public function isValidIP($sIP)
    {
        $bAllowed = false;
        $sIPSource = trim($this->fieldIpnAllowedIps);
        if ('' === $sIPSource) {
            return true;
        }

        $oNetworkHelper = new TPkgCoreUtility_Network();
        $aIPList = explode("\n", $sIPSource);
        foreach ($aIPList as $sAllowedIP) {
            $sRangeType = $oNetworkHelper->getRangeType($sAllowedIP);
            switch ($sRangeType) {
                case TPkgCoreUtility_Network::IP_RANGE_TYPE_NONE:
                    $bAllowed = ($sIP === $sAllowedIP);
                    break;
                case TPkgCoreUtility_Network::IP_RANGE_TYPE_RANGE:
                case TPkgCoreUtility_Network::IP_RANGE_TYPE_WILDCARD:
                case TPkgCoreUtility_Network::IP_RANGE_TYPE_CIDR:
                    $bAllowed = $oNetworkHelper->ipIsInRange($sIP, $sAllowedIP);
                    break;
            }

            if (true === $bAllowed) {
                break;
            }
        }

        return $bAllowed;
    }