Re: Two IP add

[Alistair Tonner <Alistair@nerdnet.ca>]

On June 5, 2003 01:54 pm, Pascal Italiaander wrote:
> Op donderdag 5 juni 2003 19:51, schreef u:
> > Op donderdag 5 juni 2003 15:29, schreef Ray Leach:
> > > On Thu, 2003-06-05 at 13:38, Dharmendra.T wrote:
> > > > On Thu, 2003-06-05 at 15:26, Paulo Andre wrote:
> > > >         I would like to do the following:
> > > >
> > > >         Stop MASQUESRADING to two servers say. 10.10.10.5 and
> > > > 10.10.10.8, how would i do this with a rule.
> > > >
> > > >         iptables -t nat -A POSTROUTING -s x.x.x.x -d ! 'servers ip'
> > > > -j MASQUERADE now how would i put in two ip address's ?
> >
> > Ok , you could do something like this:
>
> sorry in the first reply was an error !!
> this is fixed now.
>
>  NO_MASK="10.10.10.5 10.10.10.8"
>
>  if [ ${NO_MASK} != "" ] ; then
>    for nomask in ${NO_MASK}; do
>   	iptables -t nat -A POSTROUTING -s x.x.x.x -d ! ${nomask} -j MASQUERADE
>  done;
>  fi
>
> > this is a bit more flexible, cause , you can ad more ip's the NO_MASK
> > easily without changing the rule itself, or have to write a new line.
>
>  Pascal


	I somehow don't think this will do what we want here.
	rule 1 from this loop will MASQUERADE any ip that is 
	NOT 10.10.10.5, which unfortunately includes 10.10.10.8
	and rule #2 will never be hit by the 10.10.10.8 packet.

	I would suggest that we want to take the entire segment
	and manage it separately, but I have no experience with
	creating user chains in the nat table, although this *might* 
	work -- ymmv
	

iptables -t nat -N masq_filter
iptables -t nat -A POSTROUTING -s x.x.x.x -d 10.10.10.0/24 -j masq_filter 
# the above line includes an assumption that MIGHT BE WRONG!!!! I dont know 
# what your netmask is!!!!!!!!!
iptables -t nat -A masq_filter -d 10.10.10.5 -j RETURN
iptables -t nat -A masq_filter -d 10.10.10.8 -j RETURN
iptables -t nat -A masq_filter -j MASQUERADE

	filling in out the ips to NOT masquerade one at a time, perhaps with a loop
	as pascal suggests above, with appropriate modifications... 	
-- 

	Alistair Tonner
	nerdnet.ca
	Senior Systems Analyst - RSS
	
     Any sufficiently advanced technology will have the appearance of magic.
	Lets get magical!