Kaip "Windows" patvirtina "Wi-Fi" prieigą ir ar būtinas autentiškumo patvirtinimas vietoje?

In Windows 7, the notification area networking icon will show an error indicator if there is no internet access

How does Windows know whether or not it has a successful internet connection?

Presumably it is checking some online Microsoft service to see whether it has a successful connection, gets redirected to some other page, or doesn’t get any response at all, but I haven’t seen anywhere that this process or the services used are documented. Can anybody explain how this works?

After some digging (the sheer number of network and Internet related services in Windows is astonishing), I think I found it. Windows Vista and 7 have a variety of Network Awareness features, one of which is the Network Connectivity Status Indicator that performs connectivity tests that in turn are used by the network systray icon. The test for internet connectivity is simple:

1. NCSI tries to load a specific page via HTTP (more precisely: a text document) and tests whether it can be retrieved.
2. If that is not successful, Windows reports “No Internet access”.

The mechanism also checks whether the domain the document is hosted on resolves to the expected IP address. So, it might also assume proper internet access if this test is successful but the document can’t be retrieved.

The reason it reports “No Internet Access” when you haven’t authenticated on a Hotspot yet lies in the way a Hotspot works. It blocks all ports besides 80 and 443 (for HTTP and HTTPS, respectively), which get redirected to the Hotspot’s authentication server and might mess with DNS requests in one way or another. Thus, NCSI can neither resolve the domain its test file is hosted on, and even if it could it wouldn’t reach the actual file because HTTP traffic is redirected to the Authentication server.

Here are the details of the connection status determination process:

The following list describes how NCSI might communicate with a Web site to determine whether a network has Internet connectivity:

1. A request for DNS name resolution of

   dns.msftncsi.com

2. HTTP užklausa

   https://www.msftncsi.com/ncsi.txt

   grąžinamas 200 OK ir tekstas

   Microsoft NCSI

Tai gali būti išjungta registro nustatymu. Jei nustatysite:

HKEY_LOCAL_MACHINE SYSTEM CurrentControlSet Services NlaSvc Parameters Internet EnableActiveProbing

į

0

"Windows" nebebus sužinoti apie interneto ryšį.

"IOS" atlieka kažką labai panašaus, kad aptiktų interneto ryšį ir galimus "prisijungimo" "WiFi" puslapius ir tt

Nors šis procesas paprastai yra 100% skaidrus galutiniams vartotojams, kartais po autentiškumo patvirtinimo per "Wi-Fi" karšto taško interneto portalą, pamatysite, kad pamatysite tikrąjį NSCSI.txt turinį. Kaip jūs galų gale pažvelgėte į teksto dokumentą, o ne į tinklalapį, kurį bandėte įkelti, nebėra paslaptis, kai kartu su ankstesniais atsakymais šia tema.

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