Configure Networking
This page will assist you in setting up networking on Alpine Linux.
Setting System Hostname
To set the system hostname, do something like the following:
echo "hostname.domain.com" > /etc/hostname
Then, to activate the change, do the following:
hostname -F /etc/hostname
If you're using IPv6, you should also add the following special IPv6 addresses to your /etc/hosts file:
::1 localhost ipv6-localhost ipv6-loopback fe00::0 ipv6-localnet ff00::0 ipv6-mcastprefix ff02::1 ipv6-allnodes ff02::2 ipv6-allrouters ff02::3 ipv6-allhosts
For a static IP configuration, it's common to also add the machine's hostname you just set (above) to the /etc/hosts file.
Here's an IPv4 example:
192.168.1.150 hostname.domain.com
And here's an IPv6 example:
2001:470:ffff:ff::2 hostname.domain.com
Configuring DNS
/etc/resolv.conf will be completely overwritten with any nameservers provided by DHCP. Also, if DHCP does not provide any nameservers, then /etc/resolv.conf will still be overwritten, but will not contain any nameservers!For using a static IP and static nameservers, use one of the following examples.
For IPv4 nameservers, edit your /etc/resolv.conf file to look like this:
The following example uses Google's Public DNS servers.
nameserver 8.8.8.8 nameserver 8.8.4.4
For IPv6 nameservers, edit your /etc/resolv.conf file to look like this:
The following example uses Hurricane Electric's public DNS server.
nameserver 2001:470:20::2
You can also use Hurricane Electric's public DNS server via IPv4:
nameserver 74.82.42.42
/etc/resolv.conf — ironically, such as Google's Public DNS Servers.) Read here for more information.Enabling IPv6 (Optional)
If you use IPv6, do the following to enable IPv6 for now and at each boot:
modprobe ipv6 echo "ipv6" >> /etc/modules
Interface Configuration
Loopback Configuration (Required)
/etc/network/interfaces to prevent networking issues.To configure loopback, add the following to a new file /etc/network/interfaces:
auto lo iface lo inet loopback
The above works to setup the IPv4 loopback address (127.0.0.1), and the IPv6 loopback address (::1) — if you enabled IPv6.
Ethernet Configuration
For the following Ethernet configuration examples, we will assume that you are using Ethernet device eth0.
Initial Configuration
Add the following to the file /etc/network/interfaces, above any IP configuration for eth0:
auto eth0
IPv4 DHCP Configuration
Add the following to the file /etc/network/interfaces, below the auto eth0 definition:
iface eth0 inet dhcp
IPv4 Static Address Configuration
Add the following to the file /etc/network/interfaces, below the auto eth0 definition:
iface eth0 inet static
address 192.168.1.150
netmask 255.255.255.0
gateway 192.168.1.1
IPv6 Stateless Autoconfiguration
Add the following to the file /etc/network/interfaces, below the auto eth0 definition:
iface eth0 inet6 manual
pre-up echo 1 > /proc/sys/net/ipv6/conf/eth0/accept_ra
IPv6 Static Address Configuration
Add the following to the file /etc/network/interfaces, below the auto eth0 definition:
iface eth0 inet6 static
address 2001:470:ffff:ff::2
netmask 64
gateway 2001:470:ffff:ff::1
pre-up echo 0 > /proc/sys/net/ipv6/conf/eth0/accept_ra
Example: Dual-Stack Configuration
This example shows a dual-stack configuration.
auto lo
iface lo inet loopback
auto eth0
iface eth0 inet static
address 192.168.1.150
netmask 255.255.255.0
gateway 192.168.1.1
iface eth0 inet6 static
address 2001:470:ffff:ff::2
netmask 64
gateway 2001:470:ffff:ff::1
pre-up echo 0 > /proc/sys/net/ipv6/conf/eth0/accept_ra
Firewalling with iptables and ip6tables
Install iptables/ip6tables
- To install iptables:
apk add iptables
- To install ip6tables:
apk add ip6tables
- To install the man pages for iptables and ip6tables:
apk add iptables-doc
Configure iptables/ip6tables
Save Firewall Rules
For iptables
- Set iptables to start on reboot
rc-update add iptables
- Write the firewall rules to disk
/etc/init.d/iptables save
- If you use Alpine Local Backup:
- Save the configuration
lbu ci
- Save the configuration
For ip6tables
- Set ip6tables to start on reboot
rc-update add ip6tables
- Write the firewall rules to disk
/etc/init.d/ip6tables save
- If you use Alpine Local Backup:
- Save the configuration
lbu ci
- Save the configuration
Activating Changes and Testing Connectivity
Changes made to /etc/network/interfaces can be activated by running:
/etc/init.d/networking restart
If you did not get any errors, you can now test that networking is configured properly by attempting to ping out:
ping www.google.com
PING www.l.google.com (74.125.47.103) 56(84) bytes of data. 64 bytes from yw-in-f103.1e100.net (74.125.47.103): icmp_seq=1 ttl=48 time=58.5 ms 64 bytes from yw-in-f103.1e100.net (74.125.47.103): icmp_seq=2 ttl=48 time=56.4 ms 64 bytes from yw-in-f103.1e100.net (74.125.47.103): icmp_seq=3 ttl=48 time=57.0 ms 64 bytes from yw-in-f103.1e100.net (74.125.47.103): icmp_seq=4 ttl=48 time=60.2 ms ^C --- www.l.google.com ping statistics --- 4 packets transmitted, 4 received, 0% packet loss, time 3007ms rtt min/avg/max/mdev = 56.411/58.069/60.256/1.501 ms
For an IPv6 traceroute (traceroute6), you will first need to install the iputils package:
apk add iputils
Then run traceroute6:
traceroute6 ipv6.google.com
traceroute to ipv6.l.google.com (2001:4860:8009::67) from 2001:470:ffff:ff::2, 30 hops max, 16 byte packets 1 2001:470:ffff:ff::1 (2001:470:ffff:ff::1) 3.49 ms 0.62 ms 0.607 ms 2 * * * 3 * * * 4 pr61.iad07.net.google.com (2001:504:0:2:0:1:5169:1) 134.313 ms 95.342 ms 88.425 ms 5 2001:4860::1:0:9ff (2001:4860::1:0:9ff) 100.759 ms 100.537 ms 89.907 ms 6 2001:4860::1:0:5db (2001:4860::1:0:5db) 115.563 ms 102.946 ms 106.191 ms 7 2001:4860::2:0:a7 (2001:4860::2:0:a7) 101.754 ms 100.475 ms 100.512 ms 8 2001:4860:0:1::c3 (2001:4860:0:1::c3) 99.272 ms 111.989 ms 99.835 ms 9 yw-in-x67.1e100.net (2001:4860:8009::67) 101.545 ms 109.675 ms 99.431 ms