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Today's Topics:
1. Re: Change DHCP-Server Address (Bernd Nachtigall)
2. Re: Change DHCP-Server Address (Marc Haber)
3. Re: Change DHCP-Server Address (Simon Hobson)
4. Re: Change DHCP-Server Address (Glenn Satchell)
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Message: 1
Date: Mon, 28 Jun 2021 15:24:20 +0200
From: Bernd Nachtigall <bna...@web.de>
To: dhcp-users@lists.isc.org
Subject: Re: Change DHCP-Server Address
Message-ID: <952a758d-c1c7-24f5-e56e-14c25e224...@web.de>
Content-Type: text/plain; charset=utf-8; format=flowed
With the recommended option in dhcpd.conf it is running perfect :-)
But maybe they may clean up the documentation:
server-identifier hostname;
... The value specified must be an IP address for the
DHCP server, ...
Maybe is is more clear to write:
server-identifier IP-Address;
... The value specified must be an IP address for the
DHCP server, ...
Jm2c
Bernd
Am 28.06.21 um 08:50 schrieb glenn.satch...@uniq.com.au:
> On 2021-06-28 16:31, Bernd Nachtigall wrote:
>> Hi,
>>
>> there is a DHCP-Service which is configured to use a secondary
>> IP-Address. This runs fine.
>>
>> Main IP: 10.12.251.12 Sec. IP: 10.12.251.111
>>
>> But when check the answers from the service at a client it seems
>> that the service use the main IP as sender. Is there a way to
>> configure the dhcpd that it uses the sec. IP-Addr. as 'from' when
>> answering to clients?
>>
>> Bernd
>
> Hi Bernd
>
> Looks like you need to use the server-identifier statement. This is
> from the dhcpd.conf man page:
>
> The server-identifier statement
>
> server-identifier hostname;
>
> The server-identifier statement can be used to define the value that
> is sent in the DHCP Server Identifier option for a given scope. The
> value specified must be an IP address for the DHCP server, and
> must be reachable by all clients served by a particular scope.
>
> The use of the server-identifier statement is not recommended -
> the only reason to use it is to force a value other than the default
> value to be sent on occasions where the default value would be
> incorrect. The default value is the first IP address associated with
> the physical network interface on which the request arrived.
>
> The usual case where the server-identifier statement needs to be sent
> is when a physical interface has more than one IP address, and the
> one being sent by default isn't appropriate for some or all
> clients served by that interface. Another common case is when an
> alias is defined for the purpose of having a consistent IP address
> for the DHCP server, and it is desired that the clients use this IP
> address when contacting the server.
>
> Supplying a value for the dhcp-server-identifier option is equivalent
> to using the server-identifier statement.
>
> regards, Glenn
>
> _______________________________________________ ISC funds the
> development of this software with paid support subscriptions. Contact
> us at https://www.isc.org/contact/ for more information.
>
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------------------------------
Message: 2
Date: Mon, 28 Jun 2021 16:54:04 +0200
From: Marc Haber <mh+dhcp-us...@zugschlus.de>
To: Users of ISC DHCP <dhcp-users@lists.isc.org>
Subject: Re: Change DHCP-Server Address
Message-ID: <ynnijjnooxxjn...@torres.zugschlus.de>
Content-Type: text/plain; charset=utf-8
On Mon, Jun 28, 2021 at 03:24:20PM +0200, Bernd Nachtigall wrote:
> But maybe they may clean up the documentation:
>
> server-identifier hostname;
>
> ... The value specified must be an IP address for the
> DHCP server, ...
I understand that the hostname gets resolved to an IP address which is
then used as the Identifier. One less place to forget an old address
in case of a change.
Greetings
Marc
--
-----------------------------------------------------------------------------
Marc Haber | "I don't trust Computers. They | Mailadresse im Header
Leimen, Germany | lose things." Winona Ryder | Fon: *49 6224 1600402
Nordisch by Nature | How to make an American Quilt | Fax: *49 6224 1600421
------------------------------
Message: 3
Date: Mon, 28 Jun 2021 16:29:00 +0100
From: Simon Hobson <dh...@thehobsons.co.uk>
To: Users of ISC DHCP <dhcp-users@lists.isc.org>
Subject: Re: Change DHCP-Server Address
Message-ID: <8f81c22d-1155-4506-9ab6-adb41c32d...@thehobsons.co.uk>
Content-Type: text/plain; charset=us-ascii
Bernd Nachtigall <bna...@web.de> wrote:
> But maybe they may clean up the documentation:
>
> server-identifier hostname;
>
> ... The value specified must be an IP address for the
> DHCP server, ...
>
> Maybe is is more clear to write:
>
> server-identifier IP-Address;
>
> ... The value specified must be an IP address for the
> DHCP server, ...
AFAIK, almost everywhere you can use an IP address, you can use a (fully
qualified ?) host name. Names will be resolved to IP addresses during start up.
There's arguments for and against using names.
They make things clearer, and can mean that you just need to keep your DNS up
to date as you move stuff (not that key infrastructure should be moving all
that much).
But it means the DHCP service will fail to start if the DNS is down, and you
still need to restart the DHCP service if the DNS changes because teh DHCP
service will continue using the old values until restarted.
Simon
------------------------------
Message: 4
Date: Tue, 29 Jun 2021 10:11:59 +1000
From: Glenn Satchell <glenn.satch...@uniq.com.au>
To: Users of ISC DHCP <dhcp-users@lists.isc.org>
Subject: Re: Change DHCP-Server Address
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