Re: tlug: Hostname problems

["Stephen J. Turnbull" <turnbull@example.com>]

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tlug note from "Stephen J. Turnbull" <turnbull@example.com>
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>>>>> "Dennis" == Dennis McMurchy <denismcm@example.com> writes:

    Dennis>   Look, I know this has to be a very elementary problem,
    Dennis> but I have never solved it and it comes up again and again
    Dennis> at various intervals.  This error message is a good
    Dennis> example of the problem:

    Dennis>  talk: tangrending: Host name lookup failure

    Dennis> What on earth do I have to do to make it clear to other
    Dennis> programs like httpd and so on that 'tangrending', the
    Dennis> hostname specified in my /etc/HOSTNAME file is the local

I'm not clear on what the problem is here.  Is 'tangrending'
registered in a DNS somewhere?  Apparently not from the X-Sender
header, which doesn't specify a parent domain.  Why do you want httpd
and talk to recognize a domain that doesn't exist?  So you can do
"netscape http://tangrending/" and "talk denismcm@example.com" on the
local host?  What's wrong with "netscape http://localhost/" and "talk
denismcm"?

    Dennis> machine?  I can't just stick a line or an alias in
    Dennis> /etc/hosts because that seems to break the sendmail that
    Dennis> installs with Slackware 3.1 (used to be that sendmail was
    Dennis> broken without an entry defining the hostname in
    Dennis> /etc/hosts).

So much the worse for sendmail.

Look, these programs get IP addresses to open TCP streams by doing
gethostbyname(3):

       The gethostbyname() function returns a structure  of  type
       hostent  for  the given host name.  The current domain and
       its parents are searched unless name ends in  a  dot.   If
       name  doesn't  end  in  a dot and the environment variable
       HOSTALIASES is set, the alias file pointed to  by  HOSTAL(0-(B
       IASES will first be searched for name.

       The domain name queries carried out by gethostbyname() and
       gethostbyaddr()  use  a  combination  of any or all of the
       name server named(8), a broken out line  from  /etc/hosts,
       and the Network Information Service (NIS or YP), depending
       upon the contents of the  order  line  in  /etc/host.conf.
       (See   resolv+(8)).    The  default  action  is  to  query
       named(8), followed by /etc/hosts.

There just isn't any way to do what you want, AFAIK---except to put
that alias in /etc/hosts.

Now, if you're not connected to the net, evidently some versions of
sendmail will wait a long time for the net to come back up.  I know
that this was reputed to be a problem with the SparcLinux sendmail.  I
note in RHL 4.x sendmail.cf there is a Timeout.initial; setting that
to something short might help.  (I guess that the timeout is 5 min by
default; that's a long time....)

Maybe you should set up your networking so that sendmail comes up
after the network does, and is put down before the network goes down.
A problem with this, though, is that maybe you can't do mail offline.
But I think that this shouldn't be a problem, if sendmail can't find a
remote host, it should be OK.

Aha ... there's an option to set the hosts file!  Maybe if you make an 
/etc/hosts with "127.0.0.1 localhost tangrending" in it and a file
/etc/sendmail-hosts

# set in sendmail.cf as O HostsFile /etc/sendmail-hosts
127.0.0.1 localhost

life will be good....

Of course, you could just switch to smail or qmail.

HTH

-- 
                            Stephen J. Turnbull
Institute of Policy and Planning Sciences                    Yaseppochi-Gumi
University of Tsukuba                      http://turnbull.sk.tsukuba.ac.jp/
Tel: +81 (298) 53-5091;  Fax: 55-3849              turnbull@example.com
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