linux as a dial-on-demand ISDN router?

linux as a dial-on-demand ISDN router?

Post by Michael Prot » Tue, 21 Jul 1998 04:00:00

Here's a question...

Is there software currently written that can configure a Linux dist to
become an ISDN router that dials when it recieves packets from the
network. Ultimately, I'd like to set up a box that dials in via ISDN and
then uses ip masquerading to allow my vpn to access the Internet. I know
you can purchase an ISDN router that will do all of this for you, but
I'd like to run it on an old pc if possible.

I'm looking for a setup that will initate the ISDN dialup (using DHCP)
to connect when the router receives packet requests that are bound for
outside the network (running TCP/IP). My ISP disconnects automatically
after 30 minutes of inactivity, so the process would have to check to
see if the connection is still up, and if not, then to initate the

If someone could please point me in the right direction for this, I
appreciate it. Thanks!



1. ISDN Dial-On-Demand: Can't Stop dial with arp packets...

Hello again everybody,

I have installed linux 2.0.30 (Slackware 3.3) on a machine located
remotely from my office connected with ISDN dial-on-demand modem.   I
have diagnosed the dial-out of this machine with TCPDUMP to see why the
machine is dialing out for no reason every 6 minutes or so.

This is the packet that is received from tcp dump from remote host

15:28:08.980232 arp who-has tell

ryno is another linux machine on my LAN and durham is the machine on the
remote end that I would like to prevent from dialing out when this

Now, I ran into a similar problem in a previous version of linux and
modified the /usr/src/linux/net/ipv4/arp.c file and recompiling and
restarting the new kernel.  This has not worked yet as I have tried
different values for the ARP_TIMEOUT and other variables in that file.

Not sure how I can prevent this dial-out from the remote machine.
In case it matters the ISDN boxes that I use are from COMBINET now owned
by Cisco.  Maybe I can filter ARP packets from the ISDN modem?

All help is greatly appreciated.  (I need to save money on this phone


Jim Valavanis


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