ISDN Dial On Demand sendmail half working?

ISDN Dial On Demand sendmail half working?

Post by David Traver » Thu, 06 May 1999 04:00:00



I have managed to setup sendmail so that it only sends non-local emails at
preset times by issuing the sendmail -q command.

This works great, dials up the ISP at preset times and send and receives the
mail. However if there is no e-mail in the queue, sendmail doesn't dial the
ISP thus not receive possible incoming mail.

I have written a script which does the following to always force it open the
connection upon sendmail -q to check incoming mail by doing the following

    ping -c 5   mailserver |& sendmail -q

This pings the external email server, opening the connection as the IP
address is non-local, and upon connection any waiting mail is downloaded.

Is there any better way of doing this. Any tips would be most appreciated.

 
 
 

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
(durham).

15:28:08.980232 arp who-has ryno.cit-llc.com tell durham.cit-llc.com

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
happens.

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
bill).

TIA

Jim Valavanis

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