My name is Philipp C. Heckel and I write about nerdy things.
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Yearly Archives / 2018

  • Aug 05 / 2018
  • 31
Linux, Security

Using Let’s Encrypt for internal servers

Let’s Encrypt is a revolutionary new certificate authority that provides free certificates in a completely automated process. These certificates are issued via the ACME protocol. Over the last 2 years or so, the Internet has widely adopted Let’s Encrypt — over 50% of the web’s SSL/TLS certificates are now issued by Let’s Encrypt.

But while there are many tools to automatically renew certificates for publicly available webservers (certbot, simp_le, I wrote about how to do that 3 years back), it’s hard to find any useful information about how to issue certificates for internal non Internet facing servers and/or devices with Let’s Encrypt.

This blog posts describes how to issue Let’s Encrypt certificates for internal servers. At Datto, we issued a certificate for each of our 65,000 90,000+ BCDR appliances using this exact mechanism.

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  • Mar 18 / 2018
  • 0
Linux, Virtualization

USB disk causes blinking cursor at boot; how to “fix” the MBR bootstrap code

Have you ever rebooted your computer only to see a black screen with a blinking cursor? If you have a USB drive attached, chances are the blinking cursor is caused by invalid bootstrap code in the Master Boot Record (MBR) on that drive which has caused the normal boot execution to stop without returning control to the BIOS. If you have physical access to the machine, simply remove the USB drive and/or change the boot order to pick the OS disk first.

If you have no physical access, things are a bit more tricky: This exact thing happened to me at work the other day. Unfortunately, it didn’t happen to my computer, but to a few dozen of our customer backup appliances during their scheduled upgrade/reboot. Now, while dozens out of over 60k isn’t that much, our customers rely on these devices, so it’s not acceptable to have them not boot properly.

In this short post, I’ll demonstrate how to reproduce the blinking cursor problem, and how to “fix” the MBR to ensure the computer still boots, regardless of the boot order.

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