Missing CGI.pm and Other Mysteries
While we're on the subject of security, this is probably a good time for me to publicly wipe away some of the egg that remains on my face in the wake of my February column, in which I suggested that you should install CGI programs with permissions of 777, known to non-numeric types as “a+rwx”, or permission for all users on the system to read, write, and execute the program.
Suffice it to say that this is a grave error, as several readers noticed. Computer security depends on plugging as many holes as possible. On networked multiuser systems running programs that come from various sources, it's almost certainly a bad idea to install a program having permissions that let anyone on the system modify the contents of that program, particularly when a simple (and probably hard-to-notice) modification or two can turn a seemingly innocuous program into a ravenous bug-blatter beast. On a system not running one of the wrappers mentioned here, all CGI programs are run with the same permission, meaning that someone could write a program that can mess with the code or data of another.
If you are the only programmer working on a particular CGI program or Web site, then you can install your programs with 755 permission (u=rwx,ga+rx), so that others on the system—including the HTTP server, which is generally responsible for running CGI programs—can read and execute your code but cannot modify it.
If you are working with others on a site or CGI program, you can set the permissions to 775 (ug=rwx,a+rx), which lets everyone read and execute the program, but allows only the owner and members of the file's group to edit it.
There are probably times when it is appropriate to install a CGI program with 777 (a+rwx) permission, but these are rare.
That's it for the mailbag for this time. Next month, we'll return to a discussion of how to make life easier for non-programmers who might want to modify entries in tables on disk, by writing a few small CGI programs which can read and write files efficiently and easily.
Reuven M. Lerner has been playing with the Web since early 1993, when it seemed like more like a fun toy than the World's Next Great Medium. He currently works as a independent Internet and Web consultant from his apartment in Haifa, Israel. When not working on the Web or volunteering in informal educational programs, he enjoys reading on just about any subject, but particularly politics and philosophy, cooking, solving crossword puzzles and hiking. You can reach him at email@example.com or firstname.lastname@example.org.
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!
- Google's SwiftShader Released
- SUSE LLC's SUSE Manager
- Interview with Patrick Volkerding
- My +1 Sword of Productivity
- Murat Yener and Onur Dundar's Expert Android Studio (Wrox)
- Managing Linux Using Puppet
- Non-Linux FOSS: Caffeine!
- Tech Tip: Really Simple HTTP Server with Python
- SuperTuxKart 0.9.2 Released
- Parsing an RSS News Feed with a Bash Script
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