central.json

{
    "dnsServers": ["1.1.1.1", "8.8.8.8"],
    "checkServerServices": [
        {
            "url": "https://ports.yougetsignal.com/check-port.php",
            "headers": {"content-type": "application/x-www-form-urlencoded"},
            "method": "post",
            "selector": "p:nth-child(1)",
            "body": "remoteAddress=$IP&portNumber=$PORT",
            "regexpFailure": "is closed",
            "regexpSuccess": "is open"
        },
        {
            "url": "https://canyouseeme.org/",
            "headers": {"content-type": "application/x-www-form-urlencoded"},
            "method": "post",
            "selector": "div.tool > p:nth-child(1)",
            "body": "port=$PORT",
            "regexpFailure": "I could not see your service",
            "regexpSuccess": "I can see your service"
        }
    ],
    "publicIpServices": [
        "https://checkip.amazonaws.com",
        "https://ipinfo.io/ip",
        "https://ifconfig.io/ip"
    ]
}