Windows network connection indicator, NCSI

Beginning with the Windows Vista era, when the computer is connected to the network, the Windows system begins to detect the network connection status, whether it can surf the internet, etc.
The specific working principle:
1. When the computer network changes (restart, change the IP address, connect to a different network, etc.).
2. Computer tries to connect: Http://www.msftncsi.com/ncsi.txt
Ncsi.txt is a text document with a file encoding format of ANSI, with only one line of Microsoft NCSI, no carriage returns, and other extra characters.
3. The computer tries to resolve the domain name: dns.msftncsi.com, which resolves to a fixed value: 131.107.255.255

When the computer turns on ncsi.txt and resolves dns.msftncsi.com correctly, you are prompted to connect to the network normally.

You can disable the network connection state detection feature through local Group Policy or the registry.
Local Group Policy > Computer Configuration > Administrative Templates > System >internet Communication Management >internet Communication settings "Turn off the Windows Network Connection indicator activity test"

Hkey_local_machine\system\currentcontrolset\services\nlasvc\parameters\internet
Enableactiveprobing The default key value is 1, change to 0 to disable the network connection indicator.

According to the above principle, we can do a detection server by ourselves, through the local server network connection status verification.
1. Install IIS and DNS, installed by default.
2. In the root directory of IIS, C:\inetpub\wwwroot\, add ncsi.txt with the content: Microsoft NCSI
3. In the DNS Server Management console, add www.msftncsi.com parsing and dns.msftncsi.com resolution.
4. Change the client's DNS resolution to the instrumentation server.

Official Microsoft Documentation: HTTPS://TECHNET.MICROSOFT.COM/EN-US/LIBRARY/CC766017 (ws.10). Aspx#bkmk_overview

This article is from the "secret Flying Tiger Space" blog, please be sure to keep this source http://mifeihu.blog.51cto.com/2060590/1723407

Windows network connection indicator, NCSI