Web Server Administration Chapter 5 Managing a Server

Web Server Administration Chapter 5 Managing a Server

Overview n n Understand the Web server administrator's view of server management Examine networking models Learn how users are authenticated Manage users and groups

Overview n n n Manage file system permissions Share resources in a network Enforce network policies

Web Administrator's View of Server Management n n n Web server software is a product that works with the operating system The server computer can run more than one software product such as e-mail and FTP With both a LAN and the Web, controlling access is very important The Web server can be part of the LAN Web communication and LAN communication are different

Microsoft LAN Networking Models. Workgroup n Treats each computer in the network as an equal, or peer n n Also called peer-to-peer networking Each computer is a client and a server n n 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

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

Microsoft LAN Networking Models. Domain n n One or more servers centralize control Computers are part of a domain n Single, centralized logon Single point of control Users can be given access to resources anywhere in the domain

Client/Server Networking Model n n Client represents a program such as a browser or an e-mail client Server has a corresponding program that communicates with the client n n Server program known as a service in Windows or a daemon in Linux Networking in Linux follows the client/server model n Telnet is used to log on to another computer

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

Implementing an Authentication System n n If a Windows network has older computers running NT, 95, or 98, the server must use NTLM It is not as secure as Kerberos, which is the default for Windows 2000, 2003, and XP

Managing Users and Groups n Users need accounts to access resources on a server n n 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

Managing Users and Groups in Windows has an account called system n n n It represents the operating system and it has many of the same privileges of the administrator Often needed by server programs Linux typically uses unique accounts for each daemon

Users and Groups in Windows n n n 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 n Microsoft Exchange requires AD

Groups in Windows n Domain local groups have members from the same domain n n Global groups have members from the same domain n n Assign permissions to resources in the same domain Can be used to assign permissions to resources in any domain Universal groups can have members from any domain n Can be used to assign permissions to resources in any domain

Users and Groups in Linux n Properties of user accounts Item Description User name Logon name of the user Full name The full name of the user or any comment Password The password must be at least six characters Home directory The default is /home/username Group The default is to create a group with the same name as the user Login shell The default is /bin/bash, which determines the characteristic of the shell environment

File System Permissions n n n Permissions 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

File System Permissions in Windows Permission Description Full Control includes all other permissions and allows you to take ownership of the file or folder and change the attributes of a file Modify Allows read, write, and delete Read With this permission, you can read files but cannot execute them Write When set on a file, this permission allows you to write to files; when set on a folder, you can write to the folder Read & Execute Read files and run programs List Folder Contents This permission allows you to view the contents of a folder Special Permissions (Windows 2003 only) This is not a specific permission; under the list of permissions for users, when this permission is checked, it means that this user has one or more of the 14 individual permissions set

File System Permissions in Linux Permission When used with files type When used with directories Read a file or copy a file List the contents of a directory Write to the file, including deleting the file Create files Execute programs and shell scripts, which are text files containing Linux commands Modify the file permissions enter directory

Linux Permissions n n 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 n n n read = 4 write = 2 execute = 1

Using chmod to Set Permissions Command Permissions chmod 755 myfile Owner rwx Group r-x Other r-x chmod 540 myfile chmod 744 myfile r-x rwx r-r-- --r--

Sharing Resources in a Windows Network n n Shared folders require permissions When comparing share permissions and NTFS permissions, the most restrictive permission takes precedence Permission Description Full Control Allow files to be added, deleted, changed, and read Change Allow existing files to be written to Read Can only read files

Enforcing Network Policies n n n You can control a number of policies in both Windows and Linux Windows has many more policies but the majority are appropriate for LANs A common policy involves passwords n n Number of days before change allowed Number of days before change required

Summary n n n The Web server has a guest user account that is used to access Web pages Windows LAN models include the workgroup and domain models Linux only uses the client/server model Authentication is based on what you know, what you have, and who you are Core of security incorporates users, groups, and permissions