diff --git a/util/.gitignore b/util/.gitignore
index 3deeadc..21d4321 100644
--- a/util/.gitignore
+++ b/util/.gitignore
@@ -1,3 +1,7 @@
 /build
 /target
 /bin
+.classpath
+.project
+.settings/
+
diff --git a/util/pom.xml b/util/pom.xml
index 1c6672c..fa80fc1 100644
--- a/util/pom.xml
+++ b/util/pom.xml
@@ -4,7 +4,7 @@
 	<modelVersion>4.0.0</modelVersion>
 	<groupId>de.hsadmin.core</groupId>
 	<artifactId>hsadmin-util</artifactId>
-	<version>4.0.4-SNAPSHOT</version>
+	<version>4.0.5</version>
 	<properties>
 		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
 		<maven.compiler.target>1.8</maven.compiler.target>
diff --git a/util/src/main/java/de/hsadmin/core/util/IPv6Trick.java b/util/src/main/java/de/hsadmin/core/util/IPv6Trick.java
index bab3fff..760ccd7 100644
--- a/util/src/main/java/de/hsadmin/core/util/IPv6Trick.java
+++ b/util/src/main/java/de/hsadmin/core/util/IPv6Trick.java
@@ -44,6 +44,46 @@ public class IPv6Trick {
 		throw new HSAdminException("unknown IPv4 address given");
 	}
 
+	public static String IPv4Gateway (final String ipv4address) throws HSAdminException {
+		if (ipv4address == null || ipv4address.length() == 0) {
+			throw new HSAdminException("no IPv4 address given");
+		}
+ 		try {
+ 			final InetAddress inetV4Address = InetAddress.getByName(ipv4address);
+ 			final String inetV4AddressString = inetV4Address.getHostAddress();
+			if (inetV4AddressString.startsWith(IPv4_83_223_78)) return IPv4_83_223_78 + ".1";
+			if (inetV4AddressString.startsWith(IPv4_83_223_79)) return IPv4_83_223_79 + ".1";
+			if (inetV4AddressString.startsWith(IPv4_83_223_91)) return IPv4_83_223_91 + ".1";
+			if (inetV4AddressString.startsWith(IPv4_83_223_94)) return IPv4_83_223_94 + ".1";
+			if (inetV4AddressString.startsWith(IPv4_83_223_95)) return IPv4_83_223_95 + ".1";
+			throw new HSAdminException("unknown IPv4 address given");
+		} catch (UnknownHostException e) {
+			throw new HSAdminException(e);
+		}
+	}
+	
+	public static String IPv6Gateway (final String ipv4address) throws HSAdminException {
+		if (ipv4address == null || ipv4address.length() == 0) {
+			throw new HSAdminException("no IPv4 address given");
+		}
+ 		try {
+ 			final InetAddress inetV4Address = InetAddress.getByName(ipv4address);
+ 			final String inetV4AddressString = inetV4Address.getHostAddress();
+			if (inetV4AddressString.startsWith(IPv4_83_223_79) 			// Alboin-Kontor Berlin
+					|| inetV4AddressString.startsWith(IPv4_83_223_91)
+					|| inetV4AddressString.startsWith(IPv4_83_223_95) ) {
+				return IPv6_PREFIX_AK;
+			}
+			if (inetV4AddressString.startsWith(IPv4_83_223_78) 			// e-Shelter Berlin
+					|| inetV4AddressString.startsWith(IPv4_83_223_94) ) {
+				return IPv6_PREFIX_ES;
+			}
+		} catch (UnknownHostException e) {
+			throw new HSAdminException(e);
+		}
+		throw new HSAdminException("unknown IPv4 address given");
+	}
+	
 	public static boolean isKnownRemote(final String remoteAddress) {
 		boolean isKnown = false;
 		if (remoteAddress.startsWith(IPv4_LOCALHOST) || remoteAddress.startsWith(IPv6_LOCALHOST) || remoteAddress.startsWith(IPv6_LOCALHOST_ALT)) {