Handbook:Parts/Installation/Networking/it

Configurazione automatica della rete
Può funzionare fin da subito?

Se il sistema è connesso via ethernet ad una rete con un server DHCP, è molto probabile che la configurazione è stata già fatta in modo automatico. Se così fosse, molti comandi nel CD che richiedono una connessione di rete funzioneranno immediatamente (es., , , , e ).

Comando ifconfig
Se la rete è già stata configurata, il comando dovrebbe mostrare una o più interfacce di rete (a parte ). Nell'esempio qui sotto appare :

Avendo adottato dei nomi di interfaccia prevedibili,il nome dell'interfaccia di rete potrebbe essere abbastanza diverso dal classico. I supporti di installazione recenti potrebbero riportare nomi come, , o. Cerca in l'interfaccia che ha un indirizzo IP correlato alla rete locale.

Comando ip
Come alternativa a, può essere utilizzato il comando per determinale i nomi delle interfacce. L'esempio seguente mostra l'output di (il risultato è differente poiché è eseguito in un sistema diverso dal precedente):

L'output sovrastante potrebbe essere più complicato da leggere del precedente. Il nome di interfaccia in questo esempio segue direttamente il numero; è.

Nel contesto di questo manuale, verrà utilizzata l'interfaccia.

Opzionale: Configurazione dei proxy
Se si accede a internet attraverso un proxy, è necessario impostarlo durante l'installazione. Configurare un proxy è molto facile: basta definire una variabile che contiene le informazioni del server proxy.

Nella maggior parte dei casi, è sufficiente definire la variabile con l'hostname del server. Per esempio, il proxy è chiamato proxy.gentoo.org e la porta è 8080.

Per impostare un proxy HTTP (per il traffico HTTP/HTTPS):

Per configurare un proxy FTP:

Per configurare un proxy RSYNC:

Se il server richiede nome utente e password, usare la seguente sintassi per la variabile:

Testare la rete
Provare a pingare i server DNS del proprio provider (reperibili in ) e un sito web a scelta. Questo garantisce che la rete funzioni correttamente, che i pacchetti raggiungano la rete, che la risoluzione DNS funzioni correttamente, ecc.

Se tutto funziona, il resto di questo capitolo può essere saltato e passare direttamente al prossimo capitolo (Preparare i dischi).

Configurazione automatica della rete
If the network doesn't work immediately, some installation media allow the user to use (for regular or wireless networks),  (for ADSL users) or  (for PPTP users).

If the installation medium does not contain any of these tools, continue with the Manual network configuration.


 * Regular Ethernet users should continue with Default: Using net-setup
 * ADSL users should continue with Alternative: Using PPP
 * PPTP users should continue with Alternative: Using PPTP

Default: Using net-setup
The simplest way to set up networking if it didn't get configured automatically is to run the script:

will ask some questions about the network environment. When all is done, the network connection should work. Test the network connection as stated before. If the tests are positive, congratulations! Skip the rest of this section and continue with Preparing the disks.

If the network still doesn't work, continue with Manual network configuration.

Alternative: Using PPP
Assuming PPPoE is needed to connect to the Internet, the installation CD (any version) has made things easier by including ppp. Use the provided script to configure the connection. During the setup the Ethernet device that is connected to your ADSL modem, the username and password, the IPs of the DNS servers and if a basic firewall is needed or not will be asked.

If something goes wrong, double-check that the username and password are correct by looking at or  and make sure to use the right Ethernet device. If the Ethernet device does not exist, the appropriate network modules need to be loaded. In that case continue with Manual network configuration as it will explain how to load the appropriate network modules there.

If everything worked, continue with Preparing the disks.

Alternative: Using PPTP
If PPTP support is needed, use which is provided by the installation CDs. But first make sure that the configuration is correct. Edit or  so it contains the correct username/password combination:

Then adjust if necessary:

When all that is done, run (along with the options that couldn't be set in ) to connect the server:

Now continue with Preparing the disks.

Loading the appropriate network modules
When the Installation CD boots, it tries to detect all the hardware devices and loads the appropriate kernel modules (drivers) to support the hardware. In the vast majority of cases, it does a very good job. However, in some cases, it may not auto-load the kernel modules needed.

If or  failed, then it is possible that the network card wasn't found immediately. This means users may have to load the appropriate kernel modules manually.

To find out what kernel modules are provided for networking, use the command:

If a driver is found for the network device, use to load the kernel module. For instance, to load the module:

To check if the network card is now detected, use. A detected network card would result in something like this (again, here is just an example):

If however the following error is shown, the network card is not detected:

The available network interface names on the system can be listed through the file system:

In the above example, 6 interfaces are found. The one is most likely the (wired) Ethernet adapter whereas  is the wireless one.

Assuming that the network card is now detected, retry or  again (which should work now), but for the hardcore people we explain how to configure the network manually as well.

Select one of the following sections based on your network setup:


 * Using DHCP for automatic IP retrieval
 * Preparing for wireless access if a wireless network is used
 * Understanding network terminology explains the basics about networking
 * Using ifconfig and route explains how to set up networking manually

Usare DHCP
Il DHCP (Dynamic Host Configuration Protocol) rende possibile ricevere automaticamente informazioni di rete (quali indirizzo IP, maschera di rete, indirizzo di broadcast, gateway, serve DNS, ecc.). Questo funziona solo se esiste un server DCHP nella rete (o se il provider fornisce un servizio DHCP). Per far ricevere queste informazioni automaticamente all'interfaccia di rete, usare :

Alcuni amministratori di rete richiedono che l'hostname ed il domainname generati dal server DCHP vengano utilizzati dal sistema. In tal caso, usare:

Se funziona (provare a pingare alcuni server internet, come Google), si può continuare con la prossima sezione (Preparare i dischi).

Preparing for wireless access
When using a wireless (802.11) card, the wireless settings need to be configured before going any further. To see the current wireless settings on the card, one can use. Running might show something like:

To check for a current connection:

or

For most users, there are only two settings needed to connect, the ESSID (aka wireless network name) and, optionally, the WEP key.


 * First, ensure the interface is active:


 * To connect to an open network with the name GentooNode:




 * To connect with a hex WEP key, prefix the key with :




 * To connect with an ASCII WEP key:



Confirm the wireless settings by using. Once wireless is working, continue configuring the IP level networking options as described in the next section (Understanding network terminology) or use the tool as described previously.

Understanding network terminology
If all of the above fails, the network will need to be configured manually. This is not difficult at all. However, some knowledge of network terminology and basic concepts might be necessary. After reading this section, users will know what a gateway is, what a netmask serves for, how a broadcast address is formed and why systems need nameservers.

In a network, hosts are identified by their IP address (Internet Protocol address). Such an address is perceived as a combination of four numbers between 0 and 255. Well, at least when using IPv4 (IP version 4). In reality, such an IPv4 address consists of 32 bits (ones and zeros). Let's view an example:

Such an IP address is unique to a host as far as all accessible networks are concerned (i.e. every host that one wants to be able to reach must have a unique IP address). In order to distinguish between hosts inside and outside a network, the IP address is divided in two parts: the network part and the host part.

The separation is written down with the netmask, a collection of ones followed by a collection of zeros. The part of the IP that can be mapped on the ones is the network-part, the other one is the host-part. As usual, the netmask can be written down as an IP address.

In other words, 192.168.0.14 is part of the example network, but 192.168.1.2 is not.

The broadcast address is an IP address with the same network-part as the network, but with only ones as host-part. Every host on the network listens to this IP address. It is truly meant for broadcasting packets.

To be able to surf on the Internet, each computer in the network must know which host shares the Internet connection. This host is called the gateway. Since it is a regular host, it has a regular IP address (for instance 192.168.0.1).

Previously we stated that every host has its own IP address. To be able to reach this host by a name (instead of an IP address) we need a service that translates a name (such as dev.gentoo.org) to an IP address (such as 64.5.62.82). Such a service is called a name service. To use such a service, the necessary name servers need to be defined in.

In some cases, the gateway also serves as a nameserver. Otherwise the nameservers provided by the ISP need to be entered in this file.

To summarize, the following information is needed before continuing:

Using ifconfig and route
Setting up the network consists of three steps:


 * 1) Assign an IP address using
 * 2) Set up routing to the gateway using
 * 3) Finish up by placing the nameserver IPs in

To assign an IP address, the IP address, broadcast address and netmask are needed. Then execute the following command, substituting ${IP_ADDR} with the right IP address, ${BROADCAST} with the right broadcast address and ${NETMASK} with the right netmask:

Set up routing using. Substitute ${GATEWAY} with the right gateway IP address:

Now open :

Fill in the nameserver(s) using the following as a template. Make sure to substitute ${NAMESERVER1} and ${NAMESERVER2} with the appropriate nameserver addresses:

Finito. Adesso testa la connessione pingando alcuni server internet (tipo Google). Se funziona, congratulazioni. Continua con la prossima sezione (Preparare i dischi).