diff --git a/README.md b/README.md
index c4ca601..19c3bba 100644
--- a/README.md
+++ b/README.md
@@ -69,8 +69,8 @@ ciadpi --fake -1 --ttl 8
     Таймаут ожидания первого ответа от сервера в секундах
     В Linux переводится в миллисекунды, поэтому можно указать дробное число
     
--K, --proto <t,h,u>
-    Белый список протоколов: tls,http,udp
+-K, --proto <t,h,u,i>
+    Белый список протоколов: tls,http,udp,ipv4
     
 -H, --hosts <file|:string>
     Ограничить область действия параметров списком доменов
diff --git a/extend.c b/extend.c
index b23da79..99f5978 100644
--- a/extend.c
+++ b/extend.c
@@ -117,13 +117,6 @@ static int cache_add(const struct sockaddr_ina *dst, int m)
 }
 
 
-static inline bool check_port(const uint16_t *p, const struct sockaddr_in6 *dst)
-{
-    return (dst->sin6_port >= p[0] 
-            && dst->sin6_port <= p[1]);
-}
-
-
 int connect_hook(struct poolhd *pool, struct eval *val, 
         const struct sockaddr_ina *dst, int next)
 {
@@ -195,10 +188,10 @@ static bool check_host(
     return 0;
 }
 
-
+    
 static bool check_proto_tcp(int proto, const char *buffer, ssize_t n)
 {
-    if (proto & IS_TCP) {
+    if (!(proto & ~IS_IPV4)) {
         return 1;
     }
     else if ((proto & IS_HTTP) && 
@@ -213,6 +206,27 @@ static bool check_proto_tcp(int proto, const char *buffer, ssize_t n)
 }
 
 
+static bool check_l34(int proto, const uint16_t *pf, int st, const struct sockaddr_in6 *dst)
+{
+    if ((proto & IS_UDP) && (st != SOCK_DGRAM)) {
+        return 0;
+    }
+    if (proto & IS_IPV4) {
+        static const char *pat = "\0\0\0\0\0\0\0\0\0\0\xff\xff";
+        
+        if (dst->sin6_family != AF_INET 
+                && memcmp(&dst->sin6_addr, pat, 12)) {
+            return 0;
+        }
+    }
+    if (pf[0] && 
+            (dst->sin6_port < pf[0] || dst->sin6_port > pf[1])) {
+        return 0;
+    }
+    return 1;
+}
+
+
 static bool check_round(const int *nr, int r)
 {
     return (!nr[1] && r <= 1) || (r >= nr[0] && r <= nr[1]);
@@ -325,10 +339,10 @@ static int setup_conn(struct eval *client, const char *buffer, ssize_t n)
     
     if (!m) for (; m < params.dp_count; m++) {
         struct desync_params *dp = &params.dp[m];
-        if (!dp->detect &&
-                (!dp->pf[0] || check_port(dp->pf, &client->pair->in6)) &&
-                (!dp->proto || check_proto_tcp(dp->proto, buffer, n)) &&
-                (!dp->hosts || check_host(dp->hosts, buffer, n))) {
+        if (!dp->detect 
+                && (check_l34(dp->proto, dp->pf, SOCK_STREAM, &client->pair->in6)
+                    && check_proto_tcp(dp->proto, buffer, n)) 
+                && (!dp->hosts || check_host(dp->hosts, buffer, n))) {
             break;
         }
     }
@@ -528,9 +542,8 @@ ssize_t udp_hook(struct eval *val,
     if (!m) {
         for (; m < params.dp_count; m++) {
             struct desync_params *dp = &params.dp[m];
-            if (!dp->detect && 
-                    (!dp->proto || (dp->proto & IS_UDP)) &&
-                    (!dp->pf[0] || check_port(dp->pf, &dst->in6))) {
+            if (!dp->detect 
+                    && check_l34(dp->proto, dp->pf, SOCK_DGRAM, &dst->in6)) {
                 break;
             }
         }
diff --git a/main.c b/main.c
index c0cefdc..71ccbba 100644
--- a/main.c
+++ b/main.c
@@ -83,7 +83,7 @@ const static char help_text[] = {
     #ifdef TIMEOUT_SUPPORT
     "    -T, --timeout <sec>       Timeout waiting for response, after which trigger auto\n"
     #endif
-    "    -K, --proto <t,h,u>       Protocol whitelist: tls,http,udp\n"
+    "    -K, --proto <t,h,u,i>     Protocol whitelist: tls,http,udp,ipv4\n"
     "    -H, --hosts <file|:str>   Hosts whitelist, filename or :string\n"
     "    -V, --pf <port[-portr]>   Ports range whitelist\n"
     "    -R, --round <num[-numr]>  Number of request to which desync will be applied\n"
@@ -687,6 +687,9 @@ int main(int argc, char **argv)
                     case 'u': 
                         dp->proto |= IS_UDP;
                         break;
+                    case 'i': 
+                        dp->proto |= IS_IPV4;
+                        break;
                     default:
                         invalid = 1;
                         continue;
diff --git a/packets.h b/packets.h
index e2ddb42..48ab133 100644
--- a/packets.h
+++ b/packets.h
@@ -10,8 +10,9 @@
 #define IS_UDP 2
 #define IS_HTTP 4
 #define IS_HTTPS 8
-//#define IS_QUIC 16
-//#define IS_DNS 32
+#define IS_IPV4 16
+//#define IS_QUIC 64
+//#define IS_DNS 128
 
 #define MH_HMIX 1
 #define MH_SPACE 2