Handbook:IA64/Installation/Networking/it
Rilevamento automatico della rete
Può la rete funzionare fin da subito?
Se il sistema è connesso via ethernet ad una rete con un server DHCP, è molto probabile che la configurazione sia stata già fatta automaticamente. Se è così, molti comandi da CD che richiedono una connessione di rete funzioneranno immediatamente (es. ssh, scp, ping, irssi, wget e links).
Usare DHCP
DHCP (Dynamic Host Configuration Protocol) (Protocollo di Configurazione Dinamica degli Host) rende possibile ricevere automaticamente informazioni di rete (quali indirizzo IP, maschera di rete, indirizzo di broadcast, gateway, server DNS, ecc.). Ciò funziona solo se esiste un server DHCP nella rete (o se il provider fornisce un servizio DHCP). Per fornire automaticamente queste informazioni all'interfaccia di rete, usare dhcpcd:
DHCP requires that a server be running on the same Layer 2 (Ethernet) segment as the client requesting a lease. DHCP is often used on RFC1918 (private) networks, but is also used to acquire public IP information from ISPs.
Official Gentoo boot media runs dhcpcd automatically at startup. This behavior can be disabled by adding the
nodhcp argument to the boot media kernel commandline.If it is not already running, dhcpcd can be started on enp1s0 with:
root #dhcpcd eth0Alcuni amministratori di rete richiedono che l'hostname ed il domain name generati dal server DHCP vengano utilizzati dal sistema. In tal caso, usare:
root #dhcpcd -HD eth0To stop dhcpcd, -x can be used:
root #dhcpcd -xsending signal Term to pid 10831 waiting for pid 10831 to exit
Dhcpcd usage
Testare la rete
A properly configured default route is a critical component of Internet connectivity, route configuration can be checked with:
root #ip routedefault via 192.168.0.1 dev enp1s0
If no default route is defined, Internet connectivity is unavailable, and additional configuration is required.
Basic internet connectivity can be confirmed with a ping:
root #ping -c 3 1.1.1.1It's helpful to start by pinging a known IP address instead of a hostname. This can isolate DNS issues from basic Internet connectivity issues.
Outbound HTTPS access and DNS resolution can be confirmed with:
root #curl --location gentoo.org --output /dev/nullSe tutto funziona, il resto di questo capitolo può essere saltato, passando direttamente al prossimo capitolo (Preparare i dischi).
If curl reports an error, but Internet-bound pings work, DNS may need configuration.
If Internet connectivity has not been established, first interface information should be verified, then:
- net-setup can be used to assist in network configuration.
- Application specific configuration may be required.
- Manual network configuration can be attempted.
Determinare i nomi delle interfacce
If networking doesn't work out of the box, additional steps must be taken to enable Internet connectivity. Generally, the first step is to enumerate host network interfaces.
Alternativamente a ifconfig, per determinare i nomi delle interfacce si può utilizzare il comando ip. L'esempio seguente mostra l'output di ip addr (il risultato differisce dal precedente poiché eseguito su un sistema diverso):
The link argument can be used to display network interface links:
root #ip link1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
4: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
link/ether e8:40:f2:ac:25:7a brd ff:ff:ff:ff:ff:ffThe address argument can be used to query device address information:
root #ip addr2: eno1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
link/ether e8:40:f2:ac:25:7a brd ff:ff:ff:ff:ff:ff
inet 10.0.20.77/22 brd 10.0.23.255 scope global eno1
valid_lft forever preferred_lft forever
inet6 fe80::ea40:f2ff:feac:257a/64 scope link
valid_lft forever preferred_lft forever
The output of this command contains information for each network interface on the system. Entries begin with the device index, followed by the device name: enp1s0.
Se usando il comando ifconfig non viene mostrata alcuna interfaccia, si può provare ad usare lo stesso comando con l'opzione
-a. Questa opzione fa sì che vengano mostrate tutte le interfacce rilevate dal sistema, che esse siano abilitate o meno. Se ifconfig -a non mostra risultati, la scheda di rete potrebbe essere guasta o il relativo driver non caricato nel kernel. Queste situazioni vanno oltre lo scopo di questo manuale. Contattare #gentoo (webchat) per avere supporto tecnico.Nella parte rimanente del documento, il manuale considererà che l'interfaccia di rete sia chiamata eth0.
Avendo adottato nomi che indicano il tipo di interfaccia, il nome dell'interfaccia di rete potrebbe essere abbastanza diverso dal classico eth0. I dischi di installazione recenti potrebbero riportare nomi come eno0, ens1, o enp5s0. Si cerchi con ifconfig l'interfaccia che ha un indirizzo IP correlato alla rete locale.
Optional: Application specific configuration
The following methods are not generally required, but may be helpful in situations where additional configuration is required for Internet connectivity.
Opzionale: Configurazione dei proxy
Se si accede ad Internet attraverso un proxy, è necessario impostarlo durante l'installazione. Configurare un proxy è molto facile: basta definire una variabile con le informazioni del server proxy.
Certain text-mode web browsers such as links can also make use of environment variables that define web proxy settings; in particular for the HTTPS access it also will require the https_proxy environment variable to be defined. While Portage will be influenced without passing extra run time parameters during invocation, links will require proxy settings to be set.
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.
The
# symbol in the following commands is a comment. It has been added for clarity only and does not need to be typed when entering the commands.Per impostare un proxy HTTP (per il traffico HTTP/HTTPS):
root #export http_proxy="http://proxy.gentoo.org:8080"Se il proxy richiede nome utente e password, usare la seguente sintassi per la variabile:
http://username:password@proxy.gentoo.org:8080
Start links using the following parameters for proxy support:
user $links -http-proxy ${http_proxy} -https-proxy ${https_proxy} Per configurare un proxy FTP:
root #export ftp_proxy="ftp://proxy.gentoo.org:8080"Start links using the following parameter for a FTP proxy:
user $links -ftp-proxy ${ftp_proxy} Per configurare un proxy RSYNC:
root #export RSYNC_PROXY="proxy.gentoo.org:8080"Alternativa: Usare PPP
If PPPoE is required for Internet access, the Gentoo boot media includes the pppoe-setup script to simplify ppp configuration.
During setup, pppoe-setup will ask for:
- The name of the Ethernet interface connected to the ADSL modem.
- The PPPoE username and password.
- DNS server IPs.
- Whether or not a firewall is needed.
root #pppoe-setup
root #pppoe-startIn the event of failure, credentials in /etc/ppp/pap-secrets or /etc/ppp/chap-secrets should be verified. If credentials are correct, PPPoE Ethernet interface selection should be checked.
Alternativa: Usare PPTP
Se è necessario il supporto PPTP, usare pptpclient fornito dai CD di installazione. Prima però ci si assicuri che la configurazione sia corretta, modificando /etc/ppp/pap-secrets o /etc/ppp/chap-secrets affinché contengano la giusta combinazione di nome utente e password:
Edit /etc/ppp/pap-secrets or /etc/ppp/chap-secrets so it contains the correct username/password combination:
root #nano -w /etc/ppp/chap-secretsPoi, se necessario, modificare /etc/ppp/options.pptp:
root #nano -w /etc/ppp/options.pptpUna volta fatto tutto ciò, si esegua pptp (insieme alle opzioni che non potevano essere impostate su options.pptp) per connettersi al server:
root #pptp <server ipv4 address>Preparare l'accesso wireless
Do not use WEP unless it is the only option. WEP provides essentially no security over an open network.
Il supporto del comando iw potrebbe avere caratteristiche specifiche in base all'architettura. Se il comando non è disponibile, controllare che sia disponibile il pacchetto net-wireless/iw per l'architettura in uso. Il comando iw è disponibile solo se il pacchetto net-wireless/iw è installato.
Quando si utilizza una scheda wireless (802.11), è necessario configurare le impostazioni wireless prima di andare avanti. Per visualizzare le impostazioni della scheda wireless, è possibile utilizzare iw. L'esecuzione di iw potrebbe mostrare qualcosa di simile a questo:
root #iw dev wlp9s0 infoInterface wlp9s0 ifindex 3 wdev 0x1 addr 00:00:00:00:00:00 type managed wiphy 0 channel 11 (2462 MHz), width: 20 MHz (no HT), center1: 2462 MHz txpower 30.00 dBm
Per controllare la connessione in corso:
root #iw dev wlp9s0 linkNot connected.
oppure
root #iw dev wlp9s0 linkConnected to 00:00:00:00:00:00 (on wlp9s0) SSID: GentooNode freq: 2462 RX: 3279 bytes (25 packets) TX: 1049 bytes (7 packets) signal: -23 dBm tx bitrate: 1.0 MBit/s
Alcune schede wireless possono avere un nome di periferica tipo wlan0 o ra0 anziché wlp9s0. Eseguire ip link per stabilire il nome corretto del dispositivo.
Per la maggior parte degli utenti, sono necessarie solo due impostazioni per potersi connettere, l'ESSID (anche conosciuto come nome di rete wireless) e, opzionalmente, la chiave WEP.
- Prima di tutto, assicurarsi che l'interfaccia sia attiva:
root #ip link set dev wlp9s0 up
- Per connettersi ad una rete libera chiamata GentooNode:
root #iw dev wlp9s0 connect -w GentooNode
- Per connettersi con una chiave WEP esadecimale, anteporre alla chiave il prefisso
d::
root #iw dev wlp9s0 connect -w GentooNode key 0:d:1234123412341234abcd
- Per connettersi con una chiave WEP ASCII:
root #iw dev wlp9s0 connect -w GentooNode key 0:una-certa-password
Se la rete wireless è configurata con WPA o WPA2, allora si deve usare wpa_supplicant. Per ulteriori informazioni sulla configurazione delle reti wireless in Gentoo Linux, leggere il Capitolo sulle reti wireless nel Manuale di Gentoo.
Confermare le impostazioni della rete wireless usando iw dev wlp9s0 link. Una volta che la rete wireless funziona, proseguire con la configurazione delle opzione di rete per il livello IP come descritto nella sezione successiva (Comprendere la terminologia delle reti) od usando lo strumento net-setup come descritto precedentemente.
Configurazione automatica della rete
In cases where automatic network configuration is unsuccessful, the Gentoo boot media provides scripts to aid in network configuration. net-setup can be used to configure wireless network information and static IPs.
root #net-setup eth0net-setup chiederà alcune informazioni sull'ambiente di rete. Quando avrà concluso, la rete dovrebbe funzionare. Si provi la connessione di rete come precedentemente indicato. Se il test è positivo, congratulazioni! Saltare il resto di questa sezione e continuare con la Preparazione dei dischi.
Network status should be tested after any configuration steps are taken. In the event that configuration scripts do not work, manual network configuration is required.
Comprendere la terminologia delle reti
If all of the above fails, the network must be configured manually. This is not particularly difficult, but should be done with consideration. This section serves to clarify terminology and introduce users to basic networking concepts pertaining to manually configuring an Internet connection.
Some CPE (Carrier Provided Equipment) combines the functions of a router, access point, modem, DHCP server, and DNS server into one unit. It's important to differentiate the functions of a device from the physical appliance.
Interfaces and addresses
Network interfaces are logical representations of network devices. An interface needs an address to communicate with other devices on the network. While only a single address is required, multiple addresses can be assigned to a single interface. This is especially useful for dual stack (IPv4 + IPv6) configurations.
For consistency, this primer will assume the interface enp1s0 will be using the address 192.168.0.2.
IP addresses can be set arbitrarily. As a result, it's possible for multiple devices to use the same IP address, resulting in an address conflict. Address conflicts should be avoided by using DHCP or SLAAC.
IPv6 typically uses StateLess Address AutoConfiguration (SLAAC) for address configuration. In most cases, manually setting IPv6 addresses is a bad practice. If a specific address suffix is preferred, interface identification tokens can be used.
Networks and CIDR
Once an address is chosen, how does a device know how to talk to other devices?
IP addresses are associated with networks. IP networks are contiguous logical ranges of addresses.
Classless Inter-Domain Routing or CIDR notation is used to distinguish network sizes.
- The CIDR value, often notated starting with a /, represents the size of the network.
- The formula 2 ^ (32 - CIDR) can be used to calculate network size.
- Once network size is calculated, usable node count must be reduced by 2.
- The first IP in a network is the Network address, and the last is typically the Broadcast address. These addresses are special and cannot be used by normal hosts.
The most common CIDR values are /24, and /32, representing 254 nodes and a single node respectively.
A CIDR of /24 is the de-facto default network size. This corresponds to a subnet mask of 255.255.255.0, where the last 8 bits are reserved for IP addresses for nodes on a network.
The notation: 192.168.0.2/24 can be interpreted as:
- The address 192.168.0.2
- On the network 192.168.0.0
- With a size of 254 (2 ^ (32 - 24) - 2)
- Usable IPs are in the range 192.168.0.1 - 192.168.0.254
- With a broadcast address of 192.168.0.255
- In most cases, the last address on a network is used as the broadcast address, but this can be changed.
Using this configuration, a device should be able to communicate with any host on the same network (192.168.0.0).
The Internet
Once a device is on a network, how does it know how to talk to devices on the Internet?
To communicate with devices outside of local networks, routing must be used. A router is simply a network device that forwards traffic for other devices. The term default route or gateway typically refers to whatever device on the current network is used for external network access.
It's a standard practice to make the gateway the first or last IP on a network.
If an Internet-connected router is available at 192.168.0.1, it can be used as the default route, granting Internet access.
To summarize:
- Interfaces must be configured with an address and network information, such as the CIDR value.
- Local network access is used to access a router on the same network.
- The default route is configured, so traffic destined for external networks is forwarded to the gateway, providing Internet access.
The Domain Name System
Remembering IPs is hard. The Domain Name System was created to allow mapping between Domain Names and IP addresses.
Linux systems use /etc/resolv.conf to define nameservers to be used for DNS resolution.
Many routers can also function as a DNS server, and using a local DNS server can augment privacy and speed up queries through caching.
Many ISPs run a DNS server that is generally advertised to the gateway over DHCP. Using a local DNS server tends to improve query latency, but most public DNS servers will return the same results, so server usage is largely based on preference.
Configurazione manuale della rete
Interface address configuration
When manually configuring IP addresses, the local network topology must be considered. IP addresses can be set arbitrarily; conflicts may cause network disruption.
To configure enp1s0 with the address 192.168.0.2 and CIDR /24:
root #ip address add 192.168.0.2/24 dev enp1s0The start of this command can be shortened to ip a.
Default route configuration
Configuring address and network information for an interface will configure link routes, allowing communication with that network segment:
root #ip route192.168.0.0/24 dev enp1s0 proto kernel scope link src 192.168.0.2
This command can be shortened to ip r.
The default route can be set to 192.168.0.1 with:
root #ip route add default via 192.168.0.1DNS configuration
Nameserver info is typically acquired using DHCP, but can be set manually by adding nameserver entries to /etc/resolv.conf.
If dhcpcd is running, changes to /etc/resolv.conf will not persist. Status can be checked with
ps x | grep dhcpcd.nano is included in Gentoo boot media and can be used to edit /etc/resolv.conf with:
root #nano -w /etc/resolv.confLines containing the keyword nameserver followed by a DNS server IP address are queried in order of definition:
/etc/resolv.confUse Quad9 DNS.nameserver 9.9.9.9
nameserver 149.112.112.112
/etc/resolv.confUse Cloudflare DNS.nameserver 1.1.1.1
nameserver 1.0.0.1
DNS status can be checked by pinging a domain name:
root #ping -c 3 gentoo.orgOnce connectivity has been verified, continue with Preparing the disks.