Visual Basic 6.0

Check Internet Connectivity

See more Socket/SSL/TLS Examples

Demonstrates an efficient way to test for Internet connectivity. Visual Basic 6.0

Dim success As Long
success = 0

Dim socket As New ChilkatSocket
' 1. Use a reliable Anycast IP. 
'    8.8.8.8 (Google) or 1.1.1.1 (Cloudflare) are the industry standards.
Dim targetIp As String
targetIp = "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).
Dim port As Long
port = 53

' 3. Disable SSL (0). 
'    We are not doing a handshake, just a TCP connection.
Dim ssl As Long
ssl = 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.
Dim timeoutMs As Long
timeoutMs = 1500

' Connect
success = socket.Connect(targetIp,port,ssl,timeoutMs)
If (success = 0) Then
    Debug.Print socket.LastErrorText
    Exit Sub
End If

success = socket.Close(10)

Debug.Print "We have Internet connectivity."