Translations by Viet Hung

ubuntu-doc@lists.ubuntu.com (Ubuntu Documentation Project)

Keeping Your Computer Safe

2006-09-07

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Credits and License

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You are free to modify, extend, and improve the Ubuntu documentation source code under the terms of this license. All derivative works must be released under this license.

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The Ubuntu Documentation Project

This section describes how to keep your computer safe from security threats.

Lock your screen while away

Locking your screen prevents other people from accessing your computer while you are away from it. All of your applications and work remain open while the screen is locked, and the screensaver is displayed.

You can lock your screen in one of the following ways:

Press <keycombo><keycap>Control</keycap><keycap>Alt</keycap><keycap>L</keycap></keycombo> to lock the screen. This keyboard shortcut can be changed in <menuchoice><guimenu>System</guimenu><guimenuitem>Preferences</guimenuitem><guimenuitem>Keyboard Shortcuts</guimenuitem></menuchoice>.

You can add a <guibutton>Lock Screen</guibutton> button to a panel for easy access. Right-click a panel (for example, the panel at the top of the screen), select <guibutton>Add to Panel...</guibutton> and drag the <guibutton>Lock Screen</guibutton> item to the desired location.

If more than one person has a user account on your computer and the screen is locked, other users can press the <guibutton>Switch user...</guibutton> button to use the computer, even while the screen is locked. They will be unable to access your currently-open work, and you will be able to switch back to your locked session when they have finished using the computer.

Set up a firewall

You can optionally install a firewall to protect your computer against unauthorized access by people on the Internet or your network. Firewalls block connections to your computer from unknown sources, which helps to prevent security breaches.

The <application>Firewall Wizard</application> should run. If it does not, press <menuchoice><guimenu>Firewall</guimenu><guimenuitem>Run Wizard</guimenuitem></menuchoice>.

Follow the steps in the <application>Firewall Wizard</application>. After completing all of the steps, the firewall should be configured and running.

To check that your firewall is working correctly, make use of an online firewall testing service such as <ulink url="http://www.grc.com/">ShieldsUP</ulink>.

For help and advice on the advanced configuration of <application>Firestarter</application>, see the <ulink url="http://www.fs-security.com/docs.php">Firestarter Online Manual</ulink>.

Avoid Internet nuisances and crime

From time to time, you may be sent an email which carries a virus or links to a fraudulent website. This type of email is very common, and it is important to learn how to deal with it, in order to prevent your computer or your personal details from being compromised or misused.

Such messages are often received from total strangers. However, sometimes an email may appear to be from someone you know, when really it is not. This is because it is possible to include a fake sender email address in emails.

Unwanted (unsolicited) mail tends to fall in to one of several categories:

Spam (junk) email, where people offer unwanted services and products

Scam emails, where people pretend to ask for help in exchange for large sums of money

Phishing email, where the message appears to be from a bank or other online service, asking you to enter your personal and financial details, or passwords.

Below are some tips for keeping safe online:

You should never reply to unsolicited mail, or even click on the links in the mail. Doing so usually results in more junk mail being sent to you.

Never click on links in emails which lead to websites asking for your password or similar. It is possible for the text of the link to give one address, when really it opens up another (possibly dangerous) address. Instead, type the link into your web browser yourself and proceed from there.

If a website asks for your financial details, ensure that it is secure. In the <application>Firefox Web browser</application>, secure websites have a <emphasis>yellow</emphasis> address bar with a padlock icon to the right of the address. Click on the padlock to read more information about the security of the website.

Only download and run software from sources that you trust. By default, you can only download software directly from Ubuntu.

Make backup copies of your files

A problem which you may occasionally encounter is the unexpected loss of some of your work and settings for one reason or another. The causes of such <emphasis>data loss</emphasis> are many and varied; it could be anything from a power cut to accidentally deleting a file. It is highly recommended that you make regular back-up copies of your important files so that, if you do encounter a problem, you will not have lost those files.

It is wise to store back-up copies of files separately from your computer; that is, you should make use of some form of file storage which is not permanently attached to your computer. Options include:

Writable CDs and DVDs

External hard disks and flash memory devices

Another computer on the network

A simple way of backing-up your files is to manually copy them to a safe location (see above) by using the <application>File Browser</application>.

Alternatively, you can use a dedicated back-up application, such as <application>HUBackup</application>:

To make a backup, press <menuchoice><guimenu>System</guimenu><guisubmenu>Administration</guisubmenu><guimenuitem>Home User Backup</guimenuitem></menuchoice>.

Select the files which you would like to make a backup copy of and choose the location which you would like to save the backup to. If you have a CD or DVD writer, it should be present in this list.

Press <guibutton>Backup</guibutton> and follow the instructions given on-screen.

Some general advice on how to keep good back-ups is given below:

Back-up on a regular basis

Always test your back-ups after you make them, to ensure that they have been made correctly

Label your back-ups clearly, and keep them in a safe place