freebsd security - Jun 2005 - running jail with alternate IP

I am currently setting up a firewall that translates my internal network
over to 5 public IP addresses.  The addresses are dynamically assigned, so I
use ddclient to update my www.dyndns.org account.  I've set up several
aliases on the external interface of the firewall, and succeeded in having
the internal computers use those extra public IPs.

What I want to do is have 5 copies of ddclient all running in separate jails
bound to different public IPs.  I did some experimenting with jail, jailing
a shell and then running lynx to www.whatismyip.com.  I had to open up the
firewall to get it to work, and then it gave me the public IP address bound
to the first IP on the interface.  Looking at the firewall logs, it seems as
if jail is sending packets on the main IP (the non-aliased one), but
modifying the header so they return to the aliased IP that was given to it
when running the jail command.

Is this how jail is supposed to operate, or am I doing something wrong?

So, Raymond Wagner wrote:
> I am currently setting up a firewall that translates my internal network
> over to 5 public IP addresses.  The addresses are dynamically assigned,
> so I use ddclient to update my www.dyndns.org account.  I've set up
> several aliases on the external interface of the firewall, and succeeded
> in having the internal computers use those extra public IPs.
>
> What I want to do is have 5 copies of ddclient all running in separate
> jails bound to different public IPs.  I did some experimenting with
> jail, jailing a shell and then running lynx to www.whatismyip.com.  I
> had to open up the firewall to get it to work, and then it gave me the
> public IP address bound to the first IP on the interface.  Looking at
> the firewall logs, it seems as if jail is sending packets on the main IP
> (the non-aliased one), but modifying the header so they return to the
> aliased IP that was given to it when running the jail command.
>
> Is this how jail is supposed to operate, or am I doing something wrong?
i don't know about the implications of jail, but as far as i know, when
you have multiple interfaces going to the same subnet, in your case your
provider and the internet, only 1 of those ips can have it's netmask set
for that subnet and all the other netmasks have to be 255.255.255.255.
This implies that all outbound packets routed to your gateway (presumably
your provider) are routed through that one ip.

mario;>