uCertify Articles » Advanced Level Linux Professional (LPIC-2) http://www.ucertify.com/article Just another WordPress weblog Wed, 04 Nov 2009 00:00:00 +0000 http://wordpress.org/?v=2.8.4 en hourly 1 Installation and Development of LDAP (Lightweight Directory Access Protocol) http://www.ucertify.com/article/installation-and-development-of-ldap-lightweight-directory-access-protocol-2.html http://www.ucertify.com/article/installation-and-development-of-ldap-lightweight-directory-access-protocol-2.html#comments Tue, 03 Nov 2009 00:00:00 +0000 uCertify 112430 Download practice question and study guide for lpic-2 for exam. Author : Yong Mook Kim Download free practice test for lpic Linux Professional exam. Website : http://www.mkyong.com Pass LPI lpic-3 - Senior Level Linux Professional (LPIC-3) -->

LDAP is a protocol that helps us to access the database on different types of platforms. To implement LDAP on a Linux server, you need to download OpenLDAP Software. It is open source software. OpenLDAP Software comprises mainly two basic daemons:

  • slapd (Stand-alone LDAP daemon)
    • OpenLDAP server configuration file is called slapd.conf.
    • It provides authentication services through SASL (Simple Authentication and Security Layer).
    • It uses TLS (Transport Layer Security) for privacy concerns.
    • It allows or restricts access to the server by using TCP wrappers.
    • One of the most important functions of slapd is to provide a reliable access control facility.
  • slurpd (stand-alone LDAP update replication daemon)
    • This is used to replicate the database of LDAP directory.
    • The master slapd server updates the slave server by using slurpd.
    • It helps the master slapd server in distributing the load among the slave servers.

To unpack the downloaded gzipped package, you have to copy the package to a desirable directory such as /usr/local

Requirements before installation: Before installing OpenLDAP software, the LDAP server requires some additional packages:

  • OpenSSL TLS libraries: Transport Layer Security (TLS) and its predecessor, Secure Sockets Layer (SSL), are cryptographic protocols that provide security over the network. These are used to encrypt the segments of a network connection.
  • Kerberos Authentication Services: It is a distributed authentication service.
  • Database software like Berkeley DB: It stores the database using Oracle Berkeley DB package.
  • TCP Wrappers: These are used in the servers having non public information.

Installation: You can install OpenLDAP in either of the two ways.

  • Use apt-get/dpkg to install the binary package.

  • Install OpenLDAP from sources and unpack the tar gzipped package to a desirable directory.

    • Run the following commands to build the server.

Overview of LDAP Backends:

  1. BDB (Berkeley Database Backend): The BDB backend is used with a normal slapd database. It stores data with the help of Oracle Berkeley DB package.

  2. LDAP: The LDAP backend is not a real database; it only forwards the incoming requests to another LDAP server.

  3. LDIF (LDAP Data Interchange Format): LDIF is a text-based format for representing the LDAP contents.

  4. Metadirectory: The Meta backend is similar to the LDAP backend. It acts as a proxy to forward requests to a set of remote LDAP servers called target.

  5. Monitor: The running status of daemon is dynamically maintained by this backend.

  6. Null: Null backend searches return success, and updates them. The slapadd and slapcat tools are also very useful.

  7. Passwd: The Passwd backend lists the information stored in a system passwd file.

  8. Perl/Shell: This backend can be used after installing the Perl module. Perl scripts are used for interacting with the LDAP directories.

  9. SQL: The SQL backend is used with RDBMS (Relational Database Management System).

Developing LDAP Applications with Perl: perl-ldap provides an easy access to data contained in LDAP directories. You can write basic Perl scripts to interact with an LDAP directory. You need to download the following two packages:

  1. Convert-BER-1.31.tar.gz

  2. perl-ldap-0.15.tar.gz

You can unpack and install the Convert-BER-1.31.tar.gz package using the following commands.

Use the following commands to unpack and install perl-ldap-0.15.tar.gz.


Now you are able to write basic Perl scripts to interact with an LDAP directory. You can use the following statement to invoke perl-ldap:

After invoking, you have to open a new LDAP connection. Below is an example of how to connect to a computer with the hostname ldapserver.ucertify.com:

By default, LDAP uses port 389. If you want to use a different port, you need to mention it:

You can also set the timeout parameter:

Binding to the Server: After creating a connection to an LDAP server, you need to bind to it:

To close a connection, you must unbind from it:

Adding Entries to the Database: You can add LDAP entries to the directory:

Searching the directory: The ->search function is used to search the LDAP directory:

It searches the entire LDAP tree. You can confine your search only to the ou=People branch using the following command:

Modifying the directory: There are three types of modifications that can be performed in an LDAP directory:

  • add

  • delete

  • replace

Summary: perl-ldap is a convenient tool for accessing LDAP servers with Perl scripts. Now a days, LDAP is emerging as a global directory providing service to a much broader context.

Click here to get free 117-202 Advanced Level Linux Professional II exam practice questions. Click here to download 117-301 test study guide and practice question. Share/Bookmark]]> http://www.ucertify.com/article/installation-and-development-of-ldap-lightweight-directory-access-protocol-2.html/feed 0 What is chage command? http://www.ucertify.com/article/what-is-chage-command-2.html http://www.ucertify.com/article/what-is-chage-command-2.html#comments Thu, 10 Sep 2009 00:00:00 +0000 uCertify 2201121

The chage command is used for changing user password expiry information.

Syntax:

chage [-m mindays] [-M maxdays] [-d lastday] [-E expireday] [-I inactive] [-W warndays] [-l] user

The functions of the switches are as follows:

Switch Meaning
-m Minimum number of days between each successive password change.
-M Maximum number of days during which a password remains valid.
-d Number of days since January 1st, 1970 when a password was last changed.
-E The date on which the user account will no longer be accessible.
-I Number of days since the expiry of a user password when an account is locked.
-W Number of days of warning before a password change is required.
-l Used by a non-administrative user to check his account/password expiry status.
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The chage command is used for changing user password expiry information.

Syntax:

chage [-m mindays] [-M maxdays] [-d lastday] [-E expireday] [-I inactive] [-W warndays] [-l] user

The functions of the switches are as follows:

Switch Meaning
-m Minimum number of days between each successive password change.
-M Maximum number of days during which a password remains valid.
-d Number of days since January 1st, 1970 when a password was last changed.
-E The date on which the user account will no longer be accessible.
-I Number of days since the expiry of a user password when an account is locked.
-W Number of days of warning before a password change is required.
-l Used by a non-administrative user to check his account/password expiry status.
Share/Bookmark]]> http://www.ucertify.com/article/what-is-chage-command.html/feed 0 Installation and Development of LDAP (Lightweight Directory Access Protocol) http://www.ucertify.com/article/installation-and-development-of-ldap-lightweight-directory-access-protocol.html http://www.ucertify.com/article/installation-and-development-of-ldap-lightweight-directory-access-protocol.html#comments Mon, 13 Jul 2009 00:00:00 +0000 uCertify 112430 Pass LPI lpic-2 - Advanced Level Linux Professional (LPIC-2) Author : Yong Mook Kim Become LPI Linux Professional certified. Website : http://www.mkyong.com Download free practice test for LPI Senior Level Linux Professional (LPIC-3) exam. -->

LDAP is a protocol that helps us to access the database on different types of platforms. To implement LDAP on a Linux server, you need to download OpenLDAP Software. It is open source software. OpenLDAP Software comprises mainly two basic daemons:

  • slapd (Stand-alone LDAP daemon)
    • OpenLDAP server configuration file is called slapd.conf.
    • It provides authentication services through SASL (Simple Authentication and Security Layer).
    • It uses TLS (Transport Layer Security) for privacy concerns.
    • It allows or restricts access to the server by using TCP wrappers.
    • One of the most important functions of slapd is to provide a reliable access control facility.
  • slurpd (stand-alone LDAP update replication daemon)
    • This is used to replicate the database of LDAP directory.
    • The master slapd server updates the slave server by using slurpd.
    • It helps the master slapd server in distributing the load among the slave servers.

To unpack the downloaded gzipped package, you have to copy the package to a desirable directory such as /usr/local

Requirements before installation: Before installing OpenLDAP software, the LDAP server requires some additional packages:

  • OpenSSL TLS libraries: Transport Layer Security (TLS) and its predecessor, Secure Sockets Layer (SSL), are cryptographic protocols that provide security over the network. These are used to encrypt the segments of a network connection.
  • Kerberos Authentication Services: It is a distributed authentication service.
  • Database software like Berkeley DB: It stores the database using Oracle Berkeley DB package.
  • TCP Wrappers: These are used in the servers having non public information.

Installation: You can install OpenLDAP in either of the two ways.

  • Use apt-get/dpkg to install the binary package.

  • Install OpenLDAP from sources and unpack the tar gzipped package to a desirable directory.

    • Run the following commands to build the server.

Overview of LDAP Backends:

  1. BDB (Berkeley Database Backend): The BDB backend is used with a normal slapd database. It stores data with the help of Oracle Berkeley DB package.

  2. LDAP: The LDAP backend is not a real database; it only forwards the incoming requests to another LDAP server.

  3. LDIF (LDAP Data Interchange Format): LDIF is a text-based format for representing the LDAP contents.

  4. Metadirectory: The Meta backend is similar to the LDAP backend. It acts as a proxy to forward requests to a set of remote LDAP servers called target.

  5. Monitor: The running status of daemon is dynamically maintained by this backend.

  6. Null: Null backend searches return success, and updates them. The slapadd and slapcat tools are also very useful.

  7. Passwd: The Passwd backend lists the information stored in a system passwd file.

  8. Perl/Shell: This backend can be used after installing the Perl module. Perl scripts are used for interacting with the LDAP directories.

  9. SQL: The SQL backend is used with RDBMS (Relational Database Management System).

Developing LDAP Applications with Perl: perl-ldap provides an easy access to data contained in LDAP directories. You can write basic Perl scripts to interact with an LDAP directory. You need to download the following two packages:

  1. Convert-BER-1.31.tar.gz

  2. perl-ldap-0.15.tar.gz

You can unpack and install the Convert-BER-1.31.tar.gz package using the following commands.

Use the following commands to unpack and install perl-ldap-0.15.tar.gz.


Now you are able to write basic Perl scripts to interact with an LDAP directory. You can use the following statement to invoke perl-ldap:

After invoking, you have to open a new LDAP connection. Below is an example of how to connect to a computer with the hostname ldapserver.ucertify.com:

By default, LDAP uses port 389. If you want to use a different port, you need to mention it:

You can also set the timeout parameter:

Binding to the Server: After creating a connection to an LDAP server, you need to bind to it:

To close a connection, you must unbind from it:

Adding Entries to the Database: You can add LDAP entries to the directory:

Searching the directory: The ->search function is used to search the LDAP directory:

It searches the entire LDAP tree. You can confine your search only to the ou=People branch using the following command:

Modifying the directory: There are three types of modifications that can be performed in an LDAP directory:

  • add

  • delete

  • replace

Summary: perl-ldap is a convenient tool for accessing LDAP servers with Perl scripts. Now a days, LDAP is emerging as a global directory providing service to a much broader context.

Get certified in first attempt download 117-202 - Advanced Level Linux Professional II simulation. Download free practice test for LPI Senior Level Linux Professional-I exam. Share/Bookmark]]> http://www.ucertify.com/article/installation-and-development-of-ldap-lightweight-directory-access-protocol.html/feed 0 How to install LDAP? http://www.ucertify.com/article/how-to-install-ldap.html http://www.ucertify.com/article/how-to-install-ldap.html#comments Mon, 13 Jul 2009 00:00:00 +0000 uCertify 112438 Download free practice test for LPI Advanced Level Linux Professional (LPIC-2) exam. Author : Yong Mook Kim Get certified in first attempt download lpic - Linux Professional simulation. Website : http://www.mkyong.com Click here to download lpic-3 test study guide and practice question. -->

To implement LDAP on a Linux server, you need to download the OpenLDAP software. It is open source software. The OpenLDAP software comprises mainly two basic daemons: slapd and slurpd. OpenLDAP can be installed in either of the following two ways:

  1. Use apt-get/dpkg to install the binary package:

  2. Install OpenLDAP from sources and unpack the tar gzipped package to a desirable directory:

Run the following commands to build the server:

Download free practice test for 117-202 Advanced Level Linux Professional II exam. Download practice question and study guide for 117-301 for exam. Share/Bookmark]]> http://www.ucertify.com/article/how-to-install-ldap.html/feed 0 What is 3DES? http://www.ucertify.com/article/what-is-3des.html http://www.ucertify.com/article/what-is-3des.html#comments Thu, 09 Jul 2009 00:00:00 +0000 uCertify 1401439

3DES, also referred to as triple DES, is a mode of the Data Encryption Standard (DES) encryption algorithm. 3DES uses three 64-bit keys to encrypt data thrice. Primarily, it encrypts data with a 64-bit key. Then, the output data is again encrypted with the second 64-bit key. Finally, the third 64-bit key is used for encryption. DES uses the block cipher method to break a data file into 64-bit blocks, which are then encrypted.

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A hot spare disk is a hard disk drive that is flagged for use in case another drive in the RAID array fails. If a hot spare disk is configured with a RAID array, and a disk in the RAID fails, the hot spare disk is immediately available for the RAID to start rebuilding the RAID data. As soon as the rebuild is completed, the RAID array becomes fully functional without affecting the performance. All the RAIDS (0, 1, 3, 5, etc.) support hot spare disks.

Click here to get free 117-201 Advance Level Linux Professional (LPIC-2) exam practice questions. Download practice question and study guide for XK0-002 for exam. Share/Bookmark]]> http://www.ucertify.com/article/what-is-a-hot-spare-disk.html/feed 0 What is /dev directory? http://www.ucertify.com/article/what-is-dev-directory.html http://www.ucertify.com/article/what-is-dev-directory.html#comments Mon, 29 Jun 2009 00:00:00 +0000 uCertify 1401158

The /dev directory contains files that represent access points to the devices installed on a Linux computer. These devices include terminal devices, floppy disk drives, hard disk drives, RAM, CD-ROMs, etc.

Share/Bookmark]]> http://www.ucertify.com/article/what-is-dev-directory.html/feed 0 What is IFCONFIG command? http://www.ucertify.com/article/what-is-ifconfig-command.html http://www.ucertify.com/article/what-is-ifconfig-command.html#comments Mon, 29 Jun 2009 00:00:00 +0000 uCertify 1401168

IFCONFIG is a command-line tool, which is used for network interface management. Following are some of the options used with the command:

  • up: This option is used to activate the specified interface.

  • down: This option is used to deactivate the specified interface.

  • lo: This option is used to view the loopback interface.

The IFCONFIG command is also used to configure an interface.

Syntax:

IFCONFIG interface options

For example, to configure a Linux computer’s first network interface with an IP address 200.200.200.123 and subnet mask 255.255.255.0, the following command is used:

IFCONFIG eth0 200.200.200.123 netmask 255.255.255.0

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Linux uses INETD daemon to control most of the network services. INETD handles communication for these services by listening on their specific TCP/IP ports. When a request comes in, INETD enables the services required for processing the request. The /etc/inetd.conf configuration file is used to keep the configuration information of the services.

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