I had to struggle a bit with this recently. No matter what I was doing I could not get the change password screen on the remote Windows machine.

In older days (say 10 years back, in the Windows XP/Windows 7 days), all I had to do was to press CTRL-ALT-END on my physical keyboard, and this combination was being transmitted to the remote machine as CTRL-ALT-DEL. This of course would open up a screen (on the remote machine) allowing me to change my password.

But it seems this behavior is not there anymore (at least it’s not there if the remote machine is running Windows Server 2012 R2).

So what is the solution? How do I change my password on the remote Windows machine? Here it is. On the remote machine open a command prompt (cmd.exe). In that command prompt type osk.exe and press Enter (this starts the on-screen keyboard application). Now press CTRL and ALT on your physical keyboard, and then press DEL in the on-screen keyboard.

Now you will be presented (on the remote machine) with a screen allowing you to 1) Lock your computer 2) Sign out 3) Change your password or 4) Open the task manager.

## Strange Location of Java.exe on Windows XP (3)

OK… Several years later in January 2014 I had this same problem only in Windows 7 (i.e. not in Windows XP). To get some background see my first two posts on this topic here and here. These two posts are back from 2008. So I asked this question on StackOverflow (SO).

Luckily I got some very useful comments and answers there. They helped me to finally resolve this mystery (about the JVM executables which keep on reappearing in C:\Windows\System32).

As some folks noted in their comments to my SO question… it’s strange for any 3rd party programs/apps to install executables in C:\Windows\System32. That looks completely illogical… And that is what started the whole confusion some 11 years ago 🙂

Anyway… it’s good that the problem was finally solved. The solution is in the accepted answer here.

## How to solve a linear equation?

This post comes to demonstrate the support for $\LaTeX$ available in WordPress.

A linear equation is an equation of the form

$ax + b = 0 \ \ \ \ \ (1)$

where

$a,b \in \mathbb{R}\$ and $a \ne 0\$.

Let us assume that we are trying to solve this equation for real numbers only i.e. we are trying to find the real root(s) of the equation.

Solving this equation is simple, it always has a single real solution which is $x = - {b \over a} \ \ \ \ \ (2)$

## How to solve a quadratic equation?

This post comes to demonstrate the support for $\LaTeX$ available in WordPress.

A quadratic equation is an equation of the form

$ax^2 + bx + c = 0 \ \ \ \ \ (1)$

where

$a,b,c \in \mathbb{R}\$ and $a \ne 0\$.

Let us assume that we are trying to solve this equation for real numbers only i.e. we are trying to find the real root(s) of the equation.

The value

$D = b^2 - 4ac \ \ \ \ \ (*)$

is called discriminant of the equation $(1)$.

Case #1:

When $D > 0$, there are two distinct real solutions to $(1)$ and they are:

$x_{1,2} = {-b \pm \sqrt{b^2-4ac} \over 2a} \ \ \ \ \ (2)$

Case #2:

When $D = 0$, there is one real solution to $(1)$ which is:

$x = -{b \over 2a} \ \ \ \ \ (3)$

Case #3:

When $D < 0$, there are no real solutions to $(1)$.

## Revoke Trust from Java Applets

Recently I had the following problem with trusted Java Applets. I was on Windows XP and I opened a web page containing a Java Applet in Mozilla Firefox (FF). The page asked me whether I trust the publisher of this Java Applet. I answered “Yes” and also checked the box “Always trust content from that publisher”. Later on I realized that I want to revoke my trust from this Java Applet and its publisher. Unfortunately I found almost zero information of the web how to do it.

After some searching and trying I came to the following conclusions which I want to share in this post.

(1) The applet trust is not given (stored) on a per browser basis. This means that if you select what I selected on that web page (and what I described above), this choice will apply to both Internet Explorer (IE) and to Mozilla Firefox (FF), if you happen have both browsers on your system.

(2) On Windows XP the information for the trusted applets is stored in the following file

C:\Documents and Settings\<windows username>\Application Data\Sun\Java\Deployment\security\trusted.certs

Obviously this file is not browser-specific.

(3) In order to revoke (remove) your trust from all the publishers of Java Applets (which you had chosen to trust), you can delete this file.

After you restart IE and/or FF you will then be asked again if you trust the Java Appet and/or its publisher.

Although this solution is apparently not flexible enough, it is the only one I was able to find so far.

## Strange Location of Java.exe on Windows XP (2)

After my first post on this topic, I found recently that even though I was able to get rid of the JVM executables in C:\Windows\System32 by renaming them (from *.exe to *.not_exe), this was not a permanent solution. After a week or so I noticed that these files were again present there. So I continued investigating further. I am pretty sure now that the Java Control Panel (JCP) application is the one responsible for downloading (and/or automatically updating) the JRE executables and for copying them to the C:\Windows\System32 folder (on Windows XP machines). After some more research I was able to find another important web page Java 6 Release Notes which contains an interesting note (in its Windows Vista Notes section). Here is that note: “AutoDownload of JREs is Disabled (by default) in the Java Control Panel (on Windows Vista)”. So I thought… OK, since they mention this explicitly in the release notes, then probably on Windows XP machines this is not the default behavior. So I went on and changed in the JCP the way this option was configured by setting it to Never Auto Download

Java Control Panel -> Advanced Tab -> JRE Auto-Download -> Never Auto Download

Quite some time passed since then and I have no problems any more. No new versions of the JVM (java.exe) are being downloaded and installed in my C:\Windows\System32 folder.

## Strange Location of Java.exe on Windows XP (1)

I had to install recently (today actually) two different JDKs (and their respective JREs) on a single machine running Windows XP.

(1) I already had JDK 6 (update 7) installed (this one I installed about a month ago)

(2) Today I also installed JDK 5 (update 16)

After installing the second one (JDK 5) I modified my PATH variable in Windows XP to point to JDK 5. But when I opened a command prompt and typed

java -version

I was surprised to see that Windows was still finding and picking for execution the previous version that I had installed (JDK 6), and not the one which I wanted (JDK 5). After some research on the web, I found that some process regularly copies the following 4 files

java.exe
javacpl.cpl
javaw.exe
javaws.exe

to the Windows System32 folder ( C:\Windows\System32 ). And since this folder is usually the first entry in the PATH value on Windows XP, appending the JDK 5 bin folder to the PATH did not have the expected effect. I could not find an authoritative answer on the web saying which process and at what point exactly copies these files to the System32 folder.

So I renamed these 4 files on purpose (say from .exe to .not_exe) to make then not executables. I then continued experimenting and I uninstalled JDK 6 (update 7). After that I downloaded and installed another JDK 6 (update 10). After this install I was surprised to see the 4 files being in this folder again. I went to the folder and typed the following

C:\WINDOWS\system32>java -version

and as I expected the result was

java version "1.6.0_10"
Java(TM) SE Runtime Environment (build 1.6.0_10-b33)
Java HotSpot(TM) Client VM (build 11.0-b15, mixed mode, sharing)

So I tend to think that the install process of JDK 6 copies these 4 files to that location.

Or… maybe another process copies them… but in general I think one should be careful and check the C:\Windows\System32 folder from time to time just to see what java executables exist there, and which versions of the JDK they come from.

## Blogging Attempt

This is my first post here. I have just started this blog without any particular reason in mind. I am just trying to establish some online presence I guess. And also trying to share things which I find interesting with others. Hope people will not find the pages of this blog completely useless or uninteresting. But if this eventually turns out to be so (useless/uninteresting blog) I guess I will have an excuse – the home URL of this blog.