Here is a simple way to do post-mortem debugging for a program that crashes. First enable the saving of core files when program crashes by running the following command in shell before starting the program you want to test: ulimit -c unlimited When program crashes Linux creates core file named core to program running directory You →
Are you writing software that needs to be secure? Quite probably. Security critical programs include application programs used as viewers of remote data, web applications (including CGI scripts), network servers, and setuid/setgid programs. Secure Programming for Linux and Unix HOWTO — Creating Secure Software on-line book provides a set of design and implementation guidelines for →
A port scanner is a software application designed to probe a server or host for open ports. This is often used by administrators to verify security policies of their networks and by attackers to identify running services on a host. The de facto standard for port scanning always has been the venerable Nmap program. The →
News on the problems on Internet security have been very frequent during last 12 months, and there does not seem to be any stop on news on Internet security problems. The news started with NSA relevations that showed ho much NSA spied on the Internet users and how it has weakened the technologies used to →
Intel chip revenue declined in 2013 as worldwide total grew by five percent due to a focus on dwindling PC market. Intel is trying to get new growth by trying to enter actively to mobile and Internet-of-Things application. Internet of Things (IoT) is being driven by the convergence of increasingly connected devices, cloud computing, and →
I just watched though Linux Performance Analysis and Tools: Brendan Gregg’s Talk at SCaLE 11x. It is an interesting talk is about Linux Performance Analysis and Tools: specifically, observability tools and the methodologies to use them. It goes through over 20 Linux performance analysis tools, including advanced perf and DTrace for Linux, showing the reasons →
lsof is a very useful Linux command, which can be used to report a list of all open files and the processes that opened them. lsof is very useful in debugging because files in the Linux/Unix system include disk files, named pipes, network sockets and devices opened by all processes. lsof name comes from “list →
The TTY subsystem is central to the design of Linux, and UNIX in general. The TTY system in Linux is a throwback to when computers first because interactive in real-time,but is still very much relevant today. Unfortunately, its importance is often overlooked, and it is difficult to find good introductory articles about it. The TTY →
Some time ago I had to test several shell scripts how they affect the running environment on Linux. I ended up writing this simple script to help testing. This example script runs testsubject.sh script, and shows changes to enviroment variables the script causes. !/bin/bash # # Script to handle file sending to server # env →
In Linux system almost everything is a file. fsniper is a tool that monitors a given set of directories for new or modified files then applies rule based scripts. It is a very useful tool for handling files automatically when they are created. I have used if for many applications. According to fsniper documentation fsniper →