Entropy is nothing but the measure of "randomness" in a sequence of bits. The PRNG ( pseudorandom number generator ) is a special device (e.g. /dev/random on Linux) to create randomness from server hardware activities. It uses interrupts generated from the keyboard, hard disk, mouse, network and other sources. The random number generator gathers environmental noise from device drivers and other sources into an entropy pool. The randomness usually used for security purposes like creating TLS/SSL keys and the quality source of random bits is critical. For example, OpenSSL APIs can use quality randomness to make your program cryptographically secure. However, a poor source of randomness could result in loss of security. In this post, I will cover haveged and rng-utils/rng-tools to generate random numbers and feed linux random device for your virtual or dedicated Linux server.
Linux How-To Articles and Guide
Tutorials, tips, and guides for users of Linux operating systems.
Google Chrome has "Chrome PDF Viewer" to view or open pdf files. It is an unwanted feature. I do not need it at all. I want my PDF open in Preview on a MacOS X or default pdf viewer in Linux. This feature was hidden. I want to disable it from my Google Chrome browser because it was slow scrolling with a large pdf file sizes.
We have a couple of virtual servers hosted with Softlayer for processing data and backup purpose. The public interface is completely turned off i.e. no Internet access. We can only access VMs using a VPN. It resulted in decreased costs and many security problems for backend servers. However, when you order "Private Network Only" cloud VM, you cannot route outgoing traffic to the Internet using your VM.
The Debian GNU/Linux project has released an updated version of its stable distribution Debian 8 ("jessie"). You must update to get corrections for security problem as this version made a few adjustments for the serious issue found in Debian 8.2.
Rolling back to the previous version may solve the problem or free the disk space. Both CentOS/RHEL support rollback feature, but I learned hard way both Debian and Ubuntu does not support rollback feature yet.
I use the gpass password manager to store my randomly generated unique password for each site. However, many sites such as net banking prevent you from pasting a password when signing up. The site owner or webmaster disables pasting into password input fields. Want to paste your password on such site? Give it a try to don't f*ck with paste Google Chrome extension.
Tape devices should be used on a regular basis only for archiving files or for transferring data from one server to another. Usually, tape devices are all hooked up to Unix boxes, and controlled with mt or mtx. In this tutorial you will learn about:
- Tape device names
- Basic commands to manage tape drive
- Basic backup and restore commands
For new computer or Laptop or server, I need to collect the information about its hardware. This is also useful when you need to replace a disk or memory with a vendor. In order to replace hardware you need all information in advance. In this post, I'm going to list commands that you can use to collect the hardware information.
Bash (Bourne-Again SHell) is a Linux and Unix-like system shell or command language interpreter. It is a default shell on many operating systems including Linux and Apple MacOS X. Shell scripts are a fundamental part of the Unix programming environment.
If you have always used a graphic user interface like KDE or Gnome or MS-Windows or Apple OS X, you are likely to find bash shell confusing. If you spend some time with the bash shell prompt and it will be difficult for you to go back.
Here are a list of tutorials and helpful resources to help you learn bash scripting and bash shell itself. You should read the following documents if you are interested in learning the basics of shell scripting.
On a Linux or Unix-like systems each user and process runs in a specific environment. An environment includes variables, settings, aliases, functions and more. Following is a very brief introduction to some useful shell environment commands, including examples of how to use each command and setup your own environment to increase productivity in the command prompt.