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Today's Topics:
1. Annoying IoT behavior (Philip Prindeville)
----------------------------------------------------------------------
Message: 1
Date: Tue, 18 Jul 2023 11:00:25 -0600
From: Philip Prindeville <philipp_s...@redfish-solutions.com>
To: "dhcp-users@lists.isc.org" <dhcp-users@lists.isc.org>
Subject: Annoying IoT behavior
Message-ID:
<db5004f4-3b9c-407d-a5ea-cc920cad2...@redfish-solutions.com>
Content-Type: text/plain; charset=us-ascii
Hi,
I've been trying to resolve a few issues with some IoT's of various shapes and
sizes that have some really annoying behavior.
The first one was a bunch of Amazon smart dimmers on WiFi that would all use
the same default hostname, which made finding them in ARP tables or on Unifi a
royal pain. The solution was to do the following:
host island-dimmer1 {
hardware ethernet xx:xx:xx:xx:xx:xx;
fixed-address 192.168.6.211;
option host-name "island-dimmer1";
if exists dhcp-parameter-request-list {
option dhcp-parameter-request-list = concat(option
dhcp-parameter-request-list, 0c);
}
}
And force the local stack to override the hostname. Now I can see the dimmers
by the names I've given them and not "Amazon.mydomain.com
<http://amazon.mydomain.com/>" or whatever.
Same for the family's Echo's and Echo Dot's.
The one that doesn't seem to work in the Apple TV's (gen 4 and gen 5) that
renew their leases about every minute.
It's excessive, considering the lease time is 86400.
I tried doing:
host Living-Room-xxxxxxxxxxxx {
hardware ethernet xx:xx:xx:xx:xx:xx;
fixed-address 192.168.6.240;
option host-name "Living-Room";
if exists dhcp-parameter-request-list {
option dhcp-parameter-request-list = concat(option
dhcp-parameter-request-list, 3a);
}
}
And indeed, if I tcpdump the DHCP traffic, I see:
...
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message (53), length 1: ACK
Server-ID (54), length 4: 192.168.6.1
Lease-Time (51), length 4: 43200
RN (58), length 4: 21600
Subnet-Mask (1), length 4: 255.255.255.0
Default-Gateway (3), length 4: 192.168.6.1
Domain-Name-Server (6), length 4: 192.168.6.1
...
But it ignores the lease time and renewal time (RN) all the same.
Anyone else come up with a good solution for misbehaving IoTs?
Thanks,
-Philip
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