Date Created: Wed 22-Sep-2010

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    Setting up Active Directory and Samba to accommodate ClearCase Interop between Windows and Linux RedHat (RHEL5)

    This document is part of a complete set-up of installing and configuring a Windows interop environment with Linux on RHEL 5. There is not another set of detailed documents anywhere on the internet out side of our site. If this article does not contain enough information, search the rest of this site: and you will find many mini articles on Linux and Windows interop and MVFS/Samba support. Also feel free to contact me if you require ClearCase consulting and support.

    Make your windows 2003 server a PDC and create a domain. In this example I use win2003.screv.local

    The windows host will be hs001.win2003.screv.local

    ClearCase Active Directory pre-requisites

    The approach for this ClearCase setup is to have all users, groups and computers reside in a single domain. Below are some immediate reading points to explain the prerequisite tables.

    It is recommended that all users of the Windows system must have an equivalent Linux account with the same username and same case otherwise extra work will be required to maintain synchronisation by adding configuration data to the Samba user map, which will get out of date. The case and spelling must be identical between the operating systems for both the usernames and primary groups. Avoid names that have spaces or special characters that are not supported on the different operating systems.

    It is mandatory that the primary group on Linux/UNIX and Windows match.

    Rational strongly recommends that you limit your group name to 8 characters or less AND recommends that group names do not contain spaces. This is due to the fact that ClearCase on Linux/UNIX is compiled for POSIX compliance. Rational support has seen instances where groups such as “Domain Users” or groups containing more than 8 characters such as “clearcase_users” will work for a period of time; however, once these groups stop working due to group name truncation during a look-up, it is impossible to resolve the issue.

    When the Domain Security Mode is utilized, all of the user, group and machine accounts are stored on a Windows domain controller. This central repository is responsible for machine and user authentication.

    If domain authentication is used, the Samba machine must be added to the Windows domain.

    When you have Domain security enabled, the Samba server is required to have a computer account in the domain called “domain security trust account”. Once the Samba server is made a “domain member server”, all authentication requests for access to shares/services on the Samba server are passed to a Windows domain controller where the user is validated.
    A UNIX/Linux account is required for each user in order to assign a UID once the account has been authenticated by a Windows domain controller. For example, if the user’s login account to the Windows domain is DOMAIN/stever, there must be a UNIX/Linux account stever for this user.

    Security groups

    The following active directory security groups are to be created all within the same OU in Active Directory

    User groupDescription
    ccadmClearCase administrator group for administrators and albd account
    ccusr1, ccusr2, ccuser3, ccusr4,ccusr5ClearCase user groups.

    Only ccusr 1 is required for now. The other user groups can be added later on if security to restrict access to VOBs is required
    ccsysfor samba user account to join a domain


    The following user accounts and group memberships are required.
    AccountPassword to be setGroup membership requiredDescription
    cc_albdPassword123ccadmClearCase albd account that must be a member of ccadm
    vobadmnPassword123ccadm, ccusr1VOB administrator account that is a member of ccadm, ccusr
    Password123ccsysAccount for the Linux server to join a domain
    All ClearCase users accountsAs requiredccusr1User accounts for each users using ClearCase on the server

    In order to use security = domain, the Samba server must be added to the Windows domain as a “domain member server”.

    On the Windows domain controller, add a machine account for the Samba server.

    Server Active Directory membership

    The Windows ClearCase server and ClearCase Linux are to be members of the same domain of active directory as all the ClearCase groups.

    Security polices required

    The following user rights assignments policies are required to be set on the Windows ClearCase server to allow the ClearCase albd service to run and for users to log onto the server.

    AccountGroup membership requiredDescription
    Log on as serviceccadmAllows ClearCase albd account to run the ALBD service
    Allow log on locallyccadm, ccusr1Allows all users and administrators of ClearCase to log onto the server
    Allow log on through Terminal Servicesccadm, ccusr1Account for the Linux server to join a domain

    Setting up Active Directory

    Add all the users and groups as per the tables above

    Adding the Linux machine as a domain account

    You will have to edit /etc/hosts on your Linux box to resolve clearcase as the host name of Linux box and <windows_hostname>.win2003.screv.local as hostname of windows box


    Samba: smb.conf

    # This is the main Samba configuration file. You should read the
    # smb.conf(5) manual page in order to understand the options listed
    # here. Samba has a huge number of configurable options (perhaps too
    # many!) most of which are not shown in this example
    # For a step to step guide on installing, configuring and using samba,
    # read the Samba-HOWTO-Collection. This may be obtained from:
    # Many working examples of smb.conf files can be found in the
    # Samba-Guide which is generated daily and can be downloaded from:
    # Any line which starts with a ; (semi-colon) or a # (hash)
    # is a comment and is ignored. In this example we will use a #
    # for commentry and a ; for parts of the config file that you
    # may wish to enable
    # NOTE: Whenever you modify this file you should run the command "testparm"
    # to check that you have not made any basic syntactic errors.
    #======================= Global Settings =====================================
    netbios name = clearcase
    # workgroup = NT-Domain-Name or Workgroup-Name, eg: MIDEARTH
    #workgroup = win2003.screv.local
    workgroup = win2003
    # server string is the equivalent of the NT Description field
    server string = ClearCase Linux Server

    # Security mode. Defines in which mode Samba will operate. Possible
    # values are share, user, server, domain and ads. Most people will want
    # user level security. See the Samba-HOWTO-Collection for details.
    security = domain

    # This option is important for security. It allows you to restrict
    # connections to machines which are on your local network. The
    # following example restricts access to two C class networks and
    # the "loopback" interface. For more examples of the syntax see
    # the smb.conf man page
    ; hosts allow = 192.168.1. 192.168.2. 127.

    # If you want to automatically load your printer list rather
    # than setting them up individually then you'll need this
    ; load printers = yes

    # you may wish to override the location of the printcap file
    ; printcap name = /etc/printcap

    # on SystemV system setting printcap name to lpstat should allow
    # you to automatically obtain a printer list from the SystemV spool
    # system
    ; printcap name = lpstat

    # It should not be necessary to specify the print system type unless
    # it is non-standard. Currently supported print systems include:
    # bsd, cups, sysv, plp, lprng, aix, hpux, qnx
    ; printing = cups

    # This option tells cups that the data has already been rasterized
    cups options = raw

    # Uncomment this if you want a guest account, you must add this to /etc/passwd
    # otherwise the user "nobody" is used
    ; guest account = pcguest

    # this tells Samba to use a separate log file for each machine
    # that connects
    log file = /var/log/samba/%m.log

    # Put a capping on the size of the log files (in Kb).
    max log size = 50

    # Use password server option only with security = server
    # The argument list may include:
    # password server = My_PDC_Name [My_BDC_Name] [My_Next_BDC_Name]
    # or to auto-locate the domain controller/s
    password server = *
    ;password server = hs001.win2003.screv.local

    # Use the realm option only with security = ads
    # Specifies the Active Directory realm the host is part of
    realm = win2003.screv.local

    # Backend to store user information in. New installations should
    # use either tdbsam or ldapsam. smbpasswd is available for backwards
    # compatibility. tdbsam requires no further configuration.
    ; passdb backend = tdbsam

    # Using the following line enables you to customise your configuration
    # on a per machine basis. The %m gets replaced with the netbios name
    # of the machine that is connecting.
    # Note: Consider carefully the location in the configuration file of
    # this line. The included file is read at that point.
    ; include = /usr/local/samba/lib/smb.conf.%m

    # Configure Samba to use multiple interfaces
    # If you have multiple network interfaces then you must list them
    # here. See the man page for details.
    ; interfaces =

    # Browser Control Options:
    # set local master to no if you don't want Samba to become a master
    # browser on your network. Otherwise the normal election rules apply
    ; local master = no

    # OS Level determines the precedence of this server in master browser
    # elections. The default value should be reasonable
    ; os level = 33

    # Domain Master specifies Samba to be the Domain Master Browser. This
    # allows Samba to collate browse lists between subnets. Don't use this
    # if you already have a Windows NT domain controller doing this job
    ; domain master = yes

    # Preferred Master causes Samba to force a local browser election on startup
    # and gives it a slightly higher chance of winning the election
    ; preferred master = yes

    # Enable this if you want Samba to be a domain logon server for
    # Windows95 workstations.
    ; domain logons = yes

    # if you enable domain logons then you may want a per-machine or
    # per user logon script
    # run a specific logon batch file per workstation (machine)
    ; logon script = %m.bat
    # run a specific logon batch file per username
    ; logon script = %U.bat

    # Where to store roving profiles (only for Win95 and WinNT)
    # %L substitutes for this servers netbios name, %U is username
    # You must uncomment the [Profiles] share below
    ; logon path = \\%L\Profiles\%U

    # Windows Internet Name Serving Support Section:
    # WINS Support - Tells the NMBD component of Samba to enable it's WINS Server
    ; wins support = yes

    # WINS Server - Tells the NMBD components of Samba to be a WINS Client
    # Note: Samba can be either a WINS Server, or a WINS Client, but NOT both
    ; wins server = w.x.y.z

    # WINS Proxy - Tells Samba to answer name resolution queries on
    # behalf of a non WINS capable client, for this to work there must be
    # at least one WINS Server on the network. The default is NO.
    ; wins proxy = yes

    # DNS Proxy - tells Samba whether or not to try to resolve NetBIOS names
    # via DNS nslookups. The default is NO.
    dns proxy = no

    # These scripts are used on a domain controller or stand-alone
    # machine to add or delete corresponding unix accounts
    ; add user script = /usr/sbin/useradd %u
    ; add group script = /usr/sbin/groupadd %g
    ; add machine script = /usr/sbin/adduser -n -g machines -c Machine -d /dev/null -s /bin/false %u
    ; delete user script = /usr/sbin/userdel %u
    ; delete user from group script = /usr/sbin/deluser %u %g
    ; delete group script = /usr/sbin/groupdel %g

    #============================ Share Definitions ==============================
    comment = Home Directories
    browseable = no
    writeable = yes

    # Un-comment the following and create the netlogon directory for Domain Logons
    ; [netlogon]
    ; comment = Network Logon Service
    ; path = /usr/local/samba/lib/netlogon
    ; guest ok = yes
    ; writable = no
    ; share modes = no

    # Un-comment the following to provide a specific roving profile share
    # the default is to use the user's home directory
    ; path = /usr/local/samba/profiles
    ; browseable = no
    ; guest ok = yes

    # NOTE: If you have a BSD-style print system there is no need to
    # specifically define each individual printer
    comment = All Printers
    path = /usr/spool/samba
    browseable = no
    # Set public = yes to allow user 'guest account' to print
    ; guest ok = no
    ; writeable = no
    printable = yes

    # This one is useful for people to share files
    comment = Temporary file space
    path = /tmp
    writeable = yes
    guest ok = yes
    public = yes
    browseable = yes

    # A publicly accessible directory, but read only, except for people in
    # the "staff" group
    ; comment = Public Stuff
    ; path = /home/samba
    ; public = yes
    ; writable = yes
    ; printable = no
    ; write list = @staff

    # Other examples.
    # A private printer, usable only by fred. Spool data will be placed in fred's
    # home directory. Note that fred must have write access to the spool directory,
    # wherever it is.
    ; comment = Fred's Printer
    ; valid users = fred
    ; path = /homes/fred
    ; printer = freds_printer
    ; public = no
    ; writable = no
    ; printable = yes

    # A private directory, usable only by fred. Note that fred requires write
    # access to the directory.
    ; comment = Fred's Service
    ; path = /usr/somewhere/private
    ; valid users = fred
    ; public = no
    ; writable = yes
    ; printable = no

    # a service which has a different directory for each machine that connects
    # this allows you to tailor configurations to incoming machines. You could
    # also use the %U option to tailor it by user name.
    # The %m gets replaced with the machine name that is connecting.
    ; comment = PC Directories
    ; path = /usr/pc/%m
    ; public = no
    ; writable = yes

    # A publicly accessible directory, read/write to all users. Note that all files
    # created in the directory by users will be owned by the default user, so
    # any user with access can delete any other user's files. Obviously this
    # directory must be writable by the default user. Another user could of course
    # be specified, in which case all files would be owned by that user instead.
    ; path = /usr/somewhere/else/public
    ; public = yes
    ; only guest = yes
    ; writable = yes
    ; printable = no

    # The following two entries demonstrate how to share a directory so that two
    # users can place files there that will be owned by the specific users. In this
    # setup, the directory should be writable by both users and should have the
    # sticky bit set on it to prevent abuse. Obviously this could be extended to
    # as many users as required.
    ; comment = Mary's and Fred's stuff
    ; path = /usr/somewhere/shared
    ; valid users = mary fred
    ; public = no
    ; writable = yes
    ; printable = no
    ; create mask = 0765
    path = /vobstore01/
    guest ok = yes
    ; guest only = no
    writeable = yes
    ; printable = no
    ; browseable = yes

    Join the domain:

    net rpc join -U samba

    You will be prompted for a password, and you will be able to access samba resources, requiring authentication

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