1. The University of Akron Summit College Business Technology Dept.
2440: 141 Web Site Administration
Server Management
Instructor: Enoch E. Damson

2. Web Administrator's View of Server Management
The Web server software is a product that works with the operating system
The server computer can run more than one software product such as and FTP
With both a LAN and the Web, access control is very important
Server Management

3. Networking Models Two main approaches to networking includes:
Microsoft LAN approach to networking
Client/server approach to networking
Server Management

4. Microsoft LAN Networking Models
Microsoft Windows LAN is configured using one of these two models:
Workgroup
Domain
The model determines how users are organized
Server Management

5. Workgroup Networking Model
Treats each computer in the network as an equal, or peer
Also called peer-to-peer networking
Each computer is 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
Appropriate for networks with 10 or less computers
Server Management

6. Workgroup Networking Model…
Disadvantages:
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
Server Management

7. Domain Networking Model
One or more servers centralize control
Computers are part of a domain
Single, centralized logon
Single point of control
Users can be given access to resources anywhere in the domain
Server Management

8. Client/Server Networking Model
Client represents a program such as a browser or an client
Server has a corresponding program that communicates with the client
Client and server communicate using a protocol
Web browsers (client) and Web servers use HTTP to communicate
Access to servers controlled by a service/daemon
Networking in Linux follows the client/server model
Each computer has its own database of users/passwords
Server Management

9. Server Users
User account – consists of a username and password to identify each user
Usually has a home directory for storing files
User owns any files created in the home directory
Usually a user’s address (if an service is provide on the system)
Users can log in and upload files if an FTP server is running on the machine
Users & Documents

10. User Accounts
Systems administrators need to maintain user accounts by:
Creating new user accounts
Maintaining the integrity of user accounts
Deleting accounts of users not needing access
Scripts can be used to speed things up when creating many user accounts
Users & Documents

11. Creating User Accounts
Creating an account generally involves:
Creating a home directory for a user
Setting permissions and groups
Installing any login scripts or default directories and files for the user
Configuring if necessary
Users & Documents

12. Maintaining User Accounts
With many users, the users’ home directories should all be in a partition or drive separate from the core operating system
Keeps the server running smoothly even if users fill available space on the drive
Users must be given a quota to keep them from taking up too much space
Users & Documents

13. Authenticating Users
Authentication – the process of determining a user’s true identity
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
Windows authentication could be accomplished using:
Kerberos – developed at MIT to allow exchange of private information across a network
Certificates – guarantees the identify of an organization or user
Server Management

14. 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
Server Management

15. Managing Users and Groups…
Windows has an account called system
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
Server Management

16. 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
Server Management

17. 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
Server Management

18. Users and Groups in Linux
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
Server Management

19. 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
Server Management

20. File System Permissions in Windows
Description
Full Control
Includes all other permissions and allows ownership of the file or folder and change the attributes of a file
Modify
Allows read, write, and delete
Read
Read files but cannot execute them
Write
Write to files or folders
Read & Execute
Read files and run programs
Special Permissions
View the contents of a folder
Server Management

21. File System Permissions in Linux
Used on Files
Used on Directories
Read (r)
Read a file or copy a file
List the contents of a
directory
Write (w)
Write to the file, including deleting
the file
Create files
Execute (x)
Execute programs and shell scripts,
which are text files containing Linux
commands
Modify the file permissions
Server Management

22. Linux File Permission Commands
The following commands are used for Linux permissions:
umask – sets the default file/directory permission
chmod – changes the access permissions of a file or directory
chgrp – changes the group associated with a file
chown – changes the owner associated with a file
Server Management

23. Linux File Permissions
Permissions are set for three types of users:
User (u)
Group (g)
Others (o)
The three permissions (with their numeric values) are:
Read (r) = 4
Write (w) = 2
Execute (x) = 1
Linux permissions may be set using the chmod command in two ways:
Numeric values
Mnemonics
Server Management

24. Mnemonic Characters for Linux File Permissions
Types of users:
a  all
u  user
g  group
o  other
Permissions:
d  directory
r  read (4)
w  write (2)
x  execute (1)
-  none (0)
Actions:
=  assigns permission
+  adds permission
-  removes permission
Use commas to separate assignment units, with no spaces
Server Management

25. Linux File Permission Examples Using umask
The umask command uses the numeric values for read (4), write (2) and execute (1) permissions to determine which ones will be unavailable to the category of users (user, group, others) when a file is created
Setting default file permissions for all three categories of users (user, group, others) to have all (read, write and execute) permissions
umask 000
Setting default file permissions for all three categories of users (user, group, others) to have none of the permissions (read, write and execute)
umask 777
Server Management

26. Setting Linux Default File Permissions
Command
Default Permissions
User
Group
Other
umask 011
rwx
rw-
umask 233
r-x
r--
umask 000
Server Management

27. Linux File Permission Examples Using chmod
Assigning read, write and execute permissions to all users on a file:
chmod a=rwx file
chmod ugo=rwx file
chmod u=rwx,g=rwx,o=rwx file
chmod 777 file
Assigning read, write permissions to user and execute permission to group and other users on a file:
chmod u=rw,go=x file
chmod 611 file
Adding read, write permissions to all users on a file:
chmod ugo+rw file
chmod a+rw
Adding read, write permissions to user and group; and execute permission to other users on a file:
chmod ug+rw,o+x file
Removing read, write permissions from all users:
chmod a-rw file
chmod ugo-rw file
Removing write permission from group and other users:
chmod go-w file
Server Management

28. Setting Linux File Permissions Using Numeric Values
Command
Permissions
User
Group
Other
chmod 755 myfile
rwx
r-x
chmod 540 myfile
r--
---
chmod 744 myfile
Server Management

29. Setting Linux File Permissions Using Mnemomics
Command
Permissions
User
Group
Other
chmod u=rwx,go=rx myfile
rwx
r-x
chmod u=rx,g=r,o= myfile
r--
---
chmod u=rwx,go=r myfile
Server Management

30. Sharing Resources in a Windows Network
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
Server Management

31. Enforcing Network Policies
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
Number of days before change allowed
Number of days before change required
Server Management

32. Document Hierarchy
Files and directories on Web servers are organized in a file system.
File system – determines:
Where files are stored on a computer’s hard drive
How many letters a filename can contain
The security of files stored on the computer
There are many different file systems and most modern operating systems can support more than one
Users & Documents

33. Common File Systems Some of the most common file systems are:
FAT32 – Microsoft file system
NTFS – Windows NT file system
UFS – UNIX file system
ext3, ext4 – Linux file system
HFS – Macintosh hierarchical file system
NFS – Network file system
Users & Documents