Manage Services (RHEL 6)

This section describes how to manage the services using the Service Configuration tool.

1. Click System, select Administration, and click Services. This will launch the Service Configuration window.

2. In the Service Configuration window, select the service you wish to run when the system starts and click Enable.

3. To immediately run the service, click Start.

Make sure xinetd is running if you enable any on demand services.

Manage Services (RHEL 5)

This section describes how to manage the services using the Service Configuration tool.

1. Click System, select Administration, select Server Settings and click Services. This will launch the Service Configuration window.

2. In the Service Configuration window, check the service you wish to start on the next system startup, in this case the service postfix. To start the service immediately, press Start.

 

Unchecked services will not be started on the next system startup. To immediately stop a service, select the service and press Stop.

 

To restart a service, select the service and press Restart.

3. Press Save to save your changes.

4. You can also do the same for On-Demand Services.

Make sure xinetd is running if you enable any On-Demand Services. You can find xinetd in the Background Services tab.

Manage Services (Console)

Listed below are the console commands to manage the services. You need to have root level access to use the commands below.

/sbin/chkconfig ––list

/sbin/chkconfig [name] on

/usr/sbin/update-rc.d [name] defaults

/sbin/chkconfig [name] off

/usr/sbin/update-rc.d -f [name]
 remove

/sbin/service [name] start

/usr/sbin/service [name] start

/sbin/service [name] stop

/usr/sbin/service [name] stop

/sbin/service [name] restart

/usr/sbin/service [name] restart

/sbin/service [name] status

/usr/sbin/service [name] status

File Management (GUI)

Managing files in GUI mode is a simple as launching the File Browser.

1. Click Applications, select System Tools then click File Browser. This will launch the File Browser window.

2. From the File Browser tool you can now perform your desired file operation.

File Management (Console)

Below are the console commands to manage files. This is just an overview of the commands available, to get more information, type in man command to get the manual for the specified command.

Common Operations

• cp -a source dest
  copy the specified file or directory
• rm -rf name
  delete the specified file or directory and all of its contents
• mv old new
  move a file or directory to a new location. Also used to rename a file or directory
• ln -s source linkname
  create a symbolic link to the specified file or directory

Directory Operations

• cd
  change to the home directory
• cd path
  change to the specified directory
• pwd
  print working directory
• ls
  list directory
• mkdir name
  create the specified directory
• rmdir name
  delete the specified directory. Directory should be empty

File Operations

• chown owner file
  change the file owner to the specified user
• chmod permissions files
  change the file permissions
• cat file
  shows the file content
• more file
  shows the file content a few screens at a time
• less file
  shows the file content similar to how vi displays a file
• vi file
  edit the specified file. Learn how to use the vi editor
• head file
  shows the first few lines of a file
• tail file
  shows the last few lines of a file
• sort file
  shows the file content in order by lines
• uniq file
  shows the file content, discarding all but one of successive identifical lines
• grep pattern file
  searches for the pattern inside the specified file
• file filename
  determine file type
• diff file1 file1
  compares two files

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Configure Network Device (GUI)

This section describes how to configure the network device using GUI tools.

1. Click System, select Administration then click Network. This will launch the Network Configuration window.

2. Select the network device you want to modify and click Edit.

3. In the Ethernet Device window, apply your changes and click OK.

4. Click the DNS tab and apply your DNS settings.

5. To save your changes, click the File and click Save.

6. To effect your changes, click the Devices tab. Next, select the device and click Deactivate then click Activate to reactivate the device.

7. Update your /etc/hosts file.

Although the Network Configuration tool has a feature to update the /etc/hosts file, it is more reliable to edit it directly instead.

Configure Network Device (TUI)

This section describes how to configure the network device using text user interface (TUI) tools.

1. Launch the Network Configuration TUI tool using the command below. Then apply the necessary changes to your network device.

system-config-network-tui

2. To effect your changes, restart the network service using the command below.

service network restart

3. Update your /etc/hosts file.

Configure Hosts

1. Click Applications, select System Tools then click File Browser. This will launch the File Browser window.

2. In the Location field, type in /etc and press Enter. If you don’t see the Location field, click the notepad button to toggle to text-based location bar.

3. Locate and double click on the file hosts to open it for editing. Update the content similar to the lines below.

127.0.0.1       localhost.localdomain localhost
::1             localhost6.localdomain6 localhost6
192.168.0.4     mail.acme.local mail

Replace the last line with your own IP address, fully qualified domain name and host name.

Test the Host Name Lookup

1. Click Applications, select Accessories, and click Terminal. This will launch the Terminal window.

2. In the terminal window, type in the command below.

ping localhost

You should see localhost.localdomain and 127.0.0.1

3. Next, type in the command below.

ping mail

Replace mail with your own hostname. You should see your fully qualified domain name and ip address.

System Management

This section describes how to perform system management tasks.

How to manage directories and files

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 a network device

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

1. Download and install the Razor’s Edge Repository rpm package.

2. Install poppassd using the command below.

yum install poppassd

3. Enable the on-demand service poppassd. Learn how to enable on-demand services here.

Make sure xinetd is also running so it can automatically launch poppassd.

4. Edit the file /etc/pam.d/poppassd and replace the content with the lines below.

auth      required    pam_unix.so
account   required    pam_unix.so
password  requisite   pam_cracklib.so
password  sufficient  pam_unix.so md5 shadow

The line password requisite pam_cracklib.so requires the new password to be strong and at least six (6) characters long. You can leave it out if you do not want that restriction.

5. In a Terminal window, type in the highlighted commands below.

Sample poppassd session. Replace johndoe, secret and p@ssw0rd with your own valid user account, old password and new password respectively.

[root@mail ~]# telnet localhost 106
Trying 127.0.0.1...
Connected to localhost.localdomain (127.0.0.1).
Escape character is '^]'.
200 poppassd v1.8.5 hello, who are you?
user johndoe
200 Your password please.
pass secret
200 Your new password please.
newpass p@ssw0rd
200 Password changed, thank-you.
quit
200 Bye.

Adding RPMforge to Yum

The rpmforge repo package can be downloaded from the site below.

1. Launch Firefox and go to http://dag.wieers.com/rpm/FAQ.php#B2. Click on the package appropriate for your version of Red Hat Enterprise Linux or CentOS.

2. Choose Open with Software Installer (default) and click Ok.

3. The Installing packages window will appear. Click Apply to proceed.

4. Finally click Ok.

Lowering the RPMforge priority

Lowering the priority of the RPMforge repository will ensure that the base packages provided by RHEL/CentOS will not be replaced by a newer version from RPMforge.

1. Install the Yum priorities package using the command below.

yum install yum-priorities

2. Edit the file /etc/yum.repos.d/rpmforge.repo and add the line below.

priority=10

3. Test your configuration using the command below. You should see a priority protections message in the output.

yum check-update

The attributes below are required to be filled up to be able to use LDAP authentication.

• uid – User name
• userPassword – User password
• uidNumber – UID
• gidNumber – GID
• homeDirectory – Home directory
• loginShell – Login shell

If you are using Fedora Directory Server, it has a great GUI tool for managing the required Posix attributes.

Setup Authentication

1. Click System, select Administration and click Authentication. This will launch the Authentication Configuration window.

2. Check Enable LDAP Support and click the Configure LDAP button.

3. Fill in the LDAP Search Base DN and LDAP Server fields. Click Ok when you are done.

4. Click the Authentications tab and check Enable LDAP Support.

5. Click the Options tab and check Local authorization is sufficient for local users and Create home directories on the first login. Click Ok when you are done.

6. Type in getent passwd in a terminal window. You should see your LDAP user accounts.

Finally, reboot your computer. You should now be able to login using LDAP user accounts.

If your LDAP server requires authentication or its attributes does not conform to the RFC 2307 specification, you need to edit the file /etc/ldap.conf to make this work. See Active Directory Authentication for an example.

The version of sudo that comes with RHEL/CentOS 5 does not work with non local user accounts. While this is not yet fixed, use the sudo rpm package for Fedora 8.