Translations by Konstantinos Togias

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

Keeping Your Computer Safe

2006-09-07

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2004, 2005, 2006

The Ubuntu Documentation Project

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

Give a separate user account to each person

When Ubuntu is installed, it is set up for a single person to use. If more than one person will use the computer, it is best for each person to have their own user account. This way they can have separate settings, documents, and other files. If necessary, files can also be protected from being viewed or changed by non-administrators.

To set up user accounts, choose <menuchoice><guimenu>System</guimenu><guimenuitem>Administration</guimenuitem><guimenuitem>Users and Groups</guimenuitem></menuchoice>. You must be an <ulink type="help" url="ghelp:administrative">administrator</ulink> to do this.

See the <ulink type="help" url="ghelp:users-admin">Users Administration Tool manual</ulink> for more information on setting up user accounts.

Keep your software up to date

Ubuntu developers often issue updates to the Ubuntu software. These updates may improve security or fix other problems.

When updates are available, the update icon (an orange star) appears in the panel, usually near the top right of the screen. To install updates you must be an <ulink type="help" url="ghelp:administrative">administrator</ulink> and the computer must be connected to the Internet.

Click the update icon, and enter your password when asked.

In the Update Manager window, click <guibutton>Install Updates</guibutton>.

The update process may take a while if many updates need to be installed.

If a pair of blue arrows appears in the panel when the updates have finished, you need to restart the computer to complete the installation.

To check for updates yourself, choose <menuchoice><guimenu>System</guimenu><guimenuitem>Administration</guimenuitem><guimenuitem>Update Manager</guimenuitem></menuchoice> and press <guibutton>Check</guibutton>.

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 <menuchoice><guimenu>System</guimenu><guimenuitem>Quit...</guimenuitem><guimenuitem>Lock Screen</guimenuitem></menuchoice>.

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.

To unlock the screen, move the mouse or press a key. Then, type your password and either press the <keycap>Return</keycap> key or press the <guibutton>Unlock</guibutton> button.

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.

Install the <application>firestarter</application> package from the <quote>Universe</quote> repository (see <ulink type="help" url="ghelp:add-applications">Add Applications</ulink>).

To start <application>Firestarter</application>, choose <menuchoice><guimenu>System</guimenu><guimenuitem>Administration</guimenuitem><guimenuitem>Firestarter</guimenuitem></menuchoice>, and enter your administrator password when prompted.

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>.

More advanced users may wish to use the UFW firewall, which is installed by default. See the <ulink type="help" url="man:ufw">UFW manual</ulink> for more information.

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: