Finally, some good news for Apple fans who crashed System76 website a few days back. Apple makes a good laptop. However, they lack the option to add additional RAM or ports or graphics card. The new System76 Oryx laptop has a 4K HiDPI display. If you are a sysadmin, DevOps, or developer, give it a try to System76.
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, FreeBSD, and Unix-like systems are multi-user and need some way of authenticating individual users. Back in the old days, this was done in different ways. You need to change each Unix application to use different authentication scheme. Also, authentication schemes differed between a variant of Unix systems. Porting was a nightmare. For example to use Windows Server (Active Directory) or LDAP for authentication you need to make changes to an application. Each application had its way of authenticating users. So Open Group lead to the development of PAM for the Unix-like system. Today Linux, FreeBSD, MacOS X and many other Unix-like systems are configured to use a centralized authentication mechanism called Pluggable Authentication Modules (PAM). The book “PAM Mastery” deals with the black magic of PAM.