diff --git a/conf/default_basic_behavior.conf b/conf/default_basic_behavior.conf
index 415eac4..95ccb58 100644
--- a/conf/default_basic_behavior.conf
+++ b/conf/default_basic_behavior.conf
@@ -61,6 +61,9 @@ allow_game_ps3_out=false
 allow_game_ps4_out=false
 allow_game_fifa21_out=false
 
+# Gameing Steam
+#
+allow_game_steam_out=false
 
 
 # ---
diff --git a/conf/default_ports.conf b/conf/default_ports.conf
index 11f7c4a..4674e53 100644
--- a/conf/default_ports.conf
+++ b/conf/default_ports.conf
@@ -345,6 +345,23 @@ standard_game_ps4_udp_ports="3074,3478,3479"
 standard_game_fifa21_tcp_ports="1935,3478,3479,3480,3659,10000:10069,10070:10080,10081:10099,42127"
 standard_game_fifa21_udp_ports="3074,3478,3479,3659,6000"
 
+# Game Ports (Steam)
+#
+# see also: 
+#    https://www.speedguide.net/port.php?port=27015
+#    https://www.freeware.de/steam/tipp/steam-ports-richtig-in-der-firewall-freigeben/
+#    https://praxistipps.chip.de/steam-die-richtigen-ports-freigeben-so-gehts_45289
+# 
+# Steam (Valve gaming platform) uses these ports:
+# 27000-27015 udp (Steam client game client traffic)
+# 27015-27030 tcp/udp (typically matchmaking and HLTV, also used to download Steam content)
+# 27015-27050 tcp (download Steam content)
+# 27031 udp, 27036 tcp/udp, and 27037 tcp (incoming for in-home streaming)
+# 3478 udp, 4379 udp, 4380 udp (outbound - Steamworks P2P networking and voice chat)
+# 4380 udp (Steam client)
+#
+standard_game_steam_tcp_ports="27014:27050"
+standard_game_steam_udp_ports="12000,27000:27015,27016:27030,27031,27036,3478,4379,4380"
 
 # -------------
 # --- Predefined Ports
diff --git a/conf/post_decalrations.conf b/conf/post_decalrations.conf
index 811c143..4cc0116 100644
--- a/conf/post_decalrations.conf
+++ b/conf/post_decalrations.conf
@@ -1481,6 +1481,20 @@ if $allow_game_fifa21_out ; then
    done
    IFS="$CUR_IFS"
 fi
+if $allow_game_steam_out ; then
+   IFS=',' ; for _port in $standard_game_steam_udp_ports ; do
+
+      if containsElement "${_port}" "${out_udp_port_arr[@]}" ; then
+         continue
+      fi
+      
+      game_ports_udp_arr+=("$_port")
+
+      out_udp_port_arr+=("$_port")
+
+   done
+   IFS="$CUR_IFS"
+fi
 
 
 declare -a game_ports_tcp_arr
@@ -1554,6 +1568,20 @@ if $allow_game_fifa21_out ; then
    done
    IFS="$CUR_IFS"
 fi
+if $allow_game_steam_out ; then
+   IFS=',' ; for _port in $standard_game_steam_tcp_ports ; do
+
+      if containsElement "${_port}" "${out_tcp_port_arr[@]}" ; then
+         continue
+      fi
+      
+      game_ports_tcp_arr+=("$_port")
+
+      out_tcp_port_arr+=("$_port")
+
+   done
+   IFS="$CUR_IFS"
+fi
    
 # ==================================================
 # END: gather out ports