19990802: No McIDAS AREA files (cont.)

>From: "Chad W. Johnson" <address@hidden>
>Organization: University of Wisconsin - Madison
>Keywords: 199908010030.SAA12535 Unidata-Wisconsin

Chad,

>In our ldmd logs I am seeing many gethostbyaddr failures and lookup timeout
>failures. The exact errors look like.
>
>Aug 02 14:08:24 unidata rpc.ldmd[8929]: gethostbyaddr: failed for 130.39.129.3
>Aug 02 14:08:24 unidata rpc.ldmd[8929]: Denying connection from 130.39.129.3
>
>The feeds effected appear to be...
>
>128.174.80.44
>128.95.89.2
>141.213.23.92
>198.115.158.1
>128.118.28.2
>130.39.129.3

This looks like a name service problem.  If this is a complete list, then
conspicuously missing is thelma.ucar.edu.

>Our Technical Computing staff is looking into the problem. Please bear with
>us.

OK.  One problem we face on this end is that we are right in the middle
of training workshops, so our full attention is somewhat diverted.

There is something you can do to mitigate this problem in lieu of
finding/fixing the name service (or whatever) problem.  You could add
the IP address for machines you feed in your LDM ALLOW lines.  The idea
is that each ALLOW line would first contain the site's fully qualified
hostname followed by an '|' for their IP address.  This way, if the
name server did not resolve the name, the IP address would be the
second one checked for the ALLOW.  The downside to this approach is
that you then have to maintain the name-IP address correspondence in
your ldmd.conf file.  If a site's machine changes IP addresses but not
name (or visa versa), then the information in the ALLOW line would need
to be updated manually.

Example:

allow ANY ^(thelma\.ucar\.edu|192\.52\.106\.21\.?)$

This example is very specific in terms of the full name and full IP
address of the machine that will be fed.  One could further generalize
the name or IP regular expression to allow any machine from a site to
request the feed, but I assume that you already know about this.

The other thing that could be done to help out is to put the machines
you are willing to feed in your /etc/hosts file (IF you are not using
NIS).  This would help resolve the name/IP address issue IF your
machine is setup to be able to use the entries in /etc/hosts.

>From address@hidden  Mon Aug  2 10:59:18 1999

>OK, now _I've_ restarted our LDM here and it looks like connections
>from feed sites are getting through and products are getting
>broadcasted. However, nslookup's continue to fail to 130.39.129.3 and
>other IP addresses.

Strange.

>Now I'm really confused.

Me too.

>Why would restarting the
>LDM fix (if only temporarily) the gethostbyaddr problem?

I don't know, but we will look into this.

>I will
>continue to monitor the feed and see if we start running into the same
>problem - similar to yesterday after restarting the LDM.

Please see my suggestion above about allowing machines by both
name and IP address in ldmd.conf.

>We are using LDM 5.0.8 with Solaris 7 on a Sparc platform.

Thanks for the platform information.  It might well help.  A login to
unidata.ssec as the user running the LDM might also be very helpful
for troubleshooting.

Tom Yoksas