That does depend on the firewall you use. Using the "pf" firewall you can have nice clean rules which covers both.

Simple example:

    tcp_inbound = "{ ssh, domain, http, https }"
    tcp_outbound = "{ domain, http, https, imaps, smtps }"

    udp_services = "{ domain, ntp }"

    block all
    pass proto udp to any port $udp_services keep state
    pass out proto tcp to any port $tcp_outbound keep state
    pass in proto tcp to any port $tcp_inbound keep state

pfft, who is still using iptables? :)

FYI, nftables has the 'inet' table which processes both IPv4 and IPv6 packets, and 'ip' and 'ip6' which processes each respectively.

iptables' are easy to configure and available almost everywhere.

easy to configure?? iptables is the most infamously difficult firewall to configure.

Ubuntu created the ufw "uncomplicated firewall" wrapper for a reason :D

I think it's similar to CSS... I however have a sense that IPv6 is much different so we might get better and easier tools for future IP versions once IPv4 is gone, I however don't expect that to happen during my lifetime :/

And your an authority on this? I find PF much more difficult to deal with and I like having two clean interfaces to v4 and v6 in iptables....rather than some overeager tool set that thinks it knows what I mean when I create a rule and the tool then (willy-nilly) applies it across both stacks.

I’m curious to know what you find so difficult about iptables?

It has always seemed reasonably straightforward to me, although I will concede that not being able to combine tcp & udp into the same rule is a bit annoying (though also rarely needed).

That should be obvious as sunlight though, if you know anything at all about IPv6 networking.

For someone who is just doing port blocking it's less obvious. The port numbers are the same on v4 and v6.