Bypass proxy for local networks

autoproxy.pac

function FindProxyForURL(url, host)
{
    var resolved_ip = dnsResolve(host);

    if (isInNet(resolved_ip, "10.0.0.0", "255.0.0.0") ||
            isInNet(resolved_ip, "172.16.0.0",  "255.240.0.0") ||
            isInNet(resolved_ip, "192.168.0.0", "255.255.0.0") ||
            isInNet(resolved_ip, "127.0.0.0", "255.255.255.0"))
        return "DIRECT";

    return "PROXY YOUR_PROXY_IP:PORT; DIRECT";
}