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Date:   Tue, 27 Jul 2021 23:11:16 +0200
From:   Pablo Neira Ayuso <pablo@netfilter.org>
To:     Tom Yan <tom.ty89@gmail.com>
Cc:     netfilter@vger.kernel.org, netfilter-devel@vger.kernel.org
Subject: Re: [nft] Regarding `tcp flags` (and a potential bug)
Message-ID: <20210727211116.GA13897@salvia>
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On Tue, Jul 27, 2021 at 10:52:39PM +0800, Tom Yan wrote:
> Just noticed something that is even worse:
> 
> # nft add rule meh tcp_flags 'tcp flags { fin, rst, ack }'
> # nft add rule meh tcp_flags 'tcp flags == { fin, rst, ack }'
> # nft add rule meh tcp_flags 'tcp flags & ( fin | rst | ack ) != 0'
> # nft add rule meh tcp_flags 'tcp flags & ( fin | rst | ack ) == 0'
> # nft list table meh
> table ip meh {
>     chain tcp_flags {
>         tcp flags { fin, rst, ack }
>         tcp flags { fin, rst, ack }
>         tcp flags fin,rst,ack
>         tcp flags ! fin,rst,ack
>     }
> }

Could you develop the issue you're seeing here?