I have figured out the issue, now I just need to figure out how to fix it.

By default, m0n0wall only includes a rule to allow TCP traffic from the PPTP
clients.  Since DNS is a UDP protocol, all DNS lookups from PPTP clients
were being blocked.  I added a rule to allow all UDP traffic over the PPTP
interface, and this resolved the issue of being able to resolve names.

Unfortunately, it appears Windows XP tries the local DNS servers for my
network interface before trying the one on my PPTP interface.  This means
that when I try to resolve a hostname on the m0n0wall network, it first
attempts my primary local DNS server, which is a public DNS server for my
ISP.  This lookup fails, and it assumes that the host does not exist.  Is
there any way to make the DNS server served by the PPTP server take priority
over my local DNS?

On 2/12/07, Lee Sharp <leesharp at hal dash pc dot org> wrote:
>
> On Mon, 12 Feb 2007 14:44:36 -0500
>   Brian Morton <rokclimb15 at gmail dot com> wrote:
>
> > I am running 1.23b3 pc-generic on a PII 300 with 128MB RAM.  This is
> >my first set up at this location, so I can't say if this feature
> >worked prior to this version.  I have the option set to "register
> >dhcp leases in DNS forwarder".  In my prior experience with m0n0wall,
> >this should cause a Windows computer name to resolve to the internal
> >ip address (for instance, a computer named "brian" should resolve to
> >an internal address when "brian" is pinged).  This does not seem to
> >be the case when I connect via PPTP.
>
> Do an "ipconfig" on the machine you are tunneling in on.  I bet your
> DNS is NOT the remote m0n0wall.  And it will need to be to find those
> names.
>
>                            Lee
>