Is there anyway with Windows api to detect whether a Windows 7 computer's network connection is an internet connection or a LAN connection without internet access? Windows 7 and Vista indicate this in the network icon (Local only v. Local and Internet), is there anyway to grab that information progammatically?
A:
Not perfectly.
You could detect if you are on a lan from the IP address (assuming your local DHCP handed out one of the 192.168.xx.xx private addresses.)
YOu could ping a known external site to check if that lan has an internet connection.
Martin Beckett
2010-04-20 18:41:47
Just because the computer has a private IP address (which also include 10.x.x.x and 172.16-31.x.x) doesn't mean it's not connected to the Internet. As anyone accessing this site from behind a home router performing NAT can attest!
Stephen C. Steel
2010-04-20 19:20:07
It wasn't clear what the OP was asking ie. direct internet connection vs NAT
Martin Beckett
2010-04-20 21:17:04
+1
A:
Pinging 4.2.2.2 is a common means of determining if internet connectivity is present.
The story behind this lies here.
Adam Robinson
2010-04-20 18:45:44
Although now 8.8.8.8 is probably better (behold the might of google)
Martin Beckett
2010-04-20 18:55:06
@Martin: Yes, though 4.2.2.2 is now muscle memory for me. I don't know if I can bear to learn 8.8.8.8 and its uncomfortable angle between index- and middle finger.
Adam Robinson
2010-04-20 18:56:30
+2
A:
http://msdn.microsoft.com/en-us/library/aa370750(VS.85).aspx describes the difference between IsConnected and IsConnectedToInternet. Windows 7 only. I don't have a native code sample handy, sorry.
Kate Gregory
2010-04-20 19:02:48
A:
Windows 7 performs DNS query for dns.msftncsi.com 5 seconds after link establishment. Do not see any reason to do that except for checking internet connection.
Eakraly
2010-04-21 21:45:52