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Today's Topics:
1. Re: DHCID messages (Leroy Tennison)
2. DHCP failover doesn't receive DHCP requests in secondary
server (Roberto Carna)
3. Re: DHCP failover doesn't receive DHCP requests in secondary
server (perl-list)
4. Re: DHCP failover doesn't receive DHCP requests in secondary
server (Leroy Tennison)
5. Re: DHCP failover doesn't receive DHCP requests in secondary
server (Roberto Carna)
----------------------------------------------------------------------
Message: 1
Date: Wed, 15 Aug 2018 14:36:37 +0000
From: Leroy Tennison <le...@datavoiceint.com>
To: Users of ISC DHCP <dhcp-users@lists.isc.org>
Subject: Re: DHCID messages
Message-ID: <1534343797447.74...@datavoiceint.com>
Content-Type: text/plain; charset="utf-8"
Thank you for your reply, I appreciate it. I hadn't thought about different
clients trying to use the same FQDN and the other information is helpful.
Gives me some direction.
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Leroy Tennison
Network Information/Cyber Security Specialist
E: le...@datavoiceint.com
2220 Bush Dr
McKinney, Texas
75070
www.datavoiceint.com
TThis message has been sent on behalf
of a company that is part of the Harris Operating Group of
Constellation Software Inc. These companies are listed
here
.
If you prefer not to be contacted by Harris
Operating Group
please notify us
.
This message is intended exclusively for the
individual or entity to which it is addressed. This communication
may contain information that is proprietary, privileged or
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________________________________________
From: dhcp-users <dhcp-users-boun...@lists.isc.org> on behalf of Thomas
Markwalder <tm...@isc.org>
Sent: Wednesday, August 15, 2018 5:54 AM
To: dhcp-users@lists.isc.org
Subject: [EXTERNAL] Re: DHCID messages
Hello:
If you turn off conflict detection, then different clients attempting to
use the same FQDN can overwrite each other's DNS entries. Whether or not
you view that as a risk is up to you.
For DHCPv4 the DHCID is constructed from the client identifier option if
the client sends it, the MAC address otherwise. If your client always
sends the same client identifier regardless of the network it is on,
then the server should be able to update DNS entries for it as it roams
between networks and do so with conflict detection enabled.
Regards,
Thomas Markwalder
ISC Software Engineering
On 08/14/2018 05:12 PM, Leroy Tennison wrote:
> I am getting a number of messages about "Forward map from <DNS name> to <IP
> adress> FAILED: Has an address record but no DHCID, not mine. In the logs
> I'm seeing these messages prior to this:
>
> "updating zone '<DNS zone for above name>/IN': update unsuccessful: <DNS
> name>: 'name not in use' prerequisite not satisfied (YXDOMAIN)" - using
> named-compilezone with -j I'm seeing that both an A and TXT record exist (we
> are using interim as the ddns-update-style).
>
> and
>
> "updating zone '<DNS zone for above name>/IN': update unsuccessful: <DNS
> name>/TXT: 'RRset exists (value dependent)' prerequisite not satisfied
> (NXRRSET)".
>
> As best as I can tell, what is happening is the client is moving from a wired
> connection to a WiFi connection (for meetings) or vice versa. Initially I
> was looking for a way to make the MAC address rather than the system name the
> unique identifier for the system then I came across the
> update-conflict-detection parameter.
>
> Am I understanding the description correctly, if this parameter is set to off
> and the client "changes MAC addresses" (due to a switch to/from WiFi) then
> the dhcp server will remove the previous DDNS entry and replace it with the
> current one? Are there disadvantages to doing this?
>
> If that isn't the way to handle this situation, how can I make the MAC
> address (rather than the system name) the unique identifier for DDNS?
>
> Thanks for your help.
>
>
> Join us
> at the 2018 Momentum User Conference!
> Register
> here
> Leroy Tennison
> Network Information/Cyber Security Specialist
> E: le...@datavoiceint.com
> 2220 Bush Dr
> McKinney, Texas
> 75070
> www.datavoiceint.com
> TThis message has been sent on behalf
> of a company that is part of the Harris Operating Group of
> Constellation Software Inc. These companies are listed
> here
> .
> If you prefer not to be contacted by Harris
> Operating Group
> please notify us
> .
> This message is intended exclusively for the
> individual or entity to which it is addressed. This communication
> may contain information that is proprietary, privileged or
> confidential or otherwise legally exempt from disclosure. If you are
> not the named addressee, you are not authorized to read, print,
> retain, copy or disseminate this message or any part of it. If you
> have received this message in error, please notify the sender
> immediately by e-mail and delete all copies of the
> message.
>
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------------------------------
Message: 2
Date: Wed, 15 Aug 2018 12:06:08 -0300
From: Roberto Carna <robertocarn...@gmail.com>
To: dhcp-users@lists.isc.org
Subject: DHCP failover doesn't receive DHCP requests in secondary
server
Message-ID:
<CAG2Qp6uThK82P4HR+S9+UsE8hvYOYXzN=ra0weh22ec869j...@mail.gmail.com>
Content-Type: text/plain; charset="UTF-8"
Dear people,
I?ve implemented a failover scheme with ISC-DHCP-SERVER in two
different servers, with the same version of the package and OS.
Everything seems to be OK, but when a execute "service isc-dhcp-server
stop" in the primary server, in the secondary server I can see:
Aug 15 11:52:01 dhcp2 dhcpd[5839]: peer dhcp-failover: disconnected
Aug 15 11:52:01 dhcp2 dhcpd[5839]: failover peer dhcp-failover: I move
from normal to communications-interrupted
what is correct, but after that the secondary server doesnt' receive
any DHCPREQUEST packet from clients.
So, my faoilover scheme doesn't work, because if primary server goes
down, the secondary server doesn't receive any IP request from
clients. When I start the isc-dhcp-server on primary server, at this
moment I can see the DHCPREQUEST from clients to primary server.
What can be the problem with the secondary server please ???
Thanks a lot!!!
------------------------------
Message: 3
Date: Wed, 15 Aug 2018 11:38:16 -0400 (EDT)
From: perl-list <perl-l...@network1.net>
To: Users of ISC DHCP <dhcp-users@lists.isc.org>
Subject: Re: DHCP failover doesn't receive DHCP requests in secondary
server
Message-ID:
<96588610.731229.1534347496164.javamail.zim...@network1.net>
Content-Type: text/plain; charset=utf-8
The problem isn't with the secondary server. The DHCP packets must always go
to both servers. If the packets are relayed from a relay agent, then the relay
agent must be configured to send to both of the DHCP servers (On a Cisco
router, that would involve having ip helper-address listed twice, for example).
If no relay, then the DHCP servers must both be on the same LAN with the
clients.
When both of the primary and secondary servers are running, you should see logs
of the DHCP packets in both servers logs.
----- Original Message -----
> From: "Roberto Carna" <robertocarn...@gmail.com>
> To: "Users of ISC DHCP" <dhcp-users@lists.isc.org>
> Sent: Wednesday, August 15, 2018 11:06:08 AM
> Subject: DHCP failover doesn't receive DHCP requests in secondary server
> Dear people,
> I?ve implemented a failover scheme with ISC-DHCP-SERVER in two
> different servers, with the same version of the package and OS.
> Everything seems to be OK, but when a execute "service isc-dhcp-server
> stop" in the primary server, in the secondary server I can see:
> Aug 15 11:52:01 dhcp2 dhcpd[5839]: peer dhcp-failover: disconnected
> Aug 15 11:52:01 dhcp2 dhcpd[5839]: failover peer dhcp-failover: I move
> from normal to communications-interrupted
> what is correct, but after that the secondary server doesnt' receive
> any DHCPREQUEST packet from clients.
> So, my faoilover scheme doesn't work, because if primary server goes
> down, the secondary server doesn't receive any IP request from
> clients. When I start the isc-dhcp-server on primary server, at this
> moment I can see the DHCPREQUEST from clients to primary server.
> What can be the problem with the secondary server please ???
> Thanks a lot!!!
> _______________________________________________
> dhcp-users mailing list
> dhcp-users@lists.isc.org
> https://lists.isc.org/mailman/listinfo/dhcp-users
------------------------------
Message: 4
Date: Wed, 15 Aug 2018 15:54:46 +0000
From: Leroy Tennison <le...@datavoiceint.com>
To: Users of ISC DHCP <dhcp-users@lists.isc.org>
Subject: Re: DHCP failover doesn't receive DHCP requests in secondary
server
Message-ID: <1534348486255.94...@datavoiceint.com>
Content-Type: text/plain; charset="utf-8"
(Robert) you didn't provide a lot of detail so the answers are probably going
to be general. A couple of additional ideas come to mind but, without
specifics, it's hard to troubleshoot. Is a firewall somewhere in the path
blocking requests? Has the server been configured to listen on a specific
(possibly wrong) interface rather than all interfaces?
Join us
at the 2018 Momentum User Conference!
Register
here
Leroy Tennison
Network Information/Cyber Security Specialist
E: le...@datavoiceint.com
2220 Bush Dr
McKinney, Texas
75070
www.datavoiceint.com
TThis message has been sent on behalf
of a company that is part of the Harris Operating Group of
Constellation Software Inc. These companies are listed
here
.
If you prefer not to be contacted by Harris
Operating Group
please notify us
.
This message is intended exclusively for the
individual or entity to which it is addressed. This communication
may contain information that is proprietary, privileged or
confidential or otherwise legally exempt from disclosure. If you are
not the named addressee, you are not authorized to read, print,
retain, copy or disseminate this message or any part of it. If you
have received this message in error, please notify the sender
immediately by e-mail and delete all copies of the
message.
________________________________________
From: dhcp-users <dhcp-users-boun...@lists.isc.org> on behalf of perl-list
<perl-l...@network1.net>
Sent: Wednesday, August 15, 2018 10:38 AM
To: Users of ISC DHCP
Subject: [EXTERNAL] Re: DHCP failover doesn't receive DHCP requests in
secondary server
The problem isn't with the secondary server. The DHCP packets must always go
to both servers. If the packets are relayed from a relay agent, then the relay
agent must be configured to send to both of the DHCP servers (On a Cisco
router, that would involve having ip helper-address listed twice, for example).
If no relay, then the DHCP servers must both be on the same LAN with the
clients.
When both of the primary and secondary servers are running, you should see logs
of the DHCP packets in both servers logs.
----- Original Message -----
> From: "Roberto Carna" <robertocarn...@gmail.com>
> To: "Users of ISC DHCP" <dhcp-users@lists.isc.org>
> Sent: Wednesday, August 15, 2018 11:06:08 AM
> Subject: DHCP failover doesn't receive DHCP requests in secondary server
> Dear people,
> I?ve implemented a failover scheme with ISC-DHCP-SERVER in two
> different servers, with the same version of the package and OS.
> Everything seems to be OK, but when a execute "service isc-dhcp-server
> stop" in the primary server, in the secondary server I can see:
> Aug 15 11:52:01 dhcp2 dhcpd[5839]: peer dhcp-failover: disconnected
> Aug 15 11:52:01 dhcp2 dhcpd[5839]: failover peer dhcp-failover: I move
> from normal to communications-interrupted
> what is correct, but after that the secondary server doesnt' receive
> any DHCPREQUEST packet from clients.
> So, my faoilover scheme doesn't work, because if primary server goes
> down, the secondary server doesn't receive any IP request from
> clients. When I start the isc-dhcp-server on primary server, at this
> moment I can see the DHCPREQUEST from clients to primary server.
> What can be the problem with the secondary server please ???
> Thanks a lot!!!
> _______________________________________________
> dhcp-users mailing list
> dhcp-users@lists.isc.org
> https://lists.isc.org/mailman/listinfo/dhcp-users
_______________________________________________
dhcp-users mailing list
dhcp-users@lists.isc.org
https://lists.isc.org/mailman/listinfo/dhcp-users
------------------------------
Message: 5
Date: Wed, 15 Aug 2018 12:58:13 -0300
From: Roberto Carna <robertocarn...@gmail.com>
To: Users of ISC DHCP <dhcp-users@lists.isc.org>
Subject: Re: DHCP failover doesn't receive DHCP requests in secondary
server
Message-ID:
<CAG2Qp6vQTKLReQxvuVW=80hjjsy1q-mfw5xxp0x4wckm0sm...@mail.gmail.com>
Content-Type: text/plain; charset="UTF-8"
Dear, thanks for your response...So I will review the DHCP agent as you said.
But now I have a question:
If both DHCP servers always receive DHCPREQUEST packets, does it mean
that in normal condition (primary and secondary server are running UP)
both DHCP servers responds these requests ??? Or only the primary
server responds the requests in despite of the secondary server is UP
too ???
Thanks a lot again, regards !!!
2018-08-15 12:38 GMT-03:00 perl-list <perl-l...@network1.net>:
> The problem isn't with the secondary server. The DHCP packets must always go
> to both servers. If the packets are relayed from a relay agent, then the
> relay agent must be configured to send to both of the DHCP servers (On a
> Cisco router, that would involve having ip helper-address listed twice, for
> example).
>
> If no relay, then the DHCP servers must both be on the same LAN with the
> clients.
>
> When both of the primary and secondary servers are running, you should see
> logs of the DHCP packets in both servers logs.
>
> ----- Original Message -----
>> From: "Roberto Carna" <robertocarn...@gmail.com>
>> To: "Users of ISC DHCP" <dhcp-users@lists.isc.org>
>> Sent: Wednesday, August 15, 2018 11:06:08 AM
>> Subject: DHCP failover doesn't receive DHCP requests in secondary server
>
>> Dear people,
>
>> I?ve implemented a failover scheme with ISC-DHCP-SERVER in two
>> different servers, with the same version of the package and OS.
>
>> Everything seems to be OK, but when a execute "service isc-dhcp-server
>> stop" in the primary server, in the secondary server I can see:
>
>> Aug 15 11:52:01 dhcp2 dhcpd[5839]: peer dhcp-failover: disconnected
>> Aug 15 11:52:01 dhcp2 dhcpd[5839]: failover peer dhcp-failover: I move
>> from normal to communications-interrupted
>
>> what is correct, but after that the secondary server doesnt' receive
>> any DHCPREQUEST packet from clients.
>
>> So, my faoilover scheme doesn't work, because if primary server goes
>> down, the secondary server doesn't receive any IP request from
>> clients. When I start the isc-dhcp-server on primary server, at this
>> moment I can see the DHCPREQUEST from clients to primary server.
>
>> What can be the problem with the secondary server please ???
>
>> Thanks a lot!!!
>> _______________________________________________
>> dhcp-users mailing list
>> dhcp-users@lists.isc.org
>> https://lists.isc.org/mailman/listinfo/dhcp-users
> _______________________________________________
> dhcp-users mailing list
> dhcp-users@lists.isc.org
> https://lists.isc.org/mailman/listinfo/dhcp-users
------------------------------
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