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[LDM #AVX-447373]: What we're seeing...



Donna & Gerry,

> Steve, we can't seem to get LDM products flowing from us (ldm.tamu.edu) to
> the AT&T Weather Operations department - where they have downloaded
> Unidata's EDEX server software.
> 
> ?Our allow (just like for many other downstream users) is:
> allow ANY-LIGHTNING-PCWS-WSI ^((zlp17983\.vci\.att\.com)|(1
> 35\.40\.68\.210))$ .*
> 
> And, yes, I have restarted LDM on all three of our "cluster nodes". You may
> recall that we have an IP Virtual server for ldm.tamu.edu (and our ldm1,
> ldm2, ldm3 "cluster nodes").
> 
> The ldmd.conf at AT&T Weather operations looks like:
> EXEC    "pqact -e"
> EXEC    "edexBridge -s localhost"
> EXEC    "rtstats -h rtstats.unidata.ucar.edu"
> REQUEST ANY     ".*"    ldm.tamu.edu
...
> ALLOW   ANY-LIGHTNING-PCWS      ^((localhost|loopback)|(127\.0\.0\.1\.?$))
> .*

The "-LIGHTNING-PCWS" isn't necessary (because they not getting those feeds)
but won't hurt.

> Gerry has requested contact with their network/firewall person.

Good idea. Read on.

> We also have questions about their ALLOW statement.? On our EDEX server (
> awips2.tamu.edu), the ldmd.conf provided had these entries:
> 
> ALLOW ANY ^((localhost|loopback)|(127\.0\.0\.1\.?$)) .*
> ALLOW ANY ^[a-z].*\.unidata\.ucar\.edu\.?$ .*
> 
> ?We have changed ours to match our other LDM configs:
> 
> ?allow ANY
> ^((localhost|loopback)|(127\.0\.0\.1\.?$)|([a-z].*\.unidata\
> .ucar\.edu\.?$))
> 
> ?Gerry is questioning the "\.?$" at the end of the ucar entry. I have often
> wondered myself. But saying "include a possible period after "edu" sounds
> like overkill".?

Yeah. That entry was created in the dim early days of the Internet when a
reverse DNS lookup just might return a trailing period. Not a problem now.

> ?Again, any ideas??

The downstream LDM process at AT&T is seeing an ECONNRESET error when it
attempts to connect to TAMU's LDM. This means that 1) TAMU's LDM never sees
the connection attempt; and 2) somebody in the chain from AT&T to TAMU is
responding with a TCP RST (reset) packet, which kills the connection attempt.

Not good and very antisocial.

> I now think this is a hostname/Address problem on their end. Let's see what
> I can get out of their firewall and network folks.

Gerry, I'm afraid I don't see how a hostname/Address problem could lead to
a TCP reset. I can see a firewall rule causing that, however.

Please keep us apprised.

Regards,
Steve Emmerson

Ticket Details
===================
Ticket ID: AVX-447373
Department: Support LDM
Priority: Normal
Status: Closed
===================
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