firehol-modifiers - select IPv4 or IPv6 mode
ipv4 definition-or-command argument…
ipv6 definition-or-command argument…
[both] definition-or-command argument…
When preceded by a modifier, any command or definition can be made to apply to IPv4 or IPv6 only.
Without a modifier, interface and router definitions and commands that come before either get applied to both
IPv4 and IPV6.
Commands within an interface
or router
assume the same behaviour as the enclosing definition. You cannot create an IPv4 command within an IPv6 interface or router nor IPv6 within IPv4.
Examples:
interface eth0 myboth src4 192.0.2.0/24 src6 2001:DB8::/24
ipv4 server http accept
ipv6 server http accept
ipv4 interface eth0 my4only src 192.0.2.0/24
server http accept
ipv6 interface eth0 my6only src 2001:DB8::/24
server http accept
Many definitions and commands have explicitly named variants (such as router4, router6, router46) which can be used as shorthand.