How to change Windows 7 product key with command line?

This method works with Windows Vist, Windows 7 and Windows 8

1. Click on the Start Button and type: CMD (into the 'Search programs and files' field in the Start Menu)

2. The Start Menu will show 'CMD.exe', 

3. Right-click the CMD.exe file and select Run As Administrator.

4. In the CMD window, type: slmgr.vbs -ipk <type your product key here>

5. To activate windows after changing the key, type: slmgr.vbs -ato

How to change Windows XP Product Key

1. Click on Start and then Run.
   
   
   
   
   
   
   
   
   
   
   
2. In the text box in the Run window, type regedit and click OK. This will open the Registry Editor program.
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
3. Locate the HKEY_LOCAL_MACHINE folder under My Computer and click on the (+) sign next the folder name to expand the folder.
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
4. Continue to expand folders until you reach the HKEY_LOCAL_MACHINE\Software\Microsoft\WindowsNT\Current Version\WPAEvents registry key.
5. Click on the WPAEvents folder.
6. In the results that appear in the window on the right, locate OOBETimer.
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
7. Right-click on the OOBETimer entry and choose Modify from the resulting menu.
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
8. Change at least one digit in the Value data text box and click OK. This will deactivate Windows XP.
   Feel free to close Registry Editor at this point.
   
   
9. Click on Start and then Run.
   
   
10. In the text box in the Run window, type the following command and click OK.
    %systemroot%\system32\oobe\msoobe.exe /a
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
11. When the Let's activate Windows window appears, choose Yes, I want to telephone a customer service representative to activate Windows and then click Next.
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
12. Click the Change Product Key button at the bottom of the window.
    Don't worry about filling anything out on this screen.
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
13. Type your new, valid Windows XP product key in the New key: text boxes and then click the Update button.
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
14. You should now reactivate Windows XP by following the instructions on the Activate Windows by phone window which you should now be seeing or via the Internet by clicking the Back button and following the instructions on that screen.
    If you'd rather postpone activating Windows XP until a later date, you can click the Remind me later button.
15. After activating Windows XP, you can verify that activation was successful by repeating steps 9 and 10 above.
    The Windows Product Activation window that appears should say "Windows is already activated. Click OK to exit."

454 4.7.0 TLS not available due to local problem

In /var/log/syslog, I found following error messages

Sep 16 15:16:22 main2 postfix/smtpd[24908]: warning: TLS library problem: 24908:error:0906406D:PEM routines:PEM_def_callback:problems getting password:pem_lib.c:105:
Sep 16 15:16:22 main2 postfix/smtpd[24908]: warning: TLS library problem: 24908:error:0906A068:PEM routines:PEM_do_header:bad password read:pem_lib.c:403:
Sep 16 15:16:22 main2 postfix/smtpd[24908]: warning: TLS library problem: 24908:error:140B0009:SSL routines:SSL_CTX_use_PrivateKey_file:PEM lib:ssl_rsa.c:669:
Sep 16 15:28:55 main2 postfix/smtpd[26361]: warning: TLS library problem: 26361:error:0906406D:PEM routines:PEM_def_callback:problems getting password:pem_lib.c:105:
Sep 16 15:28:55 main2 postfix/smtpd[26361]: warning: TLS library problem: 26361:error:0906A068:PEM routines:PEM_do_header:bad password read:pem_lib.c:403:
Sep 16 15:28:55 main2 postfix/smtpd[26361]: warning: TLS library problem: 26361:error:140B0009:SSL routines:SSL_CTX_use_PrivateKey_file:PEM lib:ssl_rsa.c:669:

Then, i use following solution and it worked for me,

To create a new ssl cert for postfix, run these commands:


cd /etc/postfix/ssl/

openssl genrsa -des3 -rand /etc/hosts -out smtpd.key 1024
(Create your pass phrase)

chmod 600 smtpd.key

openssl req -new -key smtpd.key -out smtpd.csr

openssl x509 -req -days 3650 -in smtpd.csr -signkey smtpd.key -out smtpd.crt

openssl rsa -in smtpd.key -out smtpd.key.unencrypted

mv -f smtpd.key.unencrypted smtpd.key

openssl req -new -x509 -extensions v3_ca -keyout cakey.pem -out cacert.pem -days 3650