[Samba] Replication fails after DC re-joined to domain

Denis Cardon dcardon at tranquil.it
Wed Feb 7 17:38:20 UTC 2018

Hi Roy,

> First some background:
> ==================
> I had a test environment which had two samba DCs (running v 4.8.0rc2) and 1
> Windows Server 2008R2 DC.    The samba DCs had been upgraded from v 4.6x and the
> secrets database was not encrypted (as far as I know).    I decided to downgrade
> one of the samba DCs to v 4.7.4.
> On re-starting samba after the downgrade the log shows:
> ldb: unable to dlopen /usr/local/samba/lib/ldb/encrypted_secrets.so :
> /usr/local/samba/lib/private/libdsdb-module-samba4.so: version `SAMBA_4.8.0RC2'
> not found (required by /usr/local/samba/lib/ldb/encrypted_secrets.so)

when you are doing your downgrade, did you clean up all the 
/usr/local/samba directory or did you make && make install over the 
existing installation?

If it was a quick'n dirty make && make install over the existing 4.8 
install, could you try to do a install on a clean directory and then 
copy over etc/smb.conf, private/ and var/locks/?



> and the samba daemons are left in a failed state.
> So I removed this failed DC (dc1) from the domain, using the (working) 4.8.0rc2
> samba machine after seizing the FSMO roles and using the
> remove-other-dead-server option.   I removed all traces of the existing samba
> installation and then installed a freshly compiled copy of v. 4.7.5 and
> re-joined the domain.   All was working, including replication (as far as I
> know).
> I then demoted the other 4.8.0rc2 samba machine (dc2), with the same result, so
> had to repeat the seizing of roles and removal then install 4.7.5 and re-join.
> Current problem:
> ==============
> Replication reports successful when running samba-tool drs showrepl on both
> machines.  However, running:
> samba-tool drs replicate dc1 dc2 dc=samdom,dc=example,dc=com --full-sync
> or
> samba-tool drs replicate dc2 dc1 dc=samdom,dc=example,dc=com --full-sync
> on dc1 it runs fine.   Indeed dc1 can do a full replication to the Windows DC as
> well.
> But running the command
> samba-tool drs replicate dc1 dc2 dc=samdom,dc=example,dc=com --full-sync
> on dc2 produces an error:
> ERROR(<class 'samba.drs_utils.drsException'>): DRS connection to dc1 failed -
> drsException: DRS connection to dc1 failed: (-1073741643, '{Device Timeout} The
> specified I/O operation on %hs was not completed before the time-out period
> expired.')
>   File "/usr/local/samba/lib/python2.7/site-packages/samba/netcmd/drs.py", line
> 44, in drsuapi_connect
>     (ctx.drsuapi, ctx.drsuapi_handle, ctx.bind_supported_extensions) =
> drs_utils.drsuapi_connect(ctx.server, ctx.lp, ctx.creds)
>   File "/usr/local/samba/lib/python2.7/site-packages/samba/drs_utils.py", line
> 56, in drsuapi_connect
>     raise drsException("DRS connection to %s failed: %s" % (server, e))
> and the logs show:
> [2018/02/07 16:02:50.440699,  1]
> ../source4/auth/gensec/gensec_gssapi.c:790(gensec_gssapi_update_internal)
>   GSS server Update(krb5)(1) Update failed:  Miscellaneous failure (see text):
> Decrypt integrity check failed for checksum type hmac-sha1-96-aes256, key type
> aes256-cts-hmac-sha1-96
> [2018/02/07 16:02:50.440729,  1]
> ../auth/gensec/spnego.c:411(gensec_spnego_parse_negTokenInit)
> Replication is OK in the other direction on dc2:  ie
> samba-tool drs replicate dc2 dc1 dc=samdom,dc=example,dc=com --full-sync
> works ok.
> samba-tool dbcheck --cross-ncs shows no errors when run on either machine.
> Any help appreciated,
> Roy

Denis Cardon
Tranquil IT Systems
Les Espaces Jules Verne, bâtiment A
12 avenue Jules Verne
44230 Saint SĂ©bastien sur Loire
tel : +33 (0)

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