Trouble getting dhclient to send a prefix delegation request
Chris Cowart
ccowart at timesinks.net
Fri May 18 18:55:01 UTC 2012
Hello,
I've have two VMs that are connected to each other via their respective
em1 interfaces. Both are running FreeBSD 9.0-RELEASE.
One is configured as a DHCPv6 server with isc-dhcp42-server-4.2.3_1
installed. The other is configured as a DHCPv6 client with
isc-dhcp42-client-4.2.3 installed.
My server configuration is based on the template file from the software
distribution, with local values for nameservers. I'm using two ULA
prefixes for this testing.
On a clean attempt (removed all lease objects from the lease files for
both server and client; started server daemon), stateful
autoconfiguration works on the client:
| % sudo /usr/local/sbin/dhclient -d -6 em1
| Internet Systems Consortium DHCP Client 4.2.3-P1
| Copyright 2004-2011 Internet Systems Consortium.
| All rights reserved.
| For info, please visit https://www.isc.org/software/dhcp/
|
| Bound to *:546
| Listening on Socket/em1
| Sending on Socket/em1
| PRC: Soliciting for leases (INIT).
| XMT: Forming Solicit, 0 ms elapsed.
| XMT: X-- IA_NA 29:14:e8:44
| XMT: | X-- Request renew in +3600
| XMT: | X-- Request rebind in +5400
| XMT: Solicit on em1, interval 1040ms.
| RCV: Advertise message on em1 from fe80::250:56ff:fe2f:d131.
| RCV: X-- IA_NA 29:14:e8:44
| RCV: | X-- starts 1337325462
| RCV: | X-- t1 - renew +3600
| RCV: | X-- t2 - rebind +7200
| RCV: | X-- [Options]
| RCV: | | X-- IAADDR fd64:3e9f:b2b8:1::1:beef
| RCV: | | | X-- Preferred lifetime 604800.
| RCV: | | | X-- Max lifetime 2592000.
| RCV: X-- Server ID: 00:01:00:01:17:48:b1:a0:00:50:56:2f:d1:31
| RCV: Advertisement recorded.
| PRC: Selecting best advertised lease.
| PRC: Considering best lease.
| PRC: X-- Initial candidate 00:01:00:01:17:48:b1:a0:00:50:56:2f:d1:31 (s: 155, p: 0).
| XMT: Forming Request, 0 ms elapsed.
| XMT: X-- IA_NA 29:14:e8:44
| XMT: | X-- Requested renew +3600
| XMT: | X-- Requested rebind +5400
| XMT: | | X-- IAADDR fd64:3e9f:b2b8:1::1:beef
| XMT: | | | X-- Preferred lifetime +7200
| XMT: | | | X-- Max lifetime +7500
| XMT: V IA_NA appended.
| XMT: Request on em1, interval 1000ms.
| RCV: Reply message on em1 from fe80::250:56ff:fe2f:d131.
| RCV: X-- IA_NA 29:14:e8:44
| RCV: | X-- starts 1337325463
| RCV: | X-- t1 - renew +3600
| RCV: | X-- t2 - rebind +7200
| RCV: | X-- [Options]
| RCV: | | X-- IAADDR fd64:3e9f:b2b8:1::1:beef
| RCV: | | | X-- Preferred lifetime 604800.
| RCV: | | | X-- Max lifetime 2592000.
| RCV: X-- Server ID: 00:01:00:01:17:48:b1:a0:00:50:56:2f:d1:31
| PRC: Bound to lease 00:01:00:01:17:48:b1:a0:00:50:56:2f:d1:31.
| PRC: Renewal event scheduled in 3600 seconds, to run for 3600 seconds.
| PRC: Depreference scheduled in 604800 seconds.
| PRC: Expiration scheduled in 2592000 seconds.
However, attempts to request a prefix produce no results:
| % sudo /usr/local/sbin/dhclient -d -6 -P em1
| Internet Systems Consortium DHCP Client 4.2.3-P1
| Copyright 2004-2011 Internet Systems Consortium.
| All rights reserved.
| For info, please visit https://www.isc.org/software/dhcp/
|
| Bound to *:546
| Listening on Socket/em1
| Sending on Socket/em1
| PRC: Confirming active lease (INIT-REBOOT).
| XMT: Forming Rebind, 0 ms elapsed.
| XMT: Rebind on em1, interval 940ms.
| XMT: Forming Rebind, 940 ms elapsed.
| XMT: Rebind on em1, interval 1850ms.
| XMT: Forming Rebind, 2800 ms elapsed.
| XMT: Rebind on em1, interval 3870ms.
| XMT: Forming Rebind, 6680 ms elapsed.
| XMT: Rebind on em1, interval 7190ms.
| PRC: Depreference scheduled in 604716 seconds.
| PRC: Expiration scheduled in 2591916 seconds.
Wireshark decodes the 4 messages that went out as follows:
| DHCPv6
| Message type: Rebind (6)
| Transaction-ID: 0x009f91ef
| Client Identifier
| option type: 1
| option length: 10
| DUID type: link-layer address (3)
| Hardware type: Ethernet (1)
| Link-layer address: 00:0c:29:14:e8:44
| Option Request
| option type: 6
| option length: 4
| Requested Option code: DNS recursive name server (23)
| Requested Option code: Domain Search List (24)
| Elapsed time
| option type: 8
| option length: 2
| elapsed-time: 0 ms
The dhclient makes no forward progress. It appears to be insisting that
the server respond.
I walked through the server code with gdb, and found that my client's
Rebind messages are hitting this snippet of code:
| dhcpv6.c
|
| 1379 /*
| 1380 * Make no reply if we gave no resources and is not
| 1381 * for Information-Request.
| 1382 */
| 1383 if ((reply.ia_count == 0) && (reply.pd_count == 0)) {
| 1384 if (reply.packet->dhcpv6_msg_type !=
| 1385 DHCPV6_INFORMATION_REQUEST)
| 1386 goto exit;
| 1387
It looks like a stalemate to me.
I experimented with the dhclient.conf, though documentation (especially
examples) seem to be incredibly sparse on this front; whether provided
by ISC or a third party. Anyways, I came up with this file:
| interface "em1" {
| also request dhcp6.ia-pd;
| }
This doesn't show any syntax errors, but it also doesn't make any
difference on the results from dhclient.
After three late nights of experimentation, I came up with this
workaround. Working from the syntax of other folks' lease file snippets
online, I figured out how to trick dhclient into thinking it had an
IA_PD by adding this into my lease6 block:
| ia-pd 00:00:00:00 {
| iaprefix ::/48 {
| }
| }
Now some exciting stuff starts to happen:
| % sudo /usr/local/sbin/dhclient -d -6 -P em1
| Internet Systems Consortium DHCP Client 4.2.3-P1
| Copyright 2004-2011 Internet Systems Consortium.
| All rights reserved.
| For info, please visit https://www.isc.org/software/dhcp/
|
| Bound to *:546
| Listening on Socket/em1
| Sending on Socket/em1
| PRC: Soliciting for leases (INIT).
| XMT: Forming Solicit, 0 ms elapsed.
| XMT: X-- IA_PD 29:14:e8:44
| XMT: | X-- Request renew in +3600
| XMT: | X-- Request rebind in +5400
| XMT: Solicit on em1, interval 1010ms.
| RCV: Advertise message on em1 from fe80::250:56ff:fe2f:d131.
| RCV: X-- IA_PD 29:14:e8:44
| RCV: | X-- starts 1337326717
| RCV: | X-- t1 - renew +3600
| RCV: | X-- t2 - rebind +7200
| RCV: | X-- [Options]
| RCV: | | X-- IAPREFIX fdd9:acf6:5002::/48
| RCV: | | | X-- Preferred lifetime 604800.
| RCV: | | | X-- Max lifetime 2592000.
| RCV: X-- Server ID: 00:01:00:01:17:48:b1:a0:00:50:56:2f:d1:31
| RCV: Advertisement recorded.
| PRC: Selecting best advertised lease.
| PRC: Considering best lease.
| PRC: X-- Initial candidate 00:01:00:01:17:48:b1:a0:00:50:56:2f:d1:31 (s: 155, p: 0).
| XMT: Forming Request, 0 ms elapsed.
| XMT: X-- IA_PD 29:14:e8:44
| XMT: | X-- Requested renew +3600
| XMT: | X-- Requested rebind +5400
| XMT: | | X-- IAPREFIX fdd9:acf6:5002::/48
| XMT: | | | X-- Preferred lifetime +7200
| XMT: | | | X-- Max lifetime +7500
| XMT: V IA_PD appended.
| XMT: Request on em1, interval 1030ms.
| RCV: Reply message on em1 from fe80::250:56ff:fe2f:d131.
| RCV: X-- IA_PD 29:14:e8:44
| RCV: | X-- starts 1337326718
| RCV: | X-- t1 - renew +3600
| RCV: | X-- t2 - rebind +7200
| RCV: | X-- [Options]
| RCV: | | X-- IAPREFIX fdd9:acf6:5002::/48
| RCV: | | | X-- Preferred lifetime 604800.
| RCV: | | | X-- Max lifetime 2592000.
| RCV: X-- Server ID: 00:01:00:01:17:48:b1:a0:00:50:56:2f:d1:31
| PRC: Bound to lease 00:01:00:01:17:48:b1:a0:00:50:56:2f:d1:31.
| Prefix BOUND6 old=::/48 new=::/48
| Prefix BOUND6 old= new=fdd9:acf6:5002::/48
| PRC: Rebind event scheduled in -1337321318 seconds, to run for 1339913318 seconds.
| PRC: Depreference scheduled in -1337326718 seconds.
| PRC: Expiration scheduled in -1337326718 seconds.
| PRC: Rebinding lease on em1.
| XMT: Forming Rebind, 0 ms elapsed.
| XMT: X-- IA_PD 00:00:00:00
| XMT: | X-- Requested renew +3600
| XMT: | X-- Requested rebind +5400
| XMT: | | X-- IAPREFIX ::/48
| XMT: | | | X-- Preferred lifetime +7200
| XMT: | | | X-- Max lifetime +7500
| XMT: V IA_PD appended.
| XMT: X-- IA_PD 29:14:e8:44
| XMT: | X-- Requested renew +3600
| XMT: | X-- Requested rebind +5400
| XMT: | | X-- IAPREFIX fdd9:acf6:5002::/48
| XMT: | | | X-- Preferred lifetime +7200
| XMT: | | | X-- Max lifetime +7500
| XMT: V IA_PD appended.
| XMT: Rebind on em1, interval 10760ms.
| PRC: Prefix ::/48 depreferred.
| PRC: Depreference scheduled in 603545 seconds.
| PRC: Expiration scheduled in -1337326718 seconds.
| Prefix EXPIRE6 old=::/48 new=
| PRC: Prefix ::/48 expired.
| PRC: Depreference scheduled in 603545 seconds.
| PRC: Expiration scheduled in 2590745 seconds.
| RCV: Reply message on em1 from fe80::250:56ff:fe2f:d131.
| RCV: X-- IA_PD 00:00:00:00
| RCV: | X-- starts 1337326718
| RCV: | X-- t1 - renew +3600
| RCV: | X-- t2 - rebind +7200
| RCV: | X-- [Options]
| RCV: | | X-- IAPREFIX fdd9:acf6:5002::/48
| RCV: | | | X-- Preferred lifetime 604800.
| RCV: | | | X-- Max lifetime 2592000.
| RCV: X-- IA_PD 29:14:e8:44
| RCV: | X-- starts 1337326718
| RCV: | X-- t1 - renew +3600
| RCV: | X-- t2 - rebind +7200
| RCV: | X-- [Options]
| RCV: | | X-- IAPREFIX fdd9:acf6:5002::/48
| RCV: | | | X-- Preferred lifetime 604800.
| RCV: | | | X-- Max lifetime 2592000.
| RCV: X-- Server ID: 00:01:00:01:17:48:b1:a0:00:50:56:2f:d1:31
| PRC: Bound to lease 00:01:00:01:17:48:b1:a0:00:50:56:2f:d1:31.
| Prefix REBIND6 old=::/48 new=::/48
| Prefix REBIND6 old= new=fdd9:acf6:5002::/48
| Prefix REBIND6 old=fdd9:acf6:5002::/48 new=fdd9:acf6:5002::/48
| PRC: Renewal event scheduled in 2345 seconds, to run for 3600 seconds.
| PRC: Depreference scheduled in 603545 seconds.
| PRC: Expiration scheduled in 2590745 seconds.
Now that I have an ia-pd in the lease file, everything seems to work
fine.
Could it just be that I'm missing some kind of hint to place in the
dhclient.conf to encourage it to include the ia-pd option? It would seem
like this behavior is a bug.
--
Chris Cowart
http://www.timesinks.net/
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