diff --git a/src/common.c b/src/common.c
index 55af748..ea5e472 100644
--- a/src/common.c
+++ b/src/common.c
@@ -9,6 +9,39 @@
 
 
 #include "proxy.h"
+/* returns 0 on success, 1 if atyp is not supported for family, 2 if the
+   address is null. The address is set in both the 0 and the 2 case. */
+int socks5_setaddr(int family, int atyp, const unsigned char *addr, PROXYSOCKADDRTYPE *sa){
+	int i, len = 4;
+
+	memset(sa, 0, sizeof(*sa));
+	if(atyp == 4){
+#ifdef NOIPV6
+		return 1;
+#else
+		if(family == 4) return 1;
+		len = 16;
+		*SAFAMILY(sa) = AF_INET6;
+		memcpy(SAADDR(sa), addr, 16);
+#endif
+	}
+#ifndef NOIPV6
+	else if(family == 6){
+		unsigned char prefix[12] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 255, 255};
+
+		*SAFAMILY(sa) = AF_INET6;
+		memcpy(SAADDR(sa), prefix, 12);
+		memcpy(12 + (unsigned char *)SAADDR(sa), addr, 4);
+	}
+#endif
+	else {
+		*SAFAMILY(sa) = AF_INET;
+		memcpy(SAADDR(sa), addr, 4);
+	}
+	for(i = 0; i < len && !addr[i]; i++);
+	return (i == len)? 2 : 0;
+}
+
 #ifdef __linux__
 #include <sched.h>
 
diff --git a/src/proxy.h b/src/proxy.h
index 5702012..7a65f75 100644
--- a/src/proxy.h
+++ b/src/proxy.h
@@ -205,6 +205,7 @@ extern int timeouts[12];
 int sockmap(struct clientparam * param, int timeo, int usesplice);
 int udpsockmap(struct clientparam * param, int timeo);
 int udpbind(struct clientparam * param);
+int socks5_setaddr(int family, int atyp, const unsigned char *addr, PROXYSOCKADDRTYPE *sa);
 #ifdef __linux__
 int switch_ns(struct srvparam *srv, int target_fd);
 #endif
diff --git a/src/proxymain.c b/src/proxymain.c
index b050930..a09bcaa 100644
--- a/src/proxymain.c
+++ b/src/proxymain.c
@@ -505,8 +505,8 @@ int MODULEMAINFUNC (int argc, char** argv){
 			}
 			break;
 		 case 'N':
-			if(argv[i][3] == 'e') getip46(46, (unsigned char *)argv[i]+3, (struct sockaddr *)&srv.extNat);
-			else if(argv[i][3] == 'i') getip46(46, (unsigned char *)argv[i]+3, (struct sockaddr *)&srv.intNat);
+			if(argv[i][2] == 'e') getip46(46, (unsigned char *)argv[i]+3, (struct sockaddr *)&srv.extNat);
+			else if(argv[i][2] == 'i') getip46(46, (unsigned char *)argv[i]+3, (struct sockaddr *)&srv.intNat);
 			else getip46(46, (unsigned char *)argv[i]+2, (struct sockaddr *)&srv.extNat);
 			break;
 		 case 'n':
diff --git a/src/socks.c b/src/socks.c
index f60b0dc..76e77d3 100644
--- a/src/socks.c
+++ b/src/socks.c
@@ -107,38 +107,20 @@ void * sockschild(struct clientparam* param) {
  }
  
  size = 4;
- *SAFAMILY(&param->sinsr) = *SAFAMILY(&param->req) = AF_INET;
  switch(c) {
 #ifndef NOIPV6
 	case 4:
-		if(param->srv->family == 4) RETURN(997);
 		size = 16;
-		*SAFAMILY(&param->sinsr) = *SAFAMILY(&param->req) = AF_INET6;
 #endif
 	case 1:
 		for (i = 0; i<size; i++){
 			if ((res = sockgetcharcli(param, conf.timeouts[SINGLEBYTE_S], 0)) == EOF) {RETURN(441);}
 			buf[i] = (unsigned char)res;
 		}
-#ifndef NOIPV6
-		if (c == 1 && param->srv->family==6){
-			char prefix[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 255, 255};
-			*SAFAMILY(&param->sinsr) = *SAFAMILY(&param->req) = AF_INET6;
-			memcpy(SAADDR(&param->sinsr), prefix, 12);
-			memcpy(12 + (char *)SAADDR(&param->sinsr), buf, 4);
-			memcpy(SAADDR(&param->req), prefix, 12);
-			memcpy(12 + (char *)SAADDR(&param->req), buf, 4);
-		}
-		else {
-#endif
-			memcpy(SAADDR(&param->sinsr), buf, size);
-			memcpy(SAADDR(&param->req), buf, size);
-#ifndef NOIPV6
-		}
-#endif
-		if(command == 1 && SAISNULL(&param->req)) {
-			RETURN(431);
-		}
+		res = socks5_setaddr(param->srv->family, c, buf, &param->req);
+		if(res == 1) {RETURN(997);}
+		if(res == 2 && command == 1) {RETURN(431);}
+		param->sinsr = param->req;
 		myinet_ntop(*SAFAMILY(&param->sinsr), SAADDR(&param->sinsr), (char *)buf, 64);
 		break;
 	case 3:
@@ -285,7 +267,7 @@ CLEANRET:
 
 	sasize = sizeof(sin);
 	if(command != 3 && param->remsock != INVALID_SOCKET) param->srv->so._getsockname(param->sostate, param->remsock, (struct sockaddr *)&sin,  &sasize);
-	if(!SAISNULL(&param->srv->extNat)){
+	if(command != 3 && !SAISNULL(&param->srv->extNat)){
 	    uint16_t port;
 	    port = *SAPORT(&sin);
 	    sin = param->srv->extNat;
@@ -293,7 +275,7 @@ CLEANRET:
 	}
 	else {
 	    param->srv->so._getsockname(param->sostate, param->clisock, (struct sockaddr *)&sin,  &sasize);
-	    if(!SAISNULL(&param->srv->intNat)){
+	    if(command == 3 && !SAISNULL(&param->srv->intNat)){
 		uint16_t port;
 		port = *SAPORT(&sin);
 		sin = param->srv->intNat;
diff --git a/src/udpsockmap.c b/src/udpsockmap.c
index d3a0f45..46048f7 100644
--- a/src/udpsockmap.c
+++ b/src/udpsockmap.c
@@ -257,16 +257,16 @@ int udpsockmap(struct clientparam *param, int timeo)
 			memset(&dst, 0, sizeof(dst));
 			switch (base[3]) {
 			case 1:
-				*SAFAMILY(&dst) = AF_INET;
-				memcpy(SAADDR(&dst), base + 4, 4);
+				if (socks5_setaddr(param->srv->family, 1, base + 4, &dst)) continue;
 				i = 8;
 				break;
+#ifndef NOIPV6
 			case 4:
 				if (len < 22) return 484;
-				*SAFAMILY(&dst) = AF_INET6;
-				memcpy(SAADDR(&dst), base + 4, 16);
+				if (socks5_setaddr(param->srv->family, 4, base + 4, &dst)) continue;
 				i = 20;
 				break;
+#endif
 			case 3: {
 				int sz = base[4];
 				if (len < 7 + sz) return 485;
@@ -309,7 +309,8 @@ int udpsockmap(struct clientparam *param, int timeo)
 				if (!nhops) param->sinsr = dst;
 
 				if (!havedst) reconnect = 1;
-				else if ((param->srv->udpauth & 2) && !param->dstindep) {
+				else if (!nhops && *SAFAMILY(&dst) != *SAFAMILY(&param->sinsl)) reconnect = 1;
+				if (havedst && (param->srv->udpauth & 2) && !param->dstindep) {
 					param->preauth = 2;
 					ares = (*param->srv->authfunc)(param);
 					param->preauth = 0;