The iptables/xtables framework has been replaced by nftables. You should
 consider migrating now.
 .
 This package contains the user-space iptables (IPv6) C library from the
 Netfilter xtables framework.
 .
 iptables IPv6 ruleset ADT and kernel interface.
 .
 This library has been considered private for years (and still is), in the
 sense of changing symbols and backward compatibility not guaranteed.