--- loncom/configuration/Firewall.pm	2019/07/02 19:40:22	1.19
+++ loncom/configuration/Firewall.pm	2020/07/09 13:42:37	1.21
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA
 # Firewall configuration to allow internal LON-CAPA communication between servers   
 #
-# $Id: Firewall.pm,v 1.19 2019/07/02 19:40:22 raeburn Exp $
+# $Id: Firewall.pm,v 1.21 2020/07/09 13:42:37 raeburn Exp $
 #
 # The LearningOnline Network with CAPA
 #
@@ -181,10 +181,13 @@ sub firewall_open_port {
                         }
                     }
                 } else {
-                    print "no key found in $iphost hash ref\n";
+                    print "no key found in \$iphost hash ref.\n".
+                          "Domain Name Service (DNS) may not be available.\n".
+                          "If this LON-CAPA node is standalone, then you can fix this issue by modifying /etc/hosts.\n".
+                          "Use a text editor to add: IPaddress Hostname\n";
                 }
             } else {
-                print "$iphost is not a reference to a hash\n";
+                print "\$iphost is not a reference to a hash\n";
             }
             if (@lond_port_curropen) {
                 unless (grep(/^\Q$port\E$/,@opened)) {
@@ -276,6 +279,7 @@ sub firewall_is_port_open {
     # for other ports returns 1 if the firewall port is open, 0 if not.
     # if firewalld is in use, checks for rich rules only.
     my $count = 0;
+    # check if firewall is active or installed
     return $count if (! &firewall_is_active());
     if ($firewalld) {
         my $zone = &get_default_zone();
@@ -307,12 +311,7 @@ sub firewall_is_port_open {
                 close(PIPE);
             }
         }
-	return $count; 
-    }
-    return $count unless ($fw_chain !~ /^[\w-]+$/);
-    if (open(PIPE,"$iptables -L $fw_chain -n |")) {
-        # check if firewall is active or installed
-        return if (! &firewall_is_active());
+    } elsif (($fw_chain =~ /^[\w-]+$/) && (open(PIPE,"$iptables -L $fw_chain -n |"))) {
         while(<PIPE>) {
             if ($port eq $lond_port) {
                 if (ref($iphost) eq 'HASH') {