diff -up ypserv-2.19/rpc.yppasswdd/yppasswdd.c.ports ypserv-2.19/rpc.yppasswdd/yppasswdd.c
--- ypserv-2.19/rpc.yppasswdd/yppasswdd.c.ports	2006-01-10 20:22:20.000000000 +0100
+++ ypserv-2.19/rpc.yppasswdd/yppasswdd.c	2008-09-25 13:11:23.000000000 +0200
@@ -333,6 +333,12 @@ main (int argc, char **argv)
 	  break;
 	case '\253':
           my_port = atoi (optarg);
+	  if (my_port <= 0 || my_port > 0xffff) {
+		/* Invalid port number */
+	    fprintf (stdout, "Warning: rpc.yppasswdd: Invalid port %d (0x%x)\n", 
+			my_port, my_port);
+		my_port = -1;
+	  }
           if (debug_flag)
             log_msg ("Using port %d\n", my_port);
           break;
diff -up ypserv-2.19/rpc.ypxfrd/ypxfrd.c.ports ypserv-2.19/rpc.ypxfrd/ypxfrd.c
--- ypserv-2.19/rpc.ypxfrd/ypxfrd.c.ports	2006-01-10 20:22:20.000000000 +0100
+++ ypserv-2.19/rpc.ypxfrd/ypxfrd.c	2008-09-25 13:11:23.000000000 +0200
@@ -199,6 +199,12 @@ main (int argc, char **argv)
 	  break;
 	case 'p':
 	  my_port = atoi(optarg);
+	  if (my_port <= 0 || my_port > 0xffff) {
+	    /* Invalid port number */
+	    fprintf (stdout, "Warning: rpc.ypxfrd: Invalid port %d (0x%x)\n", 
+			my_port, my_port);
+	    my_port = -1;
+	  }
 	  if (debug_flag)
 	    log_msg("Using port %d\n", my_port);
 	  break;
diff -up ypserv-2.19/yppush/yppush.c.ports ypserv-2.19/yppush/yppush.c
--- ypserv-2.19/yppush/yppush.c.ports	2005-05-31 11:14:40.000000000 +0200
+++ ypserv-2.19/yppush/yppush.c	2008-09-25 13:11:23.000000000 +0200
@@ -649,6 +649,12 @@ main (int argc, char **argv)
 	      log_msg ("yppush cannot run in parallel with a fixed port");
 	      return 1;
 	    }
+	  if (my_port <= 0 || my_port > 0xffff) {
+	    /* Invalid port number */
+	    fprintf (stdout, "Warning: yppush: Invalid port %d (0x%x)\n", 
+			my_port, my_port);
+	    my_port = -1;
+	  }
 	  break;
 	default:
 	  Usage (1);
diff -up ypserv-2.19/ypserv/ypserv.c.ports ypserv-2.19/ypserv/ypserv.c
--- ypserv-2.19/ypserv/ypserv.c.ports	2008-09-25 13:11:23.000000000 +0200
+++ ypserv-2.19/ypserv/ypserv.c	2008-09-25 13:11:23.000000000 +0200
@@ -492,6 +492,12 @@ main (int argc, char **argv)
 	  break;
 	case 'p':
 	  my_port = atoi (optarg);
+	  if (my_port <= 0 || my_port > 0xffff) {
+	    /* Invalid port number */
+	    fprintf (stdout, "Warning: ypserv: Invalid port %d (0x%x)\n", 
+			my_port, my_port);
+	    my_port = -1;
+	  }
 	  if (debug_flag)
 	    log_msg ("Using port %d\n", my_port);
 	  break;