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[LDM #HNT-424908]: Fwd: FW: Ldm mcidas

Hi Randy,

> Yesterday we moved all of our machines to a new network requiring that
> we change the ip addresses as well.
> We have two machines which control the noaaport operations.
> NOAAPNEW which runs LDM
> NOAAPXCD which runs XCD
> We have made several changes including updating the /etc/hosts
> /etc/resolv.conf files. We have also changed various files w/n the ~ldm
> accounts to reflect the new host name. When I left yesterday NOAAPNEW
> was receiving data from the NOVRA receiver however, it could not
> transfer the data to NOAAPXCD despite the fact that I started the ldm
> and xcd and those apps were running. Before I left I rebooted both
> machines. This morning I find that NOAAPNEW is not receiving the data
> from the NOVRA. I know because I ran the ldmadmin watch and no data was
> flowing across the screen.  I can ping both machines from each other.

I assume that your ping test included both pinging by name and pinging
by IP address?

Did you verify that both forward and reverse DNS exists for both machines:

nslookup <machine_name>
nslookup <machine_IP>

The LDM attempts to look up the name from the IP address passed along in
a feed request from a downstream machine.  If the IP address can not
be translated into a fully qualified name, the LDM will not be able
to match the ~ldm/etc/ldmd.conf 'allow' entry that has been setup.  So,
if DNS is not fully setup for your machine(s), a reverse lookup will
fail, and the upstream LDM will deny the feed request.  In this case
there are a couple of things you can do:

- get the network administrator to setup forward and reverse DNS for
  your machines

- add an entry defining the machine IP address <-> name mapping in
  the upstream machines /etc/hosts file (be careful with the syntax
  of this file as whitespace is/are tabs, not spaces!)

- add an allow line for the IP address of the downstream in the
  upstream's ~ldm/etc/ldmd.conf file

If you make a change to ~ldm/etc/ldmd.conf, please remember that you
need to stop and restart the LDM to make the changes take effect:

ldmadmin stop
ldmadmin start

  -- or --

ldmadmin restart     <- current versions of the LDM

> In /usr/local/ldm/logs there are several log files which have messages
> indicating that Noaapnew rpc.ldmd[4598]: denying connection from
> noaapxcd

This implies that there is no allow line for the machine requesting
data.  This would be caused if DNS was not correct or if you really
don't have an allow for the downstream machine in the upstreams
~ldm/etc/ldmd.conf file.

> This messages gets repeated several times.

It will repeat regularly since the downstream will continue to
request a feed(s) as long as it is up and running..

> Can you provide guidance on getting this thing running again.

Please check the DNS setup for both machines.  If forward and reverse
name lookup work correctly (I am guessing that it does not), then
check to make sure that you do not have an incorrect IP <-> name
entry in the upstream machine's /etc/hosts file.

> Thanks,

No worries.


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Ticket Details
Ticket ID: HNT-424908
Department: Support LDM
Priority: Normal
Status: Closed

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