ipfw rule processing performances

[Julian Elischer]

On 10/26/11 2:39 PM, Michael Sierchio wrote:
> On Wed, Oct 26, 2011 at 11:39 AM, Julian Elischer<julian at freebsd.org>  wrote:
>
>> read up on all the things you can do with tablearg.. sometimes a single
>> table can replace dozens of rules.
> Julian - would you be so kind as to give an example?
>
> - M
>
off the top of my head:

implement an ad-hoc RErouting table using   fwd  tablearg
implement entirely differnt rules for a complicated set of subnets 
using   skipto tablearg
arbitrarily slow down all the traffic from everyone you don't like in 
the company using "lookup" and queue.

from the man page:

       The tablearg argument can be used with the following
      actions: nat, pipe, queue, divert, tee, netgraph, ngtee, fwd, skipto
      action parameters: tag, untag, rule options: limit, tagged.

and...

           # addresses we don't want to be seeing coming from outside..
         ${fwcmd} table 1 add 10.0.0.0/8
         ${fwcmd} table 1 add 172.16.0.0/12
         ${fwcmd} table 1 add 192.168.0.0/16
          # Stop draft-manning-dsua-03.txt (1 May 2000) nets (includes
          # RESERVED-1, DHCP auto-configuration, NET-TEST, MULTICAST 
(class D),
          # and class E) on the outside interface
         ${fwcmd} table 1 add 0.0.0.0/8
         ${fwcmd} table 1 add 169.254.0.0/16
         ${fwcmd} table 1 add 192.0.2.0/24
         ${fwcmd} table 1 add 224.0.0.0/4
         ${fwcmd} table 1 add 240.0.0.0/4