Re: [PATCH v2] extensions: libxt_multiport: Add translation to nft

[Pablo Neira Ayuso <pablo@netfilter.org>]

On Tue, May 31, 2016 at 12:08:57AM +0200, Arturo Borrero Gonzalez wrote:
> On 30 May 2016 at 21:47, Laura Garcia Liebana <nevola@gmail.com> wrote:
> > Add translation for multiport to nftables, which it's supported natively.
> >
> > Examples:
> >
> > $ sudo iptables-translate -t filter -A INPUT -p tcp -m multiport --dports 80,81 -j ACCEPT
> > nft add rule ip filter INPUT ip protocol tcp tcp dport { 80,81} counter accept
> >
> > $ sudo iptables-translate -t filter -A INPUT -p tcp -m multiport --dports 80:88 -j ACCEPT
> > nft add rule ip filter INPUT ip protocol tcp tcp dport { 80-88} counter accept
> >
> > $ sudo iptables-translate -t filter -A INPUT -p tcp -m multiport ! --dports 80:88 -j ACCEPT
> > nft add rule ip filter INPUT ip protocol tcp tcp dport != 80-88 counter accept
> >
> 
> Lets clarify the syntax, this is valid:
> 
> tcp dport 8000-8100
> tcp dport { 8000-8100}
> tcp dport { 8000-8100, 9000-9100}
> 
> but they mean different things. It seems we should avoid the braces {}
> for the range case, otherwise we would be using a set with a single
> element.
> 
> However,
> 
> tcp dport {8000,8100} <-- valid
> tcp dport 8000,8100 <-- invalid
> 
> So we should always use braces {} in the non-range case.
> 
> Same seems to apply in the case of inversion.
> 
> so we end with this combinations:
> 
> tcp dport {x,x}
> tcp dport != {x,x}
> tcp dport x-x
> tcp dport != x-x
> 
> BTW, related to this, there seems to be a bug in nftables:
> 
> % nft add rule t c tcp dport != {80, 81}
> BUG: invalid expression type set
> nft: evaluate.c:1463: expr_evaluate_relational: Assertion `0' failed.
> Aborted

This is not yet supported. This requires a small kernel patch to allow
inversions in the nft_lookup.c. Then, the little extra code for
libnftnl and nft.

All tests for this usecase are disabled at the moment.