Chapter 15. A Collection of Useful Tidbits
Prev | Part III. Reference Section | Next

## Chapter 15. A Collection of Useful Tidbits

Information presented here is considered to be either basic or well-known material that is informative yet helpful. Over the years, I have observed an interesting behavior. There is an expectation that the process for joining a Windows client to a Samba-controlled Windows domain may somehow involve steps different from doing so with Windows NT4 or a Windows ADS domain. Be assured that the steps are identical, as shown in the example given below.

## Joining a Domain: Windows 200x/XP Professional

Microsoft Windows NT/200x/XP Professional platforms can participate in Domain Security. This section steps through the process for making a Windows 200x/XP Professional machine a member of a Domain Security environment. It should be noted that this process is identical when joining a domain that is controlled by Windows NT4/200x as well as a Samba PDC.

Procedure 15.1. Steps to Join a Domain

1. Click Start.

2. Right-click My Computer, and then select Properties.

3. The opening panel is the same one that can be reached by clicking System on the Control Panel. See ???.

   Figure 15.1. The General Panel.

4. Click the Computer Name tab. This panel shows the Computer Description, the Full computer name, and the Workgroup or Domain name.

   Clicking the Network ID button launches the configuration wizard. Do not use this with Samba-3. If you wish to change the computer name, or join or leave the domain, click the Change button. See ???.

   Figure 15.2. The Computer Name Panel.

5. Click on Change. This panel shows that our example machine (TEMPTATION) is in a workgroup called WORKGROUP. We join the domain called MIDEARTH. See ???.

   Figure 15.3. The Computer Name Changes Panel

6. Enter the name MIDEARTH in the field below the Domain radio button.

   This panel shows that our example machine (TEMPTATION) is set to join the domain called MIDEARTH. See ???.

   Figure 15.4. The Computer Name Changes Panel Domain MIDEARTH

7. Now click the OK button. A dialog box should appear to allow you to provide the credentials (username and password) of a domain administrative account that has the rights to add machines to the domain.

   Enter the name “root” and the root password from your Samba-3 server. See ???.

   Figure 15.5. Computer Name Changes User name and Password Panel

8. Click OK.

   The “Welcome to the MIDEARTH domain” dialog box should appear. At this point, the machine must be rebooted. Joining the domain is now complete.

The screen capture shown in ??? has a button labeled More.... This button opens a panel in which you can set (or change) the Primary DNS suffix of the computer. This is a parameter that mainly affects members of Microsoft Active Directory. Active Directory is heavily oriented around the DNS namespace.

Where NetBIOS technology uses WINS as well as UDP broadcast as key mechanisms for name resolution, Active Directory servers register their services with the Microsoft Dynamic DNS server. Windows clients must be able to query the correct DNS server to find the services (like which machines are domain controllers or which machines have the Netlogon service running).

The default setting of the Primary DNS suffix is the Active Directory domain name. When you change the Primary DNS suffix, this does not affect domain membership, but it can break network browsing and the ability to resolve your computer name to a valid IP address.

The Primary DNS suffix parameter principally affects MS Windows clients that are members of an Active Directory domain. Where the client is a member of a Samba domain, it is preferable to leave this field blank.

According to Microsoft documentation, “If this computer belongs to a group with `Group Policy` enabled on `Primary DNS suffice of this computer`, the string specified in the Group Policy is used as the primary DNS suffix and you might need to restart your computer to view the correct setting. The local setting is used only if Group Policy is disabled or unspecified.”

## Samba System File Location

One of the frustrations expressed by subscribers to the Samba mailing lists revolves around the choice of where the default Samba Team build and installation process locates its Samba files. The location, chosen in the early 1990s, for the default installation is in the `/usr/local/samba` directory. This is a perfectly reasonable location, particularly given all the other Open Source software that installs into the `/usr/local` subdirectories.

Several UNIX vendors, and Linux vendors in particular, elected to locate the Samba files in a location other than the Samba Team default.

Linux vendors, working in conjunction with the Free Standards Group (FSG), Linux Standards Base (LSB), and File Hierarchy System (FHS), have elected to locate the configuration files under the `/etc/samba` directory, common binary files (those used by users) in the `/usr/bin` directory, and the administrative files (daemons) in the `/usr/sbin` directory. Support files for the Samba Web Admin Tool (SWAT) are located under the `/usr/share` directory, either in `/usr/share/samba/swat` or in `/usr/share/swat`. There are additional support files for `smbd` in the `/usr/lib/samba` directory tree. The files located there include the dynamically loadable modules for the passdb backend as well as for the VFS modules.

Samba creates runtime control files and generates log files. The runtime control files (tdb and dat files) are stored in the `/var/lib/samba` directory. Log files are created in `/var/log/samba.`

When Samba is built and installed using the default Samba Team process, all files are located under the `/usr/local/samba` directory tree. This makes it simple to find the files that Samba owns.

One way to find the Samba files that are installed on your UNIX/Linux system is to search for the location of all files called `smbd`. Here is an example:

    root#  find / -name smbd -print

You can find the location of the configuration files by running:

    root#  /path-to-binary-file/smbd -b | more
    ...
    Paths:
       SBINDIR: /usr/sbin
       BINDIR: /usr/bin
       SWATDIR: /usr/share/samba/swat
       CONFIGFILE: /etc/samba/smb.conf
       LOGFILEBASE: /var/log/samba
       LMHOSTSFILE: /etc/samba/lmhosts
       LIBDIR: /usr/lib/samba
       SHLIBEXT: so
       LOCKDIR: /var/lib/samba
       PIDDIR: /var/run/samba
       SMB_PASSWD_FILE: /etc/samba/smbpasswd
       PRIVATE_DIR: /etc/samba
    ...

If you wish to locate the Samba version, just run:

    root#  /path-to-binary-file/smbd -V
    Version 3.0.20-SUSE

Many people have been caught by installation of Samba using the default Samba Team process when it was already installed by the platform vendor's method. If your platform uses RPM format packages, you can check to see if Samba is installed by executing:

    root#  rpm -qa | grep samba
    samba3-pdb-3.0.20-1
    samba3-vscan-0.3.6-0
    samba3-winbind-3.0.20-1
    samba3-3.0.20-1
    samba3-python-3.0.20-1
    samba3-utils-3.0.20-1
    samba3-doc-3.0.20-1
    samba3-client-3.0.20-1
    samba3-cifsmount-3.0.20-1

The package names, of course, vary according to how the vendor, or the binary package builder, prepared them.

## Starting Samba

Samba essentially consists of two or three daemons. A daemon is a UNIX application that runs in the background and provides services. An example of a service is the Apache Web server for which the daemon is called `httpd`. In the case of Samba, there are three daemons, two of which are needed as a minimum.

The Samba server is made up of the following daemons:

Example 15.1. A Useful Samba Control Script for SUSE Linux

    #!/bin/bash
    #
    # Script to start/stop samba
    # Locate this in /sbin as a file called 'samba'

    RCD=/etc/rc.d

    if [ z$1 == 'z' ]; then
            echo $0 - No arguments given; must be start or stop.
            exit
    fi

    if [ $1 == 'start' ]; then
            ${RCD}/nmb start
            ${RCD}/smb start
            ${RCD}/winbind start

    fi
    if [ $1 == 'stop' ]; then
            ${RCD}/smb stop
            ${RCD}/winbind stop
            ${RCD}/nmb stop
    fi
    if [ $1 == 'restart' ]; then
            ${RCD}/smb stop
            ${RCD}/winbind stop
            ${RCD}/nmb stop
            sleep 5
            ${RCD}/nmb start
            ${RCD}/smb start
            ${RCD}/winbind start
    fi
    exit 0

nmbd

  This daemon handles all name registration and resolution requests. It is the primary vehicle involved in network browsing. It handles all UDP-based protocols. The `nmbd` daemon should be the first command started as part of the Samba startup process.

smbd

  This daemon handles all TCP/IP-based connection services for file- and print-based operations. It also manages local authentication. It should be started immediately following the startup of `nmbd`.

winbindd

  This daemon should be started when Samba is a member of a Windows NT4 or ADS domain. It is also needed when Samba has trust relationships with another domain. The `winbindd` daemon will check the `smb.conf` file for the presence of the `idmap uid` and `idmap gid` parameters. If they are not found, `winbindd` bails out and refuses to start.

When Samba has been packaged by an operating system vendor, the startup process is typically a custom feature of its integration into the platform as a whole. Please refer to your operating system platform administration manuals for specific information pertaining to correct management of Samba startup.

Example 15.2. A Sample Samba Control Script for Red Hat Linux

    #!/bin/sh
    #
    # chkconfig: 345 81 35
    # description: Starts and stops the Samba smbd and nmbd daemons \
    #              used to provide SMB network services.

    # Source function library.
    . /etc/rc.d/init.d/functions
    # Source networking configuration.
    . /etc/sysconfig/network
    # Check that networking is up.
    [ ${NETWORKING} = "no" ] && exit 0
    CONFIG=/etc/samba/smb.conf
    # Check that smb.conf exists.
    [ -f $CONFIG ] || exit 0

    # See how we were called.
    case "$1" in
      start)
            echo -n "Starting SMB services: "
            daemon smbd -D; daemon nmbd -D; echo;
            touch /var/lock/subsys/smb
            ;;
      stop)
            echo -n "Shutting down SMB services: "
            smbdpids=`ps guax | grep smbd | grep -v grep | awk '{print $2}'`
            for pid in $smbdpids; do
                    kill -TERM $pid
            done
            killproc nmbd -TERM; rm -f /var/lock/subsys/smb
            echo ""
            ;;
      status)
            status smbd; status nmbd;
            ;;
      restart)
            echo -n "Restarting SMB services: "
            $0 stop; $0 start;
            echo "done."
            ;;
      *)
            echo "Usage: smb {start|stop|restart|status}"
            exit 1
    esac

SUSE Linux implements individual control over each Samba daemon. A Samba control script that can be conveniently executed from the command line is shown in ???. This can be located in the directory `/sbin` in a file called `samba`. This type of control script should be owned by user root and group root, and set so that only root can execute it.

A sample startup script for a Red Hat Linux system is shown in ???. This file could be located in the directory `/etc/rc.d` and can be called `samba`. A similar startup script is required to control `winbind`. If you want to find more information regarding startup scripts please refer to the packaging section of the Samba source code distribution tarball. The packaging files for each platform include a startup control file.

## DNS Configuration Files

The following files are common to all DNS server configurations. Rather than repeat them multiple times, they are presented here for general reference.

### The Forward Zone File for the Loopback Adaptor

The forward zone file for the loopback address never changes. An example file is shown in ???. All traffic destined for an IP address that is hosted on a physical interface on the machine itself is routed to the loopback adaptor. This is a fundamental design feature of the TCP/IP protocol implementation. The loopback adaptor is called `localhost`.

Example 15.3. DNS Localhost Forward Zone File: `/var/lib/named/localhost.zone`

    $TTL 1W
    @		IN SOA	@   root (
    				42		; serial
    				2D		; refresh
    				4H		; retry
    				6W		; expiry
    				1W )		; minimum

    		IN NS		@
    		IN A		127.0.0.1

### The Reverse Zone File for the Loopback Adaptor

The reverse zone file for the loopback address as shown in ??? is necessary so that references to the address `127.0.0.1` can be resolved to the correct name of the interface.

Example 15.4. DNS Localhost Reverse Zone File: `/var/lib/named/127.0.0.zone`

    $TTL 1W
    @		IN SOA		localhost.   root.localhost. (
    				42		; serial
    				2D		; refresh
    				4H		; retry
    				6W		; expiry
    				1W )		; minimum

    		IN NS		localhost.
    1		IN PTR		localhost.

Example 15.5. DNS Root Name Server Hint File: `/var/lib/named/root.hint`

    ; This file is made available by InterNIC under anonymous FTP as
    ;       file                /domain/named.root
    ;       on server           FTP.INTERNIC.NET
    ; last update: Nov 5, 2002. Related version of root zone: 2002110501
    ; formerly NS.INTERNIC.NET
    .                        3600000  IN  NS    A.ROOT-SERVERS.NET.
    A.ROOT-SERVERS.NET.      3600000      A     198.41.0.4
    ; formerly NS1.ISI.EDU
    .                        3600000      NS    B.ROOT-SERVERS.NET.
    B.ROOT-SERVERS.NET.      3600000      A     128.9.0.107
    ; formerly C.PSI.NET
    .                        3600000      NS    C.ROOT-SERVERS.NET.
    C.ROOT-SERVERS.NET.      3600000      A     192.33.4.12
    ; formerly TERP.UMD.EDU
    .                        3600000      NS    D.ROOT-SERVERS.NET.
    D.ROOT-SERVERS.NET.      3600000      A     128.8.10.90
    ; formerly NS.NASA.GOV
    .                        3600000      NS    E.ROOT-SERVERS.NET.
    E.ROOT-SERVERS.NET.      3600000      A     192.203.230.10
    ; formerly NS.ISC.ORG
    .                        3600000      NS    F.ROOT-SERVERS.NET.
    F.ROOT-SERVERS.NET.      3600000      A     192.5.5.241
    ; formerly NS.NIC.DDN.MIL
    .                        3600000      NS    G.ROOT-SERVERS.NET.
    G.ROOT-SERVERS.NET.      3600000      A     192.112.36.4
    ; formerly AOS.ARL.ARMY.MIL
    .                        3600000      NS    H.ROOT-SERVERS.NET.
    H.ROOT-SERVERS.NET.      3600000      A     128.63.2.53
    ; formerly NIC.NORDU.NET
    .                        3600000      NS    I.ROOT-SERVERS.NET.
    I.ROOT-SERVERS.NET.      3600000      A     192.36.148.17
    ; operated by VeriSign, Inc.
    .                        3600000      NS    J.ROOT-SERVERS.NET.
    J.ROOT-SERVERS.NET.      3600000      A     192.58.128.30
    ; housed in LINX, operated by RIPE NCC
    .                        3600000      NS    K.ROOT-SERVERS.NET.
    K.ROOT-SERVERS.NET.      3600000      A     193.0.14.129
    ; operated by IANA
    .                        3600000      NS    L.ROOT-SERVERS.NET.
    L.ROOT-SERVERS.NET.      3600000      A     198.32.64.12
    ; housed in Japan, operated by WIDE
    .                        3600000      NS    M.ROOT-SERVERS.NET.
    M.ROOT-SERVERS.NET.      3600000      A     202.12.27.33
    ; End of File

### DNS Root Server Hint File

The content of the root hints file as shown in ??? changes slowly over time. Periodically this file should be updated from the source shown. Because of its size, this file is located at the end of this chapter.

## Alternative LDAP Database Initialization

The following procedure may be used as an alternative means of configuring the initial LDAP database. Many administrators prefer to have greater control over how system files get configured.

### Initialization of the LDAP Database

The first step to get the LDAP server ready for action is to create the LDIF file from which the LDAP database will be preloaded. This is necessary to create the containers into which the user, group, and other accounts are written. It is also necessary to preload the well-known Windows NT Domain Groups, as they must have the correct SID so that they can be recognized as special NT Groups by the MS Windows clients.

Procedure 15.2. LDAP Directory Pre-Load Steps

1. Create a directory in which to store the files you use to generate the LDAP LDIF file for your system. Execute the following:

       root#  mkdir /etc/openldap/SambaInit
       root#  chown root:root /etc/openldap/SambaInit
       root#  chmod 700 /etc/openldap/SambaInit

2. Install the files shown in ???, ???, and ??? into the directory `/etc/openldap/SambaInit/SMBLDAP-ldif-preconfig.sh.` These three files are, respectively, parts A, B, and C of the `SMBLDAP-ldif-preconfig.sh` file.

3. Install the files shown in ??? and ??? into the directory `/etc/openldap/SambaInit/.` These two files are parts A and B, respectively, of the `init-ldif.pat` file.

4. Change to the `/etc/openldap/SambaInit` directory. Execute the following:

       root#  sh SMBLDAP-ldif-preconfig.sh

       How do you wish to refer to your organization?
       Suggestions:
               Black Tire Company, Inc.
               Cat With Hat Ltd.
       How would you like your organization name to appear?
       Your organization name is: My Organization
       Enter a new name is this is not what you want, press Enter to Continue.
       Name [My Organization]: Abmas Inc.

       Samba Config File Location [/etc/samba/smb.conf]:
       Enter a new full path or press Enter to continue.
       Samba Config File Location [/etc/samba/smb.conf]:
       Domain Name: MEGANET2
       Domain SID: S-1-5-21-3504140859-1010554828-2431957765

       The name of your Internet domain is now needed in a special format
       as follows, if your domain name is mydomain.org, what we need is
       the information in the form of:
               Domain ID: mydomain
               Top level: org
       If your fully qualified hostname is: snoopy.bazaar.garagesale.net
       where "snoopy" is the name of the machine,
       Then the information needed is:
               Domain ID: garagesale
               Top Level: net

       Found the following domain name: abmas.biz
       I think the bit we are looking for might be: abmas
       Enter the domain name or press Enter to continue:

       The top level organization name I will use is: biz
       Enter the top level org name or press Enter to continue:
       root#

   This creates a file called `MEGANET2.ldif`.

5. It is now time to preload the LDAP database with the following command:

       root#  slapadd -v -l MEGANET2.ldif
       added: "dc=abmas,dc=biz" (00000001)
       added: "cn=Manager,dc=abmas,dc=biz" (00000002)
       added: "ou=People,dc=abmas,dc=biz" (00000003)
       added: "ou=Computers,dc=abmas,dc=biz" (00000004)
       added: "ou=Groups,dc=abmas,dc=biz" (00000005)
       added: "ou=Domains,dc=abmas,dc=biz" (00000006)
       added: "sambaDomainName=MEGANET2,ou=Domains,dc=abmas,dc=biz" (00000007)
       added: "cn=domadmins,ou=Groups,dc=abmas,dc=biz" (00000008)
       added: "cn=domguests,ou=Groups,dc=abmas,dc=biz" (00000009)
       added: "cn=domusers,ou=Groups,dc=abmas,dc=biz" (0000000a)

   You should verify that the account information was correctly loaded by executing:

       root#  slapcat
       dn: dc=abmas,dc=biz
       objectClass: dcObject
       objectClass: organization
       dc: abmas
       o: Abmas Inc.
       description: Posix and Samba LDAP Identity Database
       structuralObjectClass: organization
       entryUUID: af552f8e-c4a1-1027-9002-9421e01bf474
       creatorsName: cn=manager,dc=abmas,dc=biz
       modifiersName: cn=manager,dc=abmas,dc=biz
       createTimestamp: 20031217055747Z
       modifyTimestamp: 20031217055747Z
       entryCSN: 2003121705:57:47Z#0x0001#0#0000
       ...

       dn: cn=domusers,ou=Groups,dc=abmas,dc=biz
       objectClass: posixGroup
       objectClass: sambaGroupMapping
       gidNumber: 513
       cn: domusers
       sambaSID: S-1-5-21-3504140859-1010554828-2431957765-513
       sambaGroupType: 2
       displayName: Domain Users
       description: Domain Users
       structuralObjectClass: posixGroup
       entryUUID: af7e98ba-c4a1-1027-900b-9421e01bf474
       creatorsName: cn=manager,dc=abmas,dc=biz
       modifiersName: cn=manager,dc=abmas,dc=biz
       createTimestamp: 20031217055747Z
       modifyTimestamp: 20031217055747Z
       entryCSN: 2003121705:57:47Z#0x000a#0#0000

6. Your LDAP database is ready for testing. You can now start the LDAP server using the system tool for your Linux operating system. For SUSE Linux, you can do this as follows:

       root#  rcldap start

7. It is now a good idea to validate that the LDAP server is running correctly. Execute the following:

       root#  ldapsearch -x -b "dc=abmas,dc=biz" "(ObjectClass=*)"
       # extended LDIF
       #
       # LDAPv3
       # base <dc=abmas,dc=biz> with scope sub
       # filter: (ObjectClass=*)
       # requesting: ALL
       #

       # abmas.biz
       dn: dc=abmas,dc=biz
       objectClass: dcObject
       objectClass: organization
       dc: abmas
       o: Abmas Inc.
       description: Posix and Samba LDAP Identity Database
       ...
       # domusers, Groups, abmas.biz
       dn: cn=domusers,ou=Groups,dc=abmas,dc=biz
       objectClass: posixGroup
       objectClass: sambaGroupMapping
       gidNumber: 513
       cn: domusers
       sambaSID: S-1-5-21-3504140859-1010554828-2431957765-513
       sambaGroupType: 2
       displayName: Domain Users
       description: Domain Users

       # search result
       search: 2
       result: 0 Success

       # numResponses: 11
       # numEntries: 10

   Your LDAP server is ready for creation of additional accounts.

Example 15.6. LDAP Pre-configuration Script: `SMBLDAP-ldif-preconfig.sh` Part A

    #!/bin/bash
    #
    # This script prepares the ldif LDAP load file only
    #

    # Pattern File Name
    file=init-ldif.pat

    # The name of my organization
    ORGNAME="My Organization"

    # My Internet domain. ie: if my domain is: buckets.org, INETDOMAIN="buckets"
    INETDOMAIN="my-domain"

    # In the above case, md domain is: buckets.org, TLDORG="org"
    TLDORG="org"

    # This is the Samba Domain/Workgroup Name
    DOMNAME="MYWORKGROUP"

    #
    # Here We Go ...
    #

    cat <<EOF

    How do you wish to refer to your organization?

    Suggestions:
    	Black Tire Company, Inc.
    	Cat With Hat Ltd.

    How would you like your organization name to appear?

    EOF

    echo "Your organization name is: $ORGNAME"
    echo
    echo "Enter a new name or, press Enter to Continue."
    echo

Example 15.7. LDAP Pre-configuration Script: `SMBLDAP-ldif-preconfig.sh` Part B

    echo -e -n "Name [$ORGNAME]: "
    	read name

    if [ ! -z "$name" ]; then
    	ORGNAME=${name}
    fi
    echo
    sed "s/ORGNAME/${ORGNAME}/g" < $file > $file.tmp1

    # Try to find smb.conf

    if [ -e /usr/local/samba/lib/smb.conf ]; then
    	CONF=/usr/local/samba/lib/smb.conf
    elif [ -e /etc/samba/smb.conf ]; then
    	CONF=/etc/samba/smb.conf
    fi

    echo "Samba Config File Location [$CONF]: "
    echo
    echo "Enter a new full path or press Enter to continue."
    echo
    echo -n "Samba Config File Location [$CONF]: "
    	read name
    if [ ! -z "$name" ]; then
    	CONF=$name
    fi
    echo

    # Find the name of our Domain/Workgroup
    DOMNAME=`grep -i workgroup ${CONF} | sed "s/ //g" | cut -f2 -d=`
    echo Domain Name: $DOMNAME
    echo

    sed "s/DOMNAME/${DOMNAME}/g" < $file.tmp1 > $file.tmp2

    DOMSID=`net getlocalsid ${DOMNAME} | cut -f2 -d: | sed "s/ //g"`
    echo Domain SID: $DOMSID

    sed "s/DOMSID/${DOMSID}/g" < $file.tmp2 > $file.tmp1

Example 15.8. LDAP Pre-configuration Script: `SMBLDAP-ldif-preconfig.sh` Part C

    cat >>EOL
    The name of your Internet domain is now needed in a special format
    as follows, if your domain name is mydomain.org, what we need is
    the information in the form of:
    	Domain ID: mydomain
    	Top level: org

    If your fully qualified hostname is: snoopy.bazaar.garagesale.net
    where "snoopy" is the name of the machine,
    Then the information needed is:
    	Domain ID: garagesale
    	Top Level: net

    EOL
    INETDOMAIN=`hostname -d | cut -f1 -d.`
    echo Found the following domain name: `hostname -d`
    echo "I think the bit we are looking for might be: $INETDOMAIN"
    echo
    echo -n "Enter the domain name or press Enter to continue: "
    	read domnam
    if [ ! -z $domnam ]; then
    	INETDOMAIN=$domnam
    fi
    echo
    sed "s/INETDOMAIN/${INETDOMAIN}/g" < $file.tmp1 > $file.tmp2
    TLDORG=`hostname -d | sed "s/${INETDOMAIN}.//g"`
    echo "The top level organization name I will use is: ${TLDORG}"
    echo
    echo -n "Enter the top level org name or press Enter to continue: "
    	read domnam
    if [ ! -z $domnam ]; then
            TLDORG=$domnam
    fi
    sed "s/TLDORG/${TLDORG}/g" < $file.tmp2 > $DOMNAME.ldif
    rm $file.tmp*
    exit 0

Example 15.9. LDIF Pattern File Used to Pre-configure LDAP Part A

    dn: dc=INETDOMAIN,dc=TLDORG
    objectClass: dcObject
    objectClass: organization
    dc: INETDOMAIN
    o: ORGNAME
    description: Posix and Samba LDAP Identity Database

    dn: cn=Manager,dc=INETDOMAIN,dc=TLDORG
    objectClass: organizationalRole
    cn: Manager
    description: Directory Manager

    dn: ou=People,dc=INETDOMAIN,dc=TLDORG
    objectClass: top
    objectClass: organizationalUnit
    ou: People

    dn: ou=Computers,dc=INETDOMAIN,dc=TLDORG
    objectClass: top
    objectClass: organizationalUnit
    ou: Computers

    dn: ou=Groups,dc=INETDOMAIN,dc=TLDORG
    objectClass: top
    objectClass: organizationalUnit
    ou: Groups

    dn: ou=Idmap,dc=INETDOMAIN,dc=TLDORG
    objectClass: top
    objectClass: organizationalUnit
    ou: Idmap

    dn: ou=Domains,dc=INETDOMAIN,dc=TLDORG
    objectClass: top
    objectClass: organizationalUnit
    ou: Domains

    dn: sambaDomainName=DOMNAME,ou=Domains,dc=INETDOMAIN,dc=TLDORG
    objectClass: sambaDomain
    sambaDomainName: DOMNAME
    sambaSID: DOMSID
    sambaAlgorithmicRidBase: 1000
    structuralObjectClass: sambaDomain

Example 15.10. LDIF Pattern File Used to Pre-configure LDAP Part B

    dn: cn=domadmins,ou=Groups,dc=INETDOMAIN,dc=TLDORG
    objectClass: posixGroup
    objectClass: sambaGroupMapping
    gidNumber: 512
    cn: domadmins
    sambaSID: DOMSID-512
    sambaGroupType: 2
    displayName: Domain Admins
    description: Domain Administrators

    dn: cn=domguests,ou=Groups,dc=INETDOMAIN,dc=TLDORG
    objectClass: posixGroup
    objectClass: sambaGroupMapping
    gidNumber: 514
    cn: domguests
    sambaSID: DOMSID-514
    sambaGroupType: 2
    displayName: Domain Guests
    description: Domain Guests Users

    dn: cn=domusers,ou=Groups,dc=INETDOMAIN,dc=TLDORG
    objectClass: posixGroup
    objectClass: sambaGroupMapping
    gidNumber: 513
    cn: domusers
    sambaSID: DOMSID-513
    sambaGroupType: 2
    displayName: Domain Users
    description: Domain Users

## The LDAP Account Manager

The LDAP Account Manager (LAM) is an application suite that has been written in PHP. LAM can be used with any Web server that has PHP4 support. It connects to the LDAP server either using unencrypted connections or via SSL/TLS. LAM can be used to manage Posix accounts as well as SambaSAMAccounts for users, groups, and Windows machines (hosts).

LAM is available from the LAM home page and from its mirror sites. LAM has been released under the GNU GPL version 2. The current version of LAM is 0.4.9. Release of version 0.5 is expected in the third quarter of 2005.

Requirements:

- A web server that will work with PHP4.

- PHP4 (available from the PHP home page.)

- OpenLDAP 2.0 or later.

- A Web browser that supports CSS.

- Perl.

- The gettext package.

- mcrypt + mhash (optional).

- It is also a good idea to install SSL support.

LAM is a useful tool that provides a simple Web-based device that can be used to manage the contents of the LDAP directory to:

- Display user/group/host and Domain entries.

- Manage entries (Add/Delete/Edit).

- Filter and sort entries.

- Store and use multiple operating profiles.

- Edit organizational units (OUs).

- Upload accounts from a file.

- Is compatible with Samba-2.2.x and Samba-3.

When correctly configured, LAM allows convenient management of UNIX (Posix) and Samba user, group, and windows domain member machine accounts.

The default password is “lam.” It is highly recommended that you use only an SSL connection to your Web server for all remote operations involving LAM. If you want secure connections, you must configure your Apache Web server to permit connections to LAM using only SSL.

Procedure 15.3. Apache Configuration Steps for LAM

1. Extract the LAM package by untarring it as shown here:

       root#  tar xzf ldap-account-manager_0.4.9.tar.gz

   Alternatively, install the LAM DEB for your system using the following command:

       root#  dpkg -i ldap-account-manager_0.4.9.all.deb

2. Copy the extracted files to the document root directory of your Web server. For example, on SUSE Linux Enterprise Server 9, copy to the `/srv/www/htdocs` directory.

3. Set file permissions using the following commands:

       root#  chown -R wwwrun:www /srv/www/htdocs/lam
       root#  chmod 755 /srv/www/htdocs/lam/sess
       root#  chmod 755 /srv/www/htdocs/lam/tmp
       root#  chmod 755 /srv/www/htdocs/lam/config
       root#  chmod 755 /srv/www/htdocs/lam/lib/*pl

4. Using your favorite editor create the following `config.cfg` LAM configuration file:

       root#  cd /srv/www/htdocs/lam/config
       root#  cp config.cfg_sample config.cfg
       root#  vi config.cfg

   An example file is shown in ???. This is the minimum configuration that must be completed. The LAM profile file can be created using a convenient wizard that is part of the LAM configuration suite.

5. Start your Web server then, using your Web browser, connect to LAM URL. Click on the the `Configuration Login` link then click on the Configuration Wizard link to begin creation of the default profile so that LAM can connect to your LDAP server. Alternately, copy the `lam.conf_sample` file to a file called `lam.conf` then, using your favorite editor, change the settings to match local site needs.

An example of a working file is shown here in ???. This file has been stripped of comments to keep the size small. The comments and help information provided in the profile file that the wizard creates is very useful and will help many administrators to avoid pitfalls. Your configuration file obviously reflects the configuration options that are preferred at your site.

It is important that your LDAP server is running at the time that LAM is being configured. This permits you to validate correct operation. An example of the LAM login screen is provided in ???.

Figure 15.6. The LDAP Account Manager Login Screen

The LAM configuration editor has a number of options that must be managed correctly. An example of use of the LAM configuration editor is shown in ???. It is important that you correctly set the minimum and maximum UID/GID values that are permitted for use at your site. The default values may not be compatible with a need to modify initial default account values for well-known Windows network users and groups. The best work-around is to temporarily set the minimum values to zero (0) to permit the initial settings to be made. Do not forget to reset these to sensible values before using LAM to add additional users and groups.

Figure 15.7. The LDAP Account Manager Configuration Screen

LAM has some nice, but unusual features. For example, one unexpected feature in most application screens permits the generation of a PDF file that lists configuration information. This is a well thought out facility. This option has been edited out of the following screen shots to conserve space.

When you log onto LAM the opening screen drops you right into the user manager as shown in ???. This is a logical action as it permits the most-needed facility to be used immediately. The editing of an existing user, as with the addition of a new user, is easy to follow and very clear in both layout and intent. It is a simple matter to edit generic settings, UNIX specific parameters, and then Samba account requirements. Each step involves clicking a button that intuitively drives you through the process. When you have finished editing simply press the Final button.

Figure 15.8. The LDAP Account Manager User Edit Screen

The edit screen for groups is shown in ???. As with the edit screen for user accounts, group accounts may be rapidly dealt with. ??? shows a sub-screen from the group editor that permits users to be assigned secondary group memberships.

Figure 15.9. The LDAP Account Manager Group Edit Screen

Figure 15.10. The LDAP Account Manager Group Membership Edit Screen

The final screen presented here is one that you should not normally need to use. Host accounts will be automatically managed using the smbldap-tools scripts. This means that the screen ??? will, in most cases, not be used.

Figure 15.11. The LDAP Account Manager Host Edit Screen

One aspect of LAM that may annoy some users is the way it forces certain conventions on the administrator. For example, LAM does not permit the creation of Windows user and group accounts that contain spaces even though the underlying UNIX/Linux operating system may exhibit no problems with them. Given the propensity for using upper-case characters and spaces (particularly in the default Windows account names) this may cause some annoyance. For the rest, LAM is a very useful administrative tool.

The next major release, LAM 0.5, will have fewer restrictions and support the latest Samba features (e.g., logon hours). The new plugin-based architecture also allows management of much more different account types like plain UNIX accounts. The upload can now handle groups and hosts, too. Another important point is the tree view which allows browsing and editing LDAP objects directly.

Example 15.11. Example LAM Configuration File `config.cfg`

    # password to add/delete/rename configuration profiles
    password: not24get

    # default profile, without ".conf"
    default: lam

Example 15.12. LAM Profile Control File `lam.conf`

    ServerURL: ldap://massive.abmas.org:389
    Admins: cn=Manager,dc=abmas,dc=biz
    Passwd: not24get
    usersuffix: ou=People,dc=abmas,dc=biz
    groupsuffix: ou=Groups,dc=abmas,dc=biz
    hostsuffix: ou=Computers,dc=abmas,dc=biz
    domainsuffix: ou=Domains,dc=abmas,dc=biz
    MinUID: 0
    MaxUID: 65535
    MinGID: 0
    MaxGID: 65535
    MinMachine: 20000
    MaxMachine: 25000
    userlistAttributes: #uid;#givenName;#sn;#uidNumber;#gidNumber
    grouplistAttributes: #cn;#gidNumber;#memberUID;#description
    hostlistAttributes: #cn;#description;#uidNumber;#gidNumber
    maxlistentries: 30
    defaultLanguage: en_GB:ISO-8859-1:English (Great Britain)
    scriptPath:
    scriptServer:
    samba3: yes
    cachetimeout: 5
    pwdhash: SSHA

## IDEALX Management Console

IMC (the IDEALX Mamagement Console) is a tool that can be used as the basis for a comprehensive web-based management interface for UNIX and Linux systems.

The Samba toolset is the first console developped for IMC. It offers a simple and ergonomic interface for managing a Samba domain controler. The goal is to give Linux administrators who need to manage production Samba servers an effective, intuitive and consistent management experience. An IMC screenshot of the user management tool is shown in ???.

Figure 15.12. The IMC Samba User Account Screen

IMC is built on a set of Perl modules. Most modules are standard CPAN modules. Some are bundled with IMC, but will soon to be hosted on the CPAN independently, like Struts4P, a port of Struts to the Perl language.

For further information regarding IMC refer to the web site. Prebuilt RPM packages are also available.

## Effect of Setting File and Directory SUID/SGID Permissions Explained

The setting of the SUID/SGID bits on the file or directory permissions flag has particular consequences. If the file is executable and the SUID bit is set, it executes with the privilege of (with the UID of) the owner of the file. For example, if you are logged onto a system as a normal user (let's say as the user `bobj`), and you execute a file that is owned by the user `root` (uid = 0), and the file has the SUID bit set, then the file is executed as if you had logged in as the user `root` and then executed the file. The SUID bit effectively gives you (as `bobj`) administrative privilege for the use of that executable file.

The setting of the SGID bit does precisely the same as the effect of the SUID bit, except that it applies the privilege to the UNIX group setting. In other words, the file executes with the force of capability of the group.

When the SUID/SGID permissions are set on a directory, all files that are created within that directory are automatically given the ownership of the SUID user and the SGID group, as per the ownership of the directory in which the file is created. This means that the system level `create()` function executes with the SUID user and/or SGID group of the directory in which the file is created.

If you want to obtain the SUID behavior, simply execute the following command:

    root#  chmod u+s file-or-directory

To set the SGID properties on a file or a directory, execute this command:

    root#  chmod g+s file-or-directory

And to set both SUID and SGID properties, execute the following:

    root#  chmod ug+s file-or-directory

Let's consider the example of a directory `/data/accounts`. The permissions on this directory before setting both SUID and SGID on this directory are:

    root#  ls -al /data/accounts
    total 1
    drwxr-xr-x   10 root     root          232 Dec 18 17:08 .
    drwxr-xr-x   21 root     root          600 Dec 17 23:15 ..
    drwxrwxrwx    2 bobj     Domain Users  48 Dec 18 17:08 accounts/
    drwx------    2 root     root           48 Jan 26  2002 lost+found

In this example, if the user `maryv` creates a file, it is owned by her. If `maryv` has the primary group of `Accounts`, the file is owned by the group `Accounts`, as shown in this listing:

    root#  ls -al /data/accounts/maryvfile.txt
    drw-rw-r--    2 maryv    Accounts     12346 Dec 18 17:53

Now you set the SUID and SGID and check the result as follows:

    root#  chmod ug+s /data/accounts
    root#  ls -al /data/accounts
    total 1
    drwxr-xr-x   10 root     root          232 Dec 18 17:08 .
    drwxr-xr-x   21 root     root          600 Dec 17 23:15 ..
    drwsrwsr-x    2 bobj     Domain Users  48 Dec 18 17:08 accounts
    drwx------    2 root     root           48 Jan 26  2002 lost+found

If `maryv` creates a file in this directory after this change has been made, the file is owned by the user `bobj`, and the group is set to the group `Domain Users`, as shown here:

    root#  chmod ug+s /data/accounts
    root#  ls -al /data/accounts/maryvfile.txt
    total 1
    drw-rw-r--    2 bobj     Domain Users  12346 Dec 18 18:11 maryvfile.txt

## Shared Data Integrity

The integrity of shared data is often viewed as a particularly emotional issue, especially where there are concurrent problems with multiuser data access. Contrary to the assertions of some who have experienced problems in either area, the cause has nothing to do with the phases of the moons of Jupiter.

The solution to concurrent multiuser data access problems must consider three separate areas from which the problem may stem:

- application-level locking controls

- client-side locking controls

- server-side locking controls

Many database applications use some form of application-level access control. An example of one well-known application that uses application-level locking is Microsoft Access. Detailed guidance is provided here because this is the most common application for which problems have been reported.

Common applications that are affected by client- and server-side locking controls include MS Excel and Act!. Important locking guidance is provided here.

### Microsoft Access

The best advice that can be given is to carefully read the Microsoft knowledgebase articles that cover this area. Examples of relevant documents include:

- http://support.microsoft.com/default.aspx?scid=kb;en-us;208778

- http://support.microsoft.com/default.aspx?scid=kb;en-us;299373

Make sure that your MS Access database file is configured for multiuser access (not set for exclusive open). Open MS Access on each client workstation, then set the following: (Menu bar) Tools+Options+[tab] General. Set network path to Default database folder: `\\server\share\folder`.

You can configure MS Access file sharing behavior as follows: click [tab] Advanced. Set:

- Default open mode: Shared

- Default Record Locking: Edited Record

- Open databases using record_level locking

You must now commit the changes so that they will take effect. To do so, click Apply Ok. At this point, you should exit MS Access, restart it, and then validate that these settings have not changed.

### Act! Database Sharing

Where the server sharing the ACT! database(s) is running Samba,or Windows NT, 200x, or XP, you must disable opportunistic locking on the server and all workstations. Failure to do so results in data corruption. This information is available from the Act! Web site knowledgebase articles 1998223162925 as well as from article 200110485036.

These documents clearly state that opportunistic locking must be disabled on both the server (Samba in the case we are interested in here), as well as on every workstation from which the centrally shared Act! database will be accessed. Act! provides a tool called `Act!Diag` that may be used to disable all workstation registry settings that may otherwise interfere with the operation of Act! Registered Act! users may download this utility from the Act! Web site.

### Opportunistic Locking Controls

Third-party Windows applications may not be compatible with the use of opportunistic file and record locking. For applications that are known not to be compatible,[14] oplock support may need to be disabled both on the Samba server and on the Windows workstations.

Oplocks enable a Windows client to cache parts of a file that are being edited. Another windows client may then request to open the file with the ability to write to it. The server will then ask the original workstation that had the file open with a write lock to release its lock. Before doing so, that workstation must flush the file from cache memory to the disk or network drive.

Disabling of Oplocks usage may require server and client changes. Oplocks may be disabled by file, by file pattern, on the share, or on the Samba server.

The following are examples showing how Oplock support may be managed using Samba `smb.conf` file settings:

    By file:        veto oplock files = myfile.mdb

    By Pattern:     veto oplock files = /*.mdb/

    On the Share:   oplocks = No
                    level2 oplocks = No

    On the server:
    (in [global])   oplocks = No
                    level2 oplocks = No

The following registry entries on Microsoft Windows XP Professional, 2000 Professional, and Windows NT4 workstation clients must be configured as shown here:

    REGEDIT4

    [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
                Services\LanmanServer\Parameters]
          "EnableOplocks"=dword:00000000

    [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
                Services\LanmanWorkstation\Parameters]
          "UseOpportunisticLocking"=dword:00000000

Comprehensive coverage of file and record-locking controls is provided in TOSHARG2, Chapter 13. The information in that chapter was obtained from a wide variety of sources.

Prev | Up | Next
Chapter 14. Samba Support | Home | Chapter 16. Networking Primer