, regarding novel uses of dd and text-based web tools like curl and wget, over at omnipotent.net's Linux article section
The trick it describes is one you may have heard of before, or put into practice, but I liked the author's enthusiasm for the subject matter (which comes through in the writing - along with many links to other interesting pieces) and thought I'd table my own meandering thoughts for a day and turn you on to someone else's ;)
I've included the introduction below. Follow this link, or the link at the end of this section, to continue reading. In fact, just click the link. All the really cool stuff follows the opener, although it sets up the mood quite nicely :)
Enjoy and cheers,
Surprisingly, I got quite a bit of response from my last piece, "Stupid Linux Tricks." That article was something I'd dashed off at the last second because I hadn't thought of anything provocative or rant-worthy to write about. Still, it seems to have hit an interesting chord with quite a few people. The idea that the best way to convert a person is to demonstrate some of the incredibly cool, useful, or just plain well-designed stuff about Linux. So, since I'm out of ideas this week too, I'll do something similar -- but instead concentrating on some of the smaller tools and what they can do. Let's face it: Unix isn't a single, large product -- it's a fantastically modular system. It's so modular, in fact, that every component can in theory be replaced! So much so, that there is no single part of the Unix architecture that can, strictly speaking, be called Unix. The Linux kernel is just an implementation of an API, and an abstraction layer for hardware. That's not Unix. Neither are any of the potentially thousands of programs that make up Solaris, Linux, BSD, or any of the other ones. Any individual component is trivial, and is a part of a larger, cohesive whole.
Within that collective framework of tools, the user learns how to take advantage of them, one by one, learning how they interact and lock together, and their purposes and use. Often, a tool is used for purposes very unlike its intent. Almost frighteningly so, in fact. Very impressively so. Showing someone what these tools, few of which work as well as eye candy, can do to make your life easier is how you "clinch the sale" so to speak. So what if Linux can do all these cool things to impress people? Now you have to show them what it can do to make their lives easier in some small way... CONTINUE READING...
Every once in a while, it's good practice to take a look at any system you have setup (whether it be a single system, business process, program or computing environment) and make sure it's doing okay. Some sort of regular auditing also helps to find out if there are any areas in which you can make an improvement or fix errors.
One of the areas that seems to require looking over more consistently, is your DNS setup. New versions are released regularly, bugs are found just as regulary, and acceptable syntax can sometime change between releases and/or RFC's.
Note for today's script - It is intended only for your benefit, and I strongly urge you to use any free DNS reporting service you can find to accomplish what we're accomplishing here. I neither work for, nor do I do any afilliate marketing for, www.dnsstuff.com. We only use it where I work, because it's the standard. Probably, most readers already know about it. The site tools require a free registration, if you're not a paying member, but also require a payment for use after 30 DNS Reports. I have placed a very obvious "COMMENT" in the script above the only line you'd need to change to use another service. If you "do" find something equal, or better, I would recommend that you use it (and, maybe, send me an email to let me know the URL so I can check it out and update my scripts, too :) That being said, I'm not trashing them either. If you have to do this sort of thing a lot(for your employer, lets say), the company can probably shell out a few bucks a month for the service. It's worth the price if you need to use it regularly.
Aside from your own internal auditing, it's good to get a fair and objective third-party assessment of the state of your DNS setup. A great site to get this accomplished on the web is located at http://www.dnsstuff.com. They have a tool called "DNS Report" (which used to be its own domain - www.dnsreport.com) which can be used very effectively, even if you choose not to be a paying member of the site. A long long time ago, it was available to everyone for free, but since it's pay-for now, you really have to be careful not to deluge it with requests to check your DNS zones (all 30 of them, if you're doing this for free), or you'll get dumped on their blacklist and barred from using the service at all.
The little Perl script I've written below will help you to automate the usage of that web service for all of your DNS zones. The reports are nice and easy to understand, even for the highest of higher-ups (green = good, red = bad ;) and the service does a very good job of pointing out weaknesses, or areas that don't conform to current RFC expectations, in your DNS zones. This script does require that you have Perl installed (although it's just a script I whipped up so it's submitted under GPL (Gnu Public License), at best, and you can feel free to rewrite it to suite your own needs). It also makes use of curl. You can substitute lynx or wget or any other program that can download and save web pages to your Unix/Linux hard drive. And here it is, below (Please read the comments regarding use of dnsstuff's dnsreport tool):
# # 2007 - Mike Golvach - eggi@comcast.net # # Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License # # Registration is now required to use this tool - It used to be free. # When/If you register, be sure to uncheck the two opt-in mail # checkboxes at the bottom unless you want to receive those emails. # # Login to dnsstuff.com before running this script or it will just return # a page indicating that you need to log in before submitting a full request # without that request being linked to from one of their pages # # Simple Error Checking here, just want to be sure that a file exists at all. # Disregard everything else on the command line. This script will fail if the # file named on the command line doesn't include one URL per line, anyway :)
foreach $url (@url_file) { print "$url"; $| = 1; if ($pid = fork) { if ( $counter = 900 ) { $counter = 120; } else { $counter = $counter+60; } print "next\n"; } else { close (STDOUT); chomp($url); # # COMMENT <--- The Obvious One :) # CHANGE THE URL ON THIS LINE TO THE URL OF ANY OTHER SITE YOU FIND THAT # PROVIDES AN EQUAL SERVICE! # @output = `curl http://www.dnsstuff.com/tools/dnsreport.ch?domain=$url`; open(OUTPUT, ">$url.htm"); print OUTPUT @output; close(OUTPUT); exit(0); } if ( $counter = 900 ) { $counter = 120; } else { $counter = $counter + 60; } sleep $counter; } exit(0);
And that's that! As I mentioned before, this tool will blacklist you if you hit dnsstuff too hard. My script assumes that you can hit the site at the rate I used last time I used it. Since it's a pay-for service now, I would recommend changing the wait times to at least twice as much. To give you an idea, I ran this when the service was free and ended up getting blacklisted in a under a few hours. Granted, there were certain other factors that contributed to my getting the boot; most prominently that I was checking the DNS for about 300 to 400 zones we were hosting. It could have been left at checking one and making sure all the others were the same, but, as noted above, some bosses like to see reports with lots of colors and lots of pages.
Also, just so you don't feel like I'm leaving you in a lurch, if you do happen to get blacklisted, just go to their member forums (you get access to post to these since you had to do the free registration - you can only browse them if you're not registered) at http://member.dnsstuff.com/forums/ and do a search on "banned," "blacklist" or "black list." Most folks just have to start a thread and request their access back in order to get off the blacklist.
