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 From:  Manuel Kasper <mk at neon1 dot net>
 To:  William Arlofski <waa dash m0n0wall at revpol dot com>
 Cc:  m0n0wall at lists dot m0n0 dot ch
 Subject:  Re: [m0n0wall] ** NOT REALLY solved ** Internal machines accessing PPTP clients
 Date:  Sun, 16 Jan 2005 21:58:01 +0100
On 16.01.2005 14:23 -0500, William Arlofski wrote:

> Manuel, not sure if you have seen this or my other posts regarding
> this issue. I am curious to hear your thoughts. The whole thread
> between me, myself and I is quoted below. :)

I've had a look at your problem description, and while it's already a
bit late in this part of the world for sharp thinking, I'd say the
following behavior applies in your case:

When you define static routes on an interface, m0n0wall installs
non-stateful rules to pass all traffic between the statically routed
subnets and hosts on the subnet of the given interface itself. This
had to be implemented because some people with complicated network
structures needed it, and using stateful rules for traffic from and
to the same interface (which only has to pass through m0n0wall
because it may not be possible to define static routes on every
client) would be inefficient. However, I have recently decided that
this feature is too dangerous if used improperly (there's been at
least one example of somebody who defined static routes even if there
was absolutely no reason for it), so the next beta version will come
with an option to enable it (and with default to disabled).

Your problem is probably that the PPTP client subnet lies within your
LAN subnet. As such, if a packet from 192.168.1.0/24 with destination
192.168.100.16/28 comes in, it first matches a static routing bypass
rule (which specifies 192.168.100.0/24 as its destination) and is
therefore let in without creating a state table entry. However, since
FreeBSD routing then decides that there's a more specific route for
that particular packet (through the PPTP tunnel), it doesn't go out
through the LAN interface (where it would have been permitted by a
matching static routing bypass rule), but instead gets blocked by
ipfilter when it is sent out through the PPTP tunnel because there's
no state table entry for it.

You have three options:

1. Use a different subnet for PPTP clients (yes, I know that the
webGUI and manual suggest using part of the LAN subnet for it, and
proxy ARP will normally ensure it works, but it's only for the
convenience of people with simple setups that want PPTP clients to
appear like normal LAN hosts)

2. Wait for the next beta release that will come with an option to
enable/disable the static routing bypass

3. Comment out the corresponding lines in etc/inc/filter.inc (~378 -
408).

HTH,

Manuel