[TriLUG] help! weird sendmail problem

Mon Oct 7 14:28:53 EDT 2002

Greg,

A few notes:

1.  Don't tell folks your hostname/IP.  It's easy enough for them to get
it, and giving it to them just invites portscans, DoS attacks, and who
knows what else.

2.  Use a dynamic DNS service, because your hostname will not change
that way, and changing an MX record, or your machine's hostname, is just
a silly thing to have to do on an even semi-annual basis.

I can talk to you more about this on IRC, or else at the meeting on
Thursday, if you attend.

Regards,
Ben Pitzer

On Mon, 2002-10-07 at 12:42, Greg Brown wrote:
> Jason - you are correct, sir.  Here's my machine info:
> 
> Current IP Address:  66.26.92.247
> Hostname: rdu26-92-247.nc.rr.com
> 
> Actually, RR's way of doing this isn't that bad as it seems to have a 
> predictable hostname - assuming I can change the hostname of the box each 
> time my IP address changes.  I've never tried this and I'm certain it will 
> monumentally screw things up, but I'll give it a shot anyway.
> 
> Paloverde is the current hostname of the box, but that's unresolvable to 
> anyone so I'll try changing the hostname around.   
> 
> Greg
> 
> 
> 
> On Monday 07 October 2002 11:59 am, you wrote:
> > unless you are using RR business class, i don't think RR is going to give
> > what you want.  assuming your user/account name is paloverde, that doesn't
> > mean that your IP address maps to paloverde.nc.rr.com.  next time you're
> > at home, try hitting checkip.dyndns.org in a browser, this will tell you
> > your public IP address and the reverse resolution DNS name.  in my case (i
> > have earthlink cable service, very similar to RR), my 'DNS' name is:
> >
> > Current IP Address: 24.136.143.105
> > Hostname: user-0c8h3r9.cable.mindspring.com
> >
> > obviously not a very user-friendly DNS name.  note that if you resolve
> > cerient.net (my domain name that i host from home) you will get my IP
> > listed above.  if that's what you want, you'll need a dynamic DNS account
> > which you can get for free from dyndns.org.  then you could have
> > paloverde.dyndns.org always point to your RR IP address.  so when you send
> > email from your house to lucent, they can reverse resolve your domain name
> > in to the actual IP address the mail came from, and accept your mail
> >
> > i think there was a fairly long thread about dynamic DNS a week or so ago,
> > you might want to check out the archives for more info.
> >
> > jason
> >
> > > The Facts:
> > > Red Hat 7.1
> > > sendmail-8.11.2-14
> > > connected to my cable modem (outside interface)
> > > connected to my small networks serving 1 pc (in case RR is listening)
> > > (inside interface).
> > >
> > > My outside interface appears to NOT be able to resolve it's domain name.
> > >  I think this is a RR wide thing.  Is anyone running RR able to get a
> > > resolvable DNS name on the Roadrunner interface on the RR network?  If
> > > so how?  For instance, the command (issued from my linux box at work)
> > > 'dig paloverde.nc.rr.com' does not return an ip address.  Does
> > > Roadrunner just not update DNS entries or simply not support DNS for
> > > it's DHCP connected devices?
> > >
> > > My real question is this:
> > >
> > > Because my outside interface is not DNS resolvable some mail servers
> > > will not accept mail send from my box, an example of this is my
> > > employer, Lucent. Saturday, a day which I was not even in town, my mail
> > > server attempted to send mail to my work address 6480 times!!!  And it's
> > > been doing this every stinking day.
> > >
> > > Upon noticing this I freaked out, then stopped sendmail.  I looked in
> > > /var/spool/mail and sure enough, there were references to lucent.com in
> > > the three files in this directory.  I deleted every file in this
> > > directory then restarted sendmail thinking this would stop the mail from
> > > going out which had not already been delivered.
> > >
> > > No luck.  My machine is still attempting to mail lucent.com and the
> > > files in /var/spool/mail are still empty.
> > >
> > > Any ideas on where to look to get rid of the files that is causing this?
> > >
> > > Here's an example of what is showing up in my maillog:
> > > 4:03:18 paloverde sendmail[16406]: g95G0GT14652: to=gwbrown1 at lucent.com,
> > > ctladdr=root (0/0), delay=16:03:02, xdelay=00:00:18, mailer=esmtp,
> > > pri=86730161, relay=ihemail2.lucent.com. [192.11.222.163], dsn=4.0.0,
> > > stat=Deferred: ihemail2.lucent.com.: No route to host
> > >
> > > Thanks!!!
> > >
> > > Greg
> > >
> > > _______________________________________________
> > > TriLUG mailing list
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> > > TriLUG Organizational FAQ:
> > >     http://www.trilug.org/~lovelace/faq/TriLUG-faq.html
> >
> > ------------------------
> > Jason Tower
> > Cerient Technologies
> > jason at cerient.net
> >
> >
> > _______________________________________________
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> >     http://www.trilug.org/~lovelace/faq/TriLUG-faq.html
> 
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