May 2005
Intermediate to advanced
560 pages
15h 18m
English
Content preview from Classic Shell ScriptingBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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Chapter 15. Secure Shell Scripts: Getting Started
Unix security is a problem of legendary notoriety. Just about every aspect of a Unix system has some security issue associated with it, and it's usually the system administrator's job to worry about this issue.
In this chapter, we first present a list of "tips" for writing shell scripts that have a better chance of avoiding security problems. Next we cover the restricted shell, which attempts to put a straitjacket around the user's environment. Then we present the idea of a "Trojan horse," and why such things should be avoided. Finally we discuss setuid shell scripts, including the Korn shell's privileged mode.
Tip
This is not a textbook on Unix system security. Be aware that this chapter merely touches the tip of the iceberg and that there are myriad other aspects to Unix system security besides how the shell is set up.
If you would like to learn more about Unix security, we recommend Practical UNIX & Internet Security (O'Reilly).
Tips for Secure Shell Scripts
Here are some tips for writing more-secure shell scripts, courtesy of Professor Eugene (Gene) Spafford, the director of Purdue University's Center for Education and Research in Information Assurance and Security:[1]
- Don't put the current directory (dot) in PATH
Executable programs should come only from standard system directories. Having the current directory (dot) in
PATHopens the door wide for "Trojan horses," described in Section 15.3.- Protect bin directories
Make sure that ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.