Re: intrapositioned and extrapositioned negation

[Mart Frauenlob <mart.frauenlob@chello.at>]

netfilter-owner@vger.kernel.org wrote:
> Mart Frauenlob wrote:
>  
>> Mart Frauenlob wrote:
>>    
>>> Hello,
>>>
>>> today I installed iptables 1.4.5 and discovered my ruleset produces
>>> those warnings about intrapositioned  negation:
>>> Using intrapositioned negation (`--option ! this`) is deprecated in
>>> favor of extrapositioned (`! --option this`).
>>>
>>> I haven't completely looked up the changelogs, but from what I've
>>> found on the internet, this was introduced with 1.4.3.1, right?
>>>
>>> However, my ruleset is automatically generated by a self written shell
>>> script, which I now need to change.
>>> It needs to work with any 2.6 kernel and with 2.4 kernels supporting
>>> iptables.
>>> As my testing options (hardware, time) are limited, I'm asking if
>>> someone knows:
>>>
>>> Will 2.4 kernels and older iptables versions accept the
>>> extrapositioned (`! --option this`) notation?
>>> If so, I can rewrite my script to always use extrapositioned syntax.
>>> Lot's of work, but ok...
>>>
>>> If not, what kernel / iptables versions do only understand the old
>>> deprecated way?
>>> So I can query for them and take the appropriate steps.
>>>
>>> Thanks a lot!
>>>       
>> Nobody knows?
>> Well, I've found some old virtual machines, tested it with debian woody
>> and sarge, using kernel 2.4.18.bf2-4 and 2.6.18 and extrapositioned
>> negation does not seem to cause problems.
>> Am I right to assume, that all 2.4 kernels with iptables support - DON'T
>> have troubles using extrapositioned negation???
>>     
>
> The kernel doesn't care about how you specify negation, its purely
> a userspace thing. So yes, it should work properly on any kernel
> version.
>   

Hello netfilter-owner@vger.kernel.org :)

thanks for pointing that out.
In my second post I forgot to ask about the compatible iptables version.
The lowest version I tested on debian woody is: 1.2.6a.
Rephrased, do I have to expect problems using extrapositioned negation 
on older iptables versions?

Sidenote to the devels ;-P :
The man page has documented intrapositioned negation for years, this is 
the only note in the changelog for 1.4.3.2:
> iptables: print negation extrapositioned
>   

It's like with the DROP in the nat table, a short note in the change 
log, and the whole world has to find out what's going on, and change 
their programs/scripts.
Imho, changes like those should be worth a few explaining sentences.

Thanks and regards


Mart