sharing ISDN

[Michael Tibor]

Steve,  you should be able to assign an Internet routable IP address (ie
non RFC 1918) to the Linux box, and still have the router do NAT.  The
router's documentation should have step by step instructions on how to do
that.

What you'll want to be careful of is what type of traffic do you want to
trigger the ISDN line to come up?  Windows boxes generate tons of
broadcasts on UDP ports 137 and 138, so you'll probably not want to allow
that traffic to bring the line up, or it'll be up all the time.  Outgoing
DNS traffic, email, web traffic you'll probably want to have the router
bring up the line for.

Also, remember that when the line is down, the Linux box will be
unreachable and can't accept incoming email.  To handle that you'll
probably want to have another mail server (one which is on a full-time
link) take the incoming mail for you.

Mike
--
Mike Tibor         Univ. of Alaska Anchorage    (907) 786-1001 voice
LAN Technician     Consortium Library             (907) 786-6050 fax
tibor at lib.uaa.alaska.edu       http://www.lib.uaa.alaska.edu/~tibor/
http://www.lib.uaa.alaska.edu/~tibor/pgpkey  for PGP public key


On Sat, 6 Feb 1999 vladislav at davidzon.com wrote:

> Steve,
> 
> Your plan sounds right except for one real major problem... Um, if you are
> going to have a mail server on a linux machine using the routers NAT... And
> its not going to be connected to the internet, your faculty and students
> will not be able to get e-mail from outside their network!
> But yeah, you can have an internal-only mail server...
> 
> -Vladislav
> 
> > -----Original Message-----
> > From: web4lib at webjunction.org
> > [mailto:web4lib at webjunction.org]On Behalf Of Steve Witt
> > Sent: Saturday, February 06, 1999 7:26 AM
> > To: Multiple recipients of list
> > Subject: [WEB4LIB] Sharing ISDN
> >
> >
> > I am at an international branch campus of a US university in Japan
> > and am trying to peice together a viable and inexpensive solution to
> > providing email access to students and faculty.  I have two ISDN lines
> > but the Japanese phone companies charge me by the minute for accessing
> > the lines plus a monthly fee.  We have plans to upgrade to more
> > bandwidth and an NT network.  I'd like to avoid the use of Web based
> > mail, so I am wondering if it is possible to run a mail server on a
> > linux machine using the router's network address translation feature
> > while also connecting workstations in the library to the same router.
> > Could people then Telnet to their accounts and access mail on Pine
> > without actually going out onto the ISDN lines?
> >
> > Thanks,
> >
> > Steve Witt
> > Librarian
> > Associate Professor
> > SIUC in Niigata
> > switt at siu.edu
> > switt at senzoku.ac.jp