Some hypervisors for virtual machines do not properly support sending a fake system time to the guest operating system, thus making Windows guests display the wrong time if their timezone is set to anything except UTC. This happens because Windows, by default, keeps the system clock set to the local time. This is stupid. The […]
I was recently tasked with creating a local CA for a project, where we needed to verify custom client certificates, have the ability to revoke them at will, and we wanted to add additional custom fields to the certificates. Cool. The first stop after searching a bit was this excellent howto by Jamie Nguyen. There’s […]
UPDATE: See the automated script at https://blog.dhampir.no/content/script-for-creating-a-compressed-image-file-from-a-raspbian-sd-card Raspbian, by default, expands to fill the SD card it finds itself on, the first time it boots. After having customized an image to your liking it would be favourable to avoid copying 16 gigabytes of data, or however large your chosen SD card is, each time you […]
Following up on my recent post about making a minimal VPN routing virtual machine to isolate obnoxious VPN clients, another problem you’ll run into if you have the need to connect to a whole lot of client networks is that the networks of different companies tend to overlap, either with your own or with eachother. […]
After it was requested multiple times on my post about using pfSense as a Cisco AnyConnect VPN Client, I finally found some time to document the setup I ended up with as a replacement, the purpose of which was to not clutter up the pfSense box. pfSense, after all, acts as the main company router […]
I write shell scripts. A lot of them. I automate everything with scripts. Many of these scripts need to have some notion of a state. The state needs to be persistent. How do we do that? And could we draw some retro flashback line character table borders while we’re at it? The problem If I […]
I was recently debugging a case where a customer’s installation was hanging due to a database lock. The issue turned out to be that the database was not set to a default transaction level of READ COMMITTED SNAPSHOT, which the product expects. Regardless, while troubleshooting the issue, I stumbled upon a very useful SQL query […]
When configured as a router, for instance for hosting virtual machines with KVM, a Debian machine with a somewhat recent kernel will not listen to router advertisements from others. This makes sense in many cases, but when you have a VM host in your internal network, which only router function is to allow communication to […]
Exim4 introducted new behaviour in the versions included in Debian Stretch. Suddenly, the RFC max line length of 998 characters is enforced, and emails with lines exceeding this length are returned to sender. For the interested, part of the discussion about this feature is over here: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=839147 Anyway, the solution to this issue in Debian […]
Before reading this, please note that much of the information in mcelog is hardware dependent. Your mileage may vary. Memory gone bad So one of the servers, running an X99-WS/IPMI board from Asus, began putting errors into /var/log/mcelog. Thankfully, they were all the same, telling me the following: mcelog: failed to prefill DIMM database from […]