HowTo setup a DNS Appliance (Cobalt RAQ2)
November 29, 2006
Posted by Roel in : Technical , 2comments
Last weeks i spent some time working on a ‘new’ DNS appliance. DNS is light weight but you must have multiple separate servers for redundancy in multiple locations. Using a power consuming HP DL-360 server would be a serious overkill and running Microsoft Windows Server for DNS only, is a waste of licensing / money / expertise and required hardware. The need for a simple (cheap hardware), easy to manage (web interface), standard (BIND for DNS), flexible (capable of working with Active Directory) and low-power consuming DNS appliance is everywhere.
Bug in ServerXMLHTTP with POST/303
September 18, 2006
Posted by Roel in : Technical , 1 comment so far
Last night i was developing with ServerXMLHTTP. ServerXMLHTTP is included with the Microsoft XML Parser (MSXML) version 3.0 or later.
Do not confuse ServerXMLHTTP with XMLHTTP, which is designed for client applications and relies on URLMon, which is built upon Microsoft Win32 Internet (WinInet).
The following bug is regarding to ServerXMLHTTP (so also: MSXML 3 – MSXML 4 SP2)
When doing a POST to an URL, and it responses with a "HTTP 303 – See Other" code, ServerXMLHTTP will RE-POST to the given URI.
According to the HTTP specifications it should follow the given URI with a GET request.
This issue is actually a ‘wrong implementation’ by Microsoft.
I see two possible security issues:
- Reposting username/password to another URI (without user’s notice).
- Redirect Looping when the 303 is pointing to the same source (i.e. http://www.abnamro.nl/ does this for Internet Banking). However i saw that after many redirects, the ServerXMLHTTP will exit with a ‘redirect problem’ to avoid buffer overflow and other ‘damage’. I’m note sure if all versions do this.
I reported this problem to Microsoft by phone (0800-MICROSOFT, from the Netherlands) and by E-Mail (support@microsoft.com), both at September, 12th, 2006.
Summer 2006
June 8, 2006
Posted by Roel in : Life , 1 comment so far
Summer 2006 is here !
To celebrate my 25th birthday, the beautifull weather and the World Cup football, i decided to give a party (http://www.summerchill.nl/) Sunday the 11th of June 2006.
Bellow you can see the harbor Wetterwille at Loosdrecht where my sailboat is at summer (click to enlarge).
How to setup an IBM Workplace server with CentOS (RHEL) + VNC
May 15, 2006
Posted by Roel in : Technical , add a comment
Recently i installed an IBM Workplace server on CentOS with VNCServer.
The IBM Software can run on Windows as well as Linux (RedHat Enterprise or SuSe).
Because you actually have to BUY RedHat Enterprise, they say you pay for a support contract but you cannot download the install files/ISO without buying the support contract. You can only download the RedHat Enterprise source files but then you have to compile them which is a total waste of time.
So i downloaded CentOS which is almost the same. CentOS is really free and you can download the DVD IDO or installation files.
Here is the PDF file i made with a step-by-step How-To for installing CentOS, installing IBM Workplace Server and installing a VNCServer (for remote configuration). I do nothing about tuning and all the installs are quite basic. The PDF is for Newbie’s.
How To install an IBM Workplace Server.pdf
Also look at the PDF if you encounter ‘Disk is Full’ error messages during the installation of CentOS or if you have problems with configuring or connecting VNCServer (black screen/window after connecting).
Note: The installation of CentOS is in Grafics-mode. IBM Workplace server failed to install under command-line mode, after a phone call with IBM, they said it was better to install in grafics mode…
Digest authentication: Impossible to authenticate to DB and IIS Webserver
April 26, 2006
Posted by Roel in : Technical , add a comment
Due to some technical issues (i’ll show you below) it is impossible to authenticate using Digest Authentication for authenticating the user against an Database/LDAP and the webserver itself. I did this before with Basic authentication, which works fine.
Example1:
It is possible to authenticate with basic authentication against a Database, simply write a 401 header to the client, wait until the client responses, decode the response with a Base64Decode function and query a database table with that username and password. When you decode the client response with a Base64Decode function, you get the ‘username:pasword’ (separated by a colon). (more…)
[VBScript/ASP] About Isnull and =null
April 26, 2006
Posted by Roel in : Technical , 1 comment so far
Expressions in VBScript/ASP with "null" in it, will always return FALSE. See the examples below:
Dim test
If (test=null) Then Response.Write "True" Else Response.Write "False" End If
If Not(test=null) Then Response.Write "True" Else Response.Write "False" End If
Both will show "False". Because "null" is in the expression, none of them will ever return True.
This is because any expression containing a Null is itself Null and therefore False.
Too make it more confusing, look at this example:
test_avc = null
Response.Write IsNull(test_avc)
If (test_avc=null) Then response.write "True" Else Response.Write "False" End If
This will return "True … False".
See the VBScript IsNull Reference:
"Use the IsNull function to determine whether an expression contains a Null value. Expressions that you might expect to evaluate to True under some circumstances, such as If Var = Null and If Var <> Null, are always False. This is because any expression containing a Null is itself Null, and therefore, False."
Apple iPod Hi-Fi Rocks!
March 31, 2006
Posted by Roel in : Life , add a comment
First i was a bit sceptic and thought it was too expensive. However, i walked into the Apple Store (in The Netherlands), payed EUR 379,- and went home.
I must say i’ve seen a lot of real Hi-Fi installations and studios, but this thing really gives an amazing sound. Your room will be completely FULL of sound, the Low (BASS) and High tones sound great. It wouldn’t be a problem to have about 20 people on a little (birthday)party and use this ‘single box’. It is absolutelly not a MONO Speaker like some people say.
Just hear it and you’ll buy it. I have to admit it’s a bit expensive but it’s different than with other things you buy.
Most things you buy; you connect it, the wires are too short, the sounds could be better and they lack some functionality or options.
Not with this one.. It’s worth the full price. Really nothing found which could be better. Connecting it is so easy (like with all Apple products) and the buttons are also what-you-see-is-what-you-get. The wire is long enough (3 meters), on the bottom of the device is a flat anti-slip-rubber which makes it also a great device for sportive use (when sailing on a boat or outside in the park).
That’s also the reason why i bought it; for my boat. I have a sailing boat and want some good quality music on it, i’ve experience with home-build-beer-boxes with car-radios and car-batteries in it, but then you have 1 or 2 speakers and it’s quite ugly. When you have a nice wooden ship and everything is perfect, this thing is what the ship deserves.
The iPod Hi-Fi uses 6 D-cell batteries. When i load it with 6x GP 8000mAh NiMH (fully charged) it works for a maximum of 8 hours (90% volume, normal bass). When the batteries discharge, the volume will decrease (the last few hours). This is a bit anoying and it was would be better for me when they made it sound perfect till the last mAh and then let the device shut-down.
For more photos and comments see this article at Engadget.
Windows Genuine Advantage bypassed again!
March 11, 2006
Posted by Roel in : Technical , 1 comment so far
UPDATE: This bypass method described below doesn’t work anymore. Visit mydigitallife’s article for an updated (3-dec-2006) and easy method of bypassing WGA/Notifications/Visiting Windows Updates, etc.
In 2005 Microsoft introduced Windows Genuine Advantage (WGA) which was (also) meant to reduce illegal copies. Since then, people who had an ‘illegal’ Corporate copy of Windows XP or Server 2003 were not able to use the Windowsupdate site anymore.
Shortly after that people found a way to bypass the checks required by the Windowsupdate site by disabling the WGA ActiveX plugin from their Internet Explorer.
It could be done by pasting this line in your browser:
javascript:void(window.g_sDisableWGACheck='all');
Microsoft fixed it and bypassing was no longer possible after March 2005.
The following content is for informational and educational purposes only.
I came accross the website of djlizard and he found a NEW way to bypass the checks at the Windowsupdate site.
- Close all your browsers (this is really important)
- Click Start -> Run -> Type:
regsvr32 /u LegitCheckControl.dll - Go to the WindowsUpdate site, select typical or custom. It will show the Activate button to activate your copy of windows. Click Start -> Run -> Type:
regsvr32 LegitCheckControl.dlland go back one page in your browser. Now you can click typical or custom again and it won’t show the Activate button but continues to search for updates.
Script it! A logfiles compress/backup script
March 5, 2006
Posted by Roel in : Technical , 1 comment so far
Lesson of this article is: Script It!
I will also show an in depth example of a sheduled script which will zip/rotate/delete/move/copy you logfiles. This is a typical task everyone with a webserver would automate/script because you want to save your logfiles for statistics and to track ‘bad’ visitors while zipping them reduces it’s size approximately 25 times. So a 100MB logile will only be 4MB.
You can much better script the tasks you do often than doing it by hand all the time.
Advantages are:
- No human mistakes any more
- Scheduled scripts always run on time, even when you’re on holiday
- Schedule scripts at night to save server resources and minimize impact on other systems
- Last but not least: It saves you a lot of time which you can spend on scripting other things ;)
Before scripting tasks i advise you to do the tasks manually a few times, then you exactly know which steps you have to do and which are always the same, you have more feeling with the task now.
Always do your calculations based on days !
January 30, 2006
Posted by Roel in : Technical , add a comment
This is a simple example of what can happen when you calculate with years only:
Imagine you had a backup script which would delete all old backups, older than 1 year.
When you were using a VBScript (or ASP) function like:
DateDiff('yyyy', backup_create_date, Now)The 1st of January all your backups would be deleted (even the ones created at 31-12-previous_year). This is because Microsoft has quite a different way of doing math with years:
"When comparing December 31 to January 1 of the immediately succeeding year, DateDiff for Year ("yyyy") returns 1 even though only a day has elapsed."
Source: Microsoft MSDN VBScript Functions Reference – DateDiff Function
Solution: The best thing to do is always to calculate using days. The example above would be:
DateDiff('d', backup_create_date, Now).
Note: Keep in mind that years have a variable number of days (ie: 365, 366).
