Virtualbox to 4.2.12 problems with Ubuntu

After updating Virtualbox to 4.2.12 and updating the guest additions on my Ubuntu 12.10 the guest suddenly started having problems with the graphics driver ( wouldn’t start correctly, only starts in “rescue” mode). I did a bit of googling, and it seems other users are also affected (mainly 12.04 and 12.10 Ubuntu), and it seems to affect people who upgraded from virtualbox guest addditions 4.2.10 -> 4.2.12

Here the quick and dirty workaround to the problem: download the 4.2.10 guest additions and use them.

Will need to reboot or make sure the new modules are loaded and restart X afterwards.

Script to start minion in tmux

Minion is a security project from Mozilla (link). It provides a user-friendly web interface to various security scanner tools. There is a webcast demonstrating the software (link).

The software requires a few services to run, and since I like having one script take care of starting everything with the right parameters, I threw together a simple shell script that sets up a tmux session with the services started in windows with the names of the services.

How to break down CIDR subnets in Bash

I was playing around with subnets in bash recently and needed an elegant/easy way to split up a subnet into smaller subnets. First I used 2 functions I found on to convert an IP addresse to and from an integer. After that it was just a bit of math in bash to split up any networks too big.
Any network larger than $maxSubnet gets split up.
Here the useful code:

Output of script:


How to get the intersecting area of two polygons in MySQL

I was playing around with spatial features of MySQL this weekend and stumbled into a problem where I was looking for the area of two rectangles that overlap.  MySQL provides a function to check if they overlap, but no function to extract the region that overlaps.

I’ve never written a stored routine in MySQL before, so I decided it would be a good exercise to try making one. As you can see the function is pretty straightforward and it assumes you are working with rectangles, but other than that it does what it is supposed to.
You pass the function 2 polygons (e.g. Intersection(a.poly,b.poly)), and it returns the intersecting area as a new polygon.

Example comparing some rectangles in 2 tables using the function:



Updated OSSEC Web UI 0.3 files for OSSEC 2.6

OSSEC is an open source HIDS (Host-based Intrusion Detection System), and a pretty darn good one too. It also has a simple web front-end to view what’s going on, search through alerts and stuff like that  (called OSSEC Web UI, I’ll just call it “WUI” here). Unfortunately the code is a bit outdated (the last official update was from 2008 as far as I can tell) and it doesn’t support newer features of OSSEC like polling data from a database. Something I’d like to tackle if I find the time 😉

The latest version of OSSEC is 2.6, and due to some small changes to the format of the logs WUI no longer works out-of-the-box. I had a look at the code this weekend and am providing patches and downloads of the files needed to change to get everything running again with OSSEC 2.6.

List of changes:

  • Works with the OSSEC 2.6 alert log file format
  • Changed Rule ID Link to better work with the new documentation wiki
  • Added “user” field to alert output
  • Widened the layout by a few pixels (to 1000px) and changed the CSS / alert layout to make the individual alerts better readable
  • Moved some of the hardcoded formatting to CSS

Download Download changed files
Download Patch download