Howto: restart Linux network service

RedHat Linux command to reload or restart network (login as root user):

# service network restart
OR
# /etc/init.d/network restart

To start Linux network service:
# service network start

To stop Linux network service:
# service network stop

Debian Linux command to reload or restart network:
# /etc/init.d/networking restart

To start Linux network service:
# /etc/init.d/networking start

To stop Linux network service:
# /etc/init.d/networking stop

Ubuntu Linux user use sudo command with above Debian Linux command:
# sudo /etc/init.d/networking restart

To start Linux network service:
# sudo /etc/init.d/networking start

To stop Linux network service:
# sudo /etc/init.d/networking stop

Ubuntu Linux convert DHCP network configuration to static IP configuration

How to change or convert DHCP network configuration to static configuration. After initial installation, he wanted to change network settings. Further, his system is w/o GUI system aka X Windows. Here is quick way to accomplish the same:

Your main network configuration file is /etc/network/interfaces

Desired new sample settings:
=> Host IP address 192.168.1.100
=> Netmask: 255.255.255.0
=> Network ID: 192.168.1.0
=> Broadcast IP: 192.168.1.255
=> Gateway/Router IP: 192.168.1.254
=> DNS Server: 192.168.1.254

Open network configuration file
$ sudo vi /etc/network/interfacesOR$ sudo nano /etc/network/interfaces

Find and remove dhcp entry:
iface eth0 inet dhcp

Append new network settings:

iface eth0 inet static
address 192.168.1.100
netmask 255.255.255.0
network 192.168.1.0
broadcast 192.168.1.255
gateway 192.168.1.254

Save and close the file. Restart the network:
$ sudo /etc/init.d/networking restart
Task: Define new DNS servers

Open /etc/resolv.conf file
$ sudo vi /etc/resolv.conf

You need to remove old DNS server assigned by DHCP server:
search myisp.com
nameserver 192.168.1.254
nameserver 202.54.1.20
nameserver 202.54.1.30

Save and close the file.
Task: Test DNS server

$ host cyberciti.biz
Network command line cheat sheet

You can also use commands to change settings. Please note that these settings are temporary and not the permanent. Use above method to make network changes permanent or GUI tool as described below.
Task: Display network interface information

$ ifconfig
Task: Take down network interface eth0 / take a network interface down

$ sudo ifconfig eth0 downOR $ sudo ifdown eth0
Task: Bring a network interface eth0 up

$ sudo ifconfig eth0 upOR$ sudo ifup eth0
Task: Change IP address and netmask from command line

Activate network interface eth0 with a new IP (192.168.1.50) / netmask:
$ sudo ifconfig eth0 192.168.1.50 netmask 255.255.255.0 up
Task: Display the routing table

$ /sbin/route OR$ /sbin/route -n
Output:

Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
localnet * 255.255.255.0 U 0 0 0 ra0
172.16.114.0 * 255.255.255.0 U 0 0 0 eth0
172.16.236.0 * 255.255.255.0 U 0 0 0 eth1
default 192.168.1.254 0.0.0.0 UG 0 0 0 ra0

Task: Add a new gateway

$ sudo route add default gw 172.16.236.0
Task: Display current active Internet connections (servers and established connection)

$ netstat -nat
Task: Display open ports

$ sudo netstat -tulpOR$ sudo netstat -tulpn
Task: Display network interfaces stats (RX/TX etc)

$ netstat -i
Task: Display output for active/established connections only

$ netstat -e
$ netstat -te
$ netstat -tue

Where,

* -t : TCP connections
* -u : UDP connections
* -e : Established

Task: Test network connectivity

Send ICMP ECHO_REQUEST to network hosts, routers, servers etc with ping command. This verifies connectivity exists between local host and remote network system:
$ ping router
$ ping 192.168.1.254
$ ping cyberciti.biz

See simple Linux system monitoring with ping command and scripts for more information.
Task: Use GUI (Graphical Configuration) network Tool

If you are new, use GUI configuration tool, type the following command at terminal:
$ network-admin &

Above command is Ubuntu's GUI for configuring network connections tool.
Final tip - Learn how find out more information about commands

A man page is your best friend when you wanted to learn more about particular command or syntax. For example, read detailed information about ifconfig and netstat command:
$ man ifconfig
$ man netstat

Just get a short help with all command options by appending --help option to each command:
$ netstat --help

Find out what command is used for particular task by searching the short descriptions and manual page names for the keyword:
$ man -k 'delete directory'
$ apropos -s 1 remove

Display short descriptions of a command:
$ whatis rm
$ whatis netstat

Linux offers an excellent collection of utilities, which can be use to finding the files and executables, remember you cannot memorize all the commands and files ;)

Ubuntu Updates

Super-fast and great-looking, Ubuntu is a secure, intuitive operating system that powers desktops, servers, netbooks and laptops. Ubuntu is, and always will be, absolutely free.

"Get Ubuntu Desktop Edition Download"
You can download Ubuntu Desktop Edition online, completely free.

Download link :

http://www.ubuntu.com/desktop/get-ubuntu/download

how to Join Centos Domain 5.2 to Windows2003 Domain Controller

Network Setting -- Join Centos Domain 5.2

EDIT the DNS Network Configuration
-goto -sytem -administration - network

point the DNS Manually

Hostname : localhost.localdomain

Primary DNS : 192.168.1.... - IP of your Domain Controller

DNS Search hpo.hd ----- Domain DNS


continue-----------------------------------

-goto -sytem -administration - Authentication Configuration

check - enable winbind support

Windbind domain : HPO
security model : ads
winbind ADS Realm : HPO.HD
Winbind Domain Controllers : mars.hpo.hd
Template : /bin/bash

--Options :
Check shadow passwords
check local authorization is sufficient for local users
check home directories on the first login


Then -- go to File system - etc - samba

Edit the smb.conf

[global]
#--authconfig--start-line--

# Generated by authconfig on 2010/04/01 13:14:56
# DO NOT EDIT THIS SECTION (delimited by --start-line--/--end-line--)
# Any modification may be deleted or altered by authconfig in future

workgroup = HPD
password server = earth.HPO.HD
realm = HPO.HD
security = ads
idmap uid = 16777216-33554431
idmap gid = 16777216-33554431
template shell = /bin/bash
winbind use default domain = true ----- this should be add
winbind offline logon = false

Changing to OpenOffice.org 3.1 in CentOS

One of the things that I wanted to do since the installation of CentOS is to upgrade the currrently default version of OpenOffice.org, which is 2.3, to the latest available version being OpenOffice.org 3.1. I have done these upgrades before on Dreamlinux and (X)Ubuntu but this would be the first time on an “rpm based” distribution.


-- (remove old file openoffice)
-- yum remove openoffice.org-*
--cd (riht click the extracted file copy with root directory)
-- sudo rpm -i *.rpm
--cd desktop-integration
--ls
--yum install (right click not yet extracted file .tar)
--sudo rpm -i (redhat-centos)
cd ../ root
--sudo rpm -i *.rpm
--restart
--finish


Link to Resa's Blogs..

http://resa.linux-hardcore.com/?p=154

Ubuntu : Active Directory authentication in Ubuntu 8.04 and 8.10

This is a second version of this other guide that applied to previous Ubuntu versions.
Since Ubuntu 8.04 (Hardy Heron), and now Ubuntu 8.10 (Intrepid Ibex) it come the Likewise Open package that makes basic Active Directory authentication in Ubuntu a breeze.

Just follow these steps:

1. sudo apt-get update
2. sudo apt-get install likewise-open
3. sudo domainjoin-cli join fqdn.of.your.domain Administrator
4. sudo update-rc.d likewise-open defaults
5. sudo /etc/init.d/likewise-open start

and you can now log into your machine using your DOMAIN\user credentials. Remember that the DOMAIN\ part is mandatory and that it represents the short name of your Active Directory domain. You can join the domain using any user with sufficient privileges (there’s no need to use Administrator), and you can even directly join the PC in a particular OU passing the –ou argument to domainjoin-cli. The fourth point maybe won’t be necessary when Ubuntu 8.04 LTS wil be released because it seems to be a bug in the package (it won’t start likewise on reboot, so if you don’t issue this command it would seem that nothing is working after a reboot).

I’ve just started to use this method on a test machine so I’ll leave more opinions on this product in the future.

EDIT: First impressions

After some days of not so extensive usage, I’ve seen a couple of things that it’s worth notice:

• the likewise-open process seems to “die” from time to time, blocking all your login accesses with a “ERROR” message. Restarting it through init script solves the issue… but it’s something that definitely should not happen
• It informs you on login if your password is going to expire in X days (as set in your GPO). Very nice indeed.

Notes to the readers: if you’re experiencing installation problem, the best way is to report them to the likewise-open-discuss mailing list. There you can contact directly likewise developers (of Samba fame) and solve your problems or doubts.

EDIT2: it seems that with the final Ubuntu 8.04 update, likewise-open package is now 100% stable, I didn’t have a single failure since last update (one week up, while before it died at least once per day)

EDIT3: as mentioned in the comment, with likewise-open 4.x you can add

winbind use default domain = yes

in /etc/samba/lwiauthd.conf so you d’nt have to specify the DOMAIN\ part every time you log in your box.

Samba Active Directory Integration

Accessing a Samba Share

Another, use for Samba is to integrate into an existing Windows network. Once part of an Active Directory domain, Samba can provide file and print services to AD users.

The simplest way to join an AD domain is to use Likewise-open. For detailed instructions see the section called “Likewise Open”.

Once part of the domain, install the following packages:

sudo apt-get install samba smbfs smbclient

Since the likewise-open and samba packages use separate secrets.tdb files, a symlink will need to be created in /var/lib/samba:

sudo mv /var/lib/samba/secrets.tdb /var/lib/samba/secrets.tdb.orig
sudo ln -s /etc/samba/secrets.tdb /var/lib/samba

Next, edit /etc/samba/smb.conf changing:

   workgroup = EXAMPLE
 ...
 security = ads
 realm = EXAMPLE.COM
 ...
 idmap backend = lwopen
 idmap uid = 50-9999999999
 idmap gid = 50-9999999999

Restart samba for the new settings to take effect:

sudo /etc/init.d/samba restart

You should now be able to access any Samba shares from a Windows client. However, be sure to give the appropriate AD users or groups access to the share directory. See the section called “Securing a Samba File and Print Server” for more details.

Accessing a Windows Share

Now that the Samba server is part of the Active Directory domain you can access any Windows server shares:

• To mount a Windows file share enter the following in a terminal prompt:

  mount.cifs //fs01.example.com/share mount_point
  

  It is also possible to access shares on computers not part of an AD domain, but a username and password will need to be provided.

• To mount the share during boot place an entry in /etc/fstab, for example:

  //192.168.0.5/share /mnt/windows cifs auto,username=steve,password=secret,rw 0        0
  

• Another way to copy files from a Windows server is to use the smbclient utility. To list the files in a Windows share:

  smbclient //fs01.example.com/share -k -c "ls"
  

• To copy a file from the share, enter:

  smbclient //fs01.example.com/share -k -c "get file.txt"
  

  This will copy the file.txt into the current directory.

• And to copy a file to the share:

  smbclient //fs01.example.com/share -k -c "put /etc/hosts hosts"
  

  This will copy the /etc/hosts to //fs01.example.com/share/hosts.

• The -c option used above allows you to execute the smbclient command all at once. This is useful for scripting and minor file operations. To enter the smb: \> prompt, a FTP like prompt where you can execute normal file and directory commands, simply execute:

  smbclient //fs01.example.com/share -k
  

Replace all instances of fs01.example.com/share, //192.168.0.5/share, username=steve,password=secret, and file.txt with your server's IP, hostname, share name, file name, and an actual username and password with rights to the share. Likewise Open - winbind based Likewise Open simplifies the necessary configuration needed to authenticate a Linux machine to an Active Directory domain. Based on winbind, the likewise-open package takes the pain out of integrating Ubuntu authentication into an existing Windows network. Installation There are two ways to use Likewise Open, likewise-open the command line utility and likewise-open-gui. This section focuses on the command line utility. To install the likewise-open package, open a terminal prompt and enter: sudo apt-get install likewise-open With Ubuntu 9.04 Likewise Open 5.0 is available in the Universe repository. However, since upgrading from Likewise Open 4.1 currently requires the system to leave the domain and re-join, a separate package for version five was created. To install Likewise Open 5.0 enter: sudo apt-get install likewise-open5 Installing likewise-open5 over an existing likewise-open (4.1) installation will replace it. You will have to rejoin the domain after install. Joining a Domain The main executable file of the likewise-open package is /usr/bin/domainjoin-cli, which is used to join your computer to the domain. Before you join a domain you will need to make sure you have: Access to an Active Directory user with appropriate rights to join the domain. The Fully Qualified Domain Name (FQDN) of the domain you want to join. If your AD domain does not match a valid domain such as example.com, it is likely that it has the form of domainname.local. DNS for the domain setup properly. In a production AD environment this should be the case. Proper Microsoft DNS is needed so that client workstations can determine the Active Directory domain is available. If you don't have a Windows DNS server on your network, see the section called “Microsoft DNS” for details. To join a domain, from a terminal prompt enter: sudo domainjoin-cli join example.com Administrator Replace example.com with your domain name, and Administrator with the appropriate user name. You will then be prompted for the user's password. If all goes well a SUCCESS message should be printed to the console. After joining the domain, it is necessary to reboot before attempting to authenticate against the domain. After successfully joining an Ubuntu machine to an Active Directory domain you can authenticate using any valid AD user. To login you will need to enter the user name as 'domain\username'. For example to ssh to a server joined to the domain enter: ssh 'example\steve'@hostname If configuring a Desktop the user name will need to be prefixed with domain\ in the graphical logon as well. To make likewise-open use a default domain, you can add the following statement to /etc/samba/lwiauthd.conf: winbind use default domain = yes Then restart the likewise-open daemons: sudo /etc/init.d/likewise-open restart Once configured for a default domain the 'domain\' is no longer required, users can login using only their username. The domainjoin-cli utility can also be used to leave the domain. From a terminal: sudo domainjoin-cli leave Other Utilities The likewise-open package comes with a few other utilities that may be useful for gathering information about the Active Directory environment. These utilities are used to join the machine to the domain, and are the same as those available in the samba-common and winbind packages: lwinet: Returns information about the network and the domain. lwimsg: Allows interaction with the likewise-winbindd daemon. lwiinfo: Displays information about various parts of the Domain. Please refer to each utility's man page specific for details. Troubleshooting If the client has trouble joining the domain, double check that the Microsoft DNS is listed first in /etc/resolv.conf. For example: nameserver 192.168.0.1 For more information when joining a domain, use the --loglevel verbose or --advanced option of the domainjoin-cli utility: sudo domainjoin-cli --loglevel verbose join example.com Administrator If an Active Directory user has trouble logging in, check the /var/log/auth.log for details. When joining an Ubuntu Desktop workstation to a domain, you may need to edit /etc/nsswitch.conf if your AD domain uses the .local syntax. In order to join the domain the "mdns4" entry from the hosts option. For example: hosts: files mdns4_minimal [NOTFOUND=return] dns mdns4 Change the above to: hosts: files dns [NOTFOUND=return] Then restart networking by entering: sudo /etc/init.d/networking restart You should now be able to join the Active Directory domain. Microsoft DNS The following are instructions for installing DNS on an Active Directory domain controller running Windows Server 2003, but the instructions should be similar for other versions: Click Start → Administrative Tools → Manager Your Server. This will open the Server Role Mangement utility. Click Add or remove a role Click Next Select "DNS Server" Click Next Next Select "Create a forward lookup zone" if it is not selected. Click Next Make sure "This server maintains the zone" is selected and click Next. Enter your domain name and click Next Click Next to "Allow only secure dynamic updates" Click Next to "Allow only secure dynamic updates" Enter the IP for DNS servers to forward queries to, or Select "No, it should not forward queries" and click Next. Click Finish Click Finish DNS is now installed and can be further configured using the Microsoft Management Console DNS snap-in. Next, configure the Server to use itself for DNS queries: Click Start Control Panel Network Connections Right Click "Local Area Connection" Click Properties Double click "Internet Protocol (TCP/IP)" Enter the Server's IP Address as the "Preferred DNS server" Click Ok Click Ok again to save the settings

how to setup Bind in CentOS 5

BIND is an open-source software that implements the Domain Name System (DNS) protocols for the Internet. The name BIND stands for “Berkeley Internet Name Domain”. This article describes how to install and configure BIND in Red Hat Enterprise Linux 5 or CentOS 5.

Installing BIND

The steps below will install the chrooted BIND and the GUI configuration tool.

1. Type in the command below to install BIND.

yum install bind-chroot system-config-bind

2. Start the named service. Learn how to start and stop services.

3. Open the TCP port 53 and UDP port 53. Learn how to configure the firewall.

Configuring BIND

The steps shows how to configure BIND using the GUI configuration tool.

1. Click System, select Administration and click Domain Name System. This will launch the BIND Configuration GUI window.

2. Click Ok to initialize BIND with default values.

3. BIND has now been initialized. We can now create a DNS zone and add DNS records.

Creating a DNS Zone

The steps below will show you how to create a DNS zone named “acme.local”.

1. To create a DNS zone, right click DNS Server, select Add and click Zone.

2. In the New Zone window, click the Ok button under Class.

3. Next, click the Ok button under Origin Type.

4. Provide the name of the zone and click Ok.

5. Review the various settings and click Ok.

6. Click Save and click Yes.

7. You now have a new DNS zone.

Creating DNS Records

The steps below describes how to create some of the most common DNS records.

Creating an A record

An A record maps a hostname to its IPv4 address.

1. Right click the zone you where you want to add an A record, select Add and click A IPv4 Address.

2. Specify the Domain Name and IPv4 Address and click Ok.

3. Click Save and click Yes.

Creating a CNAME record

A CNAME record specifies that a domain name is an alias of another domain name.

1. Right click the zone you where you want to add a CNAME record, select Add and click CNAME Alias.

2. Specify the Domain Name and Canonical Name (target domain name) and click Ok.

3. Click Save and click Yes.

Creating an MX record

An MX record specifies how Internet e-mail should be routed using SMTP.

1. Right click the zone you where you want to add an MX record, select Add and click MX Mail Exchange.

2. Specify the Mail Server Name and click Ok.

3. Click Save and click Yes.

Testing BIND

To test your BIND setup, you can use the nslookup and dig utility.

1. Type the command below in a terminal window to use nslookup

nslookup mail.acme.local localhost

Replace mail.acme.local with the domain you want to check. If your DNS server is not on localhost then change it.

2. Type in the command below to query any records using dig.

dig @localhost acme.local ANY

Replace acme.local with your own domain. If your DNS server is not on localhost then change it.

Samba Server Types and the smb.conf File

Samba configuration is straightforward. All modifications to Samba are done in the /etc/samba/smb.conf configuration file. Although the default smb.conf file is well documented, it does not address complex topics such as LDAP, Active Directory, and the numerous domain controller implementations.

The following sections describe the different ways a Samba server can be configured. Keep in mind your needs and the changes required to the smb.conf file for a successful configuration.

Stand-alone Server

A stand-alone server can be a workgroup server or a member of a workgroup environment. A stand-alone server is not a domain controller and does not participate in a domain in any way. The following examples include several anonymous share-level security configurations and one user-level security configuration.

Anonymous Read-Only

The following smb.conf file shows a sample configuration needed to implement anonymous read-only file sharing. The security = share parameter makes a share anonymous. Note, security levels for a single Samba server cannot be mixed. The security directive is a global Samba parameter located in the [global] configuration section of the smb.conf file.

[global]
workgroup = DOCS
netbios name = DOCS_SRV
security = share 
[data]
comment = Documentation Samba Server
path = /export
read only = Yes
guest only = Yes

Anonymous Read/Write

The following smb.conf file shows a sample configuration needed to implement anonymous read/write file sharing. To enable anonymous read/write file sharing, set the read only directive to no. The force user and force group directives are also added to enforce the ownership of any newly placed files specified in the share.

Note

Although having an anonymous read/write server is possible, it is not recommended. Any files placed in the share space, regardless of user, are assigned the user/group combination as specified by a generic user (force user) and group (force group) in the smb.conf file.

[global]
workgroup = DOCS
netbios name = DOCS_SRV
security = share 
[data]
comment = Data
path = /export
force user = docsbot
force group = users
read only = No
guest ok = Yes

Anonymous Print Server

The following smb.conf file shows a sample configuration needed to implement an anonymous print server. Setting browseable to no as shown does not list the printer in Windows Network Neighborhood. Although hidden from browsing, configuring the printer explicitly is possible. By connecting to DOCS_SRV using NetBIOS, the client can have access to the printer if the client is also part of the DOCS workgroup. It is also assumed that the client has the correct local printer driver installed, as the use client driver directive is set to Yes. In this case, the Samba server has no responsibility for sharing printer drivers to the client.

[global]
workgroup = DOCS
netbios name = DOCS_SRV
security = share
printcap name = cups
disable spools= Yes
show add printer wizard = No
printing = cups 
[printers]
comment = All Printers
path = /var/spool/samba
guest ok = Yes
printable = Yes
use client driver = Yes
browseable = Yes

Secure Read/Write File and Print Server

The following smb.conf file shows a sample configuration needed to implement a secure read/write print server. Setting the security directive to user forces Samba to authenticate client connections. Notice the [homes] share does not have a force user or force group directive as the [public] share does. The [homes] share uses the authenticated user details for any files created as opposed to the force user and force group in [public].

[global]
workgroup = DOCS
netbios name = DOCS_SRV
security = user
printcap name = cups
disable spools = Yes
show add printer wizard = No
printing = cups 
[homes]
comment = Home Directories
valid users = %S
read only = No
browseable = No 
[public]
comment = Data
path = /export
force user = docsbot
force group = users
guest ok = Yes 
[printers]
comment = All Printers
path = /var/spool/samba
printer admin = john, ed, @admins
create mask = 0600
guest ok = Yes
printable = Yes
use client driver = Yes
browseable = Yes

Domain Member Server

A domain member, while similar to a stand-alone server, is logged into a domain controller (either Windows or Samba) and is subject to the domain's security rules. An example of a domain member server would be a departmental server running Samba that has a machine account on the Primary Domain Controller (PDC). All of the department's clients still authenticate with the PDC, and desktop profiles and all network policy files are included. The difference is that the departmental server has the ability to control printer and network shares.

Active Directory Domain Member Server

The following smb.conf file shows a sample configuration needed to implement an Active Directory domain member server. In this example, Samba authenticates users for services being run locally but is also a client of the Active Directory. Ensure that your kerberos realm parameter is shown in all caps (for example realm = EXAMPLE.COM). Since Windows 2000/2003 requires Kerberos for Active Directory authentication, the realm directive is required. If Active Directory and Kerberos are running on different servers, the password server directive may be required to help the distinction.

[global]
realm = EXAMPLE.COM
security = ADS
encrypt passwords = yes
# Optional. Use only if Samba cannot determine the Kerberos server automatically.
password server = kerberos.example.com

In order to join a member server to an Active Directory domain, the following steps must be completed:

• Configuration of the smb.conf file on the member server

• Configuration of Kerberos, including the /etc/krb5.conf file, on the member server

• Creation of the machine account on the Active Directory domain server

• Association of the member server to the Active Directory domain

To create the machine account and join the Windows 2000/2003 Active Directory, Kerberos must first be initialized for the member server wishing to join the Active Directory domain. To create an administrative Kerberos ticket, type the following command as root on the member server:

kinit administrator@EXAMPLE.COM

The kinit command is a Kerberos initialization script that references the Active Directory administrator account and Kerberos realm. Since Active Directory requires Kerberos tickets, kinit obtains and caches a Kerberos ticket-granting ticket for client/server authentication. For more information on Kerberos, the /etc/krb5.conf file, and the kinit command, refer to Section 42.6, “Kerberos”.

To join an Active Directory server (windows1.example.com), type the following command as root on the member server:

net ads join -S windows1.example.com -U administrator%password

Since the machine windows1 was automatically found in the corresponding Kerberos realm (the kinit command succeeded), the net command connects to the Active Directory server using its required administrator account and password. This creates the appropriate machine account on the Active Directory and grants permissions to the Samba domain member server to join the domain.

Note

Since security = ads and not security = user is used, a local password backend such as smbpasswd is not needed. Older clients that do not support security = ads are authenticated as if security = domain had been set. This change does not affect functionality and allows local users not previously in the domain.

Windows NT4-based Domain Member Server

The following smb.conf file shows a sample configuration needed to implement a Windows NT4-based domain member server. Becoming a member server of an NT4-based domain is similar to connecting to an Active Directory. The main difference is NT4-based domains do not use Kerberos in their authentication method, making the smb.conf file simpler. In this instance, the Samba member server functions as a pass through to the NT4-based domain server.

[global]
workgroup = DOCS
netbios name = DOCS_SRV
security = domain 
[homes]
comment = Home Directories
valid users = %S
read only = No
browseable = No 
[public]
comment = Data
path = /export
force user = docsbot
force group = users
guest ok = Yes

Having Samba as a domain member server can be useful in many situations. There are times where the Samba server can have other uses besides file and printer sharing. It may be beneficial to make Samba a domain member server in instances where Linux-only applications are required for use in the domain environment. Administrators appreciate keeping track of all machines in the domain, even if not Windows-based. In the event the Windows-based server hardware is deprecated, it is quite easy to modify the smb.conf file to convert the server to a Samba-based PDC. If Windows NT-based servers are upgraded to Windows 2000/2003, the smb.conf file is easily modifiable to incorporate the infrastructure change to Active Directory if needed.

Important

After configuring the smb.conf file, join the domain before starting Samba by typing the following command as root:

net rpc join -U administrator%password

Note that the -S option, which specifies the domain server hostname, does not need to be stated in the net rpc join command. Samba uses the hostname specified by the workgroup directive in the smb.conf file instead of it being stated explicitly.

Domain Controller

A domain controller in Windows NT is functionally similar to a Network Information Service (NIS) server in a Linux environment. Domain controllers and NIS servers both host user/group information databases as well as related services. Domain controllers are mainly used for security, including the authentication of users accessing domain resources. The service that maintains the user/group database integrity is called the Security Account Manager (SAM). The SAM database is stored differently between Windows and Linux Samba-based systems, therefore SAM replication cannot be achieved and platforms cannot be mixed in a PDC/BDC environment.

In a Samba environment, there can be only one PDC and zero or more BDCs.

Important

Samba cannot exist in a mixed Samba/Windows domain controller environment (Samba cannot be a BDC of a Windows PDC or vice versa). Alternatively, Samba PDCs and BDCs can coexist.

Primary Domain Controller (PDC) using tdbsam

The simplest and most common implementation of a Samba PDC uses the tdbsam password database backend. The passdb backend directive controls which backend is to be used for the PDC.

[global]
workgroup = DOCS
netbios name = DOCS_SRV 
passdb backend = tdbsam
security = user
add user script = /usr/sbin/useradd -m %u
delete user script = /usr/sbin/userdel -r %u
add group script = /usr/sbin/groupadd %g 
delete group script = /usr/sbin/groupdel %g 
add user to group script = /usr/sbin/usermod -G %g %u
add machine script = /usr/sbin/useradd -s /bin/false -d /dev/null  -g machines %u
# The following specifies the default logon script 
# Per user logon scripts can be specified in the user
# account using pdbedit logon script = logon.bat
# This sets the default profile path.
# Set per user paths with pdbedit
logon drive = H:
domain logons = Yes
os level = 35
preferred master = Yes
domain master = Yes 
[homes]
 comment = Home Directories
 valid users = %S
 read only = No 
[netlogon]
 comment = Network Logon Service
 path = /var/lib/samba/netlogon/scripts
 browseable = No 
 read only = No
# For profiles to work, create a user directory under the
# path shown.
mkdir -p /var/lib/samba/profiles/john
[Profiles]
 comment = Roaming Profile Share
 path = /var/lib/samba/profiles
 read only = No
 browseable = No
 guest ok = Yes
 profile acls = Yes 
# Other resource shares ... ...

Update CentOS 5.0 to 5.1

To update CentOS 5.0 to CentOS 5.1, all you have to do is type in yum update from the Terminal window. This command will automatically get the updated packages over the internet. But if you have the CentOS 5.1 DVD, the steps below will show you how to update from that.

1. Insert the CentOS 5.1 DVD into the DVD drive and double click the Computer icon in the CentOS Desktop.

2. On the Computer – File Browser window, double click on the CD-ROM Drive.

3. The CentOS 5.1 DVD should now be available on /media/CentOS_5.1_Final.

4. From a terminal window, type in ln -sf /media/CentOS_5.1_Final /media/CentOS and press Enter. This enables the CentOS 5.1 DVD to be located on the yum search path.

5. Edit the file /etc/yum.repos.d/CentOS-Media.repo and change beta into CentOS-5 in the line gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-beta.

6. Finally, type in yum --disablerepo=* --enablerepo=c5-media and press Enter to begin the update process.

For 64-bit users: You need to add the line login_process_size = 64 in the file /etc/dovecot.conf and restart dovecot after upgrading.

how to administer a Red Hat Enterprise Linux 5 or CentOS 5 server.

System Management

This section describes how to perform system management tasks.

How to add, edit or remove a user account

How to add or remove packages or applications

How to start, stop or restart a background service
How to enable or disable an on demand service

How to configure the firewall

How to synchronize the system clock using NTP

System Utilities

This section describes utilities you can use to manage your system.

How to setup SSH to remotely administer a Linux server using a command line

How to use VNC to remotely administer a Linux server using a GUI

How to setup Webmin, a web based system administration tool

How to use rsync to synchronize files between two computers

How to use vi, a command line editor

How to Setup Webmin in CentOS 5

1.Go to www.webmin.com and download the Webmin RPM package.

2. Double click the downloaded file to install Webmin.

3. After installing Webmin, configure the firewall to allow traffic on the TCP port 10000. Learn how to configure the firewall.

4. Start the httpd service. Learn how to start and stop services here.

5. From a web browser, connect to https://localhost:10000 and login using root.

6. That’s it. It’s working.

Webmin is a web-based interface for system administration for Unix. Using any modern web browser, you can setup user accounts, Apache, DNS, file sharing and much more. This article will show you how to install Webmin.