Translations by Joel Goguen

Networking

Credits and License

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Canonical Ltd. and members of the Ubuntu Documentation Project

The Ubuntu Documentation Project

This chapter contains information on general networking with Kubuntu. Topics covered include connecting to the internet as well as connecting and sharing files between a Windows or Mac system and Kubuntu.

Introduction to networking in Kubuntu

Networking in Kubuntu has gotten much easier for everyone. The days of configuring your settings via the command line are almost gone completely. A majority of users will never have to use the command line when configuring their network settings in order to share files between PCs or to gain access to the Internet. There are those select few who might be utilizing hardware that is not Linux certified as of yet. For those, there might be the possibility of making changes via the command line.

Some users will want to do more than surf the Internet or read Email such as sharing files between a Windows PC or a Mac. Setting up Kubuntu on a Windows network is a very simple task and at most will only require very minor command line usage.

Determining your network hardware

Common network settings

No matter the connection you are using, the network settings will usually be configured the same. Most users are probably familiar with Windows networking and seeing terms such as <acronym>IP</acronym> address, gateway address, netmask address, and <acronym>DNS</acronym> addresses. They are still the same in Kubuntu however there are two extra settings that are common with Linux systems, network address and broadcast address however these extra settings are not necessary for basic home networking and connecting to the Internet.

Please select from the following to get a brief introduction to each settings. <placeholder-1/>

Kubuntu Network Interface Setting

# eth0 is set to automatically receive its address (DHCP) auto eth0 iface eth0 inet dhcp # eth1 is setting its own address (static) auto eth1 iface eth1 inet static address 192.168.1.100 netmask 255.255.255.0 network 192.168.1.0 broadcast 192.168.0.255 gateway 192.168.1.1

<acronym>IP</acronym> Address

An <acronym>IP</acronym> address is a unique identifier, commonly known as the computer's address, that is used in communicating between other computers on a network and the Internet. There are two versions of <acronym>IP</acronym> addressing, <acronym>IPv4</acronym> which is the most widely used and the oldest, and <acronym>IPv6</acronym> which is newer. <acronym>IPv6</acronym> was created to cure the fact the world was running out of <acronym>IP</acronym> addresses.

<acronym>IPv4</acronym><acronym>IP</acronym> address

192.168.1.100

10.0.0.100

63.184.200.19

<acronym>IPv6</acronym><acronym>IP</acronym> address

E3D7:0000:0000:0000:51F4:9BC8:C0A8:6420

E3D7::51F4:9BC8:C0A8:6420

Gateway <acronym>IP</acronym> Address

A gateway address is also known as the default gateway. The gateway serves as an access point to another network and a majority of the times would be your service provider in order to gain access to the Internet. A gateway <acronym>IP</acronym> address looks the same as an <acronym>IP</acronym> address.

Netmask

A netmask address, or subnet mask, is an address that allows the splitting of a large network into small subnetworks.

<acronym>DNS</acronym><acronym>IP</acronym> Address

<acronym>DNS</acronym> (Domain Name System) translates domain names as well as computer hostnames to <acronym>IP</acronym> addresses. This is the system that will translate www.kubuntu.org into the websites actual <acronym>IP</acronym> address.

Host name

The host name is the physical, unique name of your computer. A valid hostname consists of <acronym>ASCII</acronym> letters "a" through "z", digits "0" through "9", and the hyphen (-). It can consist of any combination of the previous allowed characters.

Establishing a connection

Establishing a connection depends on various things. Are you connecting directly to the Internet utilizing a modem whether it be a <acronym>DSL</acronym> modem or a dial-up modem? Do you have broadband access and have a router or a system providing Internet sharing? Are you using Ethernet or wireless network connection? <acronym>DHCP</acronym> or static? These are just a few of the variables that need to be researched and understood prior to moving on and possibly causing more problems now or later on.

There are multiple ways of connecting to a network or the Internet however only three main topics will be covered. <placeholder-1/>

<acronym>DSL</acronym> (Digital Subscriber Line) is a form of broadband Internet service that has a modem that connects to the service providers network. Some users will either connect directly to that modem or may have a router connected to it in order to share the connection.

<acronym>DHCP</acronym> (Dynamic Host Configuration Protocol) is a networking protocol that allows your system to obtain an <acronym>IP</acronym> (Internet Protocol) address, gateway address, netmask, as well as <acronym>DNS</acronym> (Domain Name System) addresses. Using DHCP is setup by default for each network interface installed into the system. This makes connecting easier and seamless in most situations. Please <xref linkend="network-connect-settings"/>.

Ethernet

Ethernet adapters are the most common types of networking interfaces in use today. Ethernet is physically connected with a cable to either your broadband modem, router or switch, or another <acronym>PC</acronym>. The most common type of cable in use is know as Category-5 (<acronym>CAT</acronym>-5). It looks similar to the typical telephone cable, but instead of four wires inside the cable there are eight. For an example of what a <acronym>CAT</acronym>-5 cable looks like, please review <ulink url="http://en.wikipedia.org/wiki/Cat-5"/>.

A majority of users who are using this form of Ethernet for a connection are not going to run into any problems. If you do in fact run into an issue connecting with this type of connection, the following could potentially assist you in fixing your issue.

GUI based troubleshooting and settings

Network Settings

From within the <guilabel>Network Connection</guilabel> window there is a tab named <guilabel>Network Interfaces</guilabel>. Hopefully you will see your adapter labeled something like <guilabel>eth0</guilabel>. If there is an issue with the card or the settings, usually the system will automatically disable the card. If the card is disabled, you will see <guilabel>X Disabled</guilabel> under the <guilabel>State</guilabel> column. To enable the device, simply press the <guibutton>Administrator Mode...</guibutton> at the bottom of the window. This will open a password dialog in which you enter your username's password. Once you have entered this mode, simply press the <guibutton>Enable Interface</guibutton> button. If there are issues enabling the device, you will be notified with an error. To see the settings of this device, press the <guibutton>Configure Interface...</guibutton> button. The window that opens will allow you to manually configure your network settings to match your network.

Command line based troubleshooting and settings

System

The main file that the user will be working with is <filename>/etc/network/interfaces</filename>. A typical default <filename>interfaces</filename> file will look similar to the following: