Category: Windows

How to Check if Remote Network Port Open or Not Without Telnet on Windows

Use TNC in powershell

C:\>powershell
...
..
.
PS C:\> tnc google.com -port 80


ComputerName     : google.com
RemoteAddress    : 172.217.167.110
RemotePort       : 80
SourceAddress    : 10.11.12.13
TcpTestSucceeded : True


PS C:\> tnc google.com -port 99
WARNING: TCP connect to (142.250.204.14 : 99) failed


ComputerName           : google.com
RemoteAddress          : 142.250.204.14
RemotePort             : 99
SourceAddress          : 10.11.12.13
PingSucceeded          : True

TcpTestSucceeded       : False
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Windows Not Detecting the External Monitor

After HP laptop rebooted this morning, the external monitor is not detected by Windows.

The following steps have been taken :

  1. Confirmed HTML cable is a good one by connecting to other PC or laptop working fine.
  2. Updated with the latest Display Adapters driver.
  3. After the above two steps, go to Start -> Settings -> System ->  Display tab, find and press the Detect button under the heading Multiple Displays. Still not working:

SOLUTION

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How to remotely kill a Remote Desktop Session

 Check all Current RDP Sessions

C:\>qwinsta /server:SERVERNAME

 SESSIONNAME       USERNAME                 ID  STATE   TYPE        DEVICE
 console                                     0  Conn    wdcon
 rdp-tcp                                 65536  Listen  rdpwd
 rdp-tcp#1         orace                     1  Active  rdpwd

Kill a Remote Desktop Session

C:\>rwinsta /server:SERVERNAME 1

Here “1” is the ID from previous checking of RDP sessions.

The killed connection will get the following message:

BSOD/DPC Watchdog Violation Whenever WIFI is Enabled

SYMPTOMS

Every time when wifi is enabled, the PC crashes with BSOD/DPC Watchlog Violation error as below:

Environment:

  • Windows 10 64bit Home Edition.
  • TP-link Archer T4E AC1200 Wireless Dual Band PCI Express Adapter 

After disabled wifi adapter, rebooted the PC successfully without any errors, then tried to enable wifi adapter, system crashed with BSOD screen.

After disabled wifi or set wifi to MANUAL, restarted PC, then PC operated normally while offline.  As soon as connecting PC to wifi, PC froze, then BSOD/DPC WATCHDOG VIOLATION.

The following methods have been tried, but still without luck.

  • Tried restoring from earliest available restore point.
  • Uninstalled driver and installed the driver download from TP-LINK website.
  • Uninstalled driver and installed the driver from original CD.
  • Uninstalled driver, and found only two drivers left. one is from RealTek ( rtwlane.sys) and another driver is Windows native ( vwifibus.sys )
  • Uninstalled device from device manager, then scan device back again.
  • Uninstalled VPN and anti-virus software.

INVESTIGATIONS

Download and install WinDbg

Download and install WinDbg as per Download Debugging Tools for Windows

Run WinDbg

a) Click Start -> All Programs -> Windows Administrative Tool -> Windows Kits ->WinDbg( X64).

b)Select File -> Symbol file path and modify it to suit your situation, then copy and paste it into the box and click OK.

I suggest and use the following as Symbol Path:

SRV*c:\symbols*http://msdl.microsoft.com/download/symbols

c) Select File ->Select Open Crash Dump, and then navigate to the MEMORY.DMP file originated created under C:\Windows, and select Open.

d)Click on ” ! analyze -v“

From the above screen, we can see driver “rtwlane.sys” used by “TP-link Archer T4E AC1200 Wireless Dual Band PCI Express Adapter” contributed to the BSOD issue.

For further test, plug another USB Wireless Adaptor, and found it still use the same driver as “rtwlane.sys“, and the result is still same not working.

After a couple of days further testing and investigation, the problem was identified, and resolved by just modifying one configuration, and now connect to wifi without any issues every time. .

SOLUTION

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CertUtil: The system cannot find the file specified

During implementation of Oracle Centrally Managed Users (CMU), the trusted certificate needs to be exported from Active Directory Server, then the following error message occurs :

c:\Windows\System32>certutil -ca.cert root.crt
CertUtil: The system cannot find the file specified.

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Now export Certificate again Successfully.

c:\Windows\System32>certutil -ca.cert root.crt
CA cert[0]: 3 -- Valid
CA cert[0]:
-----BEGIN CERTIFICATE-----
MIIDhzCCAm+gAwIBAgIQa3rP+dtgrqFJ/gFo/3hB9jANBgkqhkiG9w0BAQsFADBW
...
..
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41ZTwYcy4cntPwLHm6kTiWXKCMtYqf0poP5NUxjkiW3pf3IQnej4ZDCqLZ7a2JzJ
J3HbajXZzMaMAI9TyvIhF795EqX+XYgCdjwsbiJ3RD/ObJqwBjJWwTjcJA==
-----END CERTIFICATE-----

CertUtil: -ca.cert command completed successfully.
c:\Windows\System32>