Translations by zhongxin

Computer networks are often comprised of diverse systems, and while operating a network made up entirely of Ubuntu desktop and server computers would certainly be fun, some network environments must consist of both Ubuntu and <trademark class="registered">Microsoft</trademark><trademark class="registered">Windows</trademark> systems working together in harmony. This section of the <phrase>Ubuntu</phrase> Server Guide introduces principles and tools used in configuring your Ubuntu Server for sharing network resources with Windows computers.

<emphasis role="bold">Authentication and Access</emphasis>. Establishing the identity of a computer or user of the network and determining the information the computer or user is authorized to access using such principles and technologies as file permissions, group policies, and the Kerberos authentication service.

Fortunately, your Ubuntu system may provide all such facilities to Windows clients and share network resources among them. One of the principle pieces of software your Ubuntu system includes for Windows networking is the SAMBA suite of SMB server applications and tools. This section of the <phrase>Ubuntu</phrase> Server Guide will briefly introduce the installation and limited configuration of the SAMBA suite of server applications and utilities. Additional, detailed documentation and information on SAMBA is beyond the scope of this documentation, but exists on the <ulink url="http://www.samba.org">SAMBA website</ulink>.

At the prompt enter the following command to install the SAMBA server applications:

You may configure the SAMBA server by editing the <filename>/etc/samba/smb.conf</filename> file to change the default settings or add new settings. More information about each setting is available in the comments of the <filename>/etc/samba/smb.conf</filename> file or by viewing the <filename>/etc/samba/smb.conf</filename> manual page from the prompt with the following command typed at a terminal prompt:

Prior to editing the configuration file, you should make a copy of the original file and protect it from writing so you will have the original settings as a reference and to re-use as necessary.

The following sections will discuss SAMBA and the supporting technologies, such as Lightweight Directory Access Protocol (LDAP) server, and Kerberos authentication server in more detail. You will also learn about some of the available configuration directives available the SAMBA configuration file which facilitate network integration with Windows clients and servers.

The LDAP server application provides Directory Services functionality to Windows computers in a manner very similar to Microsoft Active Directory services. Such services include managing the identities and relationships of computers, users, and groups of computers or users that participate in the network, and providing a consistent means to describe, locate, and manage these resources. The freely available implementation of LDAP available for your Ubuntu system is called <emphasis role="italic">OpenLDAP</emphasis>. The server daemons responsible for handling OpenLDAP directory requests and the propagation of directory data from one LDAP server to another on Ubuntu, are <application>slapd</application> and <application>slurpd</application>. OpenLDAP may be used in conjunction with SAMBA to provide File, Print, and Directory services in much the same way a Windows Domain Controller does so long as SAMBA is compiled with LDAP support.

The Kerberos authentication security system is a standardized service for providing authentication to computers and users by means of a centralized server which grants encrypted authorization tickets accepted for authorization by any other computer using Kerberos. Benefits of Kerberos authentication include mutual authentication, delegated authentication, interoperability, and simplified trust management. The primary server daemons for handling the Kerberos authentication and Kerberos database administration on Ubuntu are <application>krb5kdc</application> and <application>kadmin</application>. SAMBA may use Kerberos as a mechanism for authenticating computers and users against a Windows Domain Controller. To do so, the Ubuntu system must have Kerberos installed, and the <filename>/etc/samba/smb.conf</filename> must be modified to select the the proper <emphasis role="italic">realm</emphasis> and <emphasis role="italic">security</emphasis> mode. For example, edit the <filename>/etc/samba/smb.conf</filename> file and add the values:

You will need to restart the SAMBA daemons to effect these changes. Restart the SAMBA daemons with the following command entered at a terminal prompt:

Computer Accounts are used in Directory Services to uniquely identify computer systems participating in a network, and are even treated in the same manner as users in terms of security. Computer accounts may have passwords just as user accounts do, and are subject to authorization to network resources in the same manner as user accounts. For example, if a network user, with a valid account for a particular network attempts to authenticate with a network resource from a computer which does not have a valid computer account, depending upon policies enforced on the network, the user may be denied access to the resource if the computer the user is attempting authentication from is considered to be an unauthorized computer.

A computer account may be added to the SAMBA password file, provided the name of the computer being added exists as a valid user account in the local password database first. The syntax for adding a computer or machine account to the SAMBA password file is to use the <application>smbpasswd</application> command from a terminal prompt as follows:

Be sure to replace the token COMPUTER_NAME in the example above with the actual name of the specific computer you wish to add a machine account for.