1. Chapter 5 Managing a Server

2. Overview  Server management  Examine networking models  Learn how users are authenticated  Manage users and groups  Manage file system permissions

3. Managing a Server  Managing a server Access to the server  Who has permission to access Access restrictions to the server and its resource  File, printer, etc. Access control schemes can be through  LAN  Internet

4. Network Models  Network model How the server is configured and interact with the network  Two basic network models Microsoft LAN Approach  LAN Domain  Working Group Client/Server

5. Microsoft LAN Approach usr2 usrr3 usr1 usr4 ROUTER usr2 usrr3 usr4 ROUTER server LAN DomainWorking Group

6. Microsoft LAN Networking Models- Workgroup  Treats each computer in the network as an equal or peer Also called peer-to-peer networking Decentralized network (be able to draw it) Each computer must have complete name of users and their info.  Each computer can be either a client and a server When you allow others to access resources on your computer, your computer is acting as a server When you access resources on another computer, your computer is acting as a client

7. Microsoft LAN Networking Models- Workgroup  Appropriate for networks with 10 or less computers  A number of disadvantages Need user names and passwords of users who need resources Difficult to keep track of changing passwords Most users do not want to administer resources on their computer

8. Microsoft LAN Networking Models- LAN Domain  One or more centralized servers (single domain) Single, centralized logon Single point of control Users can be given access to resources anywhere in the domain

9. Client/Server Networking Model  Networking in Linux follows the client/server model Server provides the resource (web server) Client talks to the server (browser, e-mail program)  Server has a corresponding program that communicates with the client (runs in the background) In Windows the server program called service In Linux the server program called daemon in Linux

10. Authenticating Users  Process of determining a user's true identity  Three basic methods What you know – user name and passwords What you have – entry card Who you are – biometrics

11. Implementing an Authentication System  If a Windows network has older computers running NT, 95, or 98, the server must use NTLM NT LanManager is an authentication protocol  It is not as secure as Kerberos, which is the default for Windows 2000, 2003, and XP Authentication system developed by MIT Allows two parties exchange private information Uses the ticket (key) mechanism

12. Managing Users and Groups  Users need accounts to access resources on a server On a Web server there is a restricted account that is used on behalf of Internet users  In a LAN, users with common resource needs are put in a group and the group is given access to the resource

13. Users and Groups in Windows  Local accounts exist on a single computer and can be used to control resources only on that computer  Domain accounts can be used to control resources on all the computers that are part of the domain  Active Directory (AD) allows domains to be grouped into a forest Microsoft Exchange requires AD

14. Groups in Windows  Domain local groups have members from the same domain Assign permissions to resources in the same domain  Global groups have members from the same domain Can be used to assign permissions to resources in any domain  Universal groups can have members from any domain Can be used to assign permissions to resources in any domain Domain 1 Domain 2 Group 2 Group 1

15. File System Permissions  Permission allow you to control access to the resources on a computer such as a Web page, a document, or a program  In Windows, the NTFS file system is required in order to assign permissions  All Linux file systems incorporate permissions

16. File System Permissions in Windows PermissionDescription Full ControlFull Control includes all other permissions and allows you to take ownership of the file or folder and change the attributes of a file ModifyAllows read, write, and delete ReadWith this permission, you can read files but cannot execute them WriteWhen set on a file, this permission allows you to write to files; when set on a folder, you can write to the folder Read & ExecuteRead files and run programs List Folder ContentsThis permission allows you to view the contents of a folder

17. File System Permissions in Linux Permission type When used with filesWhen used with directories ReadRead a file or copy a fileList the contents of a directory WriteWrite to the file, including deleting the file Create files ExecuteExecute programs and shell scripts, which are text files containing Linux commands Modify the file permissions

18. Linux Permissions  Permissions are set for user, group, and others  Each permission is set with a single digit from 0 to 7 based on the combination of permissions read = 4 write = 2 execute = 1

19. Using chmod to Set Permissions CommandPermissions OwnerGroupOther chmod 755 myfile rwxr-x chmod 540 myfile r-xr----- chmod 744 myfile rwxr--

20. Do the following labs  Project 5-2 to 5-4 using Windows Your DNS must work before doing this lab Uninstalling the Active Directory  If the AD is already installed go on to 5-3 Giving control to groups  Show the permissions in the apps directory  Project 5-5 to 5-8 using Linux Giving control to groups  Show all the permissions

21. Project (March. 13)  What is the difference between the LAN Domain network model and the Service/client model (both centralized?, advantages and disadvantages of each)  Discuss some (3 examples) of the existing biometric techniques. What products are available? Who makes them? Who uses them?  Examine technical advantages of Kerboros authentication system over NT LanManager.  Describe how Kerboros works. What are other examples of authentication systems? How are they compared to MIT’s Kerboros.