[aclug-L] Re: pppd demand dial woes

[Greg House <ghouse@xxxxxxxxxxxxx>]

Thanks Carl,

I did use tcpdump, but the formatting on the msgs wasn't really adequate for
this old head to get around it. I did finally figure out that there were a
couple of applications I was using that were triggering DNS lookups, hence the
extra dialups. Unfortunately, one of them was the one application I set the
whole thing up to run and I have no control over what it does. 

I eliminated part of the extra dialouts by defining all the local hosts in
/etc/hosts, but there were other things that were still doing it. 

Since all I wanted to trigger a dialout on was pending email, I worked around
the issue by writing a little script which ran in the background checking
sendmail's outgoing queue every 10 seconds. If there was any pending mail, it'd
activate the ppp link, send the queued mail, and shut things back down. Perhaps
not the most elegant of solutions, but it did the trick for the demo I was
trying to do (well, it would have, if I'd had better error checking on the pppd
startup, but nobody seemed to notice the fact that I manually restarted it...)

I'd still like to find a better way, but this works for now (at least, after
I make some minor corrections to my script...)

Thanks,
Greg


On Sun, 13 Aug 2000, you wrote:
> Greg
> 
> I had a similar problem with a similar setup.  I used "tcpdump" to
> troubleshoot.  I don't think tcpdump came as part of the basic install.  I
> had to acquire it elsewhere.  It allows you to trace the source for calls
> that might be triggering the demand dialing.   The command looked like
> 
> tcpdump -a 'src or dst 206.53'
> 
> It helped me trace my problem to a troublesome client on the network.
> Good luck.
> 
> Carl
> 
> 
> 
> "House, Greg" wrote:
> 
> > Hi everyone,
> >
> > I know some of you have done this before, so perhaps you can
> > help me.
> >
> > I have a Linux system (RedHat 6.2, basic install with a kernel
> > update to 2.2.16-3). I set up the pppd demand dial option on it.
> > At first I thought it worked right, but later, I noticed that
> > it was dialing up at times I didn't expect.
> >
> > My machine has a local network behind it. This net doesn't need
> > access to the internet, but the machine itself needs to be able
> > to send outgoing email. I'm not routing packets from my local
> > net or ipmasqing. I just want this thing to dial up when I send
> > mail or access an address that's not on the 192.168.0.0 network
> > (the local net). The problem is that it's dialing up on a lot of local
> > network activity.
> >
> > Here's my pppd options file:
> >
> > user ghouse
> >
> > -detach
> > modem
> > lock
> > crtscts
> > defaultroute
> > asyncmap 0
> > demand
> > idle 30
> >
> > I thought perhaps it was due to the defaultroute clause
> > so I commented that out. With it that way, it wouldn't EVER
> > dial.
> >
> > I think it probably has to do with DNS lookups from things
> > like sendmail and some software my company makes, but I'm
> > not completely sure. I installed iptraf a little while ago
> > to see if it could help me, but I haven't tried it yet. Does
> > it have more readable output then tcpdump?
> >
> > I think the solution must have something to do with using
> > the filtering that pppd provides, but I can't seem to find
> > any documentation on what the keywords are.
> >
> > I could try to set up diald instead, but I've heard it's more
> > difficult to configure and I don't want to spend my whole life
> > configuring this thing.
> >
> > One final question. All I _really_ want it to do when it dials
> > out is send email. Is there any hook in sendmail (or another
> > MTU?) that will let me run a script (like /etc/ppp/ppp-on)
> > when someone send's mail?
> >
> > Thanks,
> > Greg
> >
> > -- This is the discussion@xxxxxxxxx list.  To unsubscribe,
> > visit http://tmp2.complete.org/cgi-bin/listargate-aclug.cgi
> 
> 
> -- This is the discussion@xxxxxxxxx list.  To unsubscribe,
> visit http://tmp2.complete.org/cgi-bin/listargate-aclug.cgi
-- 

----------
"Hang loose, baby. You'll get your new wings soon." - Is. 40:31

-- This is the discussion@xxxxxxxxx list.  To unsubscribe,
visit http://tmp2.complete.org/cgi-bin/listargate-aclug.cgi