diff --git a/src/process_legacy.c b/src/process_legacy.c
deleted file mode 100644
index 10757f3..0000000
--- a/src/process_legacy.c
+++ /dev/null
@@ -1,214 +0,0 @@
-#ifndef _GNU_SOURCE
-#define _GNU_SOURCE
-#endif
-#include <glib.h>
-#include <stdio.h>
-#include <unistd.h>
-#include <sys/wait.h>
-#include <sys/prctl.h>
-#include "constant.h"
-#include "flag_legacy.h"
-
-int exiting = 0;
-
-pid_t custom_pgid = 0;
-pid_t adguard_pid = 0;
-pid_t overture_pid = 0;
-pid_t domestic_dnsproxy_pid = 0;
-pid_t foreign_dnsproxy_pid = 0;
-
-void get_sub_exit();
-void server_daemon();
-void get_exit_signal();
-void server_exit(int exit_code);
-pid_t process_exec(char **command, int is_new_group);
-void init_server(char *init_script, char *custom_script);
-
-void get_exit_signal() { // get SIGINT or SIGTERM signal
-    fprintf(stderr, "[ClearDNS] Get exit signal.\n");
-    server_exit(EXIT_NORMAL);
-}
-
-void server_exit(int exit_code) { // kill sub process and exit
-    int status, ret;
-    exiting = 1; // set a exit flag
-
-    if (adguard_pid != 0) {
-        fprintf(stderr, "[ClearDNS] Kill AdGuardHome. (pid = %d)\n", adguard_pid);
-        kill(adguard_pid, SIGTERM);
-    }
-    if (overture_pid != 0) {
-        fprintf(stderr, "[ClearDNS] Kill overture. (pid = %d)\n", overture_pid);
-        kill(overture_pid, SIGTERM);
-    }
-    if (domestic_dnsproxy_pid != 0) {
-        fprintf(stderr, "[ClearDNS] Kill domestic dnsproxy. (pid = %d)\n", domestic_dnsproxy_pid);
-        kill(domestic_dnsproxy_pid, SIGTERM);
-    }
-    if (foreign_dnsproxy_pid != 0) {
-        fprintf(stderr, "[ClearDNS] Kill foreign dnsproxy. (pid = %d)\n", foreign_dnsproxy_pid);
-        kill(foreign_dnsproxy_pid, SIGTERM);
-    }
-
-    ret = waitpid(adguard_pid, &status, 0); // blocking
-    fprintf(stderr, "[ClearDNS] AdGuardHome exit. (pid = %d)\n", ret);
-
-    ret = waitpid(overture_pid, &status, 0); // blocking
-    fprintf(stderr, "[ClearDNS] overture exit. (pid = %d)\n", ret);
-
-    ret = waitpid(domestic_dnsproxy_pid, &status, 0); // blocking
-    fprintf(stderr, "[ClearDNS] domestic dnsproxy exit. (pid = %d)\n", ret);
-
-    ret = waitpid(foreign_dnsproxy_pid, &status, 0); // blocking
-    fprintf(stderr, "[ClearDNS] foreign dnsproxy exit. (pid = %d)\n", ret);
-
-    if (custom_pgid != 0) {
-        ret = waitpid(-custom_pgid, &status, WNOHANG);
-        if (ret == 0) { // custom script still running
-            fprintf(stderr, "[ClearDNS] Kill custom script. (pgid = %d)\n", custom_pgid);
-            kill(-custom_pgid, SIGTERM); // kill process group
-        }
-    }
-
-    fprintf(stderr, "[ClearDNS] Kill all subprocess.\n");
-    kill(-1, SIGTERM); // send kill signal to all process
-    while ((ret = wait(&status)) != -1) {
-        fprintf(stderr, "[ClearDNS] Subprocess exit. (pid = %d)\n", ret);
-    }
-
-    fprintf(stderr, "[ClearDNS] Exit successfully.\n");
-    exit(exit_code);
-}
-
-void get_sub_exit() { // catch child process exit
-    int ret, status;
-    int wait_time = 3; // seconds for wait before restart
-    if (exiting) { return; } // server daemon is exiting
-
-    if (adguard_pid != 0) { // check AdGuardHome
-        ret = waitpid(adguard_pid, &status, WNOHANG); // non-blocking
-        if (ret == -1) {
-            perror("[ClearDNS] Waitpid error");
-            server_exit(EXIT_WAIT_ERROR);
-        } else if (ret) { // process exit
-            adguard_pid = process_exec(adguard_command, FALSE);
-            fprintf(stderr, "[ClearDNS] Catch AdGuardHome exit and restart it. (pid = %d -> %d)\n", ret, adguard_pid);
-            sleep(wait_time); // reduce restart frequency
-            return;
-        }
-    }
-
-    if (overture_pid != 0) { // check overture
-        ret = waitpid(overture_pid, &status, WNOHANG); // non-blocking
-        if (ret == -1) {
-            perror("[ClearDNS] Waitpid error");
-            server_exit(EXIT_WAIT_ERROR);
-        } else if (ret) { // process exit
-            overture_pid = process_exec(overture_command, FALSE);
-            fprintf(stderr, "[ClearDNS] Catch overture exit and restart it. (pid = %d -> %d)\n", ret, overture_pid);
-            sleep(wait_time); // reduce restart frequency
-            return;
-        }
-    }
-
-    if (domestic_dnsproxy_pid != 0) { // check domestic dnsproxy
-        ret = waitpid(domestic_dnsproxy_pid, &status, WNOHANG); // non-blocking
-        if (ret == -1) {
-            perror("[ClearDNS] Waitpid error");
-            server_exit(EXIT_WAIT_ERROR);
-        } else if (ret) { // process exit
-            domestic_dnsproxy_pid = process_exec(domestic_dnsproxy_command, FALSE);
-            fprintf(stderr, "[ClearDNS] Catch domestic dnsproxy exit and restart it. (pid = %d -> %d)\n", ret, domestic_dnsproxy_pid);
-            sleep(wait_time); // reduce restart frequency
-            return;
-        }
-    }
-
-    if (foreign_dnsproxy_pid != 0) { // check foreign dnsproxy
-        ret = waitpid(foreign_dnsproxy_pid, &status, WNOHANG); // non-blocking
-        if (ret == -1) {
-            perror("[ClearDNS] Waitpid error");
-            server_exit(EXIT_WAIT_ERROR);
-        } else if (ret) { // process exit
-            foreign_dnsproxy_pid = process_exec(foreign_dnsproxy_command, FALSE);
-            fprintf(stderr, "[ClearDNS] Catch foreign dnsproxy exit and restart it. (pid = %d -> %d)\n", ret, foreign_dnsproxy_pid);
-            sleep(wait_time); // reduce restart frequency
-            return;
-        }
-    }
-
-    ret = waitpid(-1, &status, WNOHANG); // waitpid for all sub-process (non-blocking)
-    if (ret == -1) {
-        perror("[ClearDNS] Waitpid error");
-        server_exit(EXIT_WAIT_ERROR);
-    } else if (ret) { // process exit
-        fprintf(stderr, "[ClearDNS] Catch subprocess exit. (pid = %d)\n", ret);
-        return;
-    }
-    fprintf(stderr, "[ClearDNS] Subprocess not found.\n"); // get SIGCHLD signal but not exited subprocess found
-}
-
-pid_t process_exec(char **command, int is_new_group) {
-    pid_t pid;
-    char **env = {NULL};
-    if ((pid = fork()) < 0) {
-        perror("[ClearDNS] Fork error");
-        server_exit(EXIT_FORK_ERROR);
-    } else if (pid == 0) { // child process
-        if (is_new_group) { setpgrp(); } // new process group
-        prctl(PR_SET_PDEATHSIG, SIGKILL); // child process die with father process
-        if (execvpe(command[0], command, env) < 0) {
-            perror("[ClearDNS] Exec error");
-            server_exit(EXIT_EXEC_ERROR);
-        }
-    }
-    return pid;
-}
-
-void init_server(char *init_script, char *custom_script) { // run init script (blocking) / custom script (non-blocking)
-    int pid, status;
-    char *crond_command[] = {"crond", NULL};
-    char *init_command[] = {"sh", init_script, NULL};
-    char *custom_command[] = {"sh", custom_script, NULL};
-
-    fprintf(stderr, "[ClearDNS] Start init process.\n");
-    pid = process_exec(init_command, FALSE);
-    wait(&status); // blocking wait
-    fprintf(stderr, "[ClearDNS] Init complete. (pid = %d)\n", pid); // init process
-
-    signal(SIGINT, get_exit_signal); // catch Ctrl + C (2)
-    signal(SIGTERM, get_exit_signal); // catch exit signal (15)
-    signal(SIGCHLD, get_sub_exit); // callback when child process die
-
-    pid = process_exec(crond_command, FALSE);
-    fprintf(stderr, "[ClearDNS] Crond load success. (pid = %d)\n", pid); // crond process
-
-    if (access(custom_script, F_OK) >= 0) { // custom script exist
-        custom_pgid = process_exec(custom_command, TRUE);
-        fprintf(stderr, "[ClearDNS] Custom script is working. (pgid = %d)\n", custom_pgid); // custom process
-        usleep(200000); // wait a moment (200ms)
-    }
-}
-
-void server_daemon() { // run as a daemon of ClearDNS
-    int wait_us_time = 200000; // 200ms
-
-    adguard_pid = process_exec(adguard_command, FALSE);
-    fprintf(stderr, "[ClearDNS] Exec AdGuardHome. (pid = %d)\n", adguard_pid);
-    usleep(wait_us_time);
-
-    overture_pid = process_exec(overture_command, FALSE);
-    fprintf(stderr, "[ClearDNS] Exec overture. (pid = %d)\n", overture_pid);
-    usleep(wait_us_time);
-
-    domestic_dnsproxy_pid = process_exec(domestic_dnsproxy_command, FALSE);
-    fprintf(stderr, "[ClearDNS] Exec domestic dnsproxy. (pid = %d)\n", domestic_dnsproxy_pid);
-    usleep(wait_us_time);
-
-    foreign_dnsproxy_pid = process_exec(foreign_dnsproxy_command, FALSE);
-    fprintf(stderr, "[ClearDNS] Exec foreign dnsproxy. (pid = %d)\n", foreign_dnsproxy_pid);
-    usleep(wait_us_time);
-
-    GMainLoop *main_loop = g_main_loop_new(NULL, FALSE);
-    g_main_loop_run(main_loop);
-}