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From: Florian Westphal <fw@strlen.de>
To: Jack Ma <Jack.Ma@alliedtelesis.co.nz>
Cc: Florian Westphal <fw@strlen.de>,
	"netfilter-devel@vger.kernel.org"
	<netfilter-devel@vger.kernel.org>
Subject: Re: shift by n bits while performing '--restore-mark'
Date: Wed, 7 Feb 2018 00:53:57 +0100	[thread overview]
Message-ID: <20180206235357.GB14261@breakpoint.cc> (raw)
In-Reply-To: <1517960766867.47573@alliedtelesis.co.nz>

Jack Ma <Jack.Ma@alliedtelesis.co.nz> wrote:
> Our current condition is:
> 
> 1) only 0xfff00000 (three F available in skb->mark), but 0xfffff000 (five F available in ct->mark)
> 
> We wish to copy either 0xfff00000 or 0x00fff000 from ct->mark into skb->mark,
> 
> 
> What about '-j CONNMARK  --restore-mark --mask 0xfffff000 << 8 ( left shift 2 F)'
> 
> This will result in skb->mark = ct->mark << 8
> 
> if ct->mark = 0xabcde000, now skb->mark is changed to:  skb->mark = 0xcde00000.
> 
> Does this make sense :) ?

Yes it does.

AFAICS with nftables you could already do this but I can understand if
you need to use iptables for this.

So feel free to send a patch from xt_connmark.

Thanks for explaining this.

  reply	other threads:[~2018-02-06 23:57 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-16  2:26 conntrack enhancement Jack Ma
2018-01-16 14:17 ` Florian Westphal
2018-01-23  1:16   ` Jack Ma
2018-01-25  2:34   ` Jack Ma
     [not found]     ` <20180125062211.GE14192@breakpoint.cc>
2018-01-25 21:31       ` Jack Ma
2018-02-06 23:46       ` shift by n bits while performing '--restore-mark' Jack Ma
2018-02-06 23:53         ` Florian Westphal [this message]
2018-02-15  4:13           ` Jack Ma

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