Fix error handling bridge devices on host systems.

conf/include_functions.conf

@@ -121,6 +121,18 @@ detect_ipv6() {
 }
 
 
+# -------------
+# - Network Device Stuff
+# -------------
+
+# get virtual ethernet interfaces and the master of the given bridge
+#
+get_vth_ports() {
+  local br="$1"
+  # lists virtual interfaces (veth*)) and the master interface of the given bridge
+  ip -o link show master "$br" 2>/dev/null | awk -F': ' '{print $2}'
+}
+
 # -------------
 # - Fail2ban
 # -------------