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Managing Samba-3.0.21: The pdbedit utility, part 1

If you're migrating from Windows to Linux, or remotely managing Samba-3, knowing how to prepare and use Samba-3 PDC is a must.

John H. Terpstra, Site expert

Samba-3.0.21 has just been cut loose. So, I got busy and made the contents of this tip about the pdbedit utility line up with the update.

Administrators who want to make the most of Samba-3 need to know their PDCs (Primary Domain Controllers) . If you're migrating from Windows to Linux, or remotely managing Samba-3, knowing how to prepare and use Samba-3 PDC is a must.

Remote management of Samba is easily enabled by use of appropriate configuration settings. To achieve proper usage, you have to prepare the Samba-3 PDC for use. This article discusses the first steps, those that involve the pdbedit command. Detailed examples will be provided to demonstrate how this tool can be used to set password expiration limits, reconfigure the location of a users home folder, the location of the users roaming profile, and so on.

Additionally, the article will explain how to disable roaming profiles for all or some users, and will provide guidelines for Microsoft (MS) Windows workstation configuration to bring sanity to network management.

More Samba info:

Configuration for remote management

Windows network identity basics

User rights and privileges

Samba Learning Guide

Before we get started, let us consider again some key facts regarding the way the Samba integrates with the server operating system that is hosting it.

Samba interaction with the host operating system

A few simple facts must be stated. There are many postings to the Samba mailing lists in which the author is perplexed that certain commands have failed to produce the behavior that was expected.

Samba implements MS Windows file and print services without overriding Linux system security. What does this mean? It means that:

  • MS Windows users and groups must map to local operating system UIDs and GIDs.
  • Therefore, Samba does not create Linux (POSIX) user and group accounts, but passes this responsibility off to interface scripts.
  • All file system access is limited by the normal Linux security constraints that apply to the mapped UID/GID information. Where in the smb.conf file share stanza parameters are specified to force a particular action. For example: force user, force group, force create mode, etc. Basic Linux file system access controls remain in effect.
  • Samba tools and utilities do not interfere with Linux system administration. The tools never add user or group accounts, and that is why the administrator can specify scripts for all such operations. If the scripts are not specified in the smb.conf file, Samba will reject an attempt to add a use for which there exists no POSIX (system) account. Samba tools do not interfere with file and directory access controls.

Because Samba must deal with the semantics that are used by MS Windows networking, it provides a method by which network access can be controlled. The pdbedit tool is the primary command-line tool by which these control may be affected.

The pdbedit tool

The pdbedit tool can only be used by root. It is used to manage the passdb backend, and domain-wide account policy settings. In general, pdbedit can be used to:

  • list user and group accounts
  • migrate user, machine and group accounts
  • manage account policies
  • manage domain access policy settings

Under the terms of the Sarbanes-Oxley Act of 2002, American businesses and organizations are mandated to implement a series of internal controls and procedures to communicate, store and protect financial data. This legislation has far-reaching implications, with respect to the following issues:

  • who has access to information systems that store financial data
  • how personal and financial information is treated among employees and business partners
  • how security vulnerabilities are managed
  • security- and patch-level maintenance for all information systems
  • how information systems changes are documented and tracked
  • how information access controls are implemented and managed
  • audit ability of all information systems in respect of change and security
  • disciplinary procedures and controls to ensure privacy.

In short, the Sarbanes-Oxley Act of 2002 is an instrument of law that demands accountability in regards to business-related information systems, so as to ensure the compliance of all information systems that are used to store personal information and, particularly, for financial records processing. Similar accountabilities are being demanded around the world.

The need to be familiar with the Samba tools and facilities that permit information systems operation compliance with government laws and regulations is clear to all. The pdbedit utility is currently the only Samba command line-driven tool that provides the capacity to manage account, systems access controls and policies. During the remaining life-cycle of the Samba-3 series, it is possible the new tools may be implemented to aid in this important area.

The pdbedit tool is the lone device that can manage account security and policy settings. It is capable of superset of the old Samba smbpasswd capabilities. One particularly important purpose of the pdbedit, is to allow the migration of account information from one passdb backend to another.

So, let's get down to brass tacks, or brass code. In part two of this tip, I'll show you how to create Linux system user and group accounts; create Windows group accounts; map Windows group accounts to Linux group accounts; add Windows user accounts; and establish network access policies and controls.

Continue to part two.

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