diff --git a/installers/common.sh b/installers/common.sh
index bd1ba0ce..581bfb01 100644
--- a/installers/common.sh
+++ b/installers/common.sh
@@ -836,7 +836,7 @@ function _configure_networking() {
     "-A POSTROUTING -s 192.168.50.0/24 ! -d 192.168.50.0/24 -j MASQUERADE"
     )
     for rule in "${rules[@]}"; do
-        if grep -- "$rule" $rulesv4 > /dev/null; then
+        if sudo grep -- "$rule" $rulesv4 > /dev/null; then
             echo "Rule already exits: ${rule}"
         else
             rule=$(sed -e 's/^\(-A POSTROUTING\)/-t nat \1/' <<< $rule)