Nice to know – Volume 2

udev renames you network interfaces

Sometimes udev renames your devices. This happened to me when upgrading a server, eth0 suddenly became eth1 and vice-versa. Of course, this broke nearly all firewall scripts on the server… There is a nice explanation how to get udev to name your devices the way you want.

Visual Studio 2005 Service Pack 1 on Microsoft Windows Server 2003

When installing Visual Studio Service Pack 1 under Windows Server 2003, it might fail because it cannot verify the signature. You should take time and visit the link provided in the error message, because it will take you to a hotfix that will correct the problem.

(via Mark Caroll’s Blog)

VMWare Server on Ubuntu 8.04

A nice tutorial for getting free VMWare Server 1.0.5 running on Ubuntu 8.04.

Nice to know – Volume 1

As I definitely should post more on my blog, I now try to start a new series: “Nice to know”. It will be a collection of interesting things I consider memorable but which don’t deserve their own blog-post.

Trickle

Tricke allows you to limit bandwith for processes that do not support bandwith limitation out-of-the-box. It works by preloading and simulating the socket API. You use it as a wrapper when starting the process, like trickle -d 80 someapp.

You can use it to limit rsync speed for instance (thanks to http://www.yak.net/fqa/404.html): rsync -auvPe “trickle -d 80 ssh” user@host:/src/ /dst/

VMWare Tools and Kernel 2.6.24

VMWare Tools out of the box do not install on kernel 2.6.24 (as used in Ubuntu 8.04 for instance). A possible solution is described here. It is based on using the open-source version of the VMWare tools (open-vm-tools).

Test-driven network management

Article Teaser RJ45 close-upTest-driven development has proven to increase quality of software in many cases. I believe that the same principle should be applied to network management. From time to time, I am occupied in managing quite large and distributed networks, consisting of many different network segments, routers, servers, etc.

Primary tool in managing any network is using monitoring software which tells you if everything is alright or if you should worry. For various reasons I have become a huge fan of Nagios for monitoring networks I am responsible for, especially for the simple extensibility by writing your own check scripts (plugins).

While working through some issues in a network, I suddenly decided to try an approach I spontaneously called “test-driven network management”ยน. The steps are easy (and are a one-to-one translation of agile software-development principles):

  1. Write a Nagios test which checks for the requested/required feature.
  2. This test will fail.
  3. Implement a solution satisfying the test.

The same advantages of automated testing (better: unit testing) in software development also apply to the network management tasks:

  • The test documents what you want to achieve in a quite formal way.
  • You will (almost) immediately know when your solution breaks other requirements (if tests exist for them).
  • As networks tend to be even more fragile then software, you have to monitor whatever you implemented anyways ๐Ÿ™‚

Whenever possible, I try to add a test (or tweak an existing one) for any trouble-ticket / feature request I come around. In my experience, customer satisfaction tends to increase, because you start noticing problems before they do and you also implement measures to prevent the same problems to occur over and over again.

ยน I am quite sure there is another technical term for it, as I am quite sure I am not inventing anything new here… If you know how this is called by others, please tell me in the comments.

[tags]development, network, sysadmin, network management, test-driven development, nagios[/tags]

TrueCrypt 5.1 is out!

The new TrueCrypt 5.1 version finally enables hibernation with pre-boot authentication. I am going to try it out as soon as possible. A big thank you to all the developers!

Update 2008-03-16: Today I finally had time to test out pre-boot authentication. It simply worked great. No problems at all. As I was using it on a notebook, I was very happy about the possibility to interrupt and resume the encryption process.

[tags]encryption, windows, truecrypt[/tags]

TrueCrypt 5 is out!

ImageAfter quite some time, a new version of my favorite encryption tool is out: TrueCrypt developers have released version 5 of their product, introducing a new killer feature (among others): System Volume Encryption with pre-boot authentification (only Windows 2000/XP/Vista). This means, that TrueCrypt will encrypt everything on your system drive, including page- and hibernation file, finally making hibernation a safe and easy possibility.

I am going to look into this next week, as I need my notebook on Saturday (just in case anything goes wrong).

Update 2007-02-08: As my first commenter below points out, it seems hibernation is disabled by TrueCrypt while having your system partition encrypted. I don’t really understand why at the moment, but I will investigate further. For me this is a primary show-stopper, as this was the long-awaited functionality I was waiting for.

Nitpickers Cornerยน: Of course I am aware why encryption and hibernation in general are no-goes together, but I don’t understand why this is an issue when full-system encryption is enabled.

Update 2007-02-08 (again): Ok, in this TrueCrypt forum thread they explain why they cannot support it at the moment: Windows treats the hibernation file differently, it seems to bypass the TrueCrypt driver and therefore would still write keys to disk without encryption. Ok, still get to wait for my dream feature then, but I still refuse to buy PGP ๐Ÿ™‚ Thanks to the developers for their great work anyhow!

ยน a tribute to Raymond Chen ๐Ÿ™‚

[tags]security, encryption, truecrypt, windows, linux, osx[/tags]

CrossLoop: Free and easy remote assistance

Screenshot von CrossLoopToday I had to give quick support to a colleague working from home in order to resolve a networking issue. This was the perfect situation to evaluate CrossLoop, a free remote-assistance tool similar to NetViewer (but, as mentioned, free).

The experience was nice, it just worked “out of the box”, after installing and sending me the access key, the connection was established despite our firewalls in between. It is easy enough I would trust almost all customers to get it working. I’ll have to evaluate how the software behaves if you don’t have administrative privileges on your system.

Crossloop is based upon TightVNC and as a consequence you get the typical feeling of a VNC session, which is not as fluent as NetViewer, Remote Desktop, or similar, but it was more than enough to work on the issue at hand.

So if you are searching for a low-cost (i.e. free) alternative for quick support of family members, co-workers, or even customers, you should give CrossLoop a try. CrossLoop currently is only available for Windows, but Linux and Mac versions are planned.

By the way, CrossLoop just got a 3-Million-$ Series A investment, so hopefully this service will continue to exist for some time.

[tags]vnc, crossloop, remote access, software[/tags]

“Here Comes Another Bubble”

I normally try to avoid the “me too” blog posts, but this video is simply hilarious, especially if you or your job are somehow related to the “Web 2.0” hype. Have fun!

Update 2007-12-16: as of today, the video has been taken down due to a copyright sue. What a pity! Read more on TechCrunch.

Update 2007-12-20: a new version without the pictures in question has been published. I changed the video link below to point to the new version, called “Here Comes Another Bubble 1.1”. (via TechCrunch)

[youtube I6IQ_FOCE6I]

(via Scobleizer and TechCrunch)

Amazon S3 Storage in Europe

Logo of Amazon.com Web Services (tm)Amazon announced that they are going to offer S3 storage service inside Europe.

This for sure will provide a great boost in speed for my JungleDisk backup. I am now checking out what I have to do to get my data moved to the European data centers. I suppose I have to re-upload everything because you have to specify for each bucket if it is located in the USA or in Europe. JungleDisk at the moment does not provide support for this. I opened a topic regarding asking if they’ll support this in the near future (article1, article2).

It’s also interesting to notice that storing data in Europe is more expensive. It costs $0.18/GB/month as compared to $0.15 in the US. Bandwidth at the moment do not differ based on location. So I’d only switch if the upload/download speed is significantly higher than to/from the USA.

JungleDisk: Estimation of monthly costs for online backup

After using JungleDisk for my backup for about 12 days now (see also my previous article ), I can give you a short overview of my current costs:

Image

As you can see, I currently owe Amazon 1.04 US-$, which can be extrapolated to around 2.60 US-$ per month. I have backed up 3.3GB of data so far, plus several hundred MB of archived data I deleted from my HDD afterwards. My daily change volume is below 3MB (well, I was surprised for myself!).

I am looking forward to seeing how this is going to develop once I use it for major archiving purposes. Still, what I can say right now, is, that the costs are extremely reasonable. Up to now, I am still very determined to purchasing jungle disk once my 30-day evaluation period is over.

git-svn fails with fatal error: unable to remap

Git‘s nice Subversion (SVN) integration is one of the reasons I switched to using it within our company for my own revision control besides our official repository. Unfortunately, upgrading cygwin broke my system once again:

$ git svn dcommit
6 [main] perl 4760 C:\cygwin\bin\perl.exe: *** fatal error - unable to remap C:\cygwin\lib\perl5\site_perl\5.8\cygwin\auto\SVN\_Core\_ Core.dll to same address as parent(0x260000) != 0x990000 84 [main] perl 3224 fork: child 4760 - died waiting for dll loading, errno 11 panic: MUTEX_LOCK (45) [util.c:2331] at /usr/bin/git-svn line 787. panic: MUTEX_LOCK (45) [op.c:352].

The reason behind this behavior is a huge difference in the way processes and threads and libraries are created/handled on Windows and Linux. git-svn relies on perl within cygwin and several perl libraries that use the same base-address for libraries internally. Of course, no two libraries can be loaded to the same base-address at the same time.

Long explanation, short way to fix the problem:

  1. Quit all cygwin processes
  2. Start ash (<cygroot>\bin\ash.exe) (<edit>Use “Run as Administrator…”</edit>)
  3. Execute /usr/bin/rebaseall

Voilla, that’s all. git-svn should work again.