NAT with public interface with more than one address

[John Klos <john%klos.com@localhost>]

Hi,

It seems there are no more search engines which allow for searching for 
exact things. "npf" "nat" "multiple addresses" nets nothing, nor does +npf 
+nat +"multiple addresses". I feel like search engines are not very useful 
these days.

I'm so confused. Here's simple NAT with npf:

$ext_if = re0
$ext_ip = { inet4($ext_if) }
$localnet_lan = { 192.168.50.0/24 }
map $ext_if dynamic $localnet_lan -> $ext_if

Ok. But what happens when re0 has more than one address?

/etc/npf.conf:17:0: map segment cannot have multiple static addresses

How about:

$ext_ip = 47.150.85.30
or
$ext_ip = { 47.150.85.30 }

/etc/npf.conf:25:27: wrong variable 'ext_ip' type 'family-address-mask' for interface near '$ext_ip'

Nope. What about:

$ext_ip = 47.150.85.30/32
$ext_ip = { 47.150.85.30/32 }
/etc/npf.conf:15:0: translation address, given the specified algorithm, must be a pool or a single address

So what does inet4(interface) look like? The man page says, "Static list. 
IPv4 addresses." Not sure, but I see this in the examples:

map $ext_if dynamic $localnet_lan -> ifaddrs($ext_if)

Using ifaddrs(), either with the interface or with inet4(interface), gives 
me NAT with as many IPs as the interface has without the errors above, but 
I can't control which address NAT uses.

But I can't use $ext_ip when it is set to 47.150.85.30, even though I can 
just put 47.150.85.30 in place of $ext_ip.

I'm completely missing something here. Can someone please help?

Thanks,
John Klos