Networking

Networking

Objectives

• Explain networking terminology

• View TCP/IP settings

• Access network resources

• View folder and file sharing permissions

Guide to Parallel Operating Systems with Windows 7 and Linux 2

Networking Terminology

• Client/Server Networks

– Client/server model:

• Central idea of networking

• Relationship between two computers

– Desktop computer (the client) makes service request of another computer (the server)


Figure 11-1 Client/server relationship

Courtesy Course Technology/Cengage Learning


Peer-to-Peer Networks

• Employ desktop computers that are equally capable of being both clients and servers

• Example: small office/home office network

• Fedora 13:

– Provides peer-to-peer networking with Samba

– Samba:

• Based on Server Message Block (SMB)

• Identical to protocols provided by Windows 7


Figure 11-2 Peer-to-peer network



Networking Terminology (continued)

• LANs (local area networks)

– Usually confined to a geographic area

– Can be small, linking two or three computers

– Often link hundreds of computers used by many people

• WANs (wide area networks)

– Connects different LANs using services such as:

• Dedicated, leased data lines, satellite links, and data packet carrier services


Figure 11-3 Local area network



Figure 11-4 Wide area network

Courtesy Course Technology/Cengage Learning



• Internet

– System of linked networks

– Communications highway for millions of users

• Intranet

– Private network that uses Internet-type applications

– Available only within a single organization

– For large organizations:

• Allows easy access to Web-based applications



• VPN (virtual private network)

– Uses tunneling to transfer data securely

– Helps to save money by using:

• Public Internet to connect securely with private network

• Internet Protocol

– Main networking protocol

– Allows communication of data across a network

– Computers can deliver packets based on unique IP addresses

– Foundation of the Internet Protocol Suite



• Protocols

– Set of rules that enables two computers to talk to each other

– Computing standard that defines the syntax and regulations of a connection across a network

• Internet Protocol addresses

– Identify two computers or devices in a network

– IPv4 (IP Address Version 4):

• 32 bits divided into four octets between 0 – 255

– IPv6: consists of 128 bits


The Internet Protocol Suite

• Set of protocols used in combination for different networking tasks

• IP and TCP:

– Underlying standards that all other protocols use

– Commonly referred to as TCP/IP

• TCP:

– Organizes data into packets and sends them to IP

– Rebuilds files from individual packets IP sent


The Internet Protocol Suite (continued)

• Layers of the Internet Protocol Suite

– Network (or Network Access) layer: links computers

– Internet layer: allows IP to transfer packets across the link

– Transport layer: uses TCP to organize packets

– Application layer: consists of protocols for specific types of transfer



Figure 11-5 Internet Protocol Suite




• Application layer protocols

– HTTP (Hypertext Transfer Protocol): allows Web users to request Web sites from remote servers

– FTP (File Transfer Protocol): allows for the rapid transfer of files across the Web

– POP3 (Post Office Protocol 3): sends and receives e-mail

– SMTP (Simple Mail Transfer Protocol): sends and receives e-mail


Viewing TCP/IP Settings

• IP address:

– Numerical label assigned to devices participating in a computer network

• The subnetwork, or subnet:

– Logically visible, distinctly addressed part of a single

IP network

• The gateway IP address: node on a TCP/IP network

• DNS IP address of server providing domain name resolution:

– Translates domain names into numerical (binary) identifiers


Viewing TCP/IP Settings (continued)

• Dynamic Host Configuration Protocol (DHCP):

– Used by hosts (DHCP clients) to retrieve IP address assignments and other configuration information

– Uses a client/server architecture

• In the absence of DHCP:

– All hosts on a network must be manually configured with static IP addresses


Viewing TCP/IP Settings in Windows 7

• Use Windows 7 GUI tools or command line

• To display the Network Connection Details window:

– Click Start

– Right-click Network

– Click Properties

– Click the Local Area Connection link

– Click Details

• No value for the DHCP enabled property indicates:

– An administrator assigned a static configuration


Guide to Parallel Operating Systems with Windows 7 and Linux

Figure 11-6 Network

Connection Details window

Courtesy Course

Technology/Cengage Learning

20

Viewing TCP/IP Settings in Windows 7

(continued)

• IPCONFIG /ALL command:

– Provides network connection details

– To access this information:

• Click Start

• Point to All Programs

• Click Accessories

• Click Command Prompt

• Type IPCONFIG /ALL

• Press Enter


Figure 11-7 Network connection details



Viewing TCP/IP Parameters in Fedora

13

• Use GUI tools or Terminal window

• To display Ethernet Device settings:

– Click System, point to Administration, click Network type your password, and then click Edit, or

– Use the nm-tool command in a Terminal window, or

– Use ifconfig –a command



Figure 11-8 Ethernet Device settings

Courtesy Course


24

Figure 11-9 Network Manager tool



Accessing Network Resources

• Accessing network resources in Windows 7

– Workgroup:

• Provides a basis for file and printer sharing

• Automatically created when peer-to-peer network is created

• Default: WORKGROUP

– Homegroup:

• Makes it easy to share libraries and printers

• Protected with a password



(continued)

• Network option on the Start menu:

– Displays shortcuts to shared computers, printers, and other resources on the network

• To open the Network window:

– Click Start and then click Network

• To see shares another computer is offering:

– Type \\servername\ in Windows Search text box

– Click server name

• To see the shares another computer is offering:

– Type NET VIEW \\servername


Figure 11-10 Network resources shown in workgroup



Figure 11-11 Shares on the Host01 computer



Figure 11-12 The NET VIEW command shows shares on the other computer




(continued)

• UNC notation use:

– Requires that you know name or IP address of server and share

• To open a folder to a network location:

– Type the UNC in the search text box

• To access the files:

– Click UNC displayed in the search results text box



Figure 11-13 Accessing a network share from the

Search window

Courtesy Course


32


(continued)

• To access a network share from command prompt:

– Double-click the command Prompt icon

– Type: NET USE [drive letter | *]

\\computer name\share name

– You may specify a drive letter or permit Windows 7 to provide one:

• Example: NET USE N: \\Windows7\History


Accessing Network Resources in

Fedora 13

• To access a share, you must mount the share

• After you create a directory for mount destination:

– Type mount command

– Specify UNC for share, logon credentials, and destination directory

– Once share completes:

• Change directory to mount destination

• Issue an ls command to view the files


Figure 11-14 Mounting a Windows share in Linux



Accessing Network Printers

• It makes good economic sense to:

– Share a printer

– Make it available to several users on a network

• Network administrators:

– Responsible for setting up shared printers on the network


Folder and File Sharing Permissions

• Managing Windows NT File System permissions

– You must be able to view folder and file permissions

– Only authorized users can access local and network folders and files

• NT File System required

– To share folders and files with other network users

– Only NTFS:

• Permits user accounts and user groups to be linked to folder and file permissions


Managing Windows NT File System

Permissions (continued)

• Using local user groups

– Used to simplify management and authorization of network resource

– Groups are created to:

• Define sets of user accounts that require access to the same resources

• Viewing shared folder permissions

– When sharing folder with network users, administrators:

• Must specify the level of access

• Balance security with functionality




Table 11-1 Windows 7 shared folder permissions




• Assigning NTFS permissions

– Administrators secure folders and files on an NTFS volume

– NT file system is required to use NTFS permissions

– Assign file permissions to control access to files

• Multiple NTFS permissions

– More effective to assign permissions to user groups

– Permissions assigned at file level override those assigned at folder level




Table 11-2 NTFS folder permissions




Table 11-3 NTFS file permissions




• Permission inheritance

– Inheriting permissions of parent folder by default

– Options to prevent inheritance:

• Copy inherited permissions from parent folder

• Remove inherited permissions and retain only assigned permissions


Figure 11-16 Permission inheritance

Courtesy Course



Combining Shared Folder and NTFS

Permissions

• Administrators gain the highest level of security and control

• NTFS:

– Offers most flexible level of control

– Can be assigned to resources on an individual basis

• To determine effective permissions for a given network resource:

– Combine shared folder permissions

– Combine NTFS folder permissions

– Determine which permission is the most restrictive


Figure 11-17 The result of combining shared folder and NTFS permissions



Moving and Copying Files in NTFS

Volumes

• Files/folders inherit permissions from the destination folder

• When files/folders are moved within NTFS partition:

– They do not need to be re-created

• When you move a file/folder between NTFS volumes:

– It must be created on the destination volume

• FAT16 and FAT32 file systems

– Do not supports NTFS permissions


Viewing Fedora 13 File Permissions

• Each file and directory:

– Has permissions for owner, group, and everyone else

• Permissions for each group:

– Consist of three (binary) bits

• 10th bit is the sticky bit

• To show the file permissions:

– Use the ls command with the –l option



(continued)

Figure 11-19 File permissions in Fedora 13




(continued)

Figure 11-20 Viewing file permissions in Fedora 13



Figure 11-21 Listing file permissions in Fedora 13




(continued)

Figure 11-22 Displaying file permissions in Fedora 13


The User Identification Attribute

• File permissions bits:

– Include an execute permission bit for the file owner, the group, and others

• When the execute bit is set for the owner:

– The SUID bit (set user ID) is set to s

• Permission allows user/process that runs the file to have same access to system resources as owner


The Sticky Bit

• Ensures that:

– Only owner who created a file in directory can delete file and prevent malicious/accidental deletion

• When sticky bit is set:

– A t appears as the third character of the Others permission bits


Summary

• Network :

– Computers interconnected by communication paths

• To enable communications in a routed network:

– Computer must have an IP address, subnet mask, gateway IP address, and DNS IP address

• Network resources, folders, files, and printers are shared on the network

• File permissions:

– Enable users to access needed files

– Enable groups to share project files and folders


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