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FyhTech

Fun with Linux

Third Anniversary

Even if I was a little bit lazy and did not write much lately, I am very proud to announce the third anniversary of this blog.

Managing MaraDNS with Ansible

I wrote a role for managing MaraDNS with Ansible.

Requirements

Ansible 2.1+ (might ork with prior versions too)
Debian-based Linux-distribution

Installation

ansible-galaxy install whotwagner.maradns

check_mk-rbl - A check_mk-plugin that monitors public ipv4 addresses

Check_MK is a great monitoring tool. One of it's strengths actually is, that it can automatically detect services and monitors it. I always monitored all public ip-addresses of my servers if they are listed on any dns-blacklist. I had to add new public ip's manually, so I reached out for a new solution. I found a nice little plugin in a GitHub-repository of HeinleinSupport. The plugin waIs great, but I missed two things.

OpenElec: CVE-2017-6445 revisited

A few months ago I published a vulnerability in OpenElecs updater. I successfully hacked remotely OpenElec version 6.x.x and 7.x.x . OpenElec 8 is available for a while and reached version 8.0.4. So I tested the bug against this version and it's still open. An attacker who is Man-In-The-Middle can remotely compromise Openelec-Updates and plant a reverse-shell on the target.

Debian Stretch released

On Saturday the Debian Project announced the release of Debian 9 "Stretch". This means that Jessie will be oldstable and Wheezy won't recieve any updates anymore. So it's time to dist-upgrade.

Using the new statx() system-call

To get a feeling for statx() and to learn how to use it, I wrote a little statx()-application and published it on github. At the moment the glibc doesn't support statx() so I had to use the generic syscall()-function and create my own statx()-header-file to make it work.

Impressions of the Open Source Datacenter Conference

osdc2017

Kernel-Programming: execute call_usermodehelper() within a systemcall

In kernel-programming we should avoid doing call_usermodehelper() which allows to execute a command from kernel-space. And sometimes we even want to call this function within a systemcall. Normally, we really don't wanna do this. But, desperate times require extraordinary methods.

When I first tried to execute call_usermodehelper() within a systemcall() I got a kernel failure. So I googled and what I found was:

Containers explained in 500 lines of code

I am currently writing a work about containers and I found this amazing blog which explains containers in 500 lines of code(and about 3000 lines of very well structured text). I can definitely recommend Lizzies-Blog.