Making the most of shared memory isn’t always easy. In this article, IBM’s Sachin Agrawal shares his expertise in C++, showing how the object-oriented among us can take key advantage of a uniquely useful interprocess communications channel.
Linux Tutorials
The hottest technology for implementing mobile services is the Wireless Application Protocol (WAP). This article discusses the advantages of working with the open source gateway for WAP, which performs the protocol conversion between a Web server and a mobile phone
Secure programs must minimize privileges so that any bugs are less likely to be become security vulnerabilities. This article discusses how to minimize privileges by minimizing the privileged modules, the privileges granted, and the time the privileges are active. The article discusses not only some of the traditional UNIX-like mechanisms for privileges, but some of the newer mechanisms like the FreeBSD jail(), the Linux Security Modules (LSM) framework, and Security-Enhanced Linux (SELinux).
You can change the output of the console keyboard with loadkeys. It’s an extremely powerful command, and the man page can be confusing, but for simple use (which is often all we need it for), it’s very easy.
Your PATH (echo $PATH) is where your shell will search for executables. If a command you want to run isn’t included in $PATH, you have to be specific: /somewhere/someprog. One confusion for Unix/Linux newcomers is that if PATH doesn’t include “.” (current directory), then trying to run a program you can see right in front of your nose with “ls” is going to generate a “command not found” message from your shell.
Syslog is a wonderful thing. In theory, it lets an administrator fully control where and how messages get logged. Of course, the first requirement is that the program you wish to control uses syslog for logging, but even assuming that it does, it can still be difficult to get what you want.
Functions are the wonderful and powerful building blocks of computer programs. Functions allow you to break code down into simpler, more manageable steps. They also allow you to break programs into reusable parts — parts that are both reusable within the program and in other programs as well. In this article, learn how to create new functions at runtime based on templates, how to create functions that are configurable at runtime using function parameters, and how the Scheme language can be a valuable tool with functions.
Most Unix systems have some way of letting ordinary users perform certain tasks as root or some other privileged user. SCO Open Server has “asroot” and can also directly assign “authorizations” such as backup privileges or being able to change other user’s passwords. SCO Unixware/Open Unix 8 have a similar facility in “tfadmin”. Many Unixes, and Linux, use “sudo”.
The Openwall Project provides security related kernel patches for Linux and BSD kernels. I read about this in Hardening Linux by James Turnbull. The patch that most interested me was to prevent executable code from running in the stack. That won’t prevent all buffer overflow attacks, but it can stop some of them. I really don’t understand why this isn’t just the default nowadays – I know it can break some programs and debuggers, but it seems smart to me
If you don’t want core files at all, set “ulimit -c 0″ in your startup files. That’s the default on many systems; in /etc/profile you may find
