A new version of the Raspberry PI 3 model B+ has released, and it is incredible update over the older model. Just over two years ago, I got Raspberry Pi 3 Model B. It was my first 64-bit ARM board. It came with 64-bit CPU. Here are the complete specs for updated 64-bit credit card size computer.
Exim is a free and open source message transfer agent (MTA) developed at the University of Cambridge. It is famous on Unix and Linux systems connected to the Internet. It is freely available under the terms of the GNU General Public Licence. There is a buffer overflow in base64d() of Exim MTA that allows an attacker to run code remotely. ALL versions of Exim MTA affected by overflow vulnerability i.e. CVE-2018-6789.
Continue reading “400K+ Exim MTA affected by overflow vulnerability on Linux/Unix”
I like htop interactive process viewer. Recently I found another one called gtop. It is similar to top, but fancier. Let us see how to install and use gtop on a Linux or macOS Unix based system.
Linux/Unix sysadmins have a weird obsession with server uptime. There is a xkcd comic devoted to this subject where a good sysadmin is an unstoppable force that it stands between the forces of darkness and your cat blog’s servers.
One can tell how long the Linux system has been running using the uptime command or w command or top command. I can get a report of the historical and statistical running time of the system, keeping it between restarts using tuptime tool. Like uptime command but with the more impressive output. Recently I discovered another tool called uptimed that records statistics about a machine’s uptime. Let us see how to get uptime record statistics using uptimed and uprecords on Linux operating system.
Recently I created a simple shell script called backup.sh in /root/scripts directory to just backup MySQL database and dumped it to /nfs/mysql/ directory. I put a file (more like used the ln command to create a soft link ) in /etc/cron.hourly/ and it doesn’t run. There was no error in systemd log or cron log. Why is my cron job was not working, and here is how I troubleshoot it.
There is a serious vulnerability in sudo command that grants root access to anyone with a shell account. It works on SELinux enabled systems such as CentOS/RHEL and others too. A local user with privileges to execute commands via sudo could use this flaw to escalate their privileges to root. Patch your system as soon as possible.
In the world of mail servers, there are many software and technologies. Here is a list of 3 of them that you must know.
Raptor Engineering is working and crowdfunding a high-end power8 based desktop computer with zero proprietary firmware blobs in the Talos Secure Workstation. Traditionally IBM, Oracle(Sun), Intel/AMD and others ruled this market segment. But now there is competition to Intel for a desktop computer.
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.