diff --git a/classes/tools.class.php b/classes/tools.class.php
index e2eb3b5a..7f1c4f59 100644
--- a/classes/tools.class.php
+++ b/classes/tools.class.php
@@ -283,5 +283,20 @@ public static function update_user_notes($UserID, $AdminComment) {
 			WHERE UserID = \''.db_string($UserID).'\'');
 		G::$DB->set_query_id($QueryID);
 	}
+
+	/**
+	* Check if an IP is part of a given CIDR range.
+	* @param string $CheckIP the IP to be looked up
+	* @param string $Subnet the CIDR subnet to be checked against
+	*/
+	public static function check_cidr_range($CheckIP, $Subnet) {
+		$IP = ip2long($CheckIP);
+		$CIDR = split('/',$Subnet);
+		$SubnetIP = ip2long($CIDR[0]);
+		$SubnetMaskBits = 32 - $CIDR[1];
+
+		return (($IP>>$SubnetMaskBits) == ($SubnetIP>>$SubnetMaskBits));
+	}
+
 }
 ?>