samba - Jul 2018 - Failed to establish your Kerberos Ticket cache due time differences with the domain controller

On 7/21/2018 3:50 PM, Rowland Penny via samba wrote:
> On Sat, 21 Jul 2018 14:13:45 +0100
> Roy Eastwood via samba <samba at lists.samba.org> wrote:
> 
>> On Sat, 21 Jul 2018 12:16:42 +0100
>>> Rowland Penny via samba<samba at lists.samba.org> wrote:
>>> On Sat, 21 Jul 2018 11:24:47 +0100
>>> Roy Eastwood via samba <samba at lists.samba.org> wrote:
>>>
>>>> "Failed to establish your Kerberos Ticket cache due time
>>>> differences with the domain controller.  Please verify the
system
>>>> time."
>>>
>>> It looks like there is something wrong with your time settings,
even
>>> though you don't think there is. Do your DC's point to
themselves as
>>> the dns server or each other ?
>>
>> The DC's point to themselves in /etc/resolv.conf  (in order that
>> samba_dnsupdate works ok).
>> ie
>> debian-vb (ip address 192.168.2.6) /etc/resolv,conf:
>> ======>> search microilynx.org
>> nameserver 192.168.2.6
>> nameserver 192.168.2.4
>>
>>
>> pi-dc (ip address 129.168.2.4)
>> ========>> search microilynx.org
>> nameserver 192.168.2.4
>> nameserver 192.168.2.6
>>
>>>> Can I ignore this warning or does it point to something wrong
>>>> with the installation?
>>>
>>> You have a problem, you should not ignore it. I would peer very
>>> closely at the rpi, mainly because it doesn't have an RTC.
>>>
>>> It may help if you posted the main conf files from both DC's
>>>
>>> Rowland
>>>
>> OK, global section of smb.conf files:
>>
>>  From debian-vb:
>> ============>> # Global parameters
>> [global]
>> 	netbios name = DEBIAN-VB
>> 	realm = MICROLYNX.ORG
>> 	server role = active directory domain controller
>> 	server services = s3fs, rpc, nbt, wrepl, ldap, cldap, kdc,
>> drepl, winbindd, ntp_signd, kcc, dnsupdate
>> 	workgroup = MICROLYNX
>> 	idmap_ldb:use rfc2307 = yes
> 
> Remove the following lines, they shouldn't be in a DC
>  From here:
>> 	wins support = no
>> 	local master = yes
>> 	domain master = yes
>> 	preferred master = yes
> To here.
> 
>> # prevent CUPS errors in syslog
>> 	printcap name = /dev/null
>> 	load printers = no
>> # add the following two lines for testing - remove for production
>> 	winbind enum users = yes
>> 	winbind enum groups = yes
>> 	template shell = /bin/bash
>> 	template homedir = /home/%D/%U
>> 	log file = /var/log/samba/log.samba
>> 	log level = 1
>>
>>  From pi-dc:
>> ========>> # Global parameters
>> [global]
>> 	netbios name = PI-DC
>> 	realm = MICROLYNX.ORG
>> 	server role = active directory domain controller
>> 	server services = s3fs, rpc, nbt, wrepl, ldap, cldap, kdc,
>> drepl, winbindd, ntp_signd, kcc, dnsupdate
>> 	workgroup = MICROLYNX
> 
> As above, remove these lines
>  From here:
>> 	wins support = no
>> 	local master = no
>> 	domain master = yes
>> 	preferred master = no
> To here.
> 
>> # prevent CUPS errors in syslog
>> 	printcap name = /dev/null
>> 	load printers = no
>>
>> # add the following two lines for testing - remove for production
>> 	winbind enum users = yes
>> 	winbind enum groups = yes
>> 	
>> # allow AD users to log on
>> 	template shell = /bin/bash
>> 	template homedir = /home/%D/%U
>> 	
>> 	log file = /var/log/samba/samba.log
>> 	log level = 1
>>
>> /etc/chrony/chrony.conf:  is as per the Samba WiKi (with ip address
>> changed as appropriate and servers:0.uk.pool.ntp.org etc)
> 
> Well that must be right, I wrote it ;-)
> 
>>
>> /etc/krb5/conf:
>> ==========>> [libdefaults]
>> 	default_realm = MICROLYNX.ORG
>> 	dns_lookup_realm = false
>> 	dns_lookup_kdc = true
>>
>> I realised that the pi has no RTC, but I have now found that
there's
>> a service running called: fake-hwclock which I assume can be removed
>> or disabled now that chrony is setting the clock?   There's also a
>> systemd-timesyncd service, which is enabled - I assume that should
>> also be disabled?
> 
> If you have chrony (or ntp) running, then you don't need another time
> server (I take it 'systemd-timesyncd' is a time server,
wouldn't know,
> I do not use systemd)
> 
The service 'systemd-timesyncd' is a time client and not a time server.

https://www.freedesktop.org/software/systemd/man/systemd-timesyncd.service.html

-- 
John Doe

On Sat, 21 Jul 2018 17:01:55 +0200
john doe via samba <samba at lists.samba.org> wrote:
> On 7/21/2018 3:50 PM, Rowland Penny via samba wrote:
> > On Sat, 21 Jul 2018 14:13:45 +0100
> > Roy Eastwood via samba <samba at lists.samba.org> wrote:
> > 
> >> On Sat, 21 Jul 2018 12:16:42 +0100
> >>> Rowland Penny via samba<samba at lists.samba.org> wrote:
> >>> On Sat, 21 Jul 2018 11:24:47 +0100
> >>> Roy Eastwood via samba <samba at lists.samba.org> wrote:
> >>>
> >>>> "Failed to establish your Kerberos Ticket cache due
time
> >>>> differences with the domain controller.  Please verify the
system
> >>>> time."
> >>>
> >>> It looks like there is something wrong with your time
settings,
> >>> even though you don't think there is. Do your DC's
point to
> >>> themselves as the dns server or each other ?
> >>
> >> The DC's point to themselves in /etc/resolv.conf  (in order
that
> >> samba_dnsupdate works ok).
> >> ie
> >> debian-vb (ip address 192.168.2.6) /etc/resolv,conf:
> >> ======> >> search microilynx.org
> >> nameserver 192.168.2.6
> >> nameserver 192.168.2.4
> >>
> >>
> >> pi-dc (ip address 129.168.2.4)
> >> ========> >> search microilynx.org
> >> nameserver 192.168.2.4
> >> nameserver 192.168.2.6
> >>
> >>>> Can I ignore this warning or does it point to something
wrong
> >>>> with the installation?
> >>>
> >>> You have a problem, you should not ignore it. I would peer
very
> >>> closely at the rpi, mainly because it doesn't have an RTC.
> >>>
> >>> It may help if you posted the main conf files from both
DC's
> >>>
> >>> Rowland
> >>>
> >> OK, global section of smb.conf files:
> >>
> >>  From debian-vb:
> >> ============> >> # Global parameters
> >> [global]
> >> 	netbios name = DEBIAN-VB
> >> 	realm = MICROLYNX.ORG
> >> 	server role = active directory domain controller
> >> 	server services = s3fs, rpc, nbt, wrepl, ldap, cldap, kdc,
> >> drepl, winbindd, ntp_signd, kcc, dnsupdate
> >> 	workgroup = MICROLYNX
> >> 	idmap_ldb:use rfc2307 = yes
> > 
> > Remove the following lines, they shouldn't be in a DC
> >  From here:
> >> 	wins support = no
> >> 	local master = yes
> >> 	domain master = yes
> >> 	preferred master = yes
> > To here.
> > 
> >> # prevent CUPS errors in syslog
> >> 	printcap name = /dev/null
> >> 	load printers = no
> >> # add the following two lines for testing - remove for production
> >> 	winbind enum users = yes
> >> 	winbind enum groups = yes
> >> 	template shell = /bin/bash
> >> 	template homedir = /home/%D/%U
> >> 	log file = /var/log/samba/log.samba
> >> 	log level = 1
> >>
> >>  From pi-dc:
> >> ========> >> # Global parameters
> >> [global]
> >> 	netbios name = PI-DC
> >> 	realm = MICROLYNX.ORG
> >> 	server role = active directory domain controller
> >> 	server services = s3fs, rpc, nbt, wrepl, ldap, cldap, kdc,
> >> drepl, winbindd, ntp_signd, kcc, dnsupdate
> >> 	workgroup = MICROLYNX
> > 
> > As above, remove these lines
> >  From here:
> >> 	wins support = no
> >> 	local master = no
> >> 	domain master = yes
> >> 	preferred master = no
> > To here.
> > 
> >> # prevent CUPS errors in syslog
> >> 	printcap name = /dev/null
> >> 	load printers = no
> >>
> >> # add the following two lines for testing - remove for production
> >> 	winbind enum users = yes
> >> 	winbind enum groups = yes
> >> 	
> >> # allow AD users to log on
> >> 	template shell = /bin/bash
> >> 	template homedir = /home/%D/%U
> >> 	
> >> 	log file = /var/log/samba/samba.log
> >> 	log level = 1
> >>
> >> /etc/chrony/chrony.conf:  is as per the Samba WiKi (with ip
address
> >> changed as appropriate and servers:0.uk.pool.ntp.org etc)
> > 
> > Well that must be right, I wrote it ;-)
> > 
> >>
> >> /etc/krb5/conf:
> >> ==========> >> [libdefaults]
> >> 	default_realm = MICROLYNX.ORG
> >> 	dns_lookup_realm = false
> >> 	dns_lookup_kdc = true
> >>
> >> I realised that the pi has no RTC, but I have now found that
> >> there's a service running called: fake-hwclock which I assume
can
> >> be removed or disabled now that chrony is setting the clock?
> >> There's also a systemd-timesyncd service, which is enabled - I
> >> assume that should also be disabled?
> > 
> > If you have chrony (or ntp) running, then you don't need another
> > time server (I take it 'systemd-timesyncd' is a time server,
> > wouldn't know, I do not use systemd)
> > 
> 
> The service 'systemd-timesyncd' is a time client and not a time
> server.
> 
>
https://www.freedesktop.org/software/systemd/man/systemd-timesyncd.service.html
> 
This quote from the above link "The systemd-timesyncd service
specifically implements only SNTP", means it isn't any good for a DC.

Rowland

Thanks for that.
> > > Remove the following lines, they shouldn't be in a DC
> > >  From here:
> > >> 	wins support = no
> > >> 	local master = yes
> > >> 	domain master = yes
> > >> 	preferred master = yes
> > > To here.
> > >
> > > If you have chrony (or ntp) running, then you don't need
another
> > > time server (I take it 'systemd-timesyncd' is a time
server,
> > > wouldn't know, I do not use systemd)
> > >
> >
> > The service 'systemd-timesyncd' is a time client and not a
time
> > server.
> >
> > https://www.freedesktop.org/software/systemd/man/systemd-
> timesyncd.service.html
> >
> 
> This quote from the above link "The systemd-timesyncd service
> specifically implements only SNTP", means it isn't any good for a
DC.
> 
> Rowland
Ok, have edited the  smb.conf and removed the fake-hwclock and disabled the
systemd-timesyncd service (as I assume chrony will set the DC's clock as
well as providing the time server for domain computers?) but the problem
remains.     When I log in (via ssh) I get the above message (as in the subject)
and the following is logged in the log.wb-MICROLYNX file:

[2018/07/21 16:37:52.194656,  1]
../source3/libads/authdata.c:175(kerberos_return_pac)
  kinit failed for 'roy at MICROLYNX.ORG' with: Clock skew too great
(-1765328347)

Yet the system time is correct.   Where is it getting time from?

Roy