diff -ur iptables-1.4.3.2.orig/xtables.c iptables-1.4.3.2/xtables.c
--- iptables-1.4.3.2.orig/xtables.c	2009-05-03 16:17:53.000000000 +0200
+++ iptables-1.4.3.2/xtables.c	2009-05-03 16:27:37.000000000 +0200
@@ -1502,7 +1502,8 @@
 		else {
 			unsigned int i;
 			for (i = 0; i < ARRAY_SIZE(xtables_chain_protos); ++i) {
-				if (strcmp(s, xtables_chain_protos[i].name) == 0) {
+				if ((xtables_chain_protos[i].name != NULL) &&
+				    (strcmp(s, xtables_chain_protos[i].name) == 0)) {
 					proto = xtables_chain_protos[i].num;
 					break;
 				}