[ntp:questions] Can sync via IPv4 but not IPv6?

Dan Lowe dan at ingeni.us
Thu Mar 3 05:00:03 UTC 2005


I have a number of hosts from which I provide time service to customers.
These hosts all work perfectly fine via the IPv4 layer.  I am seeing
behavior on the IPv6 layer that I can't explain...

The IP addresses and such below are real - I invite anybody to test against
them, if you think it will be of use.  Obviously, attacks are not welcome
and will be referred to my security and legal departments. 


Some pertinent information about the server host shown below...

SunOS 5.8 (Solaris 8) Generic_108528-18
Sun UltraSPARC Netra (SUNW,UltraSPARC-IIi-cEngine)
Running NTP daemon version 4.2.0 (release)


Here's the error I get from the client.

# bin/ntpdate -6 2001:418:0:7000::53
Looking for host 2001:418:0:7000::53 and service ntp
host found : resolv1.nycmny01.us.to.verio.net
26 Feb 00:34:44 ntpdate[8801]: no server suitable for synchronization found


Looking on the server, I see that ntpd is bound to the IPv6 interfaces.
This output is from lsof; I have wrapped some of the lines.

ntpd 27693 root 5u  IPv6 0x300043d75c0 0t0 UDP *:ntp (Idle)
ntpd 27693 root 9u  IPv6 0x300016811d0 0t0 UDP localhost:ntp (Idle)
ntpd 27693 root 10u IPv6 0x300015abd00 0t0
                    UDP [fe80::a00:20ff:fed9:d5a8]:ntp (Idle)
ntpd 27693 root 11u IPv6 0x300011db708 0t0 UDP [2001:418:3ff::53]:ntp (Idle)
ntpd 27693 root 12u IPv6 0x300049681d0 0t0
                    UDP resolv1.nycmny01.us.to.verio.net:ntp (Idle)


This is a snoop of the session traffic.  It looks like exactly what I would
expect, making things even more confusing.

...:fe9e:bfa0 is a randomly chosen client host.

2001:418:3ff:2:a00:20ff:fe9e:bfa0 -> 2001:418:0:7000::53
	NTP  client (Sat Feb 26 00:41:26 2005)
2001:418:0:7000::53 -> 2001:418:3ff:2:a00:20ff:fe9e:bfa0
	NTP  server (Sat Feb 26 00:41:26 2005)
2001:418:3ff:2:a00:20ff:fe9e:bfa0 -> 2001:418:0:7000::53
	NTP  client (Sat Feb 26 00:41:27 2005)
2001:418:0:7000::53 -> 2001:418:3ff:2:a00:20ff:fe9e:bfa0
	NTP  server (Sat Feb 26 00:41:27 2005)
2001:418:3ff:2:a00:20ff:fe9e:bfa0 -> 2001:418:0:7000::53
	NTP  client (Sat Feb 26 00:41:28 2005)
2001:418:0:7000::53 -> 2001:418:3ff:2:a00:20ff:fe9e:bfa0
	NTP  server (Sat Feb 26 00:41:28 2005)
2001:418:3ff:2:a00:20ff:fe9e:bfa0 -> 2001:418:0:7000::53
	NTP  client (Sat Feb 26 00:41:29 2005)
2001:418:0:7000::53 -> 2001:418:3ff:2:a00:20ff:fe9e:bfa0
	NTP  server (Sat Feb 26 00:41:29 2005)


Thanks in advance for any help!  I am at a loss at this point...

 -dan





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