Index: sys/netinet/in.c
===================================================================
--- sys/netinet/in.c
+++ sys/netinet/in.c
@@ -413,17 +413,8 @@
 		ia->ia_subnetmask = ntohl(ia->ia_sockmask.sin_addr.s_addr);
 	} else {
 		in_addr_t i = ntohl(addr->sin_addr.s_addr);
-
-		/*
-	 	 * Be compatible with network classes, if netmask isn't
-		 * supplied, guess it based on classes.
-	 	 */
-		if (IN_CLASSA(i))
-			ia->ia_subnetmask = IN_CLASSA_NET;
-		else if (IN_CLASSB(i))
-			ia->ia_subnetmask = IN_CLASSB_NET;
-		else
-			ia->ia_subnetmask = IN_CLASSC_NET;
+		/* Assume host address if netmask is not specified */
+		ia->ia_subnetmask = INADDR_BROADCAST;
 		ia->ia_sockmask.sin_addr.s_addr = htonl(ia->ia_subnetmask);
 	}
 	ia->ia_subnet = ntohl(addr->sin_addr.s_addr) & ia->ia_subnetmask;