diff --git a/README.md b/README.md
index 79887a6..569d9be 100644
--- a/README.md
+++ b/README.md
@@ -7,7 +7,8 @@ Server proxy
 ## Installation
 N/A
 ## Usage
-./stop-output-traffic-http-https.sh
+sudo ./stop-output-traffic-http-https.sh
+The script takes a few minutes to apply the rules
 
 ### Changelog
 ### [1.0.0] - 2025-09-17
diff --git a/stop-output-traffic-http-https.sh b/stop-output-traffic-http-https.sh
index 555b10e..42bde20 100755
--- a/stop-output-traffic-http-https.sh
+++ b/stop-output-traffic-http-https.sh
@@ -22,6 +22,11 @@ version="1.0.0"
 
 set -euo pipefail
 
+# check if the effective user ID is 0 (root)
+if [[ $EUID -ne 0 ]]; then
+   echo "This script must be run as root or with sudo."
+   exit 1
+fi
 # ---------------------- CONFIG ----------------------
 PROXY_NAME="proxy.ville-geneve.ch"
 PROXY_PORT="8080"