I've got a server running FreeBSD 6.2 and PF. The server has a couple dozen jails on it. Previously, I had a few "private" services such as MySQL running on loopback IPs (127.0.0.2+) and the rest of the jails running on the public IPs.

I have to renumber my machine with a new block of public IPs so I thought I'd be clever and move all the jails onto loopback IPs. Then I could use PF to redirect the new IPs and the old ones to the corresponding jails.

The relevant parts of my PF config look like this:

ext_if="em0"
loop_if="lo0"

ext_addr="72.29.111.130"
loop_addr="127.0.0.101"

ext_net ="72.29.111.128/27"
ext_net2="208.75.180.64/27"
loop_net="127.0.0.0/8"

lo_simerson     = "127.0.0.4"
lo_toaster      = "127.0.0.6"
lo_tnpi         = "127.0.0.13"

simerson     = "72.29.111.131"
toaster      = "72.29.111.133"
tnpi         = "72.29.111.140"

# nat the jails running on loopback to their public ip
nat on $ext_if from $lo_simerson     to any -> $simerson
nat on $ext_if from $lo_toaster      to any -> $toaster
nat on $ext_if from $lo_tnpi         to any -> $tnpi

# specific jail rules
rdr on $ext_if from any to $simerson     -> $lo_simerson
rdr on $ext_if from any to $toaster      -> $lo_toaster
rdr on $ext_if from any to $tnpi         -> $lo_tnpi

This works just great. Traffic from the outside world gets redirected to the correct jail via a rdr rule. The corresponding nat rule alters the source IP from each jail to its corresponding public IP.

The problem I have with this arrangement is when a jail attempts to connect to the public IP of another jails, the connection fails. So, a client running in one jail can't send email to my mail server running in another jail. This problem is described in detail here:

    http://www.openbsd.org/faq/pf/rdr.html

And I have attempted to configure the RDR and NAT combination solution as shown. But after trying a few dozen iterations, I can't get it to work. Based on my understand of the PF manual, conceptually, the problematic connection looks like this:

simerson (127.0.0.4) -> toaster public IP (72.29.111.133) rewritten to toaster private IP (127.0.0.6)
   toaster (127.0.0.6) -> simerson (127.0.0.4)

So the simerson jail gets returned a packet from the toasters loopback IP, which it ignores because it is not the IP it sent the connection attempt to.

But no matter what I try, I can't make it work. PF is not denying any connections. Without resorting to split-horizon DNS, has anyone gotten this to work reliably on FreeBSD? I'd love to see a working configuration.

Matt

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