Add update DNS to disable systemd-resolved.service

disable-dns-service/disable_dns_service.sh

@@ -1,34 +1,77 @@
 #!/bin/bash
 
+# This script modifies the DNS settings and disables systemd-resolved
+
 # Check for root privileges
 if [[ $EUID -ne 0 ]]; then
     echo "This script must be run as root."
     exit 1
 fi
 
-# Display open files using lsof or netstat
+# Define package manager and utility-to-package mapping for Ubuntu/Debian
+PKG_MANAGER="apt-get"
+pkg_map=( ["netstat"]="net-tools" )
+
+# Update package manager
+echo "Updating package manager..."
+$PKG_MANAGER update -y
+
+# Check for required utilities and install if missing
+for cmd in "systemctl" "lsof" "netstat" "nslookup" "awk" "grep" "sed"; do
+  if ! command -v $cmd &> /dev/null; then
+    echo "$cmd is required but not installed. Attempting to install..."
+    case $cmd in
+      "netstat") sudo apt-get install -y net-tools ;;
+      "lsof") sudo apt-get install -y lsof ;;
+      "nslookup") sudo apt-get install -y dnsutils ;;
+      *) echo "$cmd is not a package or is already installed" ;;
+    esac
+  fi
+done
+
+resolv_conf="/etc/resolv.conf"
+
 echo "List of processes with port 53 open:"
 lsof -i :53 || netstat -tulpn | grep ":53 "
 
-# Ask user for confirmation
-read -p "This script will display processes using port 53 and then disable systemd-resolved service. Do you want to proceed? (y/n): " choice
+read -p "This will display processes using port 53 and then disable systemd-resolved. Continue? (y/n): " choice
 if [[ ! "$choice" =~ [yY] ]]; then
-    echo "Script execution aborted."
+    echo "Aborted."
     exit 0
 fi
 
-# Disable and stop systemd-resolved service
-echo "Disabling and stopping systemd-resolved service..."
+echo "Disabling and stopping systemd-resolved..."
 systemctl disable systemd-resolved.service
 systemctl stop systemd-resolved.service
 
-echo "Systemd-resolved service disabled and stopped."
-
-# Check if port 53 is clear
 echo "Checking if port 53 is clear..."
-port_53_status=$(lsof -i :53 | wc -l)
-if [ "$port_53_status" -eq 0 ]; then
-    echo "Port 53 is clear."
-else
+if lsof -i :53 | grep -q '.'; then
     echo "Port 53 is still in use."
+else
+    echo "Port 53 is clear."
 fi
+
+current_dns=$(grep '^nameserver' "$resolv_conf" | awk '{print $2}')
+echo "Current DNS: $current_dns"
+
+read -p "Enter new DNS (default is 1.1.1.1): " dns_server
+dns_server=${dns_server:-1.1.1.1}
+
+if nslookup bigbeartechworld.com "$dns_server" &> /dev/null; then
+    echo "$dns_server can resolve correctly."
+else
+    echo "$dns_server cannot resolve. Exiting."
+    exit 1
+fi
+
+# Backup
+if [ ! -f "$resolv_conf.bak" ]; then
+    cp "$resolv_conf" "$resolv_conf.bak"
+else
+    echo "Backup already exists, skipping backup."
+fi
+
+sed -i "s/nameserver.*/nameserver $dns_server/" "$resolv_conf"
+
+echo "Updated /etc/resolv.conf:"
+cat "$resolv_conf"