Re: connection tracking state in rules

[Florian Westphal <fw@strlen.de>]

Thomas Köller <thomas@koeller.dyndns.org> wrote:
> tried to create a rule using the conntrack state of a packet:
> 
> [root@sarkovy nftables]# cat ruleset-own.txt
> create table netdev world
> add set netdev world blacklist { type ipv4_addr; flags dynamic,timeout;
> timeout 1h; gc-interval 6h; size 256; }
> create chain netdev world ingress { type filter hook ingress device
> "eth_cable" priority filter; policy drop; }
> add rule netdev world ingress ip protocol tcp ip saddr @blacklist counter
> drop
> add rule netdev world ingress ct state established,related counter accept
> [root@sarkovy nftables]# nft -cf ruleset-own.txt
> ruleset-own.txt:5:31-38: Error: Could not process rule: Protocol error
> add rule netdev world ingress ct state established,related counter accept
>                               ^^^^^^^^
> This is rejected, but why?

Conntrack state isn't available in ingress hook.

> And, btw., which one is correct, 'ct state established,related' or 'ct state
> { established,related }'?

Both work: related and established state are mutually exclusive.

established,related is a bit more compact and doesn't need the anonymous
set.