diff --git a/src/main.cpp b/src/main.cpp
index 4fa1a7f..c4e8ca4 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1,4 +1,3 @@
-#include <unordered_map>
 #include "common.h"
 #include "tcp.h"
 #include "epoll_event.h"
@@ -57,9 +56,7 @@ int main() {
     signal_handle.add_signal(SIGINT, signal_handler);
     signal_handle.ignore_signal(SIGPIPE);
 
-    std::unordered_map<unsigned int, unsigned int> client_ip_mapper;  /* client ip 到 连接数量的映射 */
     std::unordered_map<pid_t , unsigned int> client_process_mapper;  /* client 进程到 ip 的映射 */
-    std::set<unsigned int> client_counter;  /* 当前建立连接的 client 数量 */
 
     bool terminate = false;
     while (!terminate) {
@@ -80,26 +77,10 @@ int main() {
                 utility::debug_info(std::string("Accept client: " + std::to_string(client_ip)));
 
                 /* 限流 */
-                if (configure::MAX_CONN_PER_IP > 0 && configure::MAX_CONN_PER_IP <= client_ip_mapper[client_ip]) {
-                    /* 该 IP 建立的连接数过多 */
-                    char buf[1024] = {0};
-                    snprintf(buf, sizeof(buf), "%d There are too many connections from your address.\r\n",
-                             ftp_response_code::kFTP_IP_LIMIT);
-                    tcp::send_data(connect_fd, buf, strlen(buf));
-                    close(connect_fd);
-                    continue;
-                } else if (configure::MAX_CLIENT_NUM > 0 && configure::MAX_CLIENT_NUM <= client_counter.size()) {
-                    /* 建立连接的 client 过多 */
-                    char buf[1024] = {0};
-                    snprintf(buf, sizeof(buf), "%d There are too many connected users, please try later.\r\n",
-                             ftp_response_code::kFTP_TOO_MANY_USERS);
-                    tcp::send_data(connect_fd, buf, strlen(buf));
+                if (tcp_server.limit_client_crowding(connect_fd, client_ip)) {
                     close(connect_fd);
                     continue;
                 }
-                /* 更新计数信息*/
-                client_counter.insert(client_ip);
-                ++client_ip_mapper[client_ip];
 
                 /* 创建服务进程，为 client 服务 */
                 pid_t pid = fork();
@@ -140,10 +121,7 @@ int main() {
                                 while ((pid = waitpid(-1, &stat, WNOHANG)) > 0) {
                                     /* 进程退出后的善后处理 */
                                     utility::debug_info(std::string("Subprocess: ") + std::to_string(pid) + " exited");
-                                    unsigned int client_ip = client_process_mapper[pid];
-                                    if (client_ip_mapper[client_ip] > 0) {
-                                        --client_ip_mapper[client_ip] == 0 ? client_counter.erase(client_ip) : 1;
-                                    }
+                                    tcp_server.on_a_client_exit(client_process_mapper[pid]);
                                 }
                                 break;
                             }
diff --git a/src/tcp.cpp b/src/tcp.cpp
index 62e238b..fd2d060 100644
--- a/src/tcp.cpp
+++ b/src/tcp.cpp
@@ -6,6 +6,8 @@
 #include "tcp.h"
 #include "utility.h"
 #include "common.h"
+#include "configure.h"
+#include "ftp_codes.h"
 
 static std::string g_local_ip;
 
@@ -60,6 +62,36 @@ int CLTCPServer::accept_client(struct sockaddr_in &client_address) {
     return accept(m_listen_fd, (struct sockaddr *) &client_address, &client_addr_len);
 }
 
+bool CLTCPServer::limit_client_crowding(int connect_fd, unsigned int client_ip) {
+    /* 限流 */
+    if (configure::MAX_CONN_PER_IP > 0 && configure::MAX_CONN_PER_IP <= m_client_ip_mapper[client_ip]) {
+        /* 该 IP 建立的连接数过多 */
+        char buf[1024] = {0};
+        snprintf(buf, sizeof(buf), "%d There are too many connections from your address.\r\n",
+                 ftp_response_code::kFTP_IP_LIMIT);
+        tcp::send_data(connect_fd, buf, strlen(buf));
+        return true;
+    } else if (configure::MAX_CLIENT_NUM > 0 && configure::MAX_CLIENT_NUM <= m_client_counter.size()) {
+        /* 建立连接的 client 过多 */
+        char buf[1024] = {0};
+        snprintf(buf, sizeof(buf), "%d There are too many connected users, please try later.\r\n",
+                 ftp_response_code::kFTP_TOO_MANY_USERS);
+        tcp::send_data(connect_fd, buf, strlen(buf));
+        return true;
+    }
+    /* 更新计数信息*/
+    m_client_counter.insert(client_ip);
+    ++m_client_ip_mapper[client_ip];
+
+    return false;
+}
+
+void CLTCPServer::on_a_client_exit(unsigned int client_ip) {
+    if (m_client_ip_mapper[client_ip] > 0) {
+        --m_client_ip_mapper[client_ip] == 0 ? m_client_counter.erase(client_ip) : 1;
+    }
+}
+
 namespace tcp {
     void close_fd(int fd) {
         if (close(fd) < 0)
diff --git a/src/tcp.h b/src/tcp.h
index ddc18d9..b1148cd 100644
--- a/src/tcp.h
+++ b/src/tcp.h
@@ -6,6 +6,8 @@
 #define FTPD_TCP_H
 
 #include <string>
+#include <set>
+#include <unordered_map>
 #include "common.h"
 #include "utility.h"
 
@@ -17,14 +19,22 @@ class CLTCPServer {
 
     }
 
+
     int start_listen();
 
     int accept_client(struct sockaddr_in &client_address);
 
+    bool limit_client_crowding(int connect_fd, unsigned int client_ip); /* 限流*/
+    void on_a_client_exit(unsigned int client_ip);
+
 private:
     unsigned int m_port;
     std::string m_host;
     int m_listen_fd;
+
+    /* 限流 */
+    std::unordered_map<unsigned int, unsigned int> m_client_ip_mapper;  /* client ip 到 连接数量的映射 */
+    std::set<unsigned int> m_client_counter;  /* 当前建立连接的 client 数量 */
 };
 
 namespace tcp {