(Visual FoxPro) Check Internet Connectivity

Demonstrates an efficient way to test for Internet connectivity.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

LOCAL lnSuccess
LOCAL loSocket
LOCAL lcTargetIp
LOCAL lnPort
LOCAL lnSsl
LOCAL lnTimeoutMs

lnSuccess = 0

loSocket = CreateObject('Chilkat.Socket')
* 1. Use a reliable Anycast IP. 
*    8.8.8.8 (Google) or 1.1.1.1 (Cloudflare) are the industry standards.
lcTargetIp = "8.8.8.8"

* 2. Use Port 53 (DNS). 
*    DNS servers typically listen on TCP Port 53 as well as UDP. 
*    (Alternatively, use port 443 if you suspect port 53 is blocked).
lnPort = 53

* 3. Disable SSL (0). 
*    We are not doing a handshake, just a TCP connection.
lnSsl = 0

* 4. Short Timeout (1500ms).
*    If you can't reach Google in 1.5 seconds, the connection is 
*    likely too poor for practical use anyway.
lnTimeoutMs = 1500

* Connect
lnSuccess = loSocket.Connect(lcTargetIp,lnPort,lnSsl,lnTimeoutMs)
IF (lnSuccess = 0) THEN
    ? loSocket.LastErrorText
    RELEASE loSocket
    CANCEL
ENDIF

loSocket.Close(10)

? "We have Internet connectivity."

RELEASE loSocket