Question about /etc/iptables.down.rules

[Покотиленко]

В Вск, 26/08/2007 в 22:01 -1000, TinyApps.Org пишет:
> Thanks for your reply, Покотиленко! (I hope that is the correct name  
> to use.)
> My reply is at the bottom of this message:
> 
> >> I understand that it is best to setup a set of rules to be applied
> >> when the network interface is down, saving it to:
> >>
> >>   /etc/iptables.down.rules
> >>
> >> and applying in /etc/network/interfaces via:
> >>
> >> post-down iptables-restore < /etc/iptables.down.rules
> >>
> >> What should this set of rules look like? The exact opposite
> >> of /etc/iptables.up.rules ? Or just a simple flush command?
> >> Or something else altogether?
> >
> > You can do a simple flush, but this is not required, since all rules
> > will be overwritten by iptables-restore when you bring network  
> > interface
> > up next time.
> 
> I had stumbled across the following comment:
> 
> "But to do this really clean, we need to have a script that removes  
> the rules as well for when the interface goes down. Just to make sure  
> the rules are never added twice."
> 
> on this site:
> http://my.opera.com/Jada0007/blog/show.dml/1213354
> 
> and therefore wondered if there were ever a case in which
> the rules could be applied twice... by creating a /etc/ 
> iptables.down.rules
> file, I hoped to avoid such a possibility.

man iptables-restore states:
...
       -n, --noflush

       don't flush the previous contents of the table. If not specified,
              iptables-restore flushes (deletes) all previous contents
of  the
              respective IP Table.
...

So, make sure you won't use "-n" option when calling iptables-restore.

-- 
Покотиленко Костик <casper at meteor.dp.ua>