Can't get ntp to work

[David Magda]

> On Oct 18, 2015, at 08:03, Marcin Wisnicki <mwisnicki+freebsd at gmail.com> wrote:
> 
> My ntpd stopped synchronizing clock sometime ago (default ntp.conf).
> 
> To debug the problem I've tried running ntpdate and got strange results:
> 
>> # ntpdate 0.freebsd.pool.ntp.org
>> 18 Oct 13:53:14 ntpdate[55102]: no server suitable for synchronization found
>> 	
>> # ntpdate -u 0.freebsd.pool.ntp.org
>> 18 Oct 13:53:19 ntpdate[55119]: adjust time server 193.25.222.240 offset 0.002672 sec
> 
> 
> This would point to broken firewall BUT:
> 
>> # nmap -p123 -sU 0.freebsd.pool.ntp.org
>> 
>> Starting Nmap 6.49BETA5 ( https://nmap.org ) at 2015-10-18 13:52 CEST
>> Nmap scan report for 0.freebsd.pool.ntp.org (193.25.222.240)
>> Host is up (0.027s latency).
>> Other addresses for 0.freebsd.pool.ntp.org (not scanned): 94.154.96.7 95.158.95.123 46.175.224.7
>> rDNS record for 193.25.222.240: afrodyta.complex.net.pl
>> PORT    STATE SERVICE
>> 123/udp open  ntp
>> 
>> Nmap done: 1 IP address (1 host up) scanned in 0.64 seconds
> 
> So there is nothing blocking the traffic.
> 
> Any ideas ?

Both “nmap" and “ntpdate -u” would use an unprivileged, ephemeral port, while ntpd(8) and a regular run of ntpdate(8) would use UDP 123 as the source port. Perhaps there is a firewall issue with source ports lower than 1024?