diff --git a/ip6t-firewall-gateway b/ip6t-firewall-gateway
index 544ecc9..11fc362 100755
--- a/ip6t-firewall-gateway
+++ b/ip6t-firewall-gateway
@@ -4723,6 +4723,13 @@ if $allow_gaming_out && ! $permit_local_net_to_inet ; then
          if $kernel_forward_between_interfaces ; then
             $ip6t -A FORWARD -o $_dev -p tcp --dport $_port -m conntrack --ctstate NEW -j ACCEPT
          fi
+
+         # - Rule is needed if (local) interface aliases in use (like eth0:1)
+         # -
+         if $kernel_activate_forwarding && $local_alias_interfaces ; then
+            $ip6t -A FORWARD -p tcp -o $_dev --dport $_port --tcp-flag ACK ACK -j ACCEPT
+            $ip6t -A FORWARD -p tcp -i $_dev --sport $_port --tcp-flag ACK ACK -j ACCEPT
+         fi
       done
    done
 
diff --git a/ipt-firewall-gateway b/ipt-firewall-gateway
index c508f85..d1b1995 100755
--- a/ipt-firewall-gateway
+++ b/ipt-firewall-gateway
@@ -5528,6 +5528,13 @@ if $allow_gaming_out && ! $permit_local_net_to_inet ; then
             $ipt -A FORWARD -o $_dev -p tcp --dport $_port -m conntrack --ctstate NEW -j ACCEPT
          fi
 
+         # - Rule is needed if (local) interface aliases in use (like eth0:1)
+         # -
+         if $kernel_activate_forwarding && $local_alias_interfaces ; then
+            $ipt -A FORWARD -p tcp -o $_dev --dport $_port --tcp-flag ACK ACK -j ACCEPT
+            $ipt -A FORWARD -p tcp -i $_dev --sport $_port --tcp-flag ACK ACK -j ACCEPT
+         fi
+
       done
    done