From the Editor - Our Last Spam Issue?
Get a bunch of Linux professionals together these days and the topic inevitably turns to the spam problem. How much do you get, how many sneak through your filters and, of course, what are the bad things that happened to you when a spam filter decided to eat some important legitimate mail at the worst possible time.
If you're just getting your personal e-mail via POP or IMAP, spam might merely slow you down. But when you manage mail for a lot of users it's now a major cost. A flood of unsolicited bulk e-mail actually made an entire university's e-mail system obsolete. The bad news is that spam unfairly shifts the cost of marketing from senders to recipients. The good news is that Ludovic Marcotte's team made that cost as low as possible by deploying a reliable all-open-source mail system on Linux and commodity hardware. When you read the success story on page 44, notice that the site has planned to add more machines as the spam problem gets worse.
But there is hope for the spam problem to get better in the future. We won't go quite as ga-ga with “the end of spam is coming” predictions as some tech CTOs, but we can make spamming less lucrative for the perpetrators and maybe just another Net nuisance.
SPF fights forged spam by giving other sites' mail servers a way to check whether mail is really from you. Meng Weng Wong covered how to label your mail server as legit in our last issue, and now it's time to collect the benefits. Follow the steps in both articles and you'll quickly block out all the spam that claims to be from your own domain, then get more effective protection as more sites use SPF. If you're joining us in the middle, there's a link to the Web version of Part I.
System administration isn't all fun, glamour and beating back hordes of slavering spammers to the sounds of cheers and sighs of gratitude from spam-free users. So don't worry—we cover the important behind-the-scenes tools in this issue too. Now, time is only unidirectional in Stephen Hawking movies and reality. On your RPM-based Linux system, you can go back in time to correct a good upgrade gone bad. James Olin Oden describes how to do transactions and rollback with RPM on page 40.
If you want to get every last bit of the bandwidth you paid for, but not go over and hit steeper charges, check out the article by David Mandelstam and Nenad Corbic on page 54. Now you easily can make your Net traffic use whichever connection makes sense and use low-priced, small-business connections, such as DSL and cable modems, where you can.
Let's just take a moment to give thanks for the spammers while we have them. Think about it—we've learned to do groovy text classifying math, we've developed knowledge of the SMTP protocol and where future protocols can be better, and we've given users a new appreciation of where they would be without system administrators. Thanks, spammers.
Actually, no, on second thought, let's just put the parasites out of business. Enjoy the issue.
Don Marti is editor in chief of Linux Journal.
Practical Task Scheduling Deployment
July 20, 2016 12:00 pm CDT
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
Join Linux Journal's Mike Diehl and Pat Cameron of Help Systems.
Free to Linux Journal readers.Register Now!
- Paranoid Penguin - Building a Secure Squid Web Proxy, Part IV
- SUSE LLC's SUSE Manager
- Google's SwiftShader Released
- Managing Linux Using Puppet
- Murat Yener and Onur Dundar's Expert Android Studio (Wrox)
- My +1 Sword of Productivity
- Non-Linux FOSS: Caffeine!
- SuperTuxKart 0.9.2 Released
- Parsing an RSS News Feed with a Bash Script
- Doing for User Space What We Did for Kernel Space
With all the industry talk about the benefits of Linux on Power and all the performance advantages offered by its open architecture, you may be considering a move in that direction. If you are thinking about analytics, big data and cloud computing, you would be right to evaluate Power. The idea of using commodity x86 hardware and replacing it every three years is an outdated cost model. It doesn’t consider the total cost of ownership, and it doesn’t consider the advantage of real processing power, high-availability and multithreading like a demon.
This ebook takes a look at some of the practical applications of the Linux on Power platform and ways you might bring all the performance power of this open architecture to bear for your organization. There are no smoke and mirrors here—just hard, cold, empirical evidence provided by independent sources. I also consider some innovative ways Linux on Power will be used in the future.Get the Guide