C#

Check Internet Connectivity

See more Socket/SSL/TLS Examples

Demonstrates an efficient way to test for Internet connectivity. C#

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.");