PF firewall NAT and Windows IPSEC tunnel

[Nerius Landys]

Howdy folks.  I have several computers behind a FreeBSD router (NAT
192.168.0.x using OpenBSD's PF) .  One of those computers is a Windows
machine which is using software called "Cisco Systems VPN Client" to connect
to some other computers outside of our internal network.  Our FreeBSD
router's connection to the outside world is DHCP via cable modem.  I can
connect the Windows machine directly to the cable modem, bypassing the
FreeBSD router entirely; the VPN works fine in this case.  However, when I
try going through the FreeBSD router I get dropped VPN connections after
four to eight minutes; the VPN works fine only when it first connects and
for five minutes thereafter.

  Secure VPN Connection terminated locally by the client.
  Reason 412: The remote peer is no longer responding.

We contacted the administrator on the other side and he said to do the
following:

  The following ports should be allowed through the local firewall:
  UDP port 500, port 10000
  ESP all ports
  AH all ports


I'm not quite sure what this means.

My original /etc/pf.conf:

  ext_if="fxp0"
  int_if="fxp3"
  internal_net="192.168.0.0/24
  nat on $ext_if from $internal_net to any -> ($ext_if)

and I added these three lines in trying to follow the administrator's
instructions (the Windows machine is 192.168.0.3):

  rdr on $ext_if proto udp from any to ($ext_if) port {500,10000} ->
192.168.0.3
  rdr on $ext_if proto esp from any to ($ext_if) -> 192.168.0.3
  rdr on $ext_if proto ah from any to ($ext_if) -> 192.168.0.3

But the VPN connections still get dropped after five minutes.  Any ideas?

I'm also running a bridge between several network interfaces.
My /etc/sysctl.conf looks like this:

  net.link.ether.bridge.enable=1
  net.link.ether.bridge.config=em0,em1,fxp1,fxp2,fxp3

The interesting lines from /etc/rc.conf are:

  ifconfig_fxp0="DHCP"
  ifconfig_fxp3="inet 192.168.0.254 netmask 255.255.255.0"