Powerful Open Source LDAP

From Port389

Contents

Samba & Fedora Directory Server Integration

Purpose?

This document is a rough draft intended on integrating Samba 3 with Fedora Directory Server (FDS).

NOTE: These instructions only apply to basic user and group management. If you use or plan to use Samba for computer management, you will be better off using the migration scripts from IDEALX - http://www.idealx.org/prj/samba/index.en.html

FDS Toolkit Project Announcement

(August 4,2007) A new project has been started to mitigate some of the shortcomings of IDEALX smbldap-tools with regards to FDS. This project allows you to manage posix, samba, aix, and computer accounts with command line tools very similar to IDEALX smbldap-tools, only better, with support for logging, password policies, etc. Development is currently in alpha however the command line portion is feature complete so testers and developers for the GUI portion are welcome. See the project page for more information. http://fdstools.sourceforge.net

What will you gain from this document?

By the end of this document you will have a fully working Samba PDC using FDS as its backend for storing Domain Administrators, Users, Guests, Computers.

At this time this document does not cover authentication, encryption implementations, or indexing (yet).

Requirements

From the requirements below this article will assume you have installed and are familiar with FDS (starting/stopping server/navigating/adding/deleting entries), Samba, and basic knowledge of Linux)

  • Fedora - instructions were written with Fedora Core 4 in mind but should apply to all versions
  • Packages needed :
    • openldap-servers (contains migration utilities used in this document)
    • fedora-ds (the directory server via yum install fedora-ds)
    • samba, samba-client, samba-common (samba server, also provides schema needed for storing samba information)
  • schema to ldif migration script (provided in this document used to convert provided schemas to an ldif format FDS understands)

FDS Setup

First off we need to provide FDS with a samba schema that it understands. Now lets break down how FDS implements extending schemas :

  • All schema files are in ldif format and loaded during server start
  • All schema’s are located in /opt/fedora-ds/slapd-<server>/config/schema
  • Filenames are sequential and loaded in order and 99user.ldif is always the last schema to be loaded.

For this document we are going to name our schema file 61samba.ldif. As stated above we need to provide FDS with a schema it understands which involves converting the provided /usr/share/doc/samba/LDAP/samba.schema to ldif format. Luckily, there is a utility provided 3rd party that will assist in doing this which can be found at http://directory.fedoraproject.org/download/ol-schema-migrate.pl

Use of this script is straight forward :

# perl ol-schema-migrate.pl -b /usr/share/doc/samba-*/LDAP/samba.schema > /etc/dirsrv/slapd-<server>/schema/61samba.ldif 

Once the ldif is in place restart the slapd service :

# service dirsrv restart

If you are still using Fedora DS 1.0.4 or earlier:

# perl ol-schema-migrate.pl -b /usr/share/doc/samba-*/LDAP/samba.schema > /opt/fedora-ds/slapd-<server>/config/schema/61samba.ldif 
# /opt/fedora-ds/slapd-<server>/restart-slapd

PAM Configuration

Chack if nss_ldap is installed with:

rpm -qa|grep nss_ldap

otherwise:

yum install nss_ldap

It is necessary to configure the server as somewhat of a client when doing some of the Samba operations below. Please refer to the following documentation in configuring your server to do ldap lookups through PAM. Howto:PAM

After configuring PAM, as explained here [1] you should have into /etc/ldap.conf:

uri ldap://hostname.example.com
host hostname.example.com
base dc=example,dc=com
binddn cn=Directory Manager
bindpw test123
port 389

without configuring ldap.conf, samba will not search posix accounts into ldap. Also, keep care to your dns settings, otherwise use

host 127.0.0.1

Samba Setup

Modify /etc/samba/smb.conf to have the following values (remember that YOURWORKGROUP string length < 14)

[global]
workgroup = YOURWORKGROUP
security = user
passdb backend = ldapsam:ldap://example.com
ldap admin dn = cn=Directory Manager
ldap suffix = dc=example,dc=com
ldap user suffix = ou=People
ldap machine suffix = ou=Computers
ldap group suffix = ou=Groups

log file = /var/log/%m.log
socket options = TCP_NODELAY SO_RCVBUF=8192 SO_SNDBUF=8192

os level = 33
domain logons = yes
domain master = yes
local master = yes
preferred master = yes

wins support = yes

logon home = \\%L\%u\profiles
logon path = \\%L\profiles\%u
logon drive = H:

template shell = /bin/false
winbind use default domain = no

[netlogon]
path = /var/lib/samba/netlogon
read only = yes
browsable = no

[profiles]
path = /var/lib/samba/profiles
read only = no
create mask = 0600
directory mask = 0700

[homes]
browsable = no
writable = yes

Test your Samba configuration for any problems :

# testparm
Load smb config files from /etc/samba/smb.conf
Processing section "[netlogon]"
Processing section "[profiles]"
Processing section "[homes]"
Loaded services file OK.
Server role: ROLE_DOMAIN_PDC

Create appropriate directories/permissions for the Samba shares defined in your configuration :

# mkdir -p /var/lib/samba
# mkdir /var/lib/samba/{netlogon,profiles}
# chown root:root -R /var/lib/samba
# chmod 0755 /var/lib/samba/netlogon
# chmod 1755 /var/lib/samba/profiles

Create a password for the ldap admin dn (the Directory Manager's Password) in Samba’s secret file:

# smbpasswd -w <ldap-admin-password>
Setting stored password for "cn=Directory Manager" in secrets.tdb

Populating FDS with PDC Entry

At this point you should have a Samba PDC and a properly configured FDS ready to take the appropriate Samba entries. Now we are going to provide an entry into FDS for your PDC.

First get the Samba SID for your PDC :

# net getlocalsid
SID for domain YOURWORKGROUP is: S-1-5-21-1803520230-1543781662-649387223
(your SID will vary)

Note that until now samba has never been started and it not should be running to get local SID.

Next create your Samba Domain ldif(/tmp/sambaDomainName.ldif) for entry, substituting your domain name and SID :

dn: sambaDomainName=<YOURWORKGROUP>,dc=example,dc=com
objectclass: sambaDomain
objectclass: sambaUnixIdPool
objectclass: top
sambaDomainName: <YOURWORKGROUP>
sambaSID: S-1-5-21-1803520230-1543781662-649387223
uidNumber: 550
gidNumber: 550

Populate your FDS with the above entry :

# /usr/lib/dirsrv/slapd-<server>/ldif2ldap "cn=Directory manager" password /tmp/sambaDomainName.ldif

Use /usr/lib64 instead of /usr/lib on x86_64 systems.

Or if you are still using Fedora DS 1.0.4 or earlier:

# /opt/fedora-ds/slapd-<server>/ldif2ldap "cn=Directory manager" password /tmp/sambaDomainName.ldif

Migrating Samba groups and populating FDS with Samba Users:

This is where the openldap migration scripts are going to come in handy. Lets modify the file /usr/share/openldap/migration/migrate_common.ph to apply our default domain and base.

Search for the following OrganizationalUnit :

$NAMINGCONTEXT{'group'}             = "ou=Group";

Default install of FDS will require this to be 'Groups', please change as follows :

$NAMINGCONTEXT{'group'}             = "ou=Groups";

The rest can be modified as seen below :

# Default DNS domain
$DEFAULT_MAIL_DOMAIN = "example.com";

# Default base
$DEFAULT_BASE = "dc=example,dc=com"; 

# turn this on to support more general object clases
# such as person. (not needed for our excerise but generally good idea
# to set to 1 – adam)
$EXTENDED_SCHEMA = 1;

Once complete we are now going to create our Samba Domain Groups. Open up a new file /tmp/sambaGroups and add the following :

Domain Admins:x:2512:
Domain Users:x:2513:
Domain Guests:x:2514:
Domain Computers:x:2515:
  • Note: These are your UNIX groups! They must exist on the Directory Server group list first! (if you do not have PAM setup)

Next convert /tmp/sambaGroups into an ldif to be imported into FDS :

# /usr/share/openldap/migration/migrate_group.pl /tmp/sambaGroups > /tmp/sambaGroups.ldif
# cat /tmp/sambaGroups.ldif

dn: cn=Domain Admins,ou=Groups,dc=example,dc=com
objectClass: posixGroup
objectClass: top
cn: Domain Admins
userPassword: {crypt}x
gidNumber: 2512

dn: cn=Domain Users,ou=Groups,dc=example,dc=com
objectClass: posixGroup
objectClass: top
cn: Domain Users
userPassword: {crypt}x
gidNumber: 2513

dn: cn=Domain Guests,ou=Groups,dc=example,dc=com
objectClass: posixGroup
objectClass: top
cn: Domain Guests
userPassword: {crypt}x
gidNumber: 2514

dn: cn=Domain Computers,ou=Groups,dc=example,dc=com
objectClass: posixGroup
objectClass: top
cn: Domain Computers
userPassword: {crypt}x
gidNumber: 2515

Now import /tmp/sambaGroups.ldif into FDS :

# /usr/lib/dirsrv/slapd-<server>/ldif2ldap "cn=Directory manager" password /tmp/sambaGroups.ldif

Use /usr/lib64 instead of /usr/lib on x86_64 systems.

If you are still using Fedora DS 1.0.4, do this instead:

# /opt/fedora-ds/slapd-<server>/ldif2ldap "cn=Directory manager" password /tmp/sambaGroups.ldif

Map the Samba groups to the Linux groups :

# net groupmap add rid=2512 ntgroup='Domain Admins'  unixgroup='Domain Admins'
# net groupmap add rid=2513 ntgroup='Domain Users' unixgroup='Domain Users'
# net groupmap add rid=2514 ntgroup='Domain Guests' unixgroup='Domain Guests'
# net groupmap add rid=2515 ntgroup='Domain Computers' unixgroup='Domain Computers'

Verify :

# net groupmap list

Lets create a Samba Administrator account with an RID of 500. Create a file /tmp/sambaAdmin with the following :

Administrator:x:0:0:Samba Admin:/root:/bin/bash

Migrate /tmp/sambaAdmin to the formatted ldif and import into FDS :

# /usr/share/openldap/migration/migrate_passwd.pl /tmp/sambaAdmin > /tmp/sambaAdmin.ldif
# /usr/lib/dirsrv/slapd-<server>/ldif2ldap "cn=Directory manager" password /tmp/sambaAdmin.ldif

Use /usr/lib64 instead of /usr/lib on x86_64 systems.

If you are still using Fedora DS 1.0.4, do this instead:

# /opt/fedora-ds/slapd-<server>/ldif2ldap "cn=Directory manager" password /tmp/sambaAdmin.ldif

Create a Samba Administrator account and modify the account to use the correct Samba SID :

# smbpasswd -a Administrator -w<ldap-admin-password>
# pdbedit -U $( net getlocalsid | sed 's/SID for domain YOURWORKGROUP is: //' )-500 -u Administrator -r

Finally start the Samba service and map an existing user entry to a Samba user :

# service smb start; chkconfig smb on
# smbpasswd -a testuser

Compare accounts :

# ldapsearch -x -Z '(uid=testuser)'
dn: uid=testuser,ou=People,dc=example,dc=com
uid: testuser
cn: Test User SMB
objectClass: account
objectClass: posixAccount
objectClass: top
objectClass: shadowAccount
objectClass: sambaSamAccount
shadowLastChange: 12971
shadowMax: 99999
shadowWarning: 7
loginShell: /bin/bash
uidNumber: 500
gidNumber: 500
homeDirectory: /home/testuser
gecos: Test User SMB
sambaSID: S-1-5-21-1803520230-1543781662-649387223-2000
sambaPrimaryGroupSID: S-1-5-21-1803520230-1543781662-649387223-2001
displayName: Test User SMB
sambaPwdCanChange: 1120754404
sambaPwdMustChange: 2147483647
sambaLMPassword: CFA95C51F11AB11DC2265B23734E0DAC
sambaNTPassword: B2D88A4A9B0DAEE170E75F67D54918F6
sambaPasswordHistory: 00000000000000000000000000000000000000000000000000000000
00000000
sambaPwdLastSet: 1120754404
sambaAcctFlags: [U          ]

# pdbedit -v -u testuser
Unix username:        testuser
NT username:          testuser
Account Flags:        [U          ]
User SID:             S-1-5-21-1803520230-1543781662-649387223-2000
Primary Group SID:    S-1-5-21-1803520230-1543781662-649387223-2001
Full Name:            Test User SMB
Home Directory:       \\directory\%u\profiles
HomeDir Drive:        H:
Logon Script:
Profile Path:         \\directory\profiles\%u
Domain:               YOURWORKGROUP
Account desc:
Workstations:
Munged dial:
Logon time:           0
Logoff time:          Mon, 18 Jan 2038 22:14:07 GMT
Kickoff time:         Mon, 18 Jan 2038 22:14:07 GMT
Password last set:    Thu, 07 Jul 2005 12:40:04 GMT
Password can change:  Thu, 07 Jul 2005 12:40:04 GMT
Password must change: Mon, 18 Jan 2038 22:14:07 GMT
Last bad password   : 0
Bad password count  : 0
Logon hours         : FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF\


In the above output, two Samba password hashes are shown. However, as password-cracking programs can be run on these hashes, you would not to give any access to them, except by the samba service. Therefore, you can limit access to these or any other attributes using Access Control Instructions (ACIs). One way to do this is to open the FDS Console, navigate to the directory, right click on the parent which is providing the access, choose "Set Access Permissions", select the ACI to be edited, press the Edit button, click the Targets tab, scroll to find the attribute(s), check/uncheck as desired, and press OK when done. In the above example, the access is anonymous. So the likely ACI for this situation is "Enable anonymous access". Ideally, you would not allow any anonymous access, and instead would only allow access to authenticated users for which you have precisely defined the ACIs for the attributes that user needs to read and write.

Links

Fedora Directory Server Toolkit - http://fdstools.sourceforge.net
Samba - http://www.samba.org
Samba3 LDAP HowTo - http://samba.idealx.org/dist/samba3-ldap-howto.pdf
Another Samba/LDAP How To - http://web.vcs.u52.k12.me.us/linux/smbldap/