diff --git a/html/cgi-bin/firewall.cgi b/html/cgi-bin/firewall.cgi
index 28a7f0bd2..741fada01 100755
--- a/html/cgi-bin/firewall.cgi
+++ b/html/cgi-bin/firewall.cgi
@@ -783,6 +783,10 @@ sub checkrule
 					}
 					$fwdfwsettings{'dnatport'}=join("|",@values);
 		}
+		#check if a rule with prot tcp or udp and ports is edited and now prot is "all", then delete all ports
+		if($fwdfwsettings{'PROT'} eq ''){
+			$fwdfwsettings{'dnatport'}='';
+		}
 	}
 	#check valid remark
 	if ($fwdfwsettings{'ruleremark'} ne '' && !&validremark($fwdfwsettings{'ruleremark'})){