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Re: apparent change in hostnames on LAN without admin intervention

On 12/14/19 3:56 AM, Andrei POPESCU wrote:

On Vi, 13 dec 19, 19:33:51, Jape Person wrote:

Hi folks. Did I miss something?

I've had 3 Sid/testing systems running on the same LAN behind the same
router for just shy of 3 years. Their static IP addresses have always been
issued by the DHCP server on the router. Everything has been copacetic among
the systems, with local and outside name resolution working with no issue.

A little over a week ago the systems stopped being able to access each other
by name. No changes were made in the settings or firmware of the router or
of the local network settings on the systems.

I discovered that all of the hostnames had changed from xxxxxx.local to
xxxxxx. I've tried to determine the cause of this alteration in the
hostnames on the LAN.


Please provide more info on this, specifically where / how are the
hostnames configured and where / how did you discover they changed.

Do note that .local is typically used by mDNS and in my understanding it
should not be used with a DNS server.

https://en.wikipedia.org/wiki/.local

Kind regards,
Andrei


Hi, Andrei.

The hostnames and local domain name were used during installation.
The static DHCP addresses are issued by a Luxul XWR-1750 router which associates the hostnames with the MAC and IP addresses. 

Contents of /etc/resolv.conf:

search local
nameserver 208.67.220.220
I discovered the change a few days ago when I was doing my daily check for updates by using SSH to connect to two of the systems. I received the following response to the connection command: 

ssh: Could not resolve hostname chip-nuc.local: Name or service not known
I checked to make sure I could connect to everything by IP address, and I checked DNS on the outside world. Everything looked okay. 

On a hunch I tried omitting the .local from the connection command, and it work on each client.
I figured any time the name of a client changes without deliberate action on the part of the network admin (however incompetent he may be), that could be a security issue. That's why I asked here. 

Thanks,
JP
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