Linux

Memory management is one of the most complex activity done by Linux kernel. It has various concepts/issues associated with it. This article is part of our on-going UNIX kernel overview series. In the previous article of the kernel series, we discussed about the UNIX process overview, and Reentrant Kernels. In this article we will try [...]

In the previous article of this series, we explained how to prevent from SQL-Injection attacks. In this article we will see a different kind of attack called XXS attacks. XSS stands for Cross Site Scripting. XSS is very similar to SQL-Injection. In SQL-Injection we exploited the vulnerability by injecting SQL Queries as user inputs. In [...]

This article is part of our on-going UNIX kernel overview series. In the previous article of this series, we discussed about the UNIX process overview. This article explains on a high-level about Reentrant kernels, synchronization and critical sections of UNIX kernel architecture. Reentrant Kernels As the name suggests, a reentrant kernel is the one which [...]

A process is a running instance of a program. In this article we used two terms ‘program’ and ‘running instance’. Suppose we run a program simultaneously 5 times, then corresponding to each instance there will be a process running in the system. So we say that a process is a “running instance” of a program. [...]

There are times when you might want to profile your program on parameters like: Time taken by program in user mode Time taken by program in kernel mode Average memory usage by the program etc On Linux we have a utility ‘time’ that is designed specifically for this purpose. The utility ‘time’ takes a program [...]

Every Linux distribution have some kind of logging mechanism that records all the system activities. A while back we provided a list of 20 log files that are stored under /var/log that you might be helpful during troubleshooting. These logs are very critical for sysadmin for troubleshooting purpose. The following are the three common methods to log [...]

Though TCP protocol is a connection oriented and reliable protocol but still there a various loopholes that can be exploited. These loop holes are mostly explained in terms of attacks. In the previous article on the TCP/IP Attacks series, we explained about ARP Cache Poisoning. This article explains the following two attacks:  TCP sequence prediction [...]