Diary Products - Hannes Schmidt - Operating Systems

"No DBD Authn configured!" with Apache, Digest Auth and DBD

Sat, 02 Feb 2008 13:10:26 -0800

I use mod_authn_dbd to check HTTP authentication credentials against a MySQL database. After switching from Basic to Digest authentication I got 500 errors and No DBD Authn configured! in the server's error log. It took me a while to realize that it wasn't enough to change

Sending DNS notify messages (update notifications) using Ruby

Sun, 20 Jan 2008 14:49:12 -0800

… is actually easy thanks to Dnsruby. The following code illustrates that:

Quickly enable/disable default gateway for VPN on Windows

Thu, 10 Jan 2008 13:53:46 -0800

Whether a VPN connection has the "Use default gateway on remote network" option enabled has big impact on how network traffic from your machine is routed.

Windows Vista's DNS server priority issues in VPNs

Thu, 27 Dec 2007 17:27:31 -0800

Today I ran into a subtle issue regarding the order in which Windows Vista queries connection-specific DNS servers. I tested a setup with a PPTP VPN server that also provides DNS name resolution services to its VPN clients. For that purpose I ran both a BIND 9 name server and a Poptop PPPD daemon on the same box. It is dual-homed, i.e. one interface is the private interface of the VPN tunnel endpoint and the other one is the public Ethernet interface through which the server is linked to the internet. I configured BIND to listen on both interfaces.

Ubuntu 6.01.1 "Dapper Drake" DVD Torrents

Sat, 02 Sep 2006 00:57:27 -0700

It took me sometime to find Ubuntu torrents that work. I noticed that the .torrent files on the official Ubuntu server and its mirrors point to dead torrents. After some digging, I found this tracker to be most up to date. In case you're stumbling over this problem too, give it a try. It seems to be the official Ubuntu tracker.

Installing VMware Server on Gentoo Linux (Version 3)

Sun, 09 Jul 2006 21:49:52 -0700

[This article is now somewhat obsolete because vmware-server have been included the official portage tree. There is no need for a separate overlay. The bug reports still apply. This is an updated version of a two previous article on the subject.]

The new VMware Server is going to replace VMware's GSX Server product. And it's more than just a new name: VMware will supposedly release it free of charge. Being still in beta testing, there are currently no stable ebuilds available for it on Gentoo Linux. Fortunately, Mike Auty and others are working on one and they are doing a fine job. They also seem to be streamlining and consolidating other related VMware ebuilds. You can keep track of their progress on these Bugzilla bugs:

Problems regarding the vmware-module ebuild: 137422.
Problems regarding the vmware-player ebuild: 137423.
Problems regarding the vmware-server ebuild: 137424.
Problems regarding the vmware-server-console ebuild: 137425.
Problems regarding the vmware-workstation ebuild: 137426.
Problems regarding the vmware-workstation-tools ebuild: 137428.
Problems regarding the vmware overlay in general: 122500.

The VMware Server ebuilds are not part of the official stable Gentoo portage tree so if you want to install them on your system you will have to jump through a few extra hoops. Fortunately this process has become very convenient and straight-forward thanks to Gunnar Wrobel's layman.

Installing VMware Server on Gentoo Linux (Version 2)

Wed, 15 Mar 2006 08:17:49 -0800

[This is an updated version of a previous article on the subject.]

VMWare is going to replace its GSX Server product with the new VMware Server. And it's going to be more than just a new name: the best thing about it is that VMware releases it free of charge. Being still in beta testing, there are currently no stable ebuilds available for it on Gentoo Linux. Fortunately, Mike Auty is working on one and he is doing a fine job. You should keep track of his progress on Gentoo Bugzilla bug #122500. For people with little Portage experience (author included) it can be a bit complicated to throw together an ebuild from bugzilla attachments.

Filtered: NMAP Port Scanner Sees Through IPtables Firewall

Thu, 23 Feb 2006 14:02:44 -0800

Ever wondered why port scanners like nmap are able to tell that some of the ports on your server are protected by a firewall? Have a peek at this nmap transcript:

Starting nmap 3.75 ( http://www.insecure.org/nmap/ ) at 2006-02-23 22:54 CET
Interesting ports on doodah.com (12.34.56.78):
(The 1658 ports scanned but not shown below are in state: closed)
PORT     STATE    SERVICE
21/tcp   open     ftp
22/tcp   open     ssh
53/tcp   open     domain
80/tcp   open     http
3306/tcp filtered mysql

I'm quite sure my firewall blocks access to the mysql port. Yet it bugs me that it is possible to tell that I have MySQL installed on my system simply by performing a port scan.

Installing VMware Server on Gentoo Linux (Version 1)

Wed, 22 Feb 2006 10:39:06 -0800

[This is and outdated version of the article. Read the new version!]

VMware Server is going to replace GSX server. The best thing about it is that VMware releases it free of charge. Being still in beta testing, there are currently no stable ebuilds available for it on Gentoo Linux. Fortunately, Mike Auty is working on one and he is doing a fine job. You should keep track of his progress on Gentoo Bugzilla bug #122500. For people with little Portage experience (author included) it can be a bit complicated to throw together an ebuild from bugzilla attachments.

True Geo-IP country geolocation for Google Urchin 5 statistics

Thu, 15 Dec 2005 07:58:01 -0800

If you are a user of Urchin 4 or 5 you might have noticed that Urchin’s “Countries” report does not match the standards that Urchin has set for professional website statistics. It seems to be Urchin’s weak spot. It might be ok for you but I was certainly disappointed when I discovered that Urchin determines (or should I rather say: attempts to determine) a visitor’s location from a database that is derived from reverse DNS lookups. This type of location reporting can hardly be considered state-of-the-art, even less so for a commercial website log file analytics application. This article is about how Urchin 5 can be fooled into using true Geo IP mappings for its Countries report.

Urchin 5 and dynamic URLs with query parameters/arguments

Tue, 06 Dec 2005 15:14:19 -0800

Urchin is a professional web log analysis and statistics application. It was recently acquired by Google and what used to be called Urchin 6 On Demand is now being integrated into Google Analytics. I don’t know for how long the stand-alone Urchin 5 will be around but right now it is still used by many individuals and corporations. I was not happy with the way Urchin deals with dynamic URLs, i.e. URLs that have query parameters in them. After playing around with Urchin 5's advanced filters for a while, I came to the conclusion that they can be employed to improve Urchin's dynamic URL handling.

Visual SourceSafe 2005 Internet and IIS Setup

Mon, 05 Dec 2005 17:28:42 -0800

One might think that it wouldn't be so difficult to setup Visual SourceSafe 2005 on Windows Server 2003 with IIS such that users can access the SourceSafe database using the Visual SourceSafe 2005 Internet plugin. But dude, I was so wrong! I managed to get it working in the end but it took me an etire day. Anyway, this isn't a complete HowTo. I would just like to point out a few not so obvious caveats.

VMWare: Migrating Windows XP and 2000 to a Virtual Machine

Sun, 02 Oct 2005 19:38:44 -0700

The other day I decided that I wanted to switch my laptop's German language version of Windows XP to the English language version. I could have reinstalled Windows XP from scratch but that would have meant losing all my settings and configurations and, since I have fine-tuned my system, many hours of work would have gone down the drain. Furthermore, I wanted to maintain the German version for certain tasks. What to do?

Moving Software Installation Packages between Group Policies

Thu, 08 Sep 2005 19:21:25 -0700

Let's skip the introduction. You probably googled this article anyway, so you'll know what I'm talking about. This is the scenario: You use group policies to publish or assign software packages (usually Windows Installer MSI) to your Windows workstations. At some point it would be convenient to move a package from one group policy to another, without triggering a complete reinstallation.

How to disable USB sticks and limit access to USB storage devices on Windows systems

Sat, 20 Aug 2005 09:50:45 -0700

USB storage - a possible security risk?

Decent IT administrators secure their networks behind firewalls. They install mail filters on their SMTP servers and deploy anti-virus software on all client workstations. But securing the network is not sufficient -- what happens if the users bring their own USB memory sticks and connect them to the computers at their office? A 1 Gb USB stick can sometimes hold an entire company's vital data. Within minutes or even seconds an employee has all the files they need in order to start up their own business and take all the customers with them. Alternatively, what happens if a careless user accidentally compromises the network with an infected USB stick?