2017-09-06 (last updated at June 22nd, 2018) Michael BoelenSystem Administration Leave a comment

Troubleshooting a full /boot partition on Ubuntu

A regular issue with systems running Ubuntu is that may fill up the /boot partition. You might have discovered it when running apt, which refused to work. That is unfortunate, as you also need apt to resolve the issue. After trying several options, we found a way to resolve this catch 22, with just three steps. Opposed to other solutions, you don’t need to move files or do other tricky things on your system. Still a word of caution: any tasks you […]

2017-03-21 Michael BoelenSystem Administration 8 comments

Understanding what runs on your Linux system (and why)

Linux processes and daemons Each Linux system has a bunch of processes running. Most of these processes might be familiar to you if you regularly use a command like ps or top to display them. Processes may look like just an item in a list. They are actually complicated pieces of code that are tamed by a memory manager. To truly understand how your system is running, knowledge of process (or memory) management is of great help. So let’s make […]

2015-07-06 Michael BoelenAuditing, Performance Leave a comment

The ultimate strace cheat sheet

Strace cheat sheet The strace utility is very powerful to learn what a new or running process is doing. Due to its diversity of monitoring options, the tool is less accessible at first. This strace cheat sheet helps with getting the best out of this tool. Normally cheat sheets come in a single 1 page PDF. In this case, we combined it all within a blog post. First section shows an explanation per area, the bottom of the post contains […]

2014-11-09 (last updated at February 18th, 2017) Michael BoelenCrypto, Problems 2 comments

GPG key generation: Not enough random bytes available.

Not enough random bytes available Generating keys with GnuPG Anyone who wants to create a new key set via GnuPG (GPG) may run into this error: We need to generate a lot of random bytes. It is a good idea to perform some other action (type on the keyboard, move the mouse, utilize the disks) during the prime generation; this gives the random number generator a better chance to gain enough entropy. Not enough random bytes available. Please do some […]

2014-03-02 (last updated at August 12th, 2018) Michael BoelenLynis

Lynis stuck during testing

Introduction Normal Lynis scans take a few minutes to complete, therefore any test taking more than 1 minute, might be stuck during its test. Within this article we have a look at a few things you can do. Stuck When a particular test is taking a long time, the test might be stuck. However, that’s not always the case. To determine what Lynis is doing, open up a second terminal and start with running ps aux to see what processes […]