#!/usr/sbin/nft -f

table ip nat {
	chain prerouting {
		type nat hook prerouting priority 0;

		#Thanks to nftables maps, if you have a previous iptables NAT (destination NAT) ruleset like this:
		# % iptables -t nat -A PREROUTING -p tcp --dport 1000 -j DNAT --to-destination 1.1.1.1:1234
		# % iptables -t nat -A PREROUTING -p udp --dport 2000 -j DNAT --to-destination 2.2.2.2:2345
		# % iptables -t nat -A PREROUTING -p tcp --dport 3000 -j DNAT --to-destination 3.3.3.3:3456

		# It can be easily translated to nftables in a single line:

		dnat tcp dport map { 1000 : 1.1.1.1, 2000 : 2.2.2.2, 3000 : 3.3.3.3} \
				: tcp dport map { 1000 : 1234, 2000 : 2345, 3000 : 3456 }
	}

	chain postrouting {
		type nat hook postrouting priority 0;

		#Likewise, in iptables NAT (source NAT):
		# % iptables -t nat -A POSTROUTING -s 192.168.1.1 -j SNAT --to-source 1.1.1.1
		# % iptables -t nat -A POSTROUTING -s 192.168.2.2 -j SNAT --to-source 2.2.2.2
		# % iptables -t nat -A POSTROUTING -s 192.168.3.3 -j SNAT --to-source 3.3.3.3

		# Translated to a nftables one-liner:

		snat ip saddr map { 192.168.1.1 : 1.1.1.1, 192.168.2.2 : 2.2.2.2, 192.168.3.3 : 3.3.3.3 }
	}
}