Hello, The goal was to add the L4 protocol in a DNAT map which maps an external IP and port to an internal (private) IP and port, for external services mapping to internal services. Thanks to Pablo Neira Ayuso: > map multihoming_ext { > type ipv4_addr . inet_service : ipv4_addr . inet_service type ipv4_addr . inet_proto . inet_service : ipv4_addr . inet_service > elements = { > 46.140.72.218 . 8080 : 192.168.202.10 . 80, > 193.72.186.130 . 8080 : 192.168.202.10 . 80 > } > } + 46.140.72.218 . tcp . 8080 : 192.168.202.10 . 80, + 193.72.186.130 . tcp . 8080 : 192.168.202.10 . 80, + 46.140.72.218 . udp . 5353 : 192.168.202.10 . 53 > dnat ip addr . port to ip daddr . tcp dport map @multihoming_ext # @th: transport header; destination port dnat ip addr . port to ip daddr . meta l4proto . @th,16,16 map @multihoming_ext I could test it and it works.