From mboxrd@z Thu Jan  1 00:00:00 1970
From: Florian Westphal <fw@strlen.de>
Subject: Re: conntrack enhancement
Date: Tue, 16 Jan 2018 15:17:12 +0100
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Cc: "netfilter-devel@vger.kernel.org" <netfilter-devel@vger.kernel.org>
To: Jack Ma <Jack.Ma@alliedtelesis.co.nz>
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Jack Ma <Jack.Ma@alliedtelesis.co.nz> wrote:
> Hi there,
> 
> I am planing to add new user option to allow connmark to be shifted to enable more advanced routing options.
> 
> Currently, it might be something like:
> 
> Conntrack parameters and options:
>  
> -sl, --shift-left bits                      shift mark by n bit to the left
> -sr, --shift-right bits                    shift mark by n bit to the right.
> 
> We run out of nfmark (skb->mark) in our systems due to increasing number of routes we are supporting.

I suspect this is for -j CONNMARK  --restore-mark / --save-mark ?

What would this do?

Something like

skb->mark = ct->mark >> $lshift; ?
ct->mark = skb->mark >> $lshift; ?

I don't really understand how this is supposed to work.
Could you elaborate a bit?

Thanks.