diff --git a/include/net/netfilter/nf_conntrack_helper.h b/include/net/netfilter/nf_conntrack_helper.h
index ce27edf57570..26c4ae5bfbb8 100644
--- a/include/net/netfilter/nf_conntrack_helper.h
+++ b/include/net/netfilter/nf_conntrack_helper.h
@@ -100,6 +100,10 @@ struct nf_ct_helper_expectfn {
 	void (*expectfn)(struct nf_conn *ct, struct nf_conntrack_expect *exp);
 };
 
+__printf(3,4)
+void nf_ct_helper_log(struct sk_buff *skb, const struct nf_conn *ct,
+		      const char *fmt, ...);
+
 void nf_ct_helper_expectfn_register(struct nf_ct_helper_expectfn *n);
 void nf_ct_helper_expectfn_unregister(struct nf_ct_helper_expectfn *n);
 struct nf_ct_helper_expectfn *
diff --git a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c
index 48990ada0e1e..2820aa18b542 100644
--- a/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c
+++ b/net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c
@@ -100,7 +100,6 @@ static unsigned int ipv4_helper(unsigned int hooknum,
 	enum ip_conntrack_info ctinfo;
 	const struct nf_conn_help *help;
 	const struct nf_conntrack_helper *helper;
-	unsigned int ret;
 
 	/* This is where we call the helper: as the packet goes out. */
 	ct = nf_ct_get(skb, &ctinfo);
@@ -116,13 +115,8 @@ static unsigned int ipv4_helper(unsigned int hooknum,
 	if (!helper)
 		return NF_ACCEPT;
 
-	ret = helper->help(skb, skb_network_offset(skb) + ip_hdrlen(skb),
-			   ct, ctinfo);
-	if (ret != NF_ACCEPT && (ret & NF_VERDICT_MASK) != NF_QUEUE) {
-		nf_log_packet(NFPROTO_IPV4, hooknum, skb, in, out, NULL,
-			      "nf_ct_%s: dropping packet", helper->name);
-	}
-	return ret;
+	return helper->help(skb, skb_network_offset(skb) + ip_hdrlen(skb),
+			    ct, ctinfo);
 }
 
 static unsigned int ipv4_confirm(unsigned int hooknum,
diff --git a/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c b/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c
index 8a45bb20bedb..2b6c226f5198 100644
--- a/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c
+++ b/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c
@@ -104,7 +104,6 @@ static unsigned int ipv6_helper(unsigned int hooknum,
 	const struct nf_conn_help *help;
 	const struct nf_conntrack_helper *helper;
 	enum ip_conntrack_info ctinfo;
-	unsigned int ret;
 	__be16 frag_off;
 	int protoff;
 	u8 nexthdr;
@@ -130,12 +129,7 @@ static unsigned int ipv6_helper(unsigned int hooknum,
 		return NF_ACCEPT;
 	}
 
-	ret = helper->help(skb, protoff, ct, ctinfo);
-	if (ret != NF_ACCEPT && (ret & NF_VERDICT_MASK) != NF_QUEUE) {
-		nf_log_packet(NFPROTO_IPV6, hooknum, skb, in, out, NULL,
-			      "nf_ct_%s: dropping packet", helper->name);
-	}
-	return ret;
+	return helper->help(skb, protoff, ct, ctinfo);
 }
 
 static unsigned int ipv6_confirm(unsigned int hooknum,
diff --git a/net/netfilter/nf_conntrack_amanda.c b/net/netfilter/nf_conntrack_amanda.c
index c514fe6033d2..dbdaa1149260 100644
--- a/net/netfilter/nf_conntrack_amanda.c
+++ b/net/netfilter/nf_conntrack_amanda.c
@@ -145,6 +145,7 @@ static int amanda_help(struct sk_buff *skb,
 
 		exp = nf_ct_expect_alloc(ct);
 		if (exp == NULL) {
+			nf_ct_helper_log(skb, ct, "cannot alloc expectation");
 			ret = NF_DROP;
 			goto out;
 		}
@@ -158,8 +159,10 @@ static int amanda_help(struct sk_buff *skb,
 		if (nf_nat_amanda && ct->status & IPS_NAT_MASK)
 			ret = nf_nat_amanda(skb, ctinfo, protoff,
 					    off - dataoff, len, exp);
-		else if (nf_ct_expect_related(exp) != 0)
+		else if (nf_ct_expect_related(exp) != 0) {
+			nf_ct_helper_log(skb, ct, "cannot add expectation");
 			ret = NF_DROP;
+		}
 		nf_ct_expect_put(exp);
 	}
 
diff --git a/net/netfilter/nf_conntrack_ftp.c b/net/netfilter/nf_conntrack_ftp.c
index 1ce3befb7c8a..62fb8faedb80 100644
--- a/net/netfilter/nf_conntrack_ftp.c
+++ b/net/netfilter/nf_conntrack_ftp.c
@@ -435,8 +435,8 @@ skip_nl_seq:
 		   connection tracking, not packet filtering.
 		   However, it is necessary for accurate tracking in
 		   this case. */
-		pr_debug("conntrack_ftp: partial %s %u+%u\n",
-			 search[dir][i].pattern,  ntohl(th->seq), datalen);
+		nf_ct_helper_log(skb, ct, "partial matching of `%s'",
+			         search[dir][i].pattern);
 		ret = NF_DROP;
 		goto out;
 	} else if (found == 0) { /* No match */
@@ -450,6 +450,7 @@ skip_nl_seq:
 
 	exp = nf_ct_expect_alloc(ct);
 	if (exp == NULL) {
+		nf_ct_helper_log(skb, ct, "cannot alloc expectation");
 		ret = NF_DROP;
 		goto out;
 	}
@@ -500,9 +501,10 @@ skip_nl_seq:
 				 protoff, matchoff, matchlen, exp);
 	else {
 		/* Can't expect this?  Best to drop packet now. */
-		if (nf_ct_expect_related(exp) != 0)
+		if (nf_ct_expect_related(exp) != 0) {
+			nf_ct_helper_log(skb, ct, "cannot add expectation");
 			ret = NF_DROP;
-		else
+		} else
 			ret = NF_ACCEPT;
 	}
 
diff --git a/net/netfilter/nf_conntrack_h323_main.c b/net/netfilter/nf_conntrack_h323_main.c
index 962795e839ab..7df7b36d2e24 100644
--- a/net/netfilter/nf_conntrack_h323_main.c
+++ b/net/netfilter/nf_conntrack_h323_main.c
@@ -623,7 +623,7 @@ static int h245_help(struct sk_buff *skb, unsigned int protoff,
 
       drop:
 	spin_unlock_bh(&nf_h323_lock);
-	net_info_ratelimited("nf_ct_h245: packet dropped\n");
+	nf_ct_helper_log(skb, ct, "cannot process H.245 message");
 	return NF_DROP;
 }
 
@@ -1197,7 +1197,7 @@ static int q931_help(struct sk_buff *skb, unsigned int protoff,
 
       drop:
 	spin_unlock_bh(&nf_h323_lock);
-	net_info_ratelimited("nf_ct_q931: packet dropped\n");
+	nf_ct_helper_log(skb, ct, "cannot process Q.931 message");
 	return NF_DROP;
 }
 
@@ -1795,7 +1795,7 @@ static int ras_help(struct sk_buff *skb, unsigned int protoff,
 
       drop:
 	spin_unlock_bh(&nf_h323_lock);
-	net_info_ratelimited("nf_ct_ras: packet dropped\n");
+	nf_ct_helper_log(skb, ct, "cannot process RAS message");
 	return NF_DROP;
 }
 
diff --git a/net/netfilter/nf_conntrack_helper.c b/net/netfilter/nf_conntrack_helper.c
index 2f380f73c4c0..c08768da7936 100644
--- a/net/netfilter/nf_conntrack_helper.c
+++ b/net/netfilter/nf_conntrack_helper.c
@@ -28,6 +28,7 @@
 #include <net/netfilter/nf_conntrack_helper.h>
 #include <net/netfilter/nf_conntrack_core.h>
 #include <net/netfilter/nf_conntrack_extend.h>
+#include <net/netfilter/nf_log.h>
 
 static DEFINE_MUTEX(nf_ct_helper_mutex);
 struct hlist_head *nf_ct_helper_hash __read_mostly;
@@ -332,6 +333,24 @@ nf_ct_helper_expectfn_find_by_symbol(const void *symbol)
 }
 EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_symbol);
 
+__printf(3, 4)
+void nf_ct_helper_log(struct sk_buff *skb, const struct nf_conn *ct,
+		      const char *fmt, ...)
+{
+	const struct nf_conn_help *help;
+	const struct nf_conntrack_helper *helper;
+
+	/* Called from the helper function, this call never fails */
+	help = nfct_help(ct);
+
+	/* rcu_read_lock()ed by nf_hook_slow */
+	helper = rcu_dereference(help->helper);
+
+	nf_log_packet(nf_ct_l3num(ct), 0, skb, NULL, NULL, NULL,
+		      "nf_ct_%s: dropping packet: %s ", helper->name, fmt);
+}
+EXPORT_SYMBOL_GPL(nf_ct_helper_log);
+
 int nf_conntrack_helper_register(struct nf_conntrack_helper *me)
 {
 	int ret = 0;
diff --git a/net/netfilter/nf_conntrack_irc.c b/net/netfilter/nf_conntrack_irc.c
index 3b20aa77cfc8..70985c5d0ffa 100644
--- a/net/netfilter/nf_conntrack_irc.c
+++ b/net/netfilter/nf_conntrack_irc.c
@@ -194,6 +194,8 @@ static int help(struct sk_buff *skb, unsigned int protoff,
 
 			exp = nf_ct_expect_alloc(ct);
 			if (exp == NULL) {
+				nf_ct_helper_log(skb, ct,
+						 "cannot alloc expectation");
 				ret = NF_DROP;
 				goto out;
 			}
@@ -210,8 +212,11 @@ static int help(struct sk_buff *skb, unsigned int protoff,
 						 addr_beg_p - ib_ptr,
 						 addr_end_p - addr_beg_p,
 						 exp);
-			else if (nf_ct_expect_related(exp) != 0)
+			else if (nf_ct_expect_related(exp) != 0) {
+				nf_ct_helper_log(skb, ct,
+						 "cannot add expectation");
 				ret = NF_DROP;
+			}
 			nf_ct_expect_put(exp);
 			goto out;
 		}
diff --git a/net/netfilter/nf_conntrack_sane.c b/net/netfilter/nf_conntrack_sane.c
index 295429f39088..4a2134fd3fcb 100644
--- a/net/netfilter/nf_conntrack_sane.c
+++ b/net/netfilter/nf_conntrack_sane.c
@@ -138,6 +138,7 @@ static int help(struct sk_buff *skb,
 
 	exp = nf_ct_expect_alloc(ct);
 	if (exp == NULL) {
+		nf_ct_helper_log(skb, ct, "cannot alloc expectation");
 		ret = NF_DROP;
 		goto out;
 	}
@@ -151,8 +152,10 @@ static int help(struct sk_buff *skb,
 	nf_ct_dump_tuple(&exp->tuple);
 
 	/* Can't expect this?  Best to drop packet now. */
-	if (nf_ct_expect_related(exp) != 0)
+	if (nf_ct_expect_related(exp) != 0) {
+		nf_ct_helper_log(skb, ct, "cannot add expectation");
 		ret = NF_DROP;
+	}
 
 	nf_ct_expect_put(exp);
 
diff --git a/net/netfilter/nf_conntrack_sip.c b/net/netfilter/nf_conntrack_sip.c
index 72a67bbe3518..069229d919b6 100644
--- a/net/netfilter/nf_conntrack_sip.c
+++ b/net/netfilter/nf_conntrack_sip.c
@@ -1095,8 +1095,10 @@ static int process_sdp(struct sk_buff *skb, unsigned int protoff,
 		port = simple_strtoul(*dptr + mediaoff, NULL, 10);
 		if (port == 0)
 			continue;
-		if (port < 1024 || port > 65535)
+		if (port < 1024 || port > 65535) {
+			nf_ct_helper_log(skb, ct, "wrong port %u", port);
 			return NF_DROP;
+		}
 
 		/* The media description overrides the session description. */
 		maddr_len = 0;
@@ -1107,15 +1109,20 @@ static int process_sdp(struct sk_buff *skb, unsigned int protoff,
 			memcpy(&rtp_addr, &maddr, sizeof(rtp_addr));
 		} else if (caddr_len)
 			memcpy(&rtp_addr, &caddr, sizeof(rtp_addr));
-		else
+		else {
+			nf_ct_helper_log(skb, ct, "cannot parse SDP message");
 			return NF_DROP;
+		}
 
 		ret = set_expected_rtp_rtcp(skb, protoff, dataoff,
 					    dptr, datalen,
 					    &rtp_addr, htons(port), t->class,
 					    mediaoff, medialen);
-		if (ret != NF_ACCEPT)
+		if (ret != NF_ACCEPT) {
+			nf_ct_helper_log(skb, ct,
+					 "cannot add expectation for voice");
 			return ret;
+		}
 
 		/* Update media connection address if present */
 		if (maddr_len && nf_nat_sdp_addr && ct->status & IPS_NAT_MASK) {
@@ -1123,8 +1130,10 @@ static int process_sdp(struct sk_buff *skb, unsigned int protoff,
 					      dptr, datalen, mediaoff,
 					      SDP_HDR_CONNECTION, SDP_HDR_MEDIA,
 					      &rtp_addr);
-			if (ret != NF_ACCEPT)
+			if (ret != NF_ACCEPT) {
+				nf_ct_helper_log(skb, ct, "cannot mangle SDP");
 				return ret;
+			}
 		}
 		i++;
 	}
@@ -1258,9 +1267,10 @@ static int process_register_request(struct sk_buff *skb, unsigned int protoff,
 	ret = ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen,
 				      SIP_HDR_CONTACT, NULL,
 				      &matchoff, &matchlen, &daddr, &port);
-	if (ret < 0)
+	if (ret < 0) {
+		nf_ct_helper_log(skb, ct, "cannot parse contact");
 		return NF_DROP;
-	else if (ret == 0)
+	} else if (ret == 0)
 		return NF_ACCEPT;
 
 	/* We don't support third-party registrations */
@@ -1273,8 +1283,10 @@ static int process_register_request(struct sk_buff *skb, unsigned int protoff,
 
 	if (ct_sip_parse_numerical_param(ct, *dptr,
 					 matchoff + matchlen, *datalen,
-					 "expires=", NULL, NULL, &expires) < 0)
+					 "expires=", NULL, NULL, &expires) < 0) {
+		nf_ct_helper_log(skb, ct, "cannot parse expires");
 		return NF_DROP;
+	}
 
 	if (expires == 0) {
 		ret = NF_ACCEPT;
@@ -1282,8 +1294,10 @@ static int process_register_request(struct sk_buff *skb, unsigned int protoff,
 	}
 
 	exp = nf_ct_expect_alloc(ct);
-	if (!exp)
+	if (!exp) {
+		nf_ct_helper_log(skb, ct, "cannot alloc expectation");
 		return NF_DROP;
+	}
 
 	saddr = NULL;
 	if (sip_direct_signalling)
@@ -1300,9 +1314,10 @@ static int process_register_request(struct sk_buff *skb, unsigned int protoff,
 		ret = nf_nat_sip_expect(skb, protoff, dataoff, dptr, datalen,
 					exp, matchoff, matchlen);
 	else {
-		if (nf_ct_expect_related(exp) != 0)
+		if (nf_ct_expect_related(exp) != 0) {
+			nf_ct_helper_log(skb, ct, "cannot add expectation");
 			ret = NF_DROP;
-		else
+		} else
 			ret = NF_ACCEPT;
 	}
 	nf_ct_expect_put(exp);
@@ -1356,9 +1371,10 @@ static int process_register_response(struct sk_buff *skb, unsigned int protoff,
 					      SIP_HDR_CONTACT, &in_contact,
 					      &matchoff, &matchlen,
 					      &addr, &port);
-		if (ret < 0)
+		if (ret < 0) {
+			nf_ct_helper_log(skb, ct, "cannot parse contact");
 			return NF_DROP;
-		else if (ret == 0)
+		} else if (ret == 0)
 			break;
 
 		/* We don't support third-party registrations */
@@ -1373,8 +1389,10 @@ static int process_register_response(struct sk_buff *skb, unsigned int protoff,
 						   matchoff + matchlen,
 						   *datalen, "expires=",
 						   NULL, NULL, &c_expires);
-		if (ret < 0)
+		if (ret < 0) {
+			nf_ct_helper_log(skb, ct, "cannot parse expires");
 			return NF_DROP;
+		}
 		if (c_expires == 0)
 			break;
 		if (refresh_signalling_expectation(ct, &addr, proto, port,
@@ -1408,15 +1426,21 @@ static int process_sip_response(struct sk_buff *skb, unsigned int protoff,
 	if (*datalen < strlen("SIP/2.0 200"))
 		return NF_ACCEPT;
 	code = simple_strtoul(*dptr + strlen("SIP/2.0 "), NULL, 10);
-	if (!code)
+	if (!code) {
+		nf_ct_helper_log(skb, ct, "cannot get code");
 		return NF_DROP;
+	}
 
 	if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_CSEQ,
-			      &matchoff, &matchlen) <= 0)
+			      &matchoff, &matchlen) <= 0) {
+		nf_ct_helper_log(skb, ct, "cannot parse cseq");
 		return NF_DROP;
+	}
 	cseq = simple_strtoul(*dptr + matchoff, NULL, 10);
-	if (!cseq)
+	if (!cseq) {
+		nf_ct_helper_log(skb, ct, "cannot get cseq");
 		return NF_DROP;
+	}
 	matchend = matchoff + matchlen + 1;
 
 	for (i = 0; i < ARRAY_SIZE(sip_handlers); i++) {
@@ -1471,11 +1495,15 @@ static int process_sip_request(struct sk_buff *skb, unsigned int protoff,
 			continue;
 
 		if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_CSEQ,
-				      &matchoff, &matchlen) <= 0)
+				      &matchoff, &matchlen) <= 0) {
+			nf_ct_helper_log(skb, ct, "cannot parse cseq");
 			return NF_DROP;
+		}
 		cseq = simple_strtoul(*dptr + matchoff, NULL, 10);
-		if (!cseq)
+		if (!cseq) {
+			nf_ct_helper_log(skb, ct, "cannot get cseq");
 			return NF_DROP;
+		}
 
 		return handler->request(skb, protoff, dataoff, dptr, datalen,
 					cseq);
@@ -1498,8 +1526,10 @@ static int process_sip_msg(struct sk_buff *skb, struct nf_conn *ct,
 	if (ret == NF_ACCEPT && ct->status & IPS_NAT_MASK) {
 		nf_nat_sip = rcu_dereference(nf_nat_sip_hook);
 		if (nf_nat_sip && !nf_nat_sip(skb, protoff, dataoff,
-					      dptr, datalen))
+					      dptr, datalen)) {
+			nf_ct_helper_log(skb, ct, "cannot NAT SIP message");
 			ret = NF_DROP;
+		}
 	}
 
 	return ret;
@@ -1563,11 +1593,14 @@ static int sip_help_tcp(struct sk_buff *skb, unsigned int protoff,
 		end += strlen("\r\n\r\n") + clen;
 
 		msglen = origlen = end - dptr;
-		if (msglen > datalen)
+		if (msglen > datalen) {
+			nf_ct_helper_log(skb, ct, "incomplete/bad SIP message");
 			return NF_DROP;
+		}
 
 		ret = process_sip_msg(skb, ct, protoff, dataoff,
 				      &dptr, &msglen);
+		/* process_sip_* functions report why this packet is dropped */
 		if (ret != NF_ACCEPT)
 			break;
 		diff     = msglen - origlen;
diff --git a/net/netfilter/nf_conntrack_tftp.c b/net/netfilter/nf_conntrack_tftp.c
index 81fc61c05263..e9936c830208 100644
--- a/net/netfilter/nf_conntrack_tftp.c
+++ b/net/netfilter/nf_conntrack_tftp.c
@@ -60,8 +60,10 @@ static int tftp_help(struct sk_buff *skb,
 		nf_ct_dump_tuple(&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
 
 		exp = nf_ct_expect_alloc(ct);
-		if (exp == NULL)
+		if (exp == NULL) {
+			nf_ct_helper_log(skb, ct, "cannot alloc expectation");
 			return NF_DROP;
+		}
 		tuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
 		nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT,
 				  nf_ct_l3num(ct),
@@ -74,8 +76,10 @@ static int tftp_help(struct sk_buff *skb,
 		nf_nat_tftp = rcu_dereference(nf_nat_tftp_hook);
 		if (nf_nat_tftp && ct->status & IPS_NAT_MASK)
 			ret = nf_nat_tftp(skb, ctinfo, exp);
-		else if (nf_ct_expect_related(exp) != 0)
+		else if (nf_ct_expect_related(exp) != 0) {
+			nf_ct_helper_log(skb, ct, "cannot add expectation");
 			ret = NF_DROP;
+		}
 		nf_ct_expect_put(exp);
 		break;
 	case TFTP_OPCODE_DATA:
diff --git a/net/netfilter/nf_nat_amanda.c b/net/netfilter/nf_nat_amanda.c
index 42d337881171..3b67c9d11273 100644
--- a/net/netfilter/nf_nat_amanda.c
+++ b/net/netfilter/nf_nat_amanda.c
@@ -56,15 +56,19 @@ static unsigned int help(struct sk_buff *skb,
 		}
 	}
 
-	if (port == 0)
+	if (port == 0) {
+		nf_ct_helper_log(skb, exp->master, "all ports in use");
 		return NF_DROP;
+	}
 
 	sprintf(buffer, "%u", port);
 	ret = nf_nat_mangle_udp_packet(skb, exp->master, ctinfo,
 				       protoff, matchoff, matchlen,
 				       buffer, strlen(buffer));
-	if (ret != NF_ACCEPT)
+	if (ret != NF_ACCEPT) {
+		nf_ct_helper_log(skb, exp->master, "cannot mangle packet");
 		nf_ct_unexpect_related(exp);
+	}
 	return ret;
 }
 
diff --git a/net/netfilter/nf_nat_ftp.c b/net/netfilter/nf_nat_ftp.c
index e839b97b2863..e84a578dbe35 100644
--- a/net/netfilter/nf_nat_ftp.c
+++ b/net/netfilter/nf_nat_ftp.c
@@ -96,8 +96,10 @@ static unsigned int nf_nat_ftp(struct sk_buff *skb,
 		}
 	}
 
-	if (port == 0)
+	if (port == 0) {
+		nf_ct_helper_log(skb, ct, "all ports in use");
 		return NF_DROP;
+	}
 
 	buflen = nf_nat_ftp_fmt_cmd(ct, type, buffer, sizeof(buffer),
 				    &newaddr, port);
@@ -113,6 +115,7 @@ static unsigned int nf_nat_ftp(struct sk_buff *skb,
 	return NF_ACCEPT;
 
 out:
+	nf_ct_helper_log(skb, ct, "cannot mangle packet");
 	nf_ct_unexpect_related(exp);
 	return NF_DROP;
 }
diff --git a/net/netfilter/nf_nat_irc.c b/net/netfilter/nf_nat_irc.c
index 1fedee6e7fb6..f02b3605823e 100644
--- a/net/netfilter/nf_nat_irc.c
+++ b/net/netfilter/nf_nat_irc.c
@@ -56,14 +56,18 @@ static unsigned int help(struct sk_buff *skb,
 		}
 	}
 
-	if (port == 0)
+	if (port == 0) {
+		nf_ct_helper_log(skb, exp->master, "all ports in use");
 		return NF_DROP;
+	}
 
 	ret = nf_nat_mangle_tcp_packet(skb, exp->master, ctinfo,
 				       protoff, matchoff, matchlen, buffer,
 				       strlen(buffer));
-	if (ret != NF_ACCEPT)
+	if (ret != NF_ACCEPT) {
+		nf_ct_helper_log(skb, exp->master, "cannot mangle packet");
 		nf_ct_unexpect_related(exp);
+	}
 	return ret;
 }
 
diff --git a/net/netfilter/nf_nat_sip.c b/net/netfilter/nf_nat_sip.c
index 5951146e7688..96ccdf78a29f 100644
--- a/net/netfilter/nf_nat_sip.c
+++ b/net/netfilter/nf_nat_sip.c
@@ -159,8 +159,10 @@ static unsigned int nf_nat_sip(struct sk_buff *skb, unsigned int protoff,
 					 &matchoff, &matchlen,
 					 &addr, &port) > 0 &&
 		    !map_addr(skb, protoff, dataoff, dptr, datalen,
-			      matchoff, matchlen, &addr, port))
+			      matchoff, matchlen, &addr, port)) {
+			nf_ct_helper_log(skb, ct, "cannot mangle SIP message");
 			return NF_DROP;
+		}
 		request = 1;
 	} else
 		request = 0;
@@ -193,8 +195,10 @@ static unsigned int nf_nat_sip(struct sk_buff *skb, unsigned int protoff,
 
 		olen = *datalen;
 		if (!map_addr(skb, protoff, dataoff, dptr, datalen,
-			      matchoff, matchlen, &addr, port))
+			      matchoff, matchlen, &addr, port)) {
+			nf_ct_helper_log(skb, ct, "cannot mangle Via header");
 			return NF_DROP;
+		}
 
 		matchend = matchoff + matchlen + *datalen - olen;
 
@@ -209,8 +213,10 @@ static unsigned int nf_nat_sip(struct sk_buff *skb, unsigned int protoff,
 					&ct->tuplehash[!dir].tuple.dst.u3,
 					true);
 			if (!mangle_packet(skb, protoff, dataoff, dptr, datalen,
-					   poff, plen, buffer, buflen))
+					   poff, plen, buffer, buflen)) {
+				nf_ct_helper_log(skb, ct, "cannot mangle maddr");
 				return NF_DROP;
+			}
 		}
 
 		/* The received= parameter (RFC 2361) contains the address
@@ -225,6 +231,7 @@ static unsigned int nf_nat_sip(struct sk_buff *skb, unsigned int protoff,
 					false);
 			if (!mangle_packet(skb, protoff, dataoff, dptr, datalen,
 					   poff, plen, buffer, buflen))
+				nf_ct_helper_log(skb, ct, "cannot mangle received");
 				return NF_DROP;
 		}
 
@@ -238,8 +245,10 @@ static unsigned int nf_nat_sip(struct sk_buff *skb, unsigned int protoff,
 			__be16 p = ct->tuplehash[!dir].tuple.src.u.udp.port;
 			buflen = sprintf(buffer, "%u", ntohs(p));
 			if (!mangle_packet(skb, protoff, dataoff, dptr, datalen,
-					   poff, plen, buffer, buflen))
+					   poff, plen, buffer, buflen)) {
+				nf_ct_helper_log(skb, ct, "cannot mangle rport");
 				return NF_DROP;
+			}
 		}
 	}
 
@@ -253,27 +262,35 @@ next:
 				       &addr, &port) > 0) {
 		if (!map_addr(skb, protoff, dataoff, dptr, datalen,
 			      matchoff, matchlen,
-			      &addr, port))
+			      &addr, port)) {
+			nf_ct_helper_log(skb, ct, "cannot mangle contact");
 			return NF_DROP;
+		}
 	}
 
 	if (!map_sip_addr(skb, protoff, dataoff, dptr, datalen, SIP_HDR_FROM) ||
-	    !map_sip_addr(skb, protoff, dataoff, dptr, datalen, SIP_HDR_TO))
+	    !map_sip_addr(skb, protoff, dataoff, dptr, datalen, SIP_HDR_TO)) {
+		nf_ct_helper_log(skb, ct, "cannot mangle SIP from/to");
 		return NF_DROP;
+	}
 
 	/* Mangle destination port for Cisco phones, then fix up checksums */
 	if (dir == IP_CT_DIR_REPLY && ct_sip_info->forced_dport) {
 		struct udphdr *uh;
 
-		if (!skb_make_writable(skb, skb->len))
+		if (!skb_make_writable(skb, skb->len)) {
+			nf_ct_helper_log(skb, ct, "cannot mangle packet");
 			return NF_DROP;
+		}
 
 		uh = (void *)skb->data + protoff;
 		uh->dest = ct_sip_info->forced_dport;
 
 		if (!nf_nat_mangle_udp_packet(skb, ct, ctinfo, protoff,
-					      0, 0, NULL, 0))
+					      0, 0, NULL, 0)) {
+			nf_ct_helper_log(skb, ct, "cannot mangle packet");
 			return NF_DROP;
+		}
 	}
 
 	return NF_ACCEPT;
@@ -372,15 +389,19 @@ static unsigned int nf_nat_sip_expect(struct sk_buff *skb, unsigned int protoff,
 		}
 	}
 
-	if (port == 0)
+	if (port == 0) {
+		nf_ct_helper_log(skb, ct, "all ports in use for SIP");
 		return NF_DROP;
+	}
 
 	if (!nf_inet_addr_cmp(&exp->tuple.dst.u3, &exp->saved_addr) ||
 	    exp->tuple.dst.u.udp.port != exp->saved_proto.udp.port) {
 		buflen = sip_sprintf_addr_port(ct, buffer, &newaddr, port);
 		if (!mangle_packet(skb, protoff, dataoff, dptr, datalen,
-				   matchoff, matchlen, buffer, buflen))
+				   matchoff, matchlen, buffer, buflen)) {
+			nf_ct_helper_log(skb, ct, "cannot mangle packet");
 			goto err;
+		}
 	}
 	return NF_ACCEPT;
 
@@ -573,14 +594,18 @@ static unsigned int nf_nat_sdp_media(struct sk_buff *skb, unsigned int protoff,
 		}
 	}
 
-	if (port == 0)
+	if (port == 0) {
+		nf_ct_helper_log(skb, ct, "all ports in use for SDP media");
 		goto err1;
+	}
 
 	/* Update media port. */
 	if (rtp_exp->tuple.dst.u.udp.port != rtp_exp->saved_proto.udp.port &&
 	    !nf_nat_sdp_port(skb, protoff, dataoff, dptr, datalen,
-			     mediaoff, medialen, port))
+			     mediaoff, medialen, port)) {
+		nf_ct_helper_log(skb, ct, "cannot mangle SDP message");
 		goto err2;
+	}
 
 	return NF_ACCEPT;
 
diff --git a/net/netfilter/nf_nat_tftp.c b/net/netfilter/nf_nat_tftp.c
index ccabbda71a3e..7f67e1d5310d 100644
--- a/net/netfilter/nf_nat_tftp.c
+++ b/net/netfilter/nf_nat_tftp.c
@@ -28,8 +28,10 @@ static unsigned int help(struct sk_buff *skb,
 		= ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.udp.port;
 	exp->dir = IP_CT_DIR_REPLY;
 	exp->expectfn = nf_nat_follow_master;
-	if (nf_ct_expect_related(exp) != 0)
+	if (nf_ct_expect_related(exp) != 0) {
+		nf_ct_helper_log(skb, exp->master, "cannot add expectation");
 		return NF_DROP;
+	}
 	return NF_ACCEPT;
 }