Re: [nft PATCH] List handles of added rules if requested

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

On Thu, May 04, 2017 at 02:34:21PM +0200, Phil Sutter wrote:
> Being able to retrieve an added rule's handle atomically is a crucial
> feature for scripts invoking nft command: Without it, there is no way to
> be sure a handle extracted from 'nft list ruleset' command actually
> refers to the rule one has added before or that of another process which
> ran in between.
> 
> Extracting an added rule's handle itself is not an easy task already,
> since there is a chance that a given rule is printed differently than
> when it was added before. A simple example is port number vs. service
> name:
> 
> | nft add rule ip t c tcp dport { ssh, 80 } accept
> 
> There is no way to make 'nft list ruleset' return the rule just like
> this as depending on whether '-nn' was given or not, it either prints
> the set as '{ ssh, http }' or '{ 22, 80 }' but never in the mixed form
> that was used when adding it.
> 
> This patch prints an identifying string for each added rule which may be
> used as single parameter to a later 'nft delete rule' command. So a
> simple scripting example looks like this:
> 
> | handle=$(nft add rule ip t c counter)

This is a hack.

We should follow the rule description path.