Download MCTS Guide to Microsoft Windows Server 2008 Applications

Linux Operations and
Administration
Chapter Seventeen
Networking in a Linux Environment
Objectives
• Describe key functions of the Network Information
Service
• Install and configure an NIS server and client
• Configure a local printer queue
• Install and configure a DHCP server
Linux Operations and Administration
2
Network Information Service
• Network Information Service (NIS)
– A client/server protocol that centralizes user and
group IDs
– Provides database access so that network
computers can share configuration information
• Such as contents of /etc/passwd, /etc/shadow,
and /etc/group files
• Maps
– Databases that store shared configuration
information related to NIS networks
Linux Operations and Administration
3
Network Information Service (cont’d.)
• NIS setup consists of three types of host servers:
– NIS master server
• Contains NIS maps and makes them available over
the network
– NIS slave servers
• Can be used to distribute NIS master server’s load
more evenly
– NIS clients
• All hosts in an NIS-based network, including master
and slave servers
Linux Operations and Administration
4
Network Information Service (cont’d.)
• NIS domain determines which NIS server should
process the client request
• NIS uses Remote Procedure Calls (RPC)
technology
– Standard method of allocating and managing shared
resources between NIS clients and servers
• For NIS to operate correctly, RPC portmapper must
run on both NIS client and server
Linux Operations and Administration
5
Figure 17-1 NIS communication with RPC
© Cengage Learning 2013
Linux Operations and Administration
6
Installing and Configuring NIS Servers
• To install NIS, you need to have both NIS server
and client
• Decide whether computer will be used as a master
server, a slave server, or a client
• If an NIS server (master or slave) is already
installed on Linux network:
– Need to install only the NIS client
• If there are no NIS servers on Linux network:
– Need to install the server as well as the client
Linux Operations and Administration
7
Installing and Configuring NIS Servers
(cont’d.)
• Before configuring system for use as an NIS server
or client, provide a domain name for the computer
– Done to ensure that a client and server in the same
domain can communicate with each other
– A client can’t access a server in a different domain
Linux Operations and Administration
8
Creating an NIS Domain
• domainname command
– Can be used to create an NIS domain
– Must be issued from root user account when setting
a domain name
• To save NIS domain name permanently:
– Edit runlevel script /etc/init.d/network
– Specify NIS domain name in the script
– Example:
# Set the NIS domain name
domainname example
Linux Operations and Administration
9
Installing an NIS Master Server
• NIS master server contains source files for all NIS
maps in a domain
• OpenSUSE
– Provides an NIS client by default
– Need to install an NIS server
• yast2 -i yast2-nis-server command
– Used to download and install nis-server RPM
package and dependencies
– Works from root user account
Linux Operations and Administration
10
Configuring an NIS Master Server in
YaST
• yast2 nis-server command
– Used to start YaST NIS Server module
• Opening window of module shows the current
status of NIS server
• Master Server Setup window
• NIS Master Server Slaves Setup window
• NIS Server Maps Setup window
• NIS Server Query Hosts Setup window
Linux Operations and Administration
11
Figure 17-2 The Network Information Service (NIS) Server Setup
window
© Cengage Learning 2013
Linux Operations and Administration
12
Figure 17-3 The Master server Setup window
© Cengage Learning 2013
Linux Operations and Administration
13
Figure 17-4 The NIS Master Server Slaves Setup window
© Cengage Learning 2013
Linux Operations and Administration
14
Figure 17-5 Selecting NIS maps
© Cengage Learning 2013
Linux Operations and Administration
15
Figure 17-6 The NIS Server Query Hosts Setup window
© Cengage Learning 2013
Linux Operations and Administration
16
Configuring an NIS Master Server
Manually
• After NIS server and client are installed, /var/yp/
directory is created on the same computer to store
all NIS maps
• Each NIS map consists of two files:
– Index
• Contains key values (also called “indices”) of an NIS
map arranged in hash order
• Has a .dir extension
– Data
• Contains actual data related to a key value
• Has a .pag extension
Linux Operations and Administration
17
Configuring an NIS Master Server
Manually (cont’d.)
• Table 17-1
– Describes some commonly used NIS maps
• After NIS Server module is started, NIS exports
data to /var/yp directory
• /var/yp/Makefile
– A NIS configuration file in /var/yp directory
– Can be run with make file command
• This command can be issued only from /var/yp
directory
– Used to push updated maps to NIS slave server
Linux Operations and Administration
18
Configuring an NIS Master Server
Manually (cont’d.)
Table 17-1 Common NIS maps
Linux Operations and Administration
19
Configuring an NIS Master Server
Manually (cont’d.)
• /var/yp/securenets
– A NIS configuration file in /var/yp directory
– Specifies NIS clients’ access rights to NIS server
• Activity 17-1: Installing and Configuring an NIS
Server
– Install and configure an NIS server in YaST
Linux Operations and Administration
20
Installing and Configuring NIS Clients
• YaST NIS Client module is packaged with latest
version of openSUSE
• To start NIS Client module, use yast2 nisclient command
• Activate NIS by clicking Use NIS option button
• Define NIS policy to specify how NIS configuration
will be modified
– Default: it’s handled by netconfig script
– Only Manual Changes option
– Custom Policy option
Linux Operations and Administration
21
Figure 17-7 Configuring the NIS client
© Cengage Learning 2013
Linux Operations and Administration
22
Installing and Configuring NIS Clients
(cont’d.)
• Netconfig is a modular tool for managing network
configuration settings
• Need to specify NIS domain
• Enter NIS server IP address
• Broadcast check box
• Start Automounter check box
Linux Operations and Administration
23
Installing and Configuring NIS Clients
(cont’d.)
• Open Port in Firewall check box
• Can use Expert button to open Expert settings
window
– Answer Remote Hosts setting
– Broken server setting
• Activity 17-2: Configuring an NIS Client
– Configure an NIS client in YaST
Linux Operations and Administration
24
Figure 17-8 The Expert settings window
© Cengage Learning 2013
Linux Operations and Administration
25
Managing Other Network Services
• Linux provides network services for managing
many important administrative tasks
• Two of the essential network tasks:
– Manage print queues
– Manage IP addresses on a network
Linux Operations and Administration
26
Network Printing in Linux
• Common UNIX Printing System (CUPS)
– Provides a printing interface on a local network
– CUPS software converts many different types of files
into data a printer can understand and process
– CUPS software referred to as a filter
• Enables CUPS to print to a wide variety of printers
• Printer device
– Physical printer that transfers a print job from a
computer to actual hard copy
Linux Operations and Administration
27
Network Printing in Linux (cont’d.)
• Printer driver
– Software used to manage the printer device
• Print queue
– A directory file where the printer daemon can store
print jobs
– Multiple users can use the same printer device
• YaST Printer Configurations module
– Used to set up local or remote printer queues
Linux Operations and Administration
28
Network Printing in Linux (cont’d.)
• Remote printer queue
– Located on another host in the network, not on your
local computer
– You can access and use remote printer queues, but
can’t modify them from your local computer
• yast2 printer command
– Used to start YaST Printer Configurations module
Linux Operations and Administration
29
Figure 17-9 The Printer Configurations window
© Cengage Learning 2013
Linux Operations and Administration
30
Figure 17-10 The Print via Network window
© Cengage Learning 2013
Linux Operations and Administration
31
Figure 17-11 The Share Printers window
© Cengage Learning 2013
Linux Operations and Administration
32
Overview of DHCP in Linux
• DHCP
– Used to assign IP addresses automatically for each
network host
• You don’t have to configure each host separately
– Can be used to configure other network client
settings, such as:
• Setting up name server entries in
/etc/resolv.conf file
• Configuring host gateway information
Linux Operations and Administration
33
Overview of DHCP in Linux (cont’d.)
• Table 17-2
– Describes some identifying information that DHCP
provides
• DHCP server leases IP addresses for a period you
specify and assigns them to client computers
dynamically
– Useful when not all computers in a network stay
connected permanently
Linux Operations and Administration
34
Configuring a DHCP Server
• YaST DHCP module
– Not included with openSUSE
– You have to install DNS/DHCP pattern
• yast2 dhcp-server command
– Used to start DHCP module
Linux Operations and Administration
35
Figure 17-12 Configuring dynamic DHCP settings
© Cengage Learning 2013
Linux Operations and Administration
36
Configuring a DHCP Server (cont’d.)
• Settings you can make in each window:
– Card Selection
• Select NICs for DHCP server
• Open the firewall to allow access to DHCP server from
remote computers
– Global Settings
• Configure settings such as domain name, primary and
secondary name servers’ IP addresses, default
gateway, and WINS server IP address
Linux Operations and Administration
37
Configuring a DHCP Server (cont’d.)
– Dynamic DHCP
• Review subnet information, such as network and
netmask addresses
• Configure IP address range and lease time
– Start-up
• Specify that DHCP server starts automatically when
your Linux machine boots
Linux Operations and Administration
38
Configuring a DHCP Server (cont’d.)
• Expert configuration mode
– Can be used to fine-tune settings for DHCP server
• Host Management window
– Can be used to configure static allocation
• A host can be assigned the same IP address every
time it connects to the network
Linux Operations and Administration
39
Summary
• Network Information Service is a client/server
protocol that centralizes user and group IDs
• NIS master server contains source files for all NIS
maps in a domain and makes them available
• Installing NIS server also installs NIS client
• NIS slave servers are used to distribute the master
server’s load more evenly
• All hosts in an NIS network are called NIS clients
• domainname command is used to display or
temporarily specify NIS domain name
Linux Operations and Administration
40
Summary (cont’d.)
• yast2 -i yast2-nis-server command is
used to install YaST NIS Server module
– Module started with yast2 nis-server command
• NIS maps are multicolumn database files storing
key/value pairs that provide fast database access
• YaST Printer Configurations module uses printer
daemons, such as CUPS, for setting up a local or
network printer
– Module started with yast2 printer command
Linux Operations and Administration
41
Summary (cont’d.)
• CUPS provides a printing interface on a local
network that’s used to convert files into data a
printer can process
– Printer device is the physical printer that transfers a
print job from a computer to actual hard copy
– A printer driver is the software used to manage a
printer device
• DHCP is used to assign IP addresses automatically
for each network host
– Module started with yast2 dhcp-server
command
Linux Operations and Administration
42