|
 |
|
| |
24.1 Laptops
The hardware of laptops differs from that of a normal desktop
system. This is because criteria like exchangeability, occupied space, and
power consumption are relevant properties. The manufacturers of mobile
hardware have developed the PCMCIA (Personal Computer
Memory Card International Association) standard. This standard covers
memory cards, network interface cards, ISDN and modem cards, and external
hard disks.
How the support for such hardware is implemented in Linux, what needs
to be taken into account during configuration, what software is
available for the control of PCMCIA, and how to troubleshoot any possible
problems is described in Section 25.0,
PCMCIA.
24.1.1 Power Conservation
The inclusion of energy-optimized system components when manufacturing
laptops contributes to their suitability for use without access to
the electrical power grid. Their contribution
towards conservation of power is at least as important as that of the
operating system. SUSE® Linux Enterprise Desktop supports various methods that influence the
power consumption of a laptop and have varying effects on the
operating time under battery power. The following list is in
descending order of contribution towards power conservation:
-
Throttling the CPU speed
-
Switching off the display illumination during pauses
-
Manually adjusting the display illumination
-
Disconnecting unused, hotplug-enabled accessories (USB CD-ROM,
external mouse, unused PCMCIA cards, etc.)
-
Spinning down the hard disk when idling
Detailed background information about power management in SUSE Linux Enterprise Desktop and
about operating the YaST power management module is provided in
Section 27.0,
Power Management.
24.1.2 Integration in Changing Operating Environments
Your system needs to adapt to changing operating environments when
used for mobile computing. A lot of services depend on the
environment and the underlying
clients must be reconfigured. SUSE Linux Enterprise Desktop handles this task for you.
The services affected in the case of a laptop commuting back and forth
between a small home network and an office network are:
- Network
-
This includes IP address assignment, name resolution, Internet
connectivity, and connectivity to other networks.
- Printing
-
A current database of available printers and an available print
server must be present, depending on the network.
- E-Mail and Proxies
-
As with printing, the list of the corresponding servers must be
current.
- X
-
If your laptop is temporarily connected to a beamer or an external
monitor, the different display configurations must be available.
SUSE Linux Enterprise Desktop offers several ways of integrating a laptop into existing
operating environments:
- SCPM
-
SCPM (system configuration profile management)
allows storage of arbitrary configuration states of a system into a kind
of snapshot called a profile.
Profiles can be created for different situations. They are useful when a
system is operated in changing environments (home network, office
network). It is always possible to switch between profiles. Find
information
about SCPM in Section 26.0,
System Configuration Profile Management. You can use the Kicker applet
Profile Chooser
in KDE to switch between profiles. The application requires the
root password before switching.
- NetworkManager
-
NetworkManager is especially tailored for mobile networking on
laptops. It provides a means to easily and automatically switch between
network environments or different types of networks, such as wireless
LAN and ethernet. NetworkManager supports WEP and WPA-PSK encryption in wireless
LANs. It also supports dial-up connections (with smpppd). Both
desktop environments (GNOME and KDE) include a front-end to NetworkManager.
Table 24-1 Use Cases for NetworkManager
|
is a laptop |
Yes |
|
is sometimes attached to different networks |
Yes |
|
provides network services (such as DNS or DHCP) |
No |
|
only uses a static IP address |
No |
Use the YaST tools to configure networking whenever NetworkManager should
not handle network configuration.
- SLP
-
The service location protocol (SLP) simplifies
the connection of a laptop to an existing network.
Without SLP, the
administrator of a laptop usually requires detailed knowledge of the
services available in a network. SLP broadcasts the availability of a
certain type of service to all clients in a local network. Applications
that support SLP can process the information dispatched by SLP
and be configured automatically. SLP can even be used for the
installation of a system, sparing the effort of searching for a suitable
installation source. Find detailed information about SLP in
Section 30.0,
SLP Services in the Network.
The emphasis of SCPM lies on enabling and maintaining reproducible system
conditions. SLP makes configuration of a networked computer
a lot easier by automating much of it.
24.1.3 Software Options
There are various special task areas in mobile use that are
covered by dedicated software: system monitoring (especially the battery
charge), data synchronization, and wireless communication with peripherals
and the Internet. The following sections cover the most important
applications that SUSE Linux Enterprise Desktop provides for each task.
System Monitoring
Two KDE system monitoring tools are provided by SUSE Linux Enterprise Desktop:
- KPowersave
-
KPowersave is an applet that displays the state of the
rechargeable battery in the control panel. The icon adjusts to
represent the type of power supply. When working on AC power, a small
plug icon is displayed. When working on batteries, the icon changes to
a battery. The corresponding menu opens the YaST module for power
management after requesting the root password. This allows setting the
behavior of the system for different power sources.
Find information about power management and about the corresponding
YaST
module in Section 27.0,
Power Management.
- KSysguard
-
KSysguard is an independent application that gathers all
measurable parameters of the system into one monitoring environment.
KSysguard has monitors for ACPI (battery status), CPU load, network,
partitioning, and memory usage. It can also watch and display
all system processes. The presentation and filtering of the collected
data can be customized. It is possible to monitor different system
parameters in various data pages or collect the data of various
machines in parallel over the network. KSysguard can also run as a
daemon on machines without a KDE environment. Find more information about
this program in its integrated help function or in the
SUSE help pages.
In the GNOME desktop, use the panel applet GNOME
ACPI and the application System Monitor.
Synchronizing Data
When switching between working on a mobile machine disconnected from the
network and working at a networked workstation in an office, it is
necessary to keep processed data synchronized across all instances.
This could include e-mail folders, directories, and individual files that
need to be present for work on the road as well as at the office. The
solution in both cases is as follows:
- Synchronizing E-Mail
-
Use an IMAP account for storing your e-mails in the office
network. Then access the e-mails from the workstation using any
disconnected IMAP–enabled e-mail client, like Mozilla Thunderbird
Mail, Evolution, or KMail as described in Applications.
The e-mail
client must be configured so that the same folder is always accessed
for Sent messages. This ensures that all messages
are available along with their status information after the
synchronization process has completed. Use an SMTP server implemented
in the mail client for sending messages instead of the systemwide MTA
postfix or sendmail to receive reliable feedback about unsent mail.
- Synchronizing Files and Directories
-
There are several utilities suitable for synchronizing
data between a laptop and a workstation. For detailed information,
refer to Section 37.0,
File Synchronization.
Wireless Communication
As well as connecting to a home or office network with a cable, a
laptop can also wirelessly connect to other computers, peripherals,
cellular phones, or PDAs. Linux supports three types of wireless
communication:
- WLAN
-
With the largest range of these wireless technologies, WLAN is
the only one suitable for the operation of large and sometimes even
spatially disjointed networks. Single machines can connect with each
other to form an independent wireless network or access the
Internet. Devices called access points act as base
stations for
WLAN-enabled devices and act as intermediaries for access to the
Internet. A
mobile user can switch among access points depending on
location and which access point is offering the best connection. Like in
cellular telephony, a large network is available to WLAN users without
binding them to a specific location for accessing it. Find details
about WLAN
in Section 28.1,
Wireless LAN.
- Bluetooth
-
Bluetooth has the broadest application spectrum of all wireless
technologies. It can be used for communication between computers
(laptops) and PDAs or cellular phones, as can IrDA. It can also
be used to connect various computers within visible
range. Bluetooth is also used to connect wireless system components,
like a keyboard or mouse. The range of this technology is, however, not
sufficient to connect remote systems to a network. WLAN is the
technology of choice for communicating through physical obstacles like
walls. Find more information about Bluetooth, its applications, and
configuration in Section 28.2,
Bluetooth.
- IrDA
-
IrDA is the wireless technology with the shortest range. Both
communication parties must be within viewing distance of each
other. Obstacles like walls cannot be overcome. One possible
application of IrDA is the transmission of a file from a laptop
to a cellular phone. The short path from the laptop to the
cellular phone is then covered using IrDA. The long range transport of
the file to the recipient of the file is handled by the mobile
network.
Another application of IrDA is the wireless transmission of printing
jobs in the office. Find more information about IrDA in
Section 28.3,
Infrared Data Transmission.
24.1.4 Data Security
Ideally, you protect data on your laptop against
unauthorized access in multiple ways. Possible security measures can be taken in the
following areas:
- Protection against Theft
-
Always physically secure your system against theft whenever
possible. Various securing tools, like chains, are available in retail
stores.
- Securing Data on the System
-
Important data should not only be encrypted during transmission, but
also on the hard disk. This ensures its safety in case of theft. The
creation of an encrypted partition with SUSE Linux Enterprise Desktop is described in
Section 41.0,
Encrypting Partitions and Files.
IMPORTANT: Data Security and Suspend to Disk
Encrypted partitions are not unmounted during a suspend to disk
event. Thus, all data on these partitions is available to any party who
manages to steal the hardware and issue a resume of the hard
disk.
- Network Security
-
Any transfer of data should be secured, no matter how it takes
place. Find general security issues regarding Linux
and networks in Section 43.0,
Security and Confidentiality. Security
measures related to wireless networking are
provided in Section 28.0,
Wireless Communication.
|
|
|
