Setting up Samba as a Domain Member
Introduction
A Samba domain member is a Linux machine joined to a domain that is running Samba and does not provide domain services, such as an NT4 primary domain controller (PDC) or Active Directory (AD) domain controller (DC).
On a Samba domain member, you can:
- Use domain users and groups in local ACLs on files and directories.
- Set up shares to act as a file server.
- Set up printing services to act as a print server.
- Configure PAM to enable domain users to log on locally or to authenticate to local installed services.
For details about setting up a Samba NT4 domain or Samba AD, see Domain Control.
For versions of Samba earlier than 4.15.0, never use samba-tool domain provision to create a Unix domain member, it will not work, you must follow the procedure laid out on this page. |
All AD Domain members must be in the same DNS domain and the Realm must be the DNS domain in uppercase. For example, the DNS domain could be samdom.example.com and the Realm would be SAMDOM.EXAMPLE.COM . |
Preparing the Installation
General Preparation
- Verify that no Samba processes are running:
# ps ax | egrep "samba|smbd|nmbd|winbindd"
- If the output lists any
samba
,smbd
,nmbd
, orwinbindd
processes, shut down the processes.
- If you previously run a Samba installation on this host:
- Backup the existing
smb.conf
file. To list the path to the file, enter:
- Backup the existing
# smbd -b | grep "CONFIGFILE" CONFIGFILE: /usr/local/samba/etc/samba/smb.conf
- Remove all Samba database files, such as
*.tdb
and*.ldb
files. To list the folders containing Samba databases:
- Remove all Samba database files, such as
# smbd -b | egrep "LOCKDIR|STATEDIR|CACHEDIR|PRIVATE_DIR" LOCKDIR: /usr/local/samba/var/lock/ STATEDIR: /usr/local/samba/var/locks/ CACHEDIR: /usr/local/samba/var/cache/ PRIVATE_DIR: /usr/local/samba/private/
- Starting with a clean environment helps you to prevent confusion, and no files from your previous Samba installation are mixed with your new domain member installation.
Preparing a Domain Member to Join an Active Directory Domain
Configuring DNS
Active Directory (AD) uses DNS in the background, to locate other DCs and services, such as Kerberos. Thus AD domain members and servers must be able to resolve the AD DNS zones.
The following describes how to manually configure Linux clients to use DNS servers. If you are running a DHCP server providing DNS settings to your client computers, configure your DHCP server to send the IP addresses of your DNS servers.
Configuring the /etc/resolv.conf
Set the DNS server IP and AD DNS domain in your /etc/resolv.conf
. For example:
nameserver 10.99.0.1 search samdom.example.com
Some utilities, such as NetworkManager can overwrite manual changes in that file. See your distribution's documentation for information about how to configure name resolution permanently.
For NetworkManager, set the DNS server using either the graphical interface or nmcli and restart the NetworkManager service. The visible /etc/resolv.conf file:
nameserver 127.0.0.53 search samdom.example.com
won't list the DNS server explicitly but nevertheless works correctly.
At this point, if you are joining a new AD DC, then its records will not exist, so there is no point in testing for them. Continue with joining your new AD DC and return here, if required, once the join has succeeded. |
Testing DNS resolution
To verify that your DNS settings are correct and your client or server is able to resolve IP addresses and host names use the nslookup
or host
commands. The nslookup
command is available on Linux and Windows.
Forward Lookup
To resolve a host name its IP address:
# nslookup DC1.samdom.example.com Server: 10.99.0.1 Address: 10.99.0.1#53 Name: DC1.samdom.example.com Address: 10.99.0.1
alternatively you can use the host
command:
# host DC1.samdom.example.com DC1.samdom.example.com has address 10.99.0.1
Reverse Lookup
To resolve a IP address to its host name:
# nslookup 10.99.0.1 Server: 10.99.0.1 Address: 10.99.0.1#53 1.0.99.10.in-addr.arpa name = DC1.samdom.example.com.
or
# host 10.99.0.1 1.0.99.10.in-addr.arpa domain name pointer DC1.samdom.example.com
Note that in a Samba AD, the reverse zone is not automatically configured. To set up a reverse zone, see DNS Administration.
Resolving SRV Records
Active Directory (AD) uses SRV records to locate services, such as Kerberos and LDAP. To verify that SRV records are resolved correctly, use the nslookup
interactive shell:
$ nslookup > set type=SRV > _ldap._tcp.samdom.example.com Server: 192.168.0.4 Address: 192.168.0.4#53 _ldap._tcp.samdom.example.com service = 0 100 389 dc2.samdom.example.com. _ldap._tcp.samdom.example.com service = 0 100 389 dc1.samdom.example.com. > exit
or
$ host -t SRV _ldap._tcp.samdom.example.com _ldap._tcp.samdom.example.com has SRV record 0 100 389 dc1.samdom.example.com. _ldap._tcp.samdom.example.com has SRV record 0 100 389 dc2.samdom.example.com.
Error Messages
- The DNS server is not able to resolve the host name:
** server can't find DC1.samdom.example.com: NXDOMAIN
- The DNS server is not able to resolve the IP address:
** server can't find 1.0.99.10.in-addr.arpa: NXDOMAIN
- The DNS server used is not available:
;; connection timed out; no servers could be reached
Configuring Kerberos
Samba supports Heimdal and MIT Kerberos back ends. To configure Kerberos on the domain member, set the following in your /etc/krb5.conf
file:
[libdefaults] default_realm = SAMDOM.EXAMPLE.COM dns_lookup_realm = false dns_lookup_kdc = true
The previous example configures Kerberos for the SAMDOM.EXAMPLE.COM
realm.
The Samba teams recommends to not set any further parameters in the /etc/krb5.conf
file.
If your /etc/krb5.conf
contains an include
line it will not work, you Must remove this line.
On some Linux distributions that use MIT Kerberos, it is necessary to add these lines for proper ID mapping:
[plugins] localauth = { module = winbind:/usr/lib64/samba/krb5/winbind_krb5_localauth.so enable_only = winbind }
These settings could also be necessary /etc/security/pam_winbind.conf
:
[global] krb5_auth = yes krb5_ccache_type = FILE
With distributions with crypto-policies, this command must be issued to update the system policy support for Active Directory:
update-crypto-policies --set DEFAULT:AD-SUPPORT
Configuring Time Synchronisation
Kerberos requires a synchronised time on all domain members. Thus it is recommended to set up an NTP client. For further details, see Configuring Time Synchronisation on a Unix Domain Member.
Local Host Name Resolution
When you join the host to the domain, Samba tries to register the host name in the AD DNS zone. For this, the net
utility must be able to resolve the host name using DNS or using a correct entry in the /etc/hosts
file.
To verify that your host name resolves correctly, use the getent hosts
command. For example:
# getent hosts M1 10.99.0.5 M1.samdom.example.com M1
The host name and FQDN must not resolve to the 127.0.0.1
IP address or any other IP address other than the one used on the LAN interface of the domain member.
If no output is displayed or the host is resolved to the wrong IP address and you are not using dhcp, set the correct entry in the /etc/hosts
file. For example:
127.0.0.1 localhost 10.99.0.5 M1.samdom.example.com M1
If you are using dhcp, check that /etc/hosts
only contains the '127.0.0.1' line shown above. If you continue to have problems, contact the sysadmin who controls your DHCP server.
if you need to add aliases to the machine hostname, add them to the end of the line that starts with the machines ipaddress, not the 127.0.0.1 line.
Preparing a Domain Member to Join an NT4 Domain
For joining a host to an NT4 domain, no preparation is required.
Installing Samba
For details, see Installing Samba.
Install a maintained Samba version. For details, see Samba Release Planning. |
Configuring Samba
Samba can use various winbind idmap backends, The three main ones are:
- ad
- autorid
- rid
Choosing an idmap backend
It can appear to be a complex decision choosing which winbind idmap backend to use, hopefully reading this can point you to the one to use.
If you require users and groups to have the same IDs everywhere, or have different login shells and Unix home directory paths, then you need to use the winbind idmap 'ad' backend and add RFC2307 attributes to AD. |
If you use the 'ad' backend, the RFC2307 attributes (uidNumber, gidNumber, etc) are not added automatically when users or groups are created, you must add them manually. |
The ID numbers found on a Samba DC (numbers in the 3000000 range) are NOT rfc2307 attributes. They cannot and will not be used on Unix Domain Members, you can add uidNumber & gidNumber attributes to AD and use the winbind 'ad' backend on Unix Domain Members. If you do decide to add uidNumber & gidNumber attributes to AD, you do not need to use numbers in the 3000000 range and it would definitely be a good idea to use a different range.
If you only need users and groups to have Unix IDs, you can use the 'rid' or 'autorid' idmap winbind backend. |
The 'rid' or 'autorid' idmap winbind backends calculate the user and group IDs from the Windows RID. If you use the 'rid' idmap backend and the same [global] section of the smb.conf on every Unix domain member, you will get the same IDs. Using these idmap backends, you do not add anything to AD and any added RFC2307 attributes will be ignored. When using these backends you can set the 'template shell' and 'template homedir' parameters in the smb.conf global section and everyone will get the login shell and Unix home directory path you set. If you do not set 'template shell' or 'template homedir', the defaults, '/bin/false' and '/home/%D/%U' , will be used.
Once you Have decided which winbind idmap backend to use, you have to choose the ranges to use with 'idmap config' in smb.conf.
By default on a Unix domain member, there are multiple sources and types of users & groups:
- The local system users & groups: These will typically be from 0-999
- The local Unix users and groups: These typically start at 1000
- The (AD) domain users and groups
- The default domain '*' used for the WellKnownSIDs and anything not in the 'AD' domain
- Trusted domains
As you can see from the above, if you are creating a new domain, you shouldn't set either the default domain '*' or the (AD) domain ranges to start at 999 or less, as they would interfere with the local system users & groups. You also should leave a space for any local Unix users & groups (for 'sudo' use etc.), so starting the 'idmap config' ranges at 3000 seems to be a good compromise.
Bearing the above information in mind, you could set the 'idmap config' ranges to the following:
Domain Range *
3000-7999 DOMAIN
10000-999999
You could also have any trusted domains starting at:
Domain Range TRUSTED
1000000-9999999
If you set the default domain '*' range above the 'DOMAIN' domain range, the ranges will conflict if the domain grows to the point that the next ID would be the same as the default domain range start ID.
With the above suggested ranges, no range will overlap or interfere with another.
You may also have seen examples of the '*' range being used for everything, this should only be used with the 'autorid' idmap backend.
Setting up a Basic smb.conf
File
ID mapping back ends are not supported in the smb.conf file on a Samba Active Directory (AD) domain controller (DC).Do not add any idmap config lines to a Samba Active Directory (AD) domain controller (DC) smb.conf For details, see Failure to Access Shares on Domain Controllers If idmap config Parameters Set in the smb.conf File. |
Before joining the domain, configure the domain member's smb.conf
file:
- To locate the file, enter:
# smbd -b | grep CONFIGFILE CONFIGFILE: /etc/samba/smb.conf
The following table lists the most important idmap backends with links to their documentation, click the relevant Documentation
link for how to setup each idmap backend:
Back End Documentation Man Page rid
idmap config rid idmap_rid(8)
autorid
idmap config autorid idmap_autorid(8)
ad
idmap config ad idmap_ad(8)
hash
<Do not use> idmap_hash(8)
ldap
idmap_ldap(8)
nss
idmap_nss(8)
Add an additional ID mapping configuration for every trusted domain, unless you use the autorid
idmap backend (where this is optional). The ID ranges of the default (*
) domain and other domains configured in thesmb.conf
file must not overlap.
After selecting an idmap backend and configuring the smb.conf file, following the relevant wiki page for your chosen idmap backend, you should have a basic smb.conf file that will allow the computer to join the Active Directory domain. There are a multitude of other parameters that you can add to the smb.conf file, some will be relevant to your domain, others will not, please read the smb.conf manpage for your Samba version to find the available parameters. If in doubt, post a question to the samba mailing list. |
Mapping the Domain Administrator Account to the Local root
User
Samba enables you to map domain accounts to a local account. Use this feature to execute file operations on the domain member's file system as a different user than the account that requested the operation on the client.
There is no real reason to map the domain Administrator account to the local root account. You can use a member of the Domain Admins group wherever you would use the domain Administrator on Unix instead. |
Never map the domain Administrator account to the local root
account on a Samba AD DC, it is already mapped in idmap.ldb. Mapping Administrator to root, as shown below, on a DC will break AD.
You should only map the domain Administrator account to the local root account on a Unix domain member. Configuring the mapping allows the domain Administrator to execute file operations as root on the Unix domain member. When you map Administrator to the root account, you should not attempt to log onto a Unix domain member as Administrator. Only follow the method below to map Administrator to root . |
If, for any reason, you change the domain Administrator account name, you must use your new name for Administrator in the following instead of Administrator . |
To map the domain administrator to the local root
account:
- Add the following parameter to the
[global]
section of yoursmb.conf
file:
username map = /usr/local/samba/etc/user.map
- Create the
/usr/local/samba/etc/user.map
file with the following content:
!root = SAMDOM\Administrator
When using the ad
ID mapping back end, never set auidNumber
attribute for the domain Administrator account. If the account has the attribute set, the value will override the local UID0
of theroot
user on Samba AD DC's and thus the mapping fails.
For further details, see username map
parameter in the smb.conf(5)
man page.
Joining the Domain
- To join the host to an Active Directory (AD), enter:
# net ads join -U administrator Enter administrator's password: Passw0rd Using short domain name -- SAMDOM Joined 'M1' to dns domain 'samdom.example.com'
When you join a computer to an AD domain with net ads join , the computers forward dns record should be created (if not already existing), but, if your computer has a fixed ipaddress, you will have to create the reverse PTR record yourself. |
- To join the host to an NT4 domain, enter:
# net rpc join -U administrator Enter administrator's password: Passw0rd Joined domain SAMDOM.
Joining the Domain with samba-tool (>4.15.0 only)
Before Samba 4.15.0 , you could not join a Unix domain member using samba-tool domain join , this option was unsupported, did not work and would cause problems with your AD replication. You can only use samba-tool domain join if the Unix domain member has Samba >= 4.15.0 installed. |
- To join the host to an Active Directory (AD), enter:
# samba-tool domain join samdom.example.com MEMBER -U administrator
If you have problems joining the domain, check your configuration. For further help, see Troubleshooting Samba Domain Members.
Configuring the Name Service Switch
To enable the name service switch (NSS) library to make domain users and groups available to the local system:
- Append the
winbind
entry to the following databases in the/etc/nsswitch.conf
file:
passwd: files winbind group: files winbind
- Keep the
files
entry as first source for both databases. This enables NSS to look up domain users and groups from the/etc/passwd
and/etc/group
files before querying the Winbind service.
- Keep the
- Do not add the
winbind
entry to the NSSshadow
database. This can cause thewbinfo
utility fail.
- Do not add the
If there's a line containing an initgroups
directive, add[success=continue] winbind
, otherwise the NSS library will not ask winbindd for a user's additional group memberships. Do not add theinitgroups
line if it does not exist.
Do not use the same user names in the local /etc/passwd
file as in the domain.
Do not use local Unix names when changing file and directory ownership on Samba domain shares.
If you compiled Samba, add symbolic links from the libnss_winbind
library to the operating system's library path. For details, see libnss_winbind Links. If you used packages to install Samba, the link is usually created automatically.
Starting the Services
Start the following services to have a fully functioning Unix domain member:
- The
smbd
service
- The
nmbd
service
- The
winbindd
service
If you do not require Network Browsing, you do not need to start the nmbd
service on a Unix domain member.
The latest versions of Samba (from 4.11.0) now only use SMBv2 as the minimum client & server protocols. This means that anything that relies on SMBv1 will not work, unless you manually set client min protocol = NT1
andserver min protocol = NT1
insmb.conf
. Samba no longer recommends using SMBv1.
You must not start the samba
service on a domain member. This service is required only on Active Directory (AD) domain controllers (DC).
Samba does not provide System V init scripts, systemd
, upstart
, or service files for other init services.
- If you installed Samba using packages, use the script or service configuration file provided by the package to start Samba.
- If you built Samba, see your distribution's documentation for how to create a script or configuration to start services.
Testing the Winbindd Connectivity
Sending a Winbindd Ping
To verify if the Winbindd service is able to connect to Active Directory (AD) Domain Controllers (DC) or a primary domain controller (PDC), enter:
# wbinfo --ping-dc checking the NETLOGON for domain[SAMDOM] dc connection to "DC.SAMDOM.EXAMPLE.COM" succeeded
If the previous command fails, verify:
- That the
winbindd
service is running. - Your
smb.conf
file is set up correctly.
Using Domain Accounts and Groups in Operating System Commands
Looking up Domain Users and Groups
The libnss_winbind
library enables you to look up domain users and groups. For example:
- To look up the domain user
SAMDOM\demo01
:
# getent passwd SAMDOM\\demo01 SAMDOM\demo01:*:10000:10000:demo01:/home/demo01:/bin/bash
- To look up the domain group
Domain Users
:
# getent group "SAMDOM\\Domain Users" SAMDOM\domain users:x:10000:
Assigning File Permissions to Domain Users and Groups
The name service switch (NSS) library enables you to use domain user accounts and groups in commands. For example to set the owner of a file to the demo01
domain user and the group to the Domain Users
domain group, enter:
# chown "SAMDOM\\demo01:SAMDOM\\domain users" file.txt
Setting up Additional Services on the Domain Member
On a Samba domain member, you can additionally set up:
- File shares to act as a file server. For details, see Samba File Serving.
- Print services to act as a print server. For details, see Print Server Support.
- PAM authentication of domain users for local services. For details, see Authenticating Domain Users Using PAM.
Troubleshooting
For details, see Troubleshooting Samba Domain Members.