Re: bridge(4) question new network setup

On Fri, Jan 20, 2023 at 11:09:47AM -0800, patrick keshishian wrote:
> Hello,
>
> I am trying get a new ISP setup working. The Router is
> causing some pain. There is a /28 public block assigned.
> The DSL router can't be configured in transparent bridge
> mode (they say). It holds on to one of the /28 addresses.

i'm sure they say that, but that doesn't mean it's impossible. this
will be a lot easier and more useful if you can get a dsl modem
into bridge/transparent mode and do all the routing on your own
box.

that would also give you the option to do fun stuff like NOT putting
the /28 onto an ethernet network so you could you use all 16 of the
IPs on dmz hosts instead of losing some to network/broadcast/gateway.

> The setup looks something like this:
> (and hopefully the ascii "art" remains intact from gmail)
>
> ( internet )
> |
> | [WAN IP]
> +-----o------+
> / DSL ROUTER / <-- Transparent bridge mode NOT possible
> +-----o------+
> | [ one of /28 Public IPs = $dslgw_ip ]
> |
> |
> | $ext
> +-----o------+
> | |
> | OpenBSD/pf o--- ( rest of /28 Public IP network )
> | | $dmz (DMZ: httpd, smtpd, ...)
> +-----o------+
> $lan | [10.x.x.1]
> |
> ( 10.x.x.x network )
>
>
> As far as networking goes, I need to be spoken to as if I'm
> a fledgling.
>
> I want to do the obvious: use OpenBSD/pf(4) to:
> - Filter traffic from $ext to $dmz
> - Filter traffic from $dmz outbound
> - Filter traffic from $lan (10.x.x.x) to $dmz
> - NAT traffic from $lan (10.x.x.x) outbound to internet
>
>
> I'm bridge(4)-ing $ext and $dmz. Which means I must give
> one of the /28 public IP addresses to either $ext or $dmz
> to be able to do:
>
> # route add default $dslgw_ip
>
> (!?)
>
> Am I missing something?
> Is there a better way to configure things?
>
> Thanks,
> --patrick
>