Ensurepass

27. Samba
27.1 Overview
Samba provides SMB/CIFS services to clients. The smbd daemon performs authentication, authorization, file, and print sharing services. The nmbd daemon can act as a netbios name server as well as a WINS server.
1. Packages
o samba-common
Contains files needed by both the client and server parts of Samba.
o samba-client
Contains the client side files.
o samba
Contains the server side files.
o samba-swat
A web based administration tool.
2. Ports
o smbd
TCP port 139.
o nmbd
UDP ports 137 & 138
27.2 Configuration
1. /etc/samba/smb.conf
o All configuration is done via editing this file.
o Similar in format to the windows.ini file.
o Sections
1. global
Contains all server wide or generic settings.
2. homes
Used to grant users access to their home directories.
3. printers
Used to configure printer resources/services.
2. Global Configuration
o User/Password Options
1. Encrypted Passwords
To enable encrypted passwords, the following two lines must be uncommented:
encrypt passwords = yes
smb passwd file = /etc/samba/smbpasswd

To create the password file, simply add a user:
smbpasswd -a steve

OR
smbadduser steve:steve # :
smbpasswd -u steve

The user must exist in the user system password files before adding them to the smbpasswd file. The default file created will be the password file specified by the smb passwd file option in /etc/samba/smb.conf.
2. username level
Helps Samba determine what the unix user name is. By default it tries all lower case characters. This number specifies how many uppercase combinations should be tried. The larger the number, the longer it can take to authenticate, but the better chance you’ll have success.
3. password level
Same as username level only for the password.
4. Syncing with Unix passwords
If you want the unix password changed every time the Samba password is changed, you must specify the following:
unix password sync = Yes

# unix utility to use
passwd program = /usr/bin/passwd %u

# chat string
passwd chat = *New*password* %nn *Retype*new*password* %nn *passwd:*all*au$ # chat string

o workgroup
The workgroup option specifies the name of the windows workgroup or NT domain name that the Samba Server will belong to.
o netbios name
The netbios name options specifies what the Samba server will advertise as it’s netbios name. By default, this is the same name as the first part of the host’s FQDN.
o Restricting Hosts
The hosts allow options allows you to specify which hosts are allowed to use the Samba service.
hosts allow = 192.168.1. 192.168.2. 192.168.3.20

This allows all hosts in the 192.168.1.0/24 and 192.168.2.0/24 networks and the single host 192.168.3.20 to access the Samba services.
o Printer Options
o printcap name = /etc/printcap # Specify printer definition file
o load printers = yes # Make all defined printers available to users
o printing = lprng # Specifies printing system used
o
o guest account
The account used for access permissions when connecting to shares that allow guest access. Make sure to add this account to /etc/passwd. If it isn’t specified, user “nobody” is used.
o WINS support
Samba can act as a WINS client, or a WINS server, but not both. As a WINS client it will lookup netbios names using another WINS server. As a WINS server, it will provide the netbios name to IP conversion for other clients.
To make Samba a WINS client:
wins server = 192.168.1.5

To make Samba a WINS server:
wins support = yes
name resolve order = wins lmhosts host bcast

The second option is required and defaults to “host lmhosts wins bcast”. It specifies which order to access the various resources for netbios name resolution.
1. host – Perform the standard host name to IP resolution using /etc/hosts, NIS, and DNS.
2. lmhosts – Use the name/IP address mappings specified in the lmhosts file. By default, the lmhosts file is /etc/samba/lmhosts.
3. 127.0.0.1 localhost
4. 192.168.1.5 endor
5.
6. wins – Query the host specified in the wins server option to resolve the IP address.
7. bcast – Use a netbios broadcast to resolve the IP address. This only works for hosts connected to the local network.
o Authentication Methods
Specify authentication method with the security option. Possible values are:
1. user – Authenticate by user using smbpasswd file. The user must be defined on the unix system. This is the default.
2. share – User authenticates against each individual share.
3. server – Samba validates the user using the server specified by the password server parameter. The user must still be defined on the unix system.
4. domain – Samba validates the user using the PDC or BDC as a normal NT server would. The Samba server must first be added as a valid machine to the PDC. The user must still be defined on the unix system.
o Logging Options
o log file = /var/log/samba/%m.log
o max log size = 0
o
The first options specifies that an individual log will be kept for each machine(%m) that connects to the server. The second options specifies a size limit to put on the log file (zero = unlimited).
o Browser Options
o local master = yes # Allow Samba to participate in master browser elections
o os level = 35 # The higher the level, the better chance of winning the election
o preferred master = yes # Causes Samba to force an election upon startup
o domain master = yes # Allows Samba to collate browse lists between subnets
o
o Domain Options
o domain logons = yes # Causes Samba to become a domain logon server for Windows 95 machines.
o
3. Common Share Options
o public
Share can be accessed by the “guest” account.
o browseable
Makes the share visible in browse lists.
o writable
Allows users to write to the share.
o printable
Specifies the share/resource as a printer not a disk.
o group
Specifies the UNIX group that will be assigned as the default primary group for all users connecting to the share.
o valid users
Specifies the users that are allowed to connect to the share.
o create mode/create mask
Specifies the unix file permission bits that will always be set on any file created in this directory by Samba.
o directory mode
Same as ‘create mode’ only for directories.
o write list
A list of users and/or groups that will be given write access to the share if the ‘writable’ option is set to “no”.
o path
Specifies the location of the share within the unix file system.
o only guest/guest only
If set to yes, then only guest connections to the share are permitted.
o guest ok/public
This permits the guest account to access this share.
o Special shares
Some shares have special meaning to Samba when defined, these are:
1. [printers]
Printable share that includes all system defined printers.
2. [homes]
Sets up each user’s home directory as a file share that is accessible only by that user.
3. [netlogon]
Specifies the netlogon directory for Domain Logons
4. Example Shares
o File share for research dept.
o [research]
o comment = Research Dept.
o path = /var/research # Location of share on file system
o public = yes # Shows up in browse lists
o writable = yes # Authenticated users can write to it
o printable = no
o
o Printer share configuration
o [printers] # Special share that defines all printers
o comment = All printers
o path = /var/spool/samba # Location of spooling directory for print jobs
o browseable = no # Does not show up in browse lists
o guest ok = no # Guest user is not allowed to connect to this share
o printable = yes # A printer share
o
o File share for accounting dept.
o [accounting]
o comment = Accounting
o path = /usr/local/shares/accounting
o valid users = @accounting # Only users in the unix group ‘accounting’ can access the share
o public = no
o write list = bob sue steve # Only users bob, sue, and steve can write to this share
o
o Home directory shares
o [homes]
o comment = Home Directories
o browseable = yes
o writable = yes
o valid users = %S
o create mode = 0664
o directory mode = 0775
o
27.3 Utilities
1. testparm
o Check for errors in smb.conf.
o Test security settings for a particular host
o testparm /etc/samba/smb.conf 192.168.1.20
This would return the resources available to the host at 192.168.1.20.
2. testprns
Determines whether a printer is valid for use through smbd.
testprns /etc/printcap
3. smbclient
Provides command line ftp-style retrieval of files from smb/cifs shares.
smbclient -L 192.168.1.10 # List accessible share on host 192.168.1.10
smbclient //192.168.1.10/homes # Connect to user home directory
smbclient -U steve //somehost/homes # Connect to homes share as user steve
4. nmblookup
Provides hostname and IP resolution for netbios.
nmblookup -U server -R ‘endor’ # Lookup host ‘endor’ using unicast to query WINS server ‘endor’
# and set the recursion flag on (-R)
nmblookup * # List all machines
5. smbmount
Used to mount smb/cifs shares on a local system.
# Mount share research from server endor onto mount point /mnt/smb/research as user steve
smbmount //endor/research /mnt/smb/endor -o username=steve
Samba mounts can be performed automatically at boot up by putting them in the /etc/fstab file.
//endor/research /mnt/smb/endor smbfs defaults,credentials=/etc/smb/endor.research 0 0
The credentials option specifies the file that contains the username/password pair to use. Make sure this file is protected adequately. The credentials file should contain:
username = steve
password = mypassword
27.4 Disabling Encrypted Passwords on Windows Clients
1. Windows 95 OSR2+ and Windows 98
Using the registry editor(regedit), go to:
HKEY_LOCAL_MACHINESystemCurrentControlSetServicesVxDVNETSUP
Add a DWORD value with the name of EnablePlaintextPassword. Set it’s value to 0x01.
2. Windows NT
Using the registry editor(regedit), go to:
HKEY_LOCAL_MACHINESystemCurrentControlSetServicesRdrParameters
Add a DWORD value like above.
27.5 Configuring Samba as a Primary Domain Controller
1. Make sure Samba is only PDC on network.
2. Make sure there is a WINS server on the network (NT or Samba).
3. Samba is set to use “user” level security.
4. Set the following options in the [global] section of your smb.conf file:
5. [global]
6. workgroup = MYGROUP
7. domain logons = yes
8. security = user
9. os level = 34
10. local master = yes
11. preferred master = yes
12. domain master = yes
13.
14. [netlogon]
15. comment = Domain Logon Service
16. path = /var/samba/logon
17. public = no
18. writeable = no
19. browsable = no
20. NT Clients
If you have NT clients on your network, you must also add the following option:
encrypted passwords = yes
NT client also require a trust account. Trust accounts allow the machine to log in to the PDC and become a member of the domain. Use the following steps to setup a trust account on the Samba server for the NT client:
o Add a unix system account for the machine. The logon name will always end in a “$”. Your /etc/password entry should look similar to:
o endor$:x:1000:1000:Trust Account:/dev/null:/dev/null
o
Place an * in the password field of the /etc/shadow file to prevent anyone from logging into the unix server with this account.
o Add the encrypted password for the machine:
o smbpasswd -a -m endor
o
The “-m” specifies it’s a machine trust account. The default password will be set to the netbios name of the machine. The NT client should log into the PDC asap so it can change the default password.
27.6 Default Red Hat smb.conf
This is the default smb.conf that comes with RH 7.2.
# 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
#
# 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 =====================================
[global]

# workgroup = NT-Domain-Name or Workgroup-Name
workgroup = MYGROUP

# server string is the equivalent of the NT Description field
server string = Samba Server

# 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
printcap name = /etc/printcap
load printers = yes

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

# 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 = 0

# Security mode. Most people will want user level security. See
# security_level.txt for details.
security = user

# 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 =

# Password Level allows matching of _n_ characters of the password for
# all combinations of upper and lower case.
; password level = 8
; username level = 8

# You may wish to use password encryption. Please read
# ENCRYPTION.txt, Win95.txt and WinNT.txt in the Samba documentation.
# Do not enable this option unless you have read those documents
encrypt passwords = yes
smb passwd file = /etc/samba/smbpasswd

# The following is needed to keep smbclient from spouting spurious errors
# when Samba is built with support for SSL.
; ssl CA certFile = /usr/share/ssl/certs/ca-bundle.crt

# The following are needed to allow password changing from Windows to
# update the Linux sytsem password also.
# NOTE: Use these with ‘encrypt passwords’ and ‘smb passwd file’ above.
# NOTE2: You do NOT need these to allow workstations to change only
# the encrypted SMB passwords. They allow the Unix password
# to be kept in sync with the SMB password.
; unix password sync = Yes
; passwd program = /usr/bin/passwd %u
; passwd chat = *New*password* %nn *Retype*new*password* %nn *passwd:*all*authentication*tokens*updated*successfully*

# Unix users can map to different SMB User names
; username map = /etc/samba/smbusers

# 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
; include = /etc/samba/smb.conf.%m

# This parameter will control whether or not Samba should obey PAM’s
# account and session management directives. The default behavior is
# to use PAM for clear text authentication only and to ignore any
# account or session management. Note that Samba always ignores PAM
# for authentication in the case of encrypt passwords = yes

; obey pam restrictions = yes

# Most people will find that this option gives better performance.
# See speed.txt and the manual pages for details
socket options = TCP_NODELAY SO_RCVBUF=8192 SO_SNDBUF=8192

# 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 = 192.168.12.2/24 192.168.13.2/24

# Configure remote browse list synchronisation here
# request announcement to, or browse list sync from:
# a specific host or from / to a whole subnet (see below)
; remote browse sync = 192.168.3.25 192.168.5.255
# Cause this host to announce itself to local subnets here
; remote announce = 192.168.1.255 192.168.2.44

# 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 = \%LProfiles%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 built-in default for versions 1.9.17 is yes,
# this has been changed in version 1.9.18 to no.
dns proxy = no

# Case Preservation can be handy – system default is _no_
# NOTE: These can be set on a per share basis
; preserve case = no
; short preserve case = no
# Default case is normally upper case for all DOS files
; default case = lower
# Be very careful with case sensitivity – it can break things!
; case sensitive = no

#============================ Share Definitions ==============================
[homes]
comment = Home Directories
browseable = no
writable = yes
valid users = %S
create mode = 0664
directory mode = 0775
# If you want users samba doesn’t recognize to be mapped to a guest user
; map to guest = bad user

# 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
;[Profiles]
; 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
[printers]
comment = All Printers
path = /var/spool/samba
browseable = no
# Set public = yes to allow user ‘guest account’ to print
guest ok = no
writable = no
printable = yes

# This one is useful for people to share files
;[tmp]
; comment = Temporary file space
; path = /tmp
; read only = no
; public = yes

# A publicly accessible directory, but read only, except for people in
# the “staff” group
;[public]
; 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.
;[fredsprn]
; comment = Fred’s Printer
; valid users = fred
; path = /home/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.
;[fredsdir]
; 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.
;[pchome]
; comment = PC Directories
; path = /usr/local/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.
;[public]
; 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.
;[myshare]
; comment = Mary’s and Fred’s stuff
; path = /usr/somewhere/shared
; valid users = mary fred
; public = no
; writable = yes
; printable = no
; create mask = 0765

Download the Ensurepass Latest 2013 RHCE EX300 Practise Test PDF to pass RHCE EX300 exam.

Comments are closed.