diff --git a/ggsn/lookup.h b/ggsn/lookup.h
new file mode 100755
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--- /dev/null
+++ b/ggsn/lookup.h
@@ -0,0 +1,25 @@
+/* 
+ * Hash lookup function.
+ * Copyright (C) 2003, 2004 Mondru AB.
+ * 
+ * The contents of this file may be used under the terms of the GNU
+ * General Public License Version 2, provided that the above copyright
+ * notice and this permission notice is included in all copies or
+ * substantial portions of the software.
+ * 
+ */
+
+/**
+ * lookup()
+ * Generates a 32 bit hash.
+ * Based on public domain code by Bob Jenkins
+ * It should be one of the best hash functions around in terms of both
+ * statistical properties and speed. It is NOT recommended for cryptographic
+ * purposes.
+ **/
+
+#ifndef _LOOKUP_H
+#define _LOOKUP_H
+unsigned long int lookup( unsigned char *k, unsigned long int length, unsigned long int level);
+
+#endif	/* !_LOOKUP_H */