In the X Window System , an X display manager is a graphical login manager which starts a login session on an X server from the same or another computer .
23-557: XDM , xdm , or similar can refer to: Computing [ edit ] X display manager , a part of the X Window System architecture XDM (display manager) , the default display manager included with the X Window System XDM (file format) , the Extensible Device Metadata open format for including depth maps and other metadata in standard image files XQuery and XPath Data Model Cross-document messaging , that works around
46-502: A larger company, these may all be separate positions within a computer support or Information Services (IS) department. In a smaller group they may be shared by a few sysadmins, or even a single person. Most employers require a bachelor's degree in a related field, such as computer science , information technology , electronics engineering , or computer engineering . Some schools also offer undergraduate degrees and graduate programs in system administration. In addition, because of
69-407: A message to the selected remote computer's display manager and instruct it to connect the X server on the local computer or terminal. The X Display Manager Control Protocol (XDMCP) uses UDP port 177. An X server requests that a display manager start a session by sending a Query packet. If the display manager allows access for that X server, it responds by sending a Willing packet back to
92-705: Is a person who is responsible for the upkeep, configuration, and reliable operation of computer systems , especially multi-user computers, such as servers . The system administrator seeks to ensure that the uptime , performance , resources , and security of the computers they manage meet the needs of the users , without exceeding a set budget when doing so. To meet these needs, a system administrator may acquire, install, or upgrade computer components and software ; provide routine automation; maintain security policies; troubleshoot ; train or supervise staff; or offer technical support for projects. Many organizations staff offer jobs related to system administration. In
115-421: Is a separate role responsible for overall security and the upkeep of firewalls and intrusion detection systems , but all sysadmins are generally responsible for the security of computer systems. A system administrator's responsibilities might include: In larger organizations, some of the tasks above may be divided among different system administrators or members of different organizational groups. For example,
138-545: The Xservers file, but XDM only consulted this file when it started. Thus every time a user switched a terminal off and on, the system administrator had to send a SIGHUP signal to XDM to instruct it to rescan Xservers . XDMCP arrived with the introduction of X11R4 (December 1989). With XDMCP, the X server must actively request a display manager connection from the host. An X server using XDMCP therefore no longer requires an entry in Xservers . A display manager can run on
161-575: The X Display Manager Control Protocol ( XDMCP ) in December 1989 to fix problems in the X11R3 implementation. XDM (the X Window Display Manager) originated in X11R3. This first version, written by Keith Packard of the MIT X Consortium, had several limitations, the most notable of which was that it could not detect when users switched X terminals off and on. In X11R3, XDM only knew about an X terminal from its entry in
184-453: The X server. (The X server can also send BroadcastQuery or IndirectQuery packets to start a session - this mechanism for requesting a session resembles using DHCP to request an IP address.) The display manager must authenticate itself to the server. To do this the X server sends a Request packet to the display manager, which returns an Accept packet. If the Accept packet contains
207-421: The behavior of software in order to deploy it and to troubleshoot problems, and generally know several programming languages used for scripting or automation of routine tasks. A typical sysadmin's role is not to design or write new application software but when they are responsible for automating system or application configuration with various configuration management tools, the lines somewhat blur. Depending on
230-458: The display and input devices. A server can connect, using the XDMCP protocol, to a display manager running on another computer, requesting it to start the session. In this case, the X server acts as a graphical telnet client while the display manager acts like a telnet server: users start programs from the computer running the display manager, while their input and output take place on the computer where
253-489: The display manager runs on a remote computer, it acts like a telnet server, requesting username and password and starting a remote session. X11 Release 3 introduced display managers in October 1988 with the aim of supporting the standalone X terminals , just coming onto the market. Various display managers continue in routine use to provide a graphical login prompt on standalone computer workstations running X. X11R4 introduced
SECTION 10
#1732858497510276-511: The limits set by the same origin policy in a web browser Firearms [ edit ] Springfield Armory XD-M , a pistol series sold in the United States by Springfield Armory, Inc. Gaming [ edit ] XDM: X-Treme Dungeon Mastery , a role-playing game supplement by Tracy Hickman, Curtis Hickman and Howard Tayler. Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with
299-499: The organization use the computers. Perhaps the most important skill for a system administrator is problem solving —frequently under various sorts of constraints and stress. The sysadmin is on call when a computer system goes down or malfunctions, and must be able to quickly and correctly diagnose what is wrong and how best to fix it. They may also need to have teamwork and communication skills; as well as being able to install and configure hardware and software. Sysadmins must understand
322-762: The practical nature of system administration and the easy availability of open-source server software, many system administrators enter the field self-taught. Generally, a prospective employee will be required to have experience with the computer systems they are expected to manage. In most cases, candidates are expected to possess industry certifications such as the Microsoft MCSA , MCSE , MCITP , Red Hat RHCE , Novell CNA , CNE , Cisco CCNA or CompTIA 's A+ or Network+ , Sun Certified SCNA , Linux Professional Institute , Linux Foundation Certified Engineer or Linux Foundation Certified System Administrator, among others. Sometimes, almost exclusively in smaller sites,
345-408: The response the X server expects, the display manager is authenticated. Producing the correct response might require the display manager to have access to a secret key , for example. If authentication succeeds, the X server sends a Manage packet to inform the display manager. Then the display manager displays its login screen by connecting to the X server as a regular X client. During the session,
368-411: The role of system administrator may be given to a skilled user in addition to or in replacement of their duties. The subject matter of system administration includes computer systems and the ways people use them in an organization. This entails a knowledge of operating systems and applications , as well as hardware and software troubleshooting , but also knowledge of the purposes for which people in
391-401: The same computer where the user sits—starting one or more X servers, displaying the login screen at the beginning and (optionally) every time the user logs out—or on a remote one, working according to the XDMCP protocol. The XDMCP protocol mandates that the X server starts autonomously and connects to the display manager. In the X Window System paradigm, the server runs on the computer providing
414-476: The server (and the user) sits. An administrator can typically configure an XDMCP Chooser program running on the local computer or X terminal to connect to a specific host's X display manager or to display a list of suitable hosts that the user can choose from. Most implementations enable such a list to contain: When the user selects a host from the list, the XDMCP Chooser running on the local machine will send
437-405: The server can send KeepAlive packets to the display manager at intervals. If the display manager fails to respond with an Alive packet within a certain time, the X server presumes that the display manager has ceased running, and can terminate the connection. One problem with XDMCP is that, similarly to telnet , the authentication takes place unencrypted. If snooping is possible, this leaves
460-566: The sysadmin's role and skillset they may be expected to understand equivalent key/core concepts a software engineer understands. That said, system administrators are not software engineers or developers , in the job title sense. Particularly when dealing with Internet -facing or business-critical systems, a sysadmin must have a strong grasp of computer security . This includes not merely deploying software patches, but also preventing break-ins and other security problems with preventive measures. In some organizations, computer security administration
483-536: The system vulnerable to attack. It is more secure to use an ssh tunnel for X traffic. The X Window System supplies XDM as its standard display manager. Programmers have developed other X display managers, both commercial and free, offering additional functionality over the basic display management: On some Unix distributions, the default display manager is selected in file $ PREFIX/etc/X11/default-display-manager. System administrator An IT administrator , system administrator , sysadmin , or admin
SECTION 20
#1732858497510506-469: The title XDM . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=XDM&oldid=1105586423 " Category : Disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages X display manager A display manager presents
529-484: The user with a login screen . A session starts when a user successfully enters a valid combination of username and password . When the display manager runs on the user's computer, it starts the X server before presenting the user the login screen, optionally repeating when the user logs out. In this condition, the DM realizes in the X Window System the functionality of getty and login on character-mode terminals . When
#509490