[Netkit.users] hint

Adrian van Dongen adrianvandongen at gmail.com
Fri Jul 16 09:57:40 CEST 2010

Hi Luca,

Its not so uncommon, the -n option forces iptables to show the list in
numeric output. If you do not give the option iptables will try and resolve

*  -n, --numeric
              Numeric output.  IP addresses and port numbers will be printed
in numeric format.  By default, the program will try to display them as host
names, network names, or services (whenever applicable).*

If your system does not have a properly configured DNS server (resolver)
iptables will wait for the dns timeout on each line(not sure if its for each
line or that it tries to resolve everything at once). And this can as you
have noticed take some time. So there probably is something wrong with your
DNS configuration.

Kind regards,


On Fri, Jul 16, 2010 at 8:55 AM, Luca Dionisi <luca.dionisi at gmail.com>wrote:

> Little improvement in starting a vm.
> In my system a iptables command without the flag -n takes alot of time, eg:
>   iptables -vL FORWARD
> takes 10.171s, while
>   iptables -vL FORWARD -n
> takes 0.022s.
> I'm not aware if this is common, or just a weird problem in my system.
> Anyway, the use of that flag in some point of your scripts (eg
> manage_tuntap) may be worth.
> _______________________________________________
> Netkit.users mailing list
> Netkit.users at list.dia.uniroma3.it
> http://list.dia.uniroma3.it/mailman/listinfo/netkit.users
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