Red Hat Technical Series Systems Management in the Enterprise with Red Hat Network version 1.0

Transcription

1 Red Hat Technical Series Systems Management in the Enterprise with Red Hat Network version 1.0 Copyright 2002 by Red Hat, Inc. Tammy Fox and Greg DeKoenigsberg Red Hat Network is the environment for system-level support and management of Red Hat Linux networks. Red Hat Network brings together the tools, services, and information administrators need to maximize the reliability, security, and performance of their systems. Red Hat Network can decrease the time and effort required for systems management.

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3 Table of Contents 1. Red Hat Network Overview RHN Service Offerings Enabling Technologies Security and Privacy Simplifying System Administration Summary Glossary... 16

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5 1. Red Hat Network Overview Red Hat Network (RHN) is the environment for system-level support and management of Red Hat Linux networks. Red Hat Network brings together the tools, services, and information that help administrators to maximize the reliability, security, and performance of their systems. To use RHN, system administrators must register their client systems with Red Hat Network. When the client systems request package updates, only the applicable packages for that specific client are returned, based on the System Profile stored on the RHN Servers. RPM Updates can be automatically applied or scheduled for multiple systems at the same time. Red Hat Network has the following characteristics: Scalability You can set up and manage a network of dozens of Red Hat Linux systems with ease. With Red Hat Network and Red Hat Linux, a single system administrator can set up and maintain hundreds or thousands of Red Hat Linux systems more easily, accurately, and quickly than that same administrator could maintain a single system without Red Hat Network. Security All communication between registered systems and Red Hat Network are over secure Internet connections. Refer to Section 4 for more information. Standard Protocols Red Hat Network client connections are established using XML/RPC over secure HTTP. These standard protocols maintain security and increase capability. Client Software All software required to register a client system comes with Red Hat Linux 7 and higher and can be installed for use with Red Hat Linux 6.2. To create an account go to and click on Create Account. Then, use the Red Hat Network Registration Client to register each system and create System Profiles. Use the Red Hat Update Agent to retrieve and (optionally) install RPM Updates. The Web interface provides more features than the standalone client, only requires a Web browser, and does not have to be run on the client system. System Profile The Red Hat Network registration process creates a System Profile, which is stored on the RHN Profile Server. A System Profile consists of a list of software and hardware for the registered system. It is used to customize the notifications that you receive for each system and to determine which default base channel the system is subscribed to. Digital Certificate Upon registration Red Hat Network assigns a unique Digital Certificate to the client system. The Digital Certificate is an XML file that is stored on the client, which contains information about the system including the profile name, architecture, and the Red Hat username of the person who registered the system. The Digital Certificate also contains a unique System ID, which is a string of characters and numbers that identify your system for updates and support Communication Methods There are two methods to communicate with Red Hat Network: Web Interface The Red Hat Network Web interface is accessible through any SSL-enabled Web browser; this tool allows you to manage multiple systems simultaneously. For example, a user can quickly view Errata Alerts for all registered systems, view details from Errata Reports, download RPM packages, and subscribe to different channels. Red Hat Update Agent A user can also view Errata Alerts, download the RPM packages, and (optionally) install the packages using the Red Hat Update Agent, a standalone client application. This client application uses the client system s Digital Certificate to display Errata Alerts customized for the client system.

6 6 Red Hat Technical Series 1.2. RPM Updates Using one of the two methods of communication, system administrators can retrieve the latest software packages based on the Errata Alerts for each client system. If you select automatic RPM Updates, the next time the Red Hat Network Daemon connects to the RHN Servers, the client downloads the packages according to its Red Hat Update Agent preferences and (optionally) installs them. RPM Updates work as follows (refer to Figure 1): Figure 1. Red Hat Network Components Periodically the Red Hat Network Daemon (rhnsd) running on a client forks a script that polls the Network Server using the client s System ID (a series of characters and numbers that identifies a registered system). The Network Server queries the Profile Server to see if there are any actions for the client with the specified System ID. If there are no actions, then the Profile Server passes that information back to the Network Server which in turn passes it back to the client, ending the exchange. The forked script running on the client terminates execution. If there are actions for the client, the Profile Server passes the list of actions, including the names of the required files, back to the Network Server which passes the list back to the script running on the client. What the client does when it receives the list of actions from the Profile Server depends on how the system administrator sets the preferences in the client profile. If the administrator sets the preferences to bring the files back to the client then the client automatically runs the Red Hat Update Agent which requests the files specified by the actions, one at a time, from the Red Hat Network Server. The Red Hat Network Server in turn retrieves the files from the Red Hat File Server. The files are returned back up the chain of servers to the Client. All of this happens without user intervention.

7 Red Hat Technical Series 7 The client system handles the files according to the system administrator s preferences. If the preferences state that files are to be installed automatically, then the Red Hat Update Agent installs the files. Otherwise, it stores the files in /var/spool/up2date. Until the packages are installed, the corresponding errata remain in the errata list displayed for the system by the Red Hat Update Agent and the Web interface. 2. RHN Service Offerings There are two RHN service offerings: Basic and Enterprise. The RHN Basic offering is ideal for users who need to maintain a small number of Red Hat Linux systems. It includes Errata Alerts, automatic notifications, the ability to schedule Errata Updates and package installations, and use of the Red Hat Update Agent. RHN Basic should be used by users with one or two Red Hat Linux systems to maintain. RHN Enterprise should be used by Enterprise customers with numerous systems to maintain. It provides an extended set of features such as system group management, multiple user management, multiple administrators for each organization, enhanced system details, user privileges based on system groups, and the use of the System Set Manager that allows administrators to perform actions on multiple systems at the same time. Some features of Basic include: Priority Access during periods of high load When Red Hat releases a large errata, Priority Access can be guaranteed to Enterprise subscribers so that updated packages can be retrieved immediately. Instant ISOs For customers who have purchased subscriptions to Red Hat Network, ISO images are available for immediate download. Beat the rush to the FTP servers by downloading directly from Red Hat Network. Enterprise includes the following additional features that are indispensable to the administrator of multiple systems: Errata Notification, Multiple Systems Subscriptions for multiple systems means Errata Alerts for all entitled systems in one . Errata Updates, Multiple Systems Get quick updates for multiple systems with an easy button click for each system. Package Profile Comparison Compare the package set on a system with the package sets of similar systems with one click. System Grouping Web servers, database servers, workstations, and other workload-focused systems may be grouped so that each set can be administered in common ways. Multiple Administrators Administrators may be given rights to particular system groups, easing the burden of system management within larger organizations. System Set Manager You can apply actions to sets of systems instead of single systems. Work with members of a predefined system group, or work with an ad-hoc collection of systems. Install a single package to each, subscribe them all to a new channel, or apply all errata to them with a single action. Massive Scalability Determining outdated packages for a thousand systems would take days for a dedicated system administrator. Red Hat Network Enterprise Service can do it for you in seconds. For more information, refer to

8 8 Red Hat Technical Series 2.1. Client Applications The client applications that run on client systems (Red Hat Network clients) are the software tools that make Red Hat Network perform properly. The following sections describe the Red Hat Network client-side applications Red Hat Network Registration Client The Red Hat Network Registration Client (rhn_register) collects hardware and software information from the system being registered, creates a System Profile, registers the System Profile with Red Hat Network which stores it on the Profile Server, and obtains a Digital Certificate that is stored on the client system to identify itself to the Red Hat Network Servers. The Red Hat Network Registration Client allows you to specify notification and exclude packages that you do not want Red Hat Network to update Red Hat Update Agent The Red Hat Update Agent (up2date) is a client application that retrieves (and optionally installs) the latest Red Hat packages from the Red Hat Network Public File Server based on your preferences. It is part of the Enterprise service offering. Before you run the Red Hat Update Agent, run the Red Hat Update Agent Configuration Tool (up2date-config) to configure your retrieval/installation and package-exception preferences including: Enable HTTP Proxy Specify a proxy server. Automatic package installation Automatically installs packages on the client; otherwise they are just downloaded so that you can install them manually. Package exclusion Excludes software packages from the list of packages that will be updated. File exclusion Excludes files from the list of packages that will be updated. Source RPM retrieval Downloads source files along with the binaries. Binary package preservation Keeps binary files on the system after installation. Without this option binary RPM files are deleted once installed to save disk space. Download directory Specifies a directory other than /var/spool/up2date to store downloaded files. Configuration file replacement Causes the Red Hat Update Agent to prompt you before it downloads a package in which the local configuration file has been changed Red Hat Network Daemon The Red Hat Network Daemon (rhnsd) runs on client systems and periodically starts a script that contacts Red Hat Network to see if there are any actions pending for the client. It is also a component of the Enterprise service offering. The rules defined by the Red Hat Update Agent Configuration Tool for the Red Hat Update Agent also apply to the script that the Red Hat Network Daemon runs. The rhnsd polling interval is two hours by default. To prevent the Red Hat Network servers from being overloaded, rhnsd will not accept an interval of less than one hour.

9 Red Hat Technical Series 9 3. Enabling Technologies 3.1. Internet Connectivity The Internet is fundamental to Red Hat Network. It enables easy-to-establish, secure, two-way communication between the Red Hat Network servers and each of the clients RPM RPM is integral to Red Hat Network. RPM Update manages system, application, and kernel software packages. While it installs and upgrades packages, it checks for dependencies both for the package it is installing (making sure the correct libraries are installed) as well as for any other packages dependent on any files it is updating. It can also tell you which version of a package is installed (or if it is not installed). RPM stores a list of installed RPM packages in the /var/lib/rpm/packages.rpm file. All of the binary and source packages that Red Hat Network supplies are produced by Red Hat in RPM format. Red Hat Network cannot maintain packages that are not produced by Red Hat and packages that are not in RPM format. The client s RPM database is used to create the System Profile which lists the files that Red Hat Network maintains (subject to administrative override) Standard Communication Protocols Red Hat Network uses industry standard communication protocols that work effectively over a WAN (wide area network) such as the Internet. These protocols include: HTTPS All connections to Red Hat Network servers are made using the secure version of HyperText Transport Protocol (HTTPS). This protocol enables secure two-way communication between RHN Enterprise and a Web browser XML-RPC XML-RPC (extensible Markup Language-Remote Procedure Calls) enables software running on different operating systems and in different environments to use the Internet for making remote procedure calls (instructions from a computer that execute commands on another computer). XML-RPC implements remote procedure calls using an HTTPS transport and XML encoding. It is a simple, extensible, lightweight RPC method that is easy to implement and use, yet robust enough to transmit, process, and return complex data structures. Red Hat Network uses XML-RPC for communication between the Red Hat Network Server and a client running Red Hat Network Registration Client, Red Hat Update Agent, and the Red Hat Network Daemon SSL All connections between a client and Red Hat Network (over the Internet) are encrypted using SSL, and all SSL encrypted information is signed with Red Hat s cryptography key. Clients verify the signature with Red Hat s public key which is installed on all clients.

10 10 Red Hat Technical Series 4. Security and Privacy With the advent of new technology such as Red Hat Network where systems outside of your network hold valuable system data and communicate with your systems on a regular basis there is an obvious concern for the security and privacy of your data. Red Hat understands these concerns and addresses them as described in the following sections Red Hat Network Security and Integrity Using the Red Hat Network will not compromise client system security. From the data that Red Hat Network loads onto a client system to maintaining the impenetrability of client systems, Red Hat Network does not lessen (nor does it make it easier to lessen) the integrity of client data. All communication with Red Hat Network is initiated by the client. There is no process, daemon, or port that waits for communication from Red Hat Network. A client will not respond to communication that is initiated by an impostor claiming to be Red Hat Network because it is not listening for this type of communication and because it may violate firewall policy. The sole purpose of the RHN client daemon is to initiate periodic communication with Red Hat Network. When a client initiates contact with Red Hat Network, the client expects and accepts a response and takes security measures to make sure that the response is valid. Red Hat Network uses the following mechanisms to protect client/customer information from malicious users (security) and from lost data (integrity): User name and password required You can only log into the Web interface with the correct user name and password. Transaction authentication During registration, a unique Digital Certificate is generated and stored on the client system. Red Hat Network uses the System ID in the Digital Certificate to authenticate each transaction between itself and the client system. Secure private internal networks All data that is transferred between Red Hat internal systems flows across secure, private, nonadvertised, networks that are not accessible to the public. Operating system security All Red Hat Network servers run Red Hat Linux. SSL encryption All transactions across the Internet use a 128-bit Secure Sockets Layer (SSL) protocol that provides encrypted communications. Electronic signature All software packages come directly from Red Hat quality control and are digitally signed with Red Hat s cryptographic key, using GNU Privacy Guard, to ensure authenticity. Users control As the user, you choose which tasks you want Red Hat Network to perform and which you want to handle yourself. Red Hat Network can download, install, and upgrade Red Hat Network software packages as they are released. If you prefer, Red Hat Network can simply notify you when a new package is available and (optionally) download the package.

11 Red Hat Technical Series 11 Minimal Required User Information When you register a system, you provide Red Hat Network with as much or as little information as you choose to provide. Red Hat Network requires only a user name, password, and a valid address Red Hat Network Privacy The Red Hat promise of privacy is straightforward: The users personal information is theirs; it does not belong to Red Hat. Users tell Red Hat how it may or may not use their information and Red Hat will respect their wishes. When users register products or services on the Red Hat website, they will be asked if they would like to be contacted by Red Hat and, if they would, how. If users do not want to be contacted, Red Hat will not contact them. When users participate in surveys, contests, promotions, or other features that appear on redhat.com, Red Hat will let them know how their information may be used. Questions or concerns may be ed to <feedback@redhat.com>. Red Hat never sells its customers personal information or provides it to others without making it clear that there is intent to do so. If users receive any sort of communication from Red Hat that they find intrusive, whether via phone, , or regular mail, they can let Red Hat know so that Red Hat can prevent that type of communication from happening again. Go to for more details about Red Hat s security and privacy practices. 5. Simplifying System Administration The introduction of RHN Enterprise Service simplifies the system administration tasks of an organization in several ways. The ability to apply updates to multiple systems, to assign management duties to multiple users, to group and administer systems according to location or function, and to schedule updates during defined maintenance periods all make Enterprise indispensable to the busy Red Hat Linux system administrator Updating Multiple Systems For example, if Red Hat issues an Errata that fixes a security hole, all users with administration privileges to the affected systems will receive an RHN Errata Alert with the summary and description of the Errata. This notification will also contain a list of all systems to which that user has administrative privileges. Using the RHN Web interface, you can apply an errata to every system within a system group with just a few clicks: 1. Log in to 2. Click Systems => System Group list on the left navigation bar. 3. Click the Work With Group link for the system group. 4. Click the Errata tab. 5. Select the appropriate Errata from the list.

12 12 Red Hat Technical Series 6. Click the Apply Selected Errata button. 7. Select when to apply the Errata Update. 8. Click the Schedule Errata Updates button. The Errata Update will be applied to the applicable systems within the system group at the selected time. Compare the RHN Errata Update process to the manual process for keeping Red Hat Linux systems updated in the absence of Red Hat Network: 1. Go to periodically and watch the list of Errata Alert for Errata Updates applicable to any systems within the organization. 2. Download the appropriate packages for each Errata you want to apply. 3. Determine whether the Errata Alert is applicable to the system. 4. Log in as root on an affected system. 5. Upgrade the packages from the Errata Alert. 6. Resolve the software dependencies, if any. Depending upon the severity of the alert, many additional packages could be affected, each of which would have to be downloaded and applied. 7. Repeat the previous steps for each affected system in your organization. This manual process might seem comparable for one Red Hat Linux system, but it would take a considerable amount of time to apply just one Errata Update to dozens of systems Multiple System Administrators As an organization deploys more Red Hat Linux systems, maintaining proper security practices becomes more difficult. If a system administrator is expected to perform any useful action on a particular system, he must have the root password for that system. Red Hat Network gives system administrators the power to keep systems properly updated without having to keep track of a long laundry list of root passwords. With RHN, the Organization Administrator grants RHN-registered system administers permission to administer specific entitled systems. Authentication to administer the system through RHN is granted based on the RHN user s user name and password combination, the unique Digital Certificate installed on the entitled system, and the membership of the system in a predefined system group to which the RHN user must be given administrative access. RHN also stores the history of completed and pending actions for each system so that administrators can keep track of when an Errata Update was applied. The actions can be viewed for the entire organization or for each system. This feature is extremely helpful if the organization has multiple administrators per system. Administrators do not have to waste valuable time determining which Errata Updates were applied to each system.

13 Red Hat Technical Series 13 Figure 2. RHN Scheduled Actions Any user that has permission to administer the system can add a note. The notes can be used to give other administrators information about the system, to manually record the system s planned or unplanned outage, to list future plans for the system, or to store any information that can be written in text format. Figure 3. RHN Notes 5.3. Updating Systems by Group One of the most important features of Enterprise is its grouping functionality. Common sense dictates that similar systems should be administered in similar ways. Enterprise allows you to group systems by characteristics that you define. Once these groups have been defined, applying actions to the whole group is a simple task. Some of the more common means of grouping systems are presented in the following examples.

14 14 Red Hat Technical Series Figure 4. RHN System Groups Grouping by Physical Location Scenario: Systems in the New York office are different from systems in the San Jose collocation facility. Solution: Create a New York group and a San Jose group, and assign a particular administrator to each. When new systems are profiled, the Organization Administrator places them in the appropriate group, and management responsibility is automatically assigned to the proper system administrators Grouping by Function Scenario: Different system administrators maintain different functional groups, such as all mail servers or all Web servers. The sendmail expert keeps your mail servers updated, and the Apache expert keeps your Web farm updated. Solution: Create a Web Server group and a Mail Server group so that you can assign different privileges to different system administrators. When the latest version of Apache is released, the Apache expert applies the Apache Errata Update without affecting any of the mail servers. When the latest version of sendmail is released, the sendmail expert applies the Sendmail Errata Update without affecting any of the Web servers Grouping by OS Version Scenario: Production servers are running Red Hat Linux version 6.2, while all desktop systems are running Red Hat Linux version 7.2. All Errata Updates do not apply to all versions of Red Hat Linux. Solution: Group systems by OS version to make it easy to apply Errata Updates quickly and cleanly. When a system admininstrator receives an Errata Alert that only affects Red Hat Linux 7.2 systems, he can quickly and easily apply the Errata Update the group containing only Red Hat Linux 7.2 systems Grouping by Hardware Scenario: The developer workstations require the development packages and the SMP kernel package because they are multi-processor machines. The laptops require a small installation and the latest PCMCIA kernel. Solution: Create a Developer Machines group and a Laptops group. When an Errata Update is released for a development packages such as python-devel, apply it to the Developer Machines system group. When an Errata Update for the PCMCIA kernel is released, apply it to the Laptops group without affecting the Developer Machines group that does not need the PCM- CIA kernel.

15 Red Hat Technical Series Grouping by Multiple Characteristics Scenario: A laptop is used as a developer machine, and a different laptop belongs to an employee in the Sales department. Solution: Assign both laptops to the Laptops group, and then assign one to the Developer Machines group and the other to the Sales group. A system be a member of as many groups as you deem appropriate Maintenance of Production Systems Altering the running package set on a production system is a delicate operation. Red Hat strongly recommends maintaining a QA environment to mirror any application servers that are mission-critical. Enterprise provides tools to help the careful system administrator complete this task with minimal downtime. The Profile Comparison tool helps administrators keep the QA environments in sync with the production systems. When Errata Alerts are issued, they may safely be applied to the QA system. When the administrator is confident that the Errata Update applied to the QA system had the desired effect, the same Errata Update may then be scheduled for deployment to the production systems during a particular maintenance window. In many cases, a package may be applied to a production system without any downtime at all. Many packages are built to stop the service before the upgrade and then restart the service when the package has been successfully upgraded. Red Hat Network also provides tools to assist in failure recovery. Because RHN stores a list of RPM packages for each registered system, if a system is compromised or has a catastrophic hardware failure, the system administrator can log in to the RHN website and retrieve the full software profile for that system with complete accuracy Updating Private Packages The nature of open source dictates that most organizations come to rely upon applications that are not part of the standard Red Hat Linux distribution. Whether these applications are GPL or are developed by the organization for the organization, at some point they become essential elements of the systems management equation for an organization. For these customers, RHN Proxy Server is a reasonable alternative. Available to customers who manage 50 or more Red Hat Linux systems through Red Hat Network, the RHN Proxy Server provides both a local caching mechanism for Red Hat Network packages and a distribution mechanism for custom-built packages. Packages built and stored on the RHN Proxy Server can be managed in exactly the same way that standard Red Hat Linux packages are managed. For more information on the RHN Proxy Server, please consult the Deploying RHN Proxy in the Enterprise paper available at 6. Summary Proper system management is a difficult task. Deploying, auditing, upgrading, and removing software can be a difficult task even for a handful of systems; for an entire organization it can seem impossible. Customized in-house solutions can mitigate the management task for some customers, but the cost of building, deploying, and maintaining such a system is prohibitive to most. A robust, easily maintained,

16 16 Red Hat Technical Series easily deployed toolset with a centralized interface is essential for the effective management of any broad software deployment. Enterprise for Red Hat Network was built to solve this problem. Red Hat Network is the future of computing, today. In the past, upgrades, bug fixes, and security alerts were something a system administrator had to monitor on a constant basis. Now, they are just a few clicks away with customized, automatic delivery. If you have any questions about Red Hat Network, visit Glossary A Action A task that is scheduled by a system administrator using Red Hat Network to be performed on one or more client systems. For example, an action can be scheduled to update the kernel packages on all the systems within a selected group. Activation Key RHN Enterprise customers can generate activation keys through the RHN website. Each unique key can then be used to register a RHL system, entitle the system to RHN Enterprise, subscribe the system to specific channels, and subscribe the system to RHN system groups through the command line utility rhnreg_ks from the rhn_register package. B Base Channel A base channel is a type of Channel that consists of a list of packages based on a specific architecture and Red Hat Linux release. For example, all the packages in Red Hat Linux 7.3 for the x86 architecture make a base channel. Basic One of the RHN service level offerings. Basic was formerly called Software Manager. Basic offers the same services as the Software Manager subscription did, plus more new features. Bug Fix Alert An Errata Alert that pertains to a bug fix. Bugzilla Bugzilla is an online application ( that allows users to communicate directly with the developers. From Bugzilla, users can submit bug reports and feature requests for Red Hat Linux and related open source packages.

17 Red Hat Technical Series 17 C Channel A channel is a list of Red Hat Linux packages. Channels are used to choose packages to be installed from client systems. Every client system must be subscribed to one Base Channel and can be subscribed to one or more Child Channel. Child Channel A child channel is a Channel associated with a Base Channel but contains extra packages. Client System See Registered System. D Digital Certificate A client component in XML format that is stored in the /etc/sysconfig/rhn/systemid file on registered systems. Red Hat Network verifies this certificate to authenticate the registered system before each connection. This certificate is issued by Red Hat and passed to the system as part of the registration process. It includes unique information about the registered system to avoid fraudulent use. E Notification Similar to an Errata Alert, except the information is delivered via . If the notifications option is selected, notifications are sent for every Red Hat Network Errata Alert. The includes the type of Errata Alert, summary of the Errata, description of the Errata, and a list of which systems are affected by the report. Enhancement Alert An Errata Alert that pertains to a package enhancement request.

18 18 Red Hat Technical Series Enterprise One of the RHN service level offering. It has more features than the Basic service level, including user management, system groups, and enhanced system details. Entitled Server A server that is subscribed to Software Manager. Because the server is entitled, the Software Manager interface can be used to manage its packages. Errata Information published by Red Hat describing security fixes, bug fixes, and package enhancements for Red Hat Linux. The information includes the topics of the Errata, Bugzilla bug IDs, relevant releases/architectures, solutions including required RPMs, and MD5 checksums for verification. Errata are also available at Each RHN Errata Alert is based on the Red Hat Linux Errata List. Security issues and bug fixes are submitted by Red Hat engineers as well as the Linux community through Bugzilla which generates a bug report for each issue. Red Hat engineering evaluates the reports, resolves the bug, and generates new RPM packages. After the Red Hat quality assurance team tests new packages they are placed on the Red Hat Public File Server and on the Red Hat Network Server and an Errata is generated. Errata Alert RHN Errata Alert that updated packages based on Red Hat Errata are available for one or more systems within an organization. There are three types of Errata Alerts: Security Alerts, Bug Fix Alerts, and Enhancement Alerts. O Organization Administrator Organization Administrator are sets of users that have the highest level of control over an organization s Red Hat Network account. Members of this group can add users, systems, and system groups to the organization as well as remove them. An Organization Administrator can also give users administrative privileges to system groups. An RHN organization must have at least one member of the Organization Administrator group. P Package All software in Red Hat Linux is divided into software packages. Software updates are released in the form of RPM packages that can be installed on a Red Hat Linux system.

19 Red Hat Technical Series 19 R Registered System A system that is registered with Red Hat Network. Also known as a client system. Red Hat Network Daemon The RHN client daemon (rhnsd) that periodically polls Red Hat Network for updates and notifications. Red Hat Network Registration Client The RHN client application (rhn_register) that collects information about the client system, creates a System Profile and Digital Certificate, establishes a connection with the Red Hat Network servers, and registers the system with Red Hat Network. Red Hat Update Agent The RHN client application (up2date) that allows users to retrieve and install all updated packages for the client system on which the application is run. Use the Red Hat Update Agent Configuration Tool to configure its preferences, including whether to install the packages after they are downloaded. RPM A software package manager that was developed by Red Hat. It can be used to build, install, query, verify, update, and uninstall software packages. All software updates from RHN are delivered in RPM format. RPM Database Each Red Hat Linux system has an RPM database that stores information about all the RPM packages installed on the system. This information includes the version of the package, which files were installed with the package, a brief description of the package, the installation date, and more. RPM Update Red Hat Network option to deliver the RPM packages based on the Errata Alert list to a client system automatically and without user intervention. If this feature is selected, packages are delivered through the Red Hat Network Daemon running on the client system.

20 20 Red Hat Technical Series S Security Alert An Errata Alert that pertains to system security. Service Level A Red Hat Network subscription service. Different service levels offer different features of RHN. There are two service levels currently available: RHN Basic and RHN Enterprise. Software Manager The name of the first Service Level offering for Red Hat Network. Software Manager is now known as RHN Basic. System Directory The System Directory section of Red Hat Network allows an organization to divide its client systems into system groups. Only members of the Organization Administrator group can add systems to the organization. System ID A unique string of characters and numbers that identifies a registered system. It is stored in the system s Digital Certificate. System Profile Hardware and software information about the client system. It is created during the registration process. The software information is a list of RPM packages and their versions installed on the client system. The System Profile is used to determine every Errata Alert relevant to each client system. System Set Manager Interface that allows users to perform actions on multiple systems. Actions include applying Errata Updates, upgrading packages, and adding/removing systems to/from system groups.