Tag Archives | server

Unprivileged Unix Users vs. Untrusted Unix Users. How to harden your server security by confining shell users into a minimal jail

As a server administrator, I recently discovered a severe oversight of mine, one that was so big that I didn’t consciously see it for years. What can Unprivileged Unix Users do on your server? Any so-called “unprivileged Unix users” who have SSH access to a server (be it simply for the purpose of rsync’ing files) is not really “unprivileged” as the […]

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GDFL 1.2

Do not Panic! Remote Server (Hetzner) not rebooting any more – A Solution

I went through this experience recently. First of all, don’t panic! I panicked, and because of this, I made a mistake: I didn’t wait long enough for it to come online. Had I waited up to 60 minutes, it would probably have come online (see reason below). The story: I had broken packages on my Ubuntu […]

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Crash

Adventures with various Segfaults due to defective RAM

If you get various segfaults on your Linux server, like these:

or:

or

or

etc. etc., then, no, your system is not suddenly crazy. Nor are you. It is highly likely that you RAM is defective. You should reboot your server and run the  RAM test from your boot manager (Grub […]

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Setting correct file permissions for ssh is a bit tricky

File permissions for successful SSH login via authorized_keys

If you want to ssh into your server without being repeatedly prompted for the password you can copy your public ssh key into a file called authorized_keys  in the .ssh subdirectory of the home directory of the remove server account. However, this works only if the permissions for this file are set correctly. First, if you have […]

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Radio

How to set up audio streaming (internet radio) in Linux

This tutorial will show you how you can go live with your own internet radio station in a few minutes. Demystifying “streams” There is a lot of information, disinformation and irrelevant information about this in the internet. When you listen to internet radio, and you inspect the network requests in your Google Chrome Developer Tools […]

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Email logo

Setting up Exim4 Mail Transfer Agent with Anti-Spam, Greylisting and Anti-Malware

Recently my Exim mail server was hopelessly spammed to such an extent that I wasn’t even able to clear the mail queue with rm ./*, nor even list the files, nor even count the files with ls.  How still I managed to delete probably millions of mail files in one folder can be read in […]

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