O Ubuntu distribui um número de utilidades gráficas para configurar seus equipamentos de rede. Este documento tem como foco administradores de servidores e focalizará em como administrar sua rede usando a linha de comando.
Most ethernet configuration is centralized in a single file,
/etc/network/interfaces
. If you have no ethernet devices, only
the loopback interface will appear in this file, and it will look something like
this:
# This file describes the network interfaces available on your system # and how to activate them. For more information, see interfaces(5). # The loopback network interface auto lo iface lo inet loopback address 127.0.0.1 netmask 255.0.0.0
If you have only one ethernet device, eth0, and it gets its configuration from a DHCP server, and it should come up automatically at boot, only two additional lines are required:
auto eth0 iface eth0 inet dhcp
The first line specifies that the eth0 device should come up automatically when you boot.
The second line means that interface (“iface”) eth0 should have an IPv4 address
space (replace “inet” with “inet6” for an IPv6 device) and that
it should get its configuration automatically from DHCP. Assuming your network and DHCP
server are properly configured, this machine's network should need no further configuration to
operate properly. The DHCP server will provide the default gateway (implemented via the
route command), the device's IP address (implemented via the
ifconfig command), and DNS servers used on the network
(implemented in the /etc/resolv.conf
file.)
To configure your ethernet device with a static IP address and custom configuration,
some more information will be required. Suppose you want to assign the IP address
192.168.0.2 to the device eth1, with the typical netmask of 255.255.255.0. Your default
gateway's IP address is 192.168.0.1. You would enter something like this into
/etc/network/interfaces
:
iface eth1 inet static address 192.168.0.2 netmask 255.255.255.0 gateway 192.168.0.1
In this case, you will need to specify your DNS servers manually in
/etc/resolv.conf
, which should look something like this:
search mydomain.example nameserver 192.168.0.1 nameserver 4.2.2.2
The search directive will append mydomain.example
to hostname queries in an attempt to resolve names to your network. For example,
if your network's domain is mydomain.example and you try to ping the host
“mybox”, the DNS query will be modified to “mybox.mydomain.example”
for resolution. The nameserver directives
specifiy DNS servers to be used to resolve hostnames to IP addresses. If you use
your own nameserver, enter it here. Otherwise, ask your Internet Service Provider
for the primary and secondary DNS servers to use, and enter them into
/etc/resolv.conf
as shown above.
Diversas outras configurações são possíveis, incluindo interfaces PPP, rede em IPv6, interfaces VPN, entre outras. Execute o comando man 5 interfaces para mais informações e para as opções suportadas. Lembre-se que /etc/network/interfaces
é utilizado pelos scripts ifup/ifdown como um esquema de configuração de mais alto nível, que pode ser utilizado por outras distribuições, e que os utilitários de baixo nível, como ifconfig, route e dhclient continuam disponíveis para configurações ad hoc.
This section explains how to configure which nameserver to use when resolving IP addresses to hostnames and vice versa. It does not explain how to configure the system as a name server.
Para gerenciar entradas de DNS, você pode adicionar, alterar ou remover nomes de DNS do arquivo /etc/resolv.conf
. Um arquivo de exemplo pode ser visto abaixo:
search com nameserver 204.11.126.131 nameserver 64.125.134.133 nameserver 64.125.134.132 nameserver 208.185.179.218
The search key specifies the string which will be appended to an incomplete hostname. Here, we have configured it to com. So, when we run: ping ubuntu it would be interpreted as ping ubuntu.com.
The nameserver key specifies the nameserver IP address. It will be used to resolve a given IP address or hostname. This file can have multiple nameserver entries. The nameservers will be used by the network query in the same order.
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If the DNS server names are retrieved dynamically from DHCP or PPPoE (retrieved from your ISP), do not add nameserver entries in this file. It will be overwritten. |
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The changes you make in |
Para gerenciar hosts, você pode adicionar, alterar ou remover hosts do arquivo /etc/hosts
. O arquivo contêm endereços IP e seus nomes de host correspondentes. Quando seu sistema tenta resolver um nome de host para um endereço IP ou determinar um nome de host para um endereço IP, ele procura para o arquivo /etc/hosts
antes de usar os servidores de nome. Se o endereço IP está listado no arquivo /etc/hosts
, os servidores de nome não serão utilizados. Este comportamento pode ser alterado, bastando para isso editar o arquivo /etc/nsswitch.conf
como quiser.
Se sua rede possui computadores cujos endereços IP não estão listadas no DNS, é recomendado que você os adicione ao arquivo /etc/hosts
.