Samba 4.8 Features added/changed

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Samba 4.8.0rc4

Release Notes for Samba 4.8.0rc4
March 1, 2018

Release Announcements

This is the third release candidate of Samba 4.8. This is *not* intended for production environments and is designed for testing purposes only. Please report any defects via the Samba bug reporting system at

Samba 4.8 will be the next version of the Samba suite.


New GUID Index mode in sam.ldb for the AD DC

Users who upgrade a Samba AD DC in-place will experience a short delay in the first startup of Samba while the sam.ldb is re-indexed.

Unlike in previous releases a transparent downgrade is not possible. If you wish to downgrade such a DB to a Samba 4.7 or earlier version, please run the source4/scripting/bin/sambaundoguididx script first.

smbclient reparse point symlink parameters reversed

See the more detailed description below.

Changed trusted domains listing with wbinfo -m --verbose

See the more detailed description below.


New GUID Index mode in sam.ldb for the AD DC

The new layout used for sam.ldb is GUID, rather than DN oriented. This provides Samba's Active Directory Domain Controller with a faster database, particularly at larger scale.

The underlying DB is still TDB, simply the choice of key has changed.

The new mode is not optional, so no configuration is required. Older Samba versions cannot read the new database (see the upgrade note above).

KDC GPO application

Adds Group Policy support for the Samba kdc. Applies password policies (minimum/maximum password age, minimum password length, and password complexity) and kerberos policies (user/service ticket lifetime and renew lifetime).

Adds the samba_gpoupdate script for applying and unapplying policy. Can be applied automatically by setting

'apply group policies = yes'.

Time Machine Support with vfs_fruit

Samba can be configured as a Time Machine target for Apple Mac devices through the vfs_fruit module. When enabling a share for Time Machine support the relevant Avahi records to support discovery will be published for installations that have been built against the Avahi client library.

Shares can be designated as a Time Machine share with the following setting:

 'fruit:time machine = yes'

Support for lower casing the MDNS Name

Allows the server name that is advertised through MDNS to be set to the hostname rather than the Samba NETBIOS name. This allows an administrator to make Samba registered MDNS records match the case of the hostname rather than being in all capitals.

This can be set with the following settings:

 'mdns name = mdns'

Encrypted secrets

Attributes deemed to be sensitive are now encrypted on disk. The sensitive values are currently: pekList msDS-ExecuteScriptPassword currentValue dBCSPwd initialAuthIncoming initialAuthOutgoing lmPwdHistory ntPwdHistory priorValue supplementalCredentials trustAuthIncoming trustAuthOutgoing unicodePwd clearTextPassword

This encryption is enabled by default on a new provision or join, it can be disabled at provision or join time with the new option '--plaintext-secrets'.

However, an in-place upgrade will not encrypt the database.

Once encrypted, it is not possible to do an in-place downgrade (eg to 4.7) of the database. To obtain an unencrypted copy of the database a new DC join should be performed, specifying the '--plaintext-secrets' option.

The key file "encrypted_secrets.key" is created in the same directory as the database and should NEVER be disclosed. It is included by the samba_backup script.

Active Directory replication visualisation

To work out what is happening in a replication graph, it is sometimes helpful to use visualisations. We introduce a samba-tool subcommand to write Graphviz dot output and generate text-based heatmaps of the distance in hops between DCs.

There are two subcommands, two graphical modes, and (roughly) two modes of operation with respect to the location of authority.

  • 'samba-tool visualize ntdsconn' looks at NTDS Connections.
  • 'samba-tool visualize reps' looks at repsTo and repsFrom objects.

In '--distance' mode (default), the distances between DCs are shown in a matrix in the terminal. With '--color=yes', this is depicted as a heatmap. With '--utf8' it is a lttle prettier.

In '--dot' mode, Graphviz dot output is generated. When viewed using dot or xdot, this shows the network as a graph with DCs as vertices and connections edges. Certain types of degenerate edges are shown in different colours or line-styles.

smbclient reparse point symlink parameters reversed

A bug in smbclient caused the 'symlink' command to reverse the meaning of the new name and link target parameters when creating a reparse point symlink against a Windows server. As this is a little used feature the ordering of these parameters has been reversed to match the parameter ordering of the UNIX extensions 'symlink' command. The usage message for this command has also been improved to remove confusion.

Winbind changes

The dependency to global list of trusted domains within the winbindd processes has been reduced a lot.

The construction of that global list is not reliable and often incomplete in complex trust setups. In most situations the list is not needed any more for winbindd to operate correctly. E.g. for plain file serving via SMB using a simple idmap setup with autorid, tdb or ad. However some more complex setups require the list, e.g. if you specify idmap backends for specific domains. Some pam_winbind setups may also require the global list.

If you have a setup that doesn't require the global list, you should set "winbind scan trusted domains = no".

Improved support for trusted domains (as AD DC)

The support for trusted domains/forests has improved a lot.

External domain trusts, as well a transitive forest trusts, are supported in both directions (inbound and outbound) for Kerberos and NTLM authentication now.

The LSA LookupNames and LookupSids implementations support resolving names and sids from trusts domains/forest now. This is important in order to allow Samba based domain members to make use of the trust.

However there are currently still a few limitations:

  • It's not possible to add users/groups of a trusted domainvinto domain groups. So group memberships are not expanded on trust boundaries.
  • Both sides of the trust need to fully trust each other!
  • No SID filtering rules are applied at all!
  • This means DCs of domain A can grant domain admin rights in domain B.
  • Selective (CROSS_ORIGANIZATION) authentication is not supported. It's possible to create such a trust, but the KDC and winbindd ignore them.

Changed trusted domains listing with wbinfo -m --verbose

The trust properties printed by wbinfo -m --verbose have been changed to correctly reflect the view of the system where wbinfo is executed.

The trust type field in particular can show additional values that correctly reflect the type of the trust: "Local" for the local SAM and BUILTIN, "Workstation" for a workstation trust to the primary domain, "RWDC" for the SAM on a AD DC, "RODC" for the SAM on a read-only DC, "PDC" for the SAM on a NT4-style DC, "Forest" for a AD forest trust and "External" for quarantined, external or NT4-style trusts.

Indirect trusts are shown as "Routed" including the routing domain.

Example, on a AD DC (SDOM1):

Domain Name DNS Domain          Trust Type  Transitive  In   Out
BUILTIN                         Local
SDOM1          RWDC
WDOM3          Forest      Yes         No   Yes
WDOM2          Forest      Yes         Yes  Yes
SUBDOM31 Routed (via WDOM3)
SUBDOM21 Routed (via WDOM2)

Same setup, on a member of WDOM2:

Domain Name DNS Domain          Trust Type  Transitive  In   Out
BUILTIN                         Local
TITAN                           Local
WDOM2          Workstation Yes         No   Yes
WDOM1          Routed (via WDOM2)
WDOM3          Routed (via WDOM2)
SUBDOM21 Routed (via WDOM2)
SDOM1          Routed (via WDOM2)
SUBDOM11 Routed (via WDOM2)

The list of trusts may be incomplete and additional domains may appear as "Routed" if a user of an unknown domain is successfully authenticated.

VirusFilter VFS module

This new module integrates with Sophos, F-Secure and ClamAV anti-virus software to provide scanning and filtering of files on a Samba share.


'net serverid' commands removed

The two commands 'net serverid list' and 'net serverid wipe' have been removed, because the file serverid.tdb is not used anymore.

'net serverid list' can be replaced by listing all files in the subdirectory "msg.lock" of Samba's "lock directory". The unique id listed by 'net serverid list' is stored in every process' lockfile in "msg.lock".

'net serverid wipe' is not necessary anymore. It was meant primarily for clustered environments, where the serverid.tdb file was not properly cleaned up after single node crashes. Nowadays smbd and winbind take care of cleaning up the msg.lock and msg.sock directories automatically.

NT4-style replication based net commands removed

The following commands and sub-commands have been removed from the "net" utility:

  • net rpc samdump
  • net rpc vampire ldif

Also, replicating from a real NT4 domain with "net rpc vampire" and "net rpc vampire keytab" has been removed.

The NT4-based commands were accidentially broken in 2013, and nobody noticed the breakage. So instead of fixing them including tests (which would have meant writing a server for the protocols, which we don't have) we decided to remove them.

For the same reason, the "samsync", "samdeltas" and "database_redo" commands have been removed from rpcclient.

"net rpc vampire keytab" from Active Directory domains continues to be supported.

vfs_aio_linux module removed

The current Linux kernel aio does not match what Samba would do. Shipping code that uses it leads people to false assumptions. Samba implements async I/O based on threads by default, there is no special module required to see benefits of read and write request being sent do the disk in parallel.

smb.conf changes

 Parameter Name                     Description             Default
 --------------                     -----------             -------
 apply group policies               New                     no
 auth methods                       Removed
 binddns dir                        New
 client schannel                    Default changed/        yes
 gpo update command                 New
 ldap ssl ads                       Deprecated
 map untrusted to domain            Removed
 oplock contention limit            Removed
 prefork children                   New                     1
 mdns name                          New                     netbios
 fruit:time machine                 New                     false
 profile acls                       Removed
 use spnego                         Removed
 server schannel                    Default changed/        yes
 unicode                            Deprecated
 winbind scan trusted domains       New                     yes
 winbind trusted domains only       Removed




  • Ralph Boehme <>
  • BUG 13287: Fix numerous trust related bugs in winbindd and s4 LSA RPC server.
  • BUG 13296: vfs_fruit: Use off_t, not size_t for TM size calculations.
  • Alexander Bokovoy <>
  • BUG 13304: mit-kdb: Support MIT Kerberos 1.16 KDB API changes.
  • Günther Deschner <>
  • BUG 13277: build: Fix libceph-common detection.
  • Poornima G <>
  • BUG 13297: vfs_glusterfs: Fix the wrong pointer being sent in glfs_fsync_async.
  • Volker Lendecke <>
  • BUG 13305: vfs_fileid: Fix the 32-bit build.
  • Stefan Metzmacher <>
  • BUG 13206: Unable to authenticate with an empty string domain .
  • BUG 13276: configure aborts without libnettle/gnutls.
  • BUG 13278: winbindd (on an AD DC) should only use netlogon/lsa against trusted domains.
  • BUG 13287: Fix numerous trust related bugs in winbindd and s4 LSA RPC server.
  • BUG 13290: A disconnecting winbind client can cause a problem in the winbind parent child communication.
  • BUG 13291: tevent: version 0.9.36.
  • BUG 13292: winbind requests could get stuck in the queue of a busy child, while later requests could get served fine by other children.
  • BUG 13293: Minimize the lifetime of winbindd_cli_state->{pw,gr}ent_state.
  • BUG 13294: Avoid using fstrcpy(domain->dcname,...) on a char *.
  • BUG 13295: winbind parent should find the dc of a foreign domain via the primary domain.
  • BUG 13299: Disable support for CROSS_ORGANIZATION domains.
  • BUG 13306: ldb: version 1.3.2.
  • Sachin Prabhu <>
  • BUG 13303: vfs_glusterfs: Add fallocate support for vfs_glusterfs.
  • Garming Sam <>
  • BUG 13031: subnet: Avoid a segfault when renaming subnet objects.
  • BUG 13269: RODC may skip objects during replication due to naming conflicts.


  • Trever L. Adams <>
  • Ralph Boehme <>
  • BUG #13228: dbcheck: Add support for restoring missing forward links.
  • Güther Deschner <>
  • Stefan Metzmacher <>
  • BUG #13228: dbcheck: Add support for restoring missing forward links.


  • Günther Deschner <>
  • BUG #13227: packaging: Fix default systemd-dir path.
  • BUG #13238: build: Deal with recent glibc sunrpc header removal.
  • Stefan Metzmacher <>
  • BUG #13228: repl_meta_data: fix linked attribute corruption on databases with unsorted links on expunge.
  • Christof Schmitt <>
  • BUG #13217: s3/smbd: Remove file system sharemode before calling unlink.
  • Andreas Schneider <>
  • BUG #13209: Small improvements in winbindd for the resource cleanup in error cases.
  • BUG #13238: Make Samba work with tirpc and libnsl2.