> > > My goal:
> > > To at least establish a connection between my P550 and P575 that will
> > > support TCP/IP communication.
> > 
> > Can do. Just use a printer cable to hook the two computers together and
> > run ppp.
> 
> Just out of curiousity, anyone know about doing this between a freeBSD Box or
> a Linux Box (like a P75 or P133) and a Mac using a printer cable? I would
> think that it would be the same basic process, but for some reason I always 
> thought I would need a gender switcher instead of my plain old DIN9->25 serial 
> cable.

Mac printer cables are wired as gender changers. All the printers w/ mini-DIN
plugs use standard Mac serial pin outs (that's why they can use standard
LocalTalk boxes), so the cable must gender change.

Mac Modem cables don't gender change, so you'd need a null modem.

You should be able to fire ppp up under NetBSD to another Unix box. Though
if you have the cables, I'd recommend not running ppp on the console. If
there's ever trouble, like a panic, a message gets printed to the console,
and then the kernel waits for input. If you're in the middle of ppp, you
might have a problem. If you have two serial ports (and cables), running
ppp on the other line would eliminate any problems.

But you might not have a problem. :-)

> > They should be able to do that. Sounds like you forgot to tell one of the
> > sides the IP addresses. On the NetBSD side, you will need two options files,
> > one for the modem ppp, and one for the to-MacOS ppp. In the to-mac options
> > file, add a "10.0.0.1:10.0.0.2" and set the netmask for this ppp to be
> > "255.255.255.255". On the modem options, add "defaultroute", as it's
> > the default route out.
> > 
> > In /etc/hosts, add two entries like:
> > 10.0.0.1	mybox-backdoor
> > 10.0.0.2	macosbox
> 
> and so the IP address would become (if the NetBSD box were foo.bar.com)
> 	macosbox.bar.com and mybox-backdoor.bar.com
> 
> 			?

As Ken said, macosbox and mybox-backdoor are names, not IP addresses.

10.X.X.X addresses are special. They are defined to be site-only. Normally
there can be only one network interface in the world with a given IP address.
Thus you can get from any one address to another. But 10.X.X.X is a
special class-A address. It is NOT unique, and is (generally) not
exported to other computers or sites.

The idea is that you can put two ethernet cards in a computer. Give one
the normal IP address, and all the telnetting and ftping go through it.
Wire this ethernet up to the router which goes to the rest of the world.
Give the other card a 10.X.X.X address. Link together a lot of NFS
servers and their clients, but NOT a gateway to the rest of the world.
Tell the NFS clients that the server has the IP address of the card on
the 10.X.X.X net, and all the NFS/NIS stuff will flow on the second ethernet,
partitioning NFS/NIS data from everything else.

The idea here is that the 10.0.0.1 and 10.0.0.2 address are NOT
known about by the computers on the other side of the modem link. Since
you're never going to be able to find a computer numbered 10.X.X.X,
using it here won't hurt. :-)

The firewall kit is the thing which will let the MacOS box see and be seen
correctly by the outside world.

Thus macosbox.bar.com and mybox-backdoor.bar.com don't make sense. No
one else on the net will be able to see the IP addresses, so the
names aren't needed. Plus, it's not likely that another computer
at a different site could correctly get packets to 10.0.0.X on the ppp
link.

That's also why I could get away with specifying IP address even though I
don't know the NetBSD box's modem IP address, or even its network. :-)

Take care,

Bill