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Subject: Re: [nftables/nft] nft equivalent of "ipset test"
To:     Florian Westphal <fw@strlen.de>
Cc:     netfilter@vger.kernel.org
References: <652EC034.7090501@mutluit.com>
 <20231017213507.GD5770@breakpoint.cc> <652F02EC.2050807@mutluit.com>
 <20231017220539.GE5770@breakpoint.cc>
From:   "U.Mutlu" <um@mutluit.com>
Organization: mutluit.com
Message-ID: <652F0C75.8010006@mutluit.com>
Date:   Wed, 18 Oct 2023 00:36:37 +0200
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Florian Westphal wrote on 10/18/23 00:05:
> U.Mutlu <um@mutluit.com> wrote:
>> Florian Westphal wrote on 10/17/23 23:35:
>>> U.Mutlu <um@mutluit.com> wrote:
>>>> The "ipset" commandline tool has the "test" command
>>>> for testing whether a given item (ie. an IP) is in a given set.
>>>> Is there an equivalent for the "nft" commandline tool of nftables?
>>>> I unfortunately couldn't find the answer in the manpage of nft.
>>>
>>> nft "get element inet tablename setname { 1.2.3.4 }"
>>
>> But isn't that printing the whole item on stdout?
>> I just need to quickly test it only,
>> ie. need just a return code of 0 or 1, or so,
>> for use in a shell script (bash).
>
> ?
>
> nft "get element inet t s { 1.2.3.4 }" > /dev/null 2>&1; echo $?
> 1
> nft "add element inet t s { 1.2.3.4 }"
> nft "get element inet t s { 1.2.3.4 }" > /dev/null 2>&1; echo $?
> 0

Actualy I need to do this monster:   :-)

IP="1.2.3.4"
! nft "get element inet mytable myset  { $IP }" > /dev/null 2>&1 && \
! nft "get element inet mytable myset2 { $IP }" > /dev/null 2>&1 && \
   nft "add element inet mytable myset  { $IP }"

Ie. add it to the set myset only if it's not already present in any of myset 
and myset2.

A true "test" command w/o any output, much like in "ipset test", would be a 
better method, IMO.

I've not switched yet to nftables, just (dry-) evaluating it.