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People are creatures of habit. That assertion has both good and bad connotations. The good is that we tend to do things the same way every time we do them. The bad part is that we don't tend to venture out from our routines. That routine keeps changes consistent and surprises to a minimum. The last thing any sysadminwants to hear another sysadmin say is, "Whoops." But, that's a whole other story. Today's topic is unfamiliar commands. Six unfamiliar commands to be exact. I think you'll like these because they're useful and outside the peripheral vision of most sysadmins.
For most of my Linux-oriented career, the X protocol (TCP port 6000-60nn) that runs over the network has not been allowed. Most security policies ban the X protocol and have it silently blocked on network equipment. I guess I'm OK with that. I've mildly argued the point a few times but I generally accept the walls in which I must operate.
The uptime command is straightforward and simple, but it can still be nice to see how some sysadmins use these common tools. Documenting the system's uptime may be important for service level agreements, performance monitoring, and general troubleshooting.
Scripting is one of the key tools for a sysadmin to manage a set of day-to-day activities such as running backups, adding users/groups, installing/updating packages, etc. While writing a script, error handling is one of the crucial things to manage.
This article shows some basic/intermediate techniques of dealing with error handling in Bash scripting. I discuss how to obtain the error codes, get verbose output while executing the script, deal with the debug function, and standard error redirection. Using these techniques, sysadmins can make their daily work easy.
There are certain commands or tricks that you start using as a sysadmin, which you simply incorporate into your arsenal and never really stop to analyze in-depth all the options or alternatives to them.
Ansible is a configuration management tool. While working with Ansible, you can create various playbooks, inventory files, variable files, etc. Some of the files contain sensitive and important data like usernames and passwords. Ansible provides a feature named Ansible Vault that prevents this data from being exposed. It keeps passwords and other sensitive data in an encrypted file rather than in plain text files. It provides password-based authentication.
If you're working on a cloud environment that requires the Continuous Integration (CI) process from CI/CD, you need to consider how to store and manage the built packages. What do I mean by packages? These packages can be archive files like WAR or EAR files for Java, but they can also be containerized images that include the compiled sources combined with a programming run time. They might also be base images like NodeJS, CentOS, RHEL, Windows, Python, etc.
Editor's note: This is an opinion piece and meant in a spirit of good humor. Do you have a different set of tools you never use? We invite guest articles via enable-sysadmin@redhat.com.
Public key infrastructure has some known weaknesses. See how Certificate Authority Authorization and Certificate Transparency help strengthen certificate infrastructures.
This article is Part 3 out of three in my series about SSL/TLS encryption. Part 1 covers the basics of well-known encryption concepts. Part 2 gives a brief introduction to OpenSSL and PKI. This part broaches the issue of PKI weakness and introduces two countermeasures.
In my Static and dynamic IP address configurations for DHCP article, I discussed the pros and cons of static versus dynamic IP address allocation. Typically, sysadmins will manually configure servers and network devices (routers, switches, firewalls, etc.) with static IP address configurations. These addresses don’t change (unless the administrator changes them), which is important for making services easy to find on the network.
