(.NET Core C#) Check Internet Connectivity

Demonstrates an efficient way to test for Internet connectivity.

Chilkat .NET Downloads Chilkat .NET Framework Chilkat for .NET Core

bool success = false;

Chilkat.Socket socket = new Chilkat.Socket();
// 1. Use a reliable Anycast IP. 
//    8.8.8.8 (Google) or 1.1.1.1 (Cloudflare) are the industry standards.
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).
int port = 53;

// 3. Disable SSL (0). 
//    We are not doing a handshake, just a TCP connection.
bool ssl = false;

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

// Connect
success = socket.Connect(targetIp,port,ssl,timeoutMs);
if (success == false) {
    Debug.WriteLine(socket.LastErrorText);
    return;
}

socket.Close(10);

Debug.WriteLine("We have Internet connectivity.");