The Problem With IPv4 & IPv6 DDNS in The Same Zone
Mirsad Goran Todorovac
mirsad.todorovac at alu.unizg.hr
Tue Jun 21 21:09:21 UTC 2022
Hi all,
After two weeks I've made ISC DHCPv6 running with DDNS updates this
morning, and I feel very good about
how it works.
(Unlike the Windows Server 2016 variant which gave me semaphore timeouts
with far less diagnostics as clearly
being a closed system.)
It is great that now VPN users for example can access their work PCs
from home even without knowing their
PC's IPv6 address (and it would be error prone to tell them one over the
phone each time DHCPv6 changes it,
even when it tries to assign the same address if possible and the
address pool is substantial).
My idea was to have A and AAAA records in the same zone local.alu.hr or
slava.alu.hr, and to allow
the clients to access the hosts from a VPN connection over either IPv4
or IPv6 address transparently,
whichever (IPv4 or IPv6) is configured on their client PC. (Or to select
it at runtime as in ping -4 hostname and
ping -6 hostname).
This way the Professor or Assistant wouldn't have to even know if he is
connecting via IPv4 or IPv6
address, we could upgrade client PCs and laptops one by one, and the
transition would become seamless
and without an interruption of service.
From configuration here:
https://subatomicsolutions.org/8-freebsd/17-ipv4-ipv6-isc-dhcp-server-on-a-dual-stack-network
I've got the DDNS configuration:
### DDNS Configuration
ddns-updates on;
ddns-update-style standard;
# ddns-dual-stack-mixed-mode true;
update-conflict-detection true;
update-optimization false;
deny client-updates;
authoritative;
allow unknown-clients;
update-static-leases on;
log-facility local7;
ddns-domainname "local.alu.hr.";
ddns-rev-domainname "ip6.arpa.";
However I get the errors like this one:
Jun 21 15:08:44 domac dhcpd: Forward map from PC-PAVAO.slava.alu.hr to
193.198.186.212 FAILED: Has an address record but no DHCID, not mine.
Here:
https://www.isc.org/blogs/using-dual-stack-mixed-mode-dsmm-with-ddns-in-isc-dhcp-4-4/
it says:
"The DHCPv4 and DHCPv6 protocols are very different; the client requests
for v4 and v6 addresses will be asynchronous and thus need some sort of
signalling mechanism to ensure that:
* Two clients don’t get the same name (one with the A RR and the other
with the AAAA)."
But I want exactly for the A RR and AAAA RR to have the same hostname
(PC-PAVAO.slava.alu.hr) because it is the same client with IPv4 and IPv6
address!
I would like the PC to have something like:
$ORIGIN slava.alu.hr.
PC-PAVAO IN A 193.198.186.212
PC-PAVAO IN AAAA 2001:b68:2:2a00::10c4
This way our colleague could use PC-PAVAO.slava.alu.hr as his address
without having to know whether he uses IPv4 or IPv6 (and it would take
quite a conversation to explain the difference to an art historian for
example).
My goal is for IPv6 to be used seamlessly via FQDN names, as it is
already been done with the server names.
I figured out that I could use two zones like ipv4.slava.alu.hr and
ipv6.slava.alu.hr, but I think that is awkward and the users like
artists would never adopt that inconvenience. And the system that is
inconvenient would probably not be used, even if it offers flow control,
multimedia streaming to multicast addresses and lots of sensors, cameras
and IoT devices ...
Here is the complete transaction log for the host:
Jun 21 15:08:44 domac dhcpd: Relay-forward message from
2001:b68:ff:ff:a2b:0:a8:2 port 547, link address 2001:b68:2:2a00::1,
peer address fe80::51e5:1df6:c605:a036
Jun 21 15:08:44 domac dhcpd: Reply NA: address 2001:b68:2:2a00::10c4 to
client with duid 00:01:00:01:25:c4:85:9c:1c:a0:b8:7d:11:aa iaid =
102539448 valid for 2592000 seconds
Jun 21 15:08:44 domac dhcpd: ddns.c(150): Allocating ddns_cb=0x556354446280
Jun 21 15:08:44 domac dhcpd: DDNS: ddns_fwd_srv_connector: ddns_cb:
0x556354446280 flags: 50b state: DDNS_STATE_CLEANUP cur_func: <null>
eresult: 0
Jun 21 15:08:44 domac dhcpd: DDNS: ddns_modify_fwd
Jun 21 15:08:44 domac dhcpd: DDNS: build_fwd_add1:
pname:[PC-PAVAO.slava.alu.hr] uname:[PC-PAVAO.slava.alu.hr]
Jun 21 15:08:44 domac dhcpd: DDNS request: id ptr 0x7f4e1040a338
DDNS_STATE_ADD_FW_NXDOMAIN 2001:b68:2:2a00::10c4 for
PC-PAVAO.slava.alu.hr zone: slava.alu.hr.dhcid:
[00:02:01:de:c5:41:4f:69:a0:e4:6
5:2a:e6:39:c5:77:2b:c6:a3:7e:2f:28:82:74:51:66:b2:f9:46:38:9e:af:bf:cc:c6
Jun 21 15:08:44 domac dhcpd: ddns.c(1722): Updating lease_ptr for
ddns_cp=0x556354446280 (addr=2001:b68:2:2a00::10c4)
Jun 21 15:08:44 domac dhcpd: Sending Relay-reply to
2001:b68:ff:ff:a2b:0:a8:2 port 547
Jun 21 15:08:44 domac dhcpd: DDNS reply: id ptr 0x7f4e1040a338, result:
YXDOMAIN
Jun 21 15:08:44 domac dhcpd: DDNS: ddns_fwd_srv_add1: ddns_cb:
0x556354446280 flags: 50b state: DDNS_STATE_ADD_FW_NXDOMAIN cur_func:
ddns_fwd_srv_add1 eresult: 196614
Jun 21 15:08:44 domac dhcpd: DDNS: ddns_modify_fwd
Jun 21 15:08:44 domac dhcpd: DDNS: build_fwd_add2:
pname:[PC-PAVAO.slava.alu.hr] uname:[PC-PAVAO.slava.alu.hr]
Jun 21 15:08:44 domac dhcpd: DDNS request: id ptr 0x7f4e1040a338
DDNS_STATE_ADD_FW_YXDHCID 2001:b68:2:2a00::10c4 for
PC-PAVAO.slava.alu.hr zone: slava.alu.hr.dhcid:
[00:02:01:de:c5:41:4f:69:a0:e4:65
:2a:e6:39:c5:77:2b:c6:a3:7e:2f:28:82:74:51:66:b2:f9:46:38:9e:af:bf:cc:c6
Jun 21 15:08:44 domac dhcpd: DDNS reply: id ptr 0x7f4e1040a338, result:
success
Jun 21 15:08:44 domac dhcpd: DDNS:ddns_fwd_srv_add2: ddns_cb:
0x556354446280 flags: 50b state: DDNS_STATE_ADD_FW_YXDHCID cur_func:
ddns_fwd_srv_add2 eresult: 0
Jun 21 15:08:44 domac dhcpd: Added new forward map from
PC-PAVAO.slava.alu.hr to 2001:b68:2:2a00::10c4
Jun 21 15:08:44 domac dhcpd: DDNS: ddns_modify_ptr
Jun 21 15:08:44 domac dhcpd: DDNS request: id ptr 0x7f4e1040a338
DDNS_STATE_ADD_PTR PC-PAVAO.slava.alu.hr for
4.c.0.1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.a.2.2.0.0.0.8.6.b.0.1.0.0.2.ip6.arpa.
zone: 0.0.a.2.
2.0.0.0.8.6.b.0.1.0.0.2.ip6.arpa.dhcid:
[00:02:01:de:c5:41:4f:69:a0:e4:65:2a:e6:39:c5:77:2b:c6:a3:7e:2f:28:82:74:51:66:b2:f9:46:38:9e:af:bf:cc:c6
Jun 21 15:08:44 domac dhcpd: DDNS reply: id ptr 0x7f4e1040a338, result:
success
Jun 21 15:08:44 domac dhcpd: Added reverse map from
4.c.0.1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.a.2.2.0.0.0.8.6.b.0.1.0.0.2.ip6.arpa.
to PC-PAVAO.slava.alu.hr
Jun 21 15:08:44 domac dhcpd: ddns.c(1325): Updating lease_ptr for
ddns_cp=0x556354446280 (addr=2001:b68:2:2a00::10c4)
Jun 21 15:08:44 domac dhcpd: ddns.c(1326): freeing ddns_cb=0x556354446280
Jun 21 15:08:44 domac dhcpd: ddns.c(150): Allocating ddns_cb=0x5604136c60a0
Jun 21 15:08:44 domac dhcpd: DDNS: ddns_fwd_srv_connector: ddns_cb:
0x5604136c60a0 flags: 50b state: DDNS_STATE_CLEANUP cur_func: <null>
eresult: 0
Jun 21 15:08:44 domac dhcpd: DDNS: ddns_modify_fwd
Jun 21 15:08:44 domac dhcpd: DDNS: build_fwd_add1:
pname:[PC-PAVAO.slava.alu.hr] uname:[PC-PAVAO.slava.alu.hr]
Jun 21 15:08:44 domac dhcpd: DDNS request: id ptr 0x7fdc349e8010
DDNS_STATE_ADD_FW_NXDOMAIN 193.198.186.212 for PC-PAVAO.slava.alu.hr
zone: slava.alu.hr.dhcid: [00:01:01:7c:09:a5:ff:06:c6:fb:6d:76:2
1:b8:70:29:bc:ea:c3:e4:79:35:ce:76:3d:79:32:99:5b:b9:06:20:4c:bf:38
Jun 21 15:08:44 domac dhcpd: ddns.c(1722): Updating lease_ptr for
ddns_cp=0x5604136c60a0 (addr=193.198.186.212)
Jun 21 15:08:44 domac dhcpd: DHCPREQUEST for 193.198.186.212 from
1c:a0:b8:7d:11:aa (PC-PAVAO) via eth0
Jun 21 15:08:44 domac dhcpd: DHCPACK on 193.198.186.212 to
1c:a0:b8:7d:11:aa (PC-PAVAO) via eth0
Jun 21 15:08:44 domac dhcpd: DDNS reply: id ptr 0x7fdc349e8010, result:
YXDOMAIN
Jun 21 15:08:44 domac dhcpd: DDNS: ddns_fwd_srv_add1: ddns_cb:
0x5604136c60a0 flags: 50b state: DDNS_STATE_ADD_FW_NXDOMAIN cur_func:
ddns_fwd_srv_add1 eresult: 196614
Jun 21 15:08:44 domac dhcpd: DDNS: ddns_modify_fwd
Jun 21 15:08:44 domac dhcpd: DDNS: build_fwd_add2:
pname:[PC-PAVAO.slava.alu.hr] uname:[PC-PAVAO.slava.alu.hr]
Jun 21 15:08:44 domac dhcpd: DDNS request: id ptr 0x7fdc349e8010
DDNS_STATE_ADD_FW_YXDHCID 193.198.186.212 for PC-PAVAO.slava.alu.hr
zone: slava.alu.hr.dhcid: [00:01:01:7c:09:a5:ff:06:c6:fb:6d:76:21
:b8:70:29:bc:ea:c3:e4:79:35:ce:76:3d:79:32:99:5b:b9:06:20:4c:bf:38
Jun 21 15:08:44 domac dhcpd: DDNS reply: id ptr 0x7fdc349e8010, result:
NXRRSET
Jun 21 15:08:44 domac dhcpd: DDNS:ddns_fwd_srv_add2: ddns_cb:
0x5604136c60a0 flags: 50b state: DDNS_STATE_ADD_FW_YXDHCID cur_func:
ddns_fwd_srv_add2 eresult: 196616
Jun 21 15:08:44 domac dhcpd: Forward map from PC-PAVAO.slava.alu.hr to
193.198.186.212 FAILED: Has an address record but no DHCID, not mine.
Jun 21 15:08:44 domac dhcpd: ddns.c(1505): Updating lease_ptr for
ddns_cp=0x5604136c60a0 (addr=193.198.186.212)
Jun 21 15:08:44 domac dhcpd: ddns.c(1505):
find_lease_by_ip_addr(193.198.186.212) successful:lease=0x560413628910
Jun 21 15:08:44 domac dhcpd: ddns.c(1506): freeing ddns_cb=0x5604136c60a0
Sorry for my long email. English is not my first language, and I am
still learning how to be concise.
Thank you very much.
Kind regards,
Mirsad
--
Mirsad Goran Todorovac
CARNet sistem inženjer
Grafički fakultet | Akademija likovnih umjetnosti
Sveučilište u Zagrebu
--
CARNet system engineer
Faculty of Graphic Arts | Academy of Fine Arts
University of Zagreb, Republic of Croatia
The European Union
tel. +385 (0)1 3711 451
mob. +385 91 57 88 355
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