Access Control and Resource Sharing in Client-Server Networks, Slides of Computer Networks

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Fundamentals of Soft Resource Sharing docsity.com Chapter Objectives • Describe the step-by-step process of placing a soft resource for sharing and removing the same from sharing • Discuss the access control that could be exercised at the file level • Relate permission to effective access control • Demonstrate the mapping of resources • Describe the concept of administrative shares • Discuss the sharing process in a mixed client-server and peer-to-peer environment docsity.com x CHAPTER Fundamentals of Soft CATO pe ey C) Chapter Objectives • Present an overview of the sharing mechanism in client-server networks • Explain the different types of access controls that could be imposed on resources • Describe the permissions that could be assigned to users for using resources docsity.com Chapter Modules • Overview of Windows Client-Server Sharing • Access Control in the Client-Server Environment • Windows Permissions docsity.com Basic Client-Server Sharing • As in peer-to-peer sharing, the act of sharing usually involves the following persons: – Resource Administrator – Network User • As the name implies, sharing is a two step process docsity.com Resource Administrator and the User • Resource Administrator gives the user the permission to access certain – Known as the Administrator – Resources are, in general, held at the server – Different types of servers may be present in a network • Application server, Exchange server etc. • Network User uses the resource within the confines of his or her privileges – Different types of network users can be given privileges to different resources docsity.com Resources, Resource Administrator and the Users Server Client Client Folder Resource (Folder to be shared). User User User Administrator docsity.com The Sharing Process Resource Access privilege Administrator Network user Security Server Client docsity.com Resource Classification for Sharing • Soft resource – Files – Subdirectories and directories – Hard disks etc. • Hard resource – Printer – Modem etc. docsity.com Sharing and Resource Types Soft resource on the network Share as any local logical resource Hard resource (device) on the network Install as a local logical device Share the logical device docsity.com Module Objectives • Overview of access control in client-server networks • Permission: The effective access to a resource • Basic permissions for files and directories • Read, write, execute, delete and taking ownership • A sample permission entry • Demonstration on viewing a user’s permission on a directory docsity.com Overview of Access Control in Client-Server Networks • More sophisticated than in peer-to-peer networks • Peer-to-peer – Share level – User-level • Client-Server – Share level – User level docsity.com Effective Access to a Resource Resource User Permission docsity.com Read and Write • Read – Folder • View the files and subdirectories – File • Read the file’s data • Write – Folder • Add files and subdirectories – Files • Write to the file docsity.com Execute and Delete • Execute – Folder • Enter subdirectories – File • Execute the file • Delete – Delete folder and file docsity.com Change Permission and Take Ownership • Change Permission – Change the permission on the folder and file • Take Ownership – Take ownership of the folder and file docsity.com Oe em eam Ou Ua aw aeRO mia rela maa C docsity.com v END OF MODULE docsity.com © N. Ganesan, All rights reserved. MODULE The Concept of Placing a Resource for Sharing docsity.com A Note on File Sharing • Files are shared by making the folder containing the file shareable in the fist instance • However, unlike in peer-to-peer sharing, considerable control can be exercised on file sharing in client-server sharing docsity.com Sharing in Different Architectures • Peer-to-Peer network architecture (FAT Only) – Sharing is limited to access control based on passwords – Also known as share level control – Control can be exercised based on user names as well if the peer-to-peer network is based on an operating system such as Windows 2000 or Windows XP • Client-Server network architecture (NTFS) – Sophisticated control of access to resources can be exercised based on user names docsity.com Types of Access Control in Different Peer-to-Peer Architectures Peer-to-Peer Networks Share-Level Control User Level Control Windows 9x/Me Windows 2000 Prof Windows XP docsity.com The FAT File System • Known as FAT32 • The older file system is known as FAT16 • Supported in Windows 95 OSR2, Windows 98 and Windows Me • NT 4.0 does not offer the support for accessing disks formatted under FAT32 • Windows 2000 and Windows XP, however, do offer support for FAT32 docsity.com Security Concerns with FAT FAT NTFS A Drive Bootable Non-bootable docsity.com Sample Server Configurations NTFS NTFS FAT Windows 9x/ NT OS CD Copy One or more partitions under NTFS docsity.com Share-Name View on the Network Canada (Root Fol.) Trade (Sub-Fol.) Rules (Shared Sub-Fol.) Canada (Peer) Rules (Shared Sub-Fol.) Local View Network View docsity.com The Concept of Owner Creator • The user who creates a folder for instance becomes the owner creator of the folder • He or she can assign the others permission to access the folder • Note that access to a folder created in a user’s home directory can be restricted to the creator only – Even the network administrator cannot access this folder docsity.com A Note on Sharing • All files in the folder can be shared when the folder is shared • It is also possible to limit the sharing to only a few files in the folder docsity.com © N. Ganesan, All rights reserved. MODULE Case Example: Single User Permission docsity.com Module Objectives • Giving folder access permission to a single user • Placing the resource Tariff for sharing • Giving access to user California docsity.com Sharing Scenario 1: Single User Permission • User California is to be given access to the Tariff directory • Permission is to be restricted to Change – (RWXD) (RWXD) docsity.com Placing Sub-directory Tariff for Sharing by User California: Demonstration docsity.com v END OF MODULE docsity.com © N. Ganesan, All rights reserved. MODULE Case Example: Group Sharing docsity.com Group Sharing: Opening the Directory Permission Windows Open the Explorer on the server named US. Right select the subdirectory named Tariff. Select Sharing. Select Security and then Permissions. docsity.com Assign the Group Inspectors the Permission to Tariff Folder Permissions Window Select Inspectors Specify type of Access as Change. Add Add/OK Check Replace Permission on Existing Files. docsity.com Placing the Sub-Folder Tariff for Sharing by the Group Inspectors: Demonstration docsity.com v END OF MODULE docsity.com © N. Ganesan, All rights reserved. MODULE Case Example: Permission Given to Creator Owner docsity.com Module Objectives • Use of creator owner to give permissions • The required permissions • Permissions to be assigned • Demonstration of the creator owner features docsity.com Permissions to be Assigned Creator Owner- Full Everyone - Add (WX) (Not Specified) Inspectors- Change (RWXD) (RWXD) docsity.com Use of Creator Owner: Demonstration docsity.com v END OF MODULE docsity.com Special Access • Directory and file access is not limited to pre-defined Microsoft access types (permissions) • Customized permissions can also be granted docsity.com Special Access to a Resource: Scenario 4 • Allow everyone to read the files in the Report directory • Add the Read permission to everyone – Using Special Access to Files option : docsity.com Adding the Read Access to the Files in the Directory Reports for Everyone: Steps Directory Permissions Window Select Everyone Select Type of Access as Special File Access. Check Read access to grant Read permission to the files to everyone. docsity.com © N. Ganesan, All rights reserved. MODULE File Access Control docsity.com Module Objectives • File permissions • File security permissions in NTFS • Predefined file access permissions • Illustration of the permission assignment process using a case example • Assignment of read-only permission assignment to the file Rates – The procedure – Demonstration docsity.com File Permissions • Unlike in peer-to-peer networking (FAT), better file control is available in client-server networks • Greater control on files can be exercised independent of the directory in which they reside docsity.com Specifying File Access Permission: Case Example • Restrict the access to the file Rates in the directory Tariff to the inspectors only • Limit the permission given to the file Rates to read only • The intention is to prevent unauthorized changes from being made docsity.com Location of the File Named Rates US Canada Mexico Tariff Directory to be shared. Rates A file in the directory. NAFTA (Domain) (Server) docsity.com The Permission Assignment Process • Open the file permission window • Set the type of access for Inspectors to Read, by selecting Special Permissions and then ensuring that only the Read box is checked docsity.com Assigning Read Only Permission to the File Rates: Demonstration docsity.com v END OF MODULE docsity.com © N. Ganesan, All rights reserved. MODULE Removing a File from Access docsity.com Preventing Access to the File Rates: Case Example • Prevent the user Texas from accessing the file Rates • This would eliminate Texas from accessing the file although he/she is a part of the group Inspectors • The group Inspectors was given access to the file Rates earlier docsity.com Preventing Texas from Accessing the File Rates: Steps File Permissions Window Add Texas Select Type of Access as No Access Finish OK OK docsity.com Preventing Texas from Accessing the File Rates: Demonstration docsity.com