diff -ur v2.4.27/linux/net/ipv4/netfilter/ip_nat_core.c linux/net/ipv4/netfilter/ip_nat_core.c
--- v2.4.27/linux/net/ipv4/netfilter/ip_nat_core.c	2004-08-08 10:56:48.000000000 +0300
+++ linux/net/ipv4/netfilter/ip_nat_core.c	2004-11-13 17:09:23.284430360 +0200
@@ -762,7 +762,7 @@
 	    struct sk_buff **pskb)
 {
 	unsigned int i;
-	struct ip_nat_helper *helper;
+	struct ip_nat_helper *helper = NULL;
 	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
 	int is_tcp = (*pskb)->nh.iph->protocol == IPPROTO_TCP;
 
@@ -797,9 +797,9 @@
 				  &info->manips[i].manip,
 				  info->manips[i].maniptype,
 				  &(*pskb)->nfcache);
+			helper = info->helper;
 		}
 	}
-	helper = info->helper;
 	READ_UNLOCK(&ip_nat_lock);
 
 	if (helper) {
diff -ur v2.4.27/linux/net/ipv4/netfilter/ip_nat_ftp.c linux/net/ipv4/netfilter/ip_nat_ftp.c
--- v2.4.27/linux/net/ipv4/netfilter/ip_nat_ftp.c	2003-08-25 22:06:13.000000000 +0300
+++ linux/net/ipv4/netfilter/ip_nat_ftp.c	2004-11-13 17:09:23.285430208 +0200
@@ -44,6 +44,8 @@
 	IP_NF_ASSERT(master);
 
 	IP_NF_ASSERT(!(info->initialized & (1<<HOOK2MANIP(hooknum))));
+	if (!(info->initialized & (1<<HOOK2MANIP(hooknum))))
+		return NF_ACCEPT;
 
 	DEBUGP("nat_expected: We have a connection!\n");
 	exp_ftp_info = &ct->master->help.exp_ftp_info;