func isHostIP(ipAddress string) bool {
	host, _, err := net.SplitHostPort(ipAddress)
	if err != nil {
		host = ipAddress
	}
	// Strip off IPv6 zone information.
	if i := strings.Index(host, "%"); i > -1 {
		host = host[:i]
	}
	return net.ParseIP(host) != nil
}

// extractHostPort - extracts host/port from many address formats