Configure Networking: Difference between revisions
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traceroute to ipv6.l.google.com (2001:4860:8009::67) from 2001:470:ffff:ff::2, 30 hops max, 16 byte packets | traceroute to ipv6.l.google.com (2001:4860:8009::67) from 2001:470:ffff:ff::2, 30 hops max, 16 byte packets |
Revision as of 00:42, 12 January 2024
This page will assist you in setting up networking on Alpine Linux.
Setting System Hostname
To set the system hostname:
# echo "shortname" > /etc/hostname
Then, to activate the change:
# hostname -F /etc/hostname
If you're using IPv6, you should also add the following special IPv6 addresses to your /etc/hosts file:
Contents of /etc/hosts
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:
Contents of /etc/hosts
And here's an IPv6 example:
Contents of /etc/hosts
Configuring DNS
For a static IP address 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.
Contents of /etc/resolv.conf
For IPv6 nameservers, edit your /etc/resolv.conf file to look like this:
The following example uses Hurricane Electric's public DNS server.
Contents of /etc/resolv.conf
You can also use Hurricane Electric's public IPv4 DNS server:
Contents of /etc/resolv.conf
Interface Configuration
Loopback Configuration (Required)
To configure loopback, add the following to a new file /etc/network/interfaces:
Contents of /etc/network/interfaces
The above works to set up the IPv4 loopback address (127.0.0.1), and the IPv6 loopback address (::1
) — if you enabled IPv6.
Wireless Configuration
See Connecting to a wireless access point.
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
:
Contents of /etc/network/interfaces
IPv4 DHCP Configuration
Add the following to the file /etc/network/interfaces, below the auto eth0
definition:
Contents of /etc/network/interfaces
By default, the busybox DHCP client (udhcpc) requests a static set of options from the DHCP server. If you need to extend this set, you can do so by setting some additional command line options for the DHCP client, via the udhcpc_opts
in your interface configuration. The following example requests
domain-search
option:
Contents of /etc/network/interfaces
For a complete list of command line options for udhcpc, see this document.
IPv4 Static Address Configuration
Add the following to the file /etc/network/interfaces, below the auto eth0
definition:
Contents of /etc/network/interfaces
Since Alpine 3.13 (and only if you have ifupdown-ng
installed) must be:
Contents of /etc/network/interfaces
Additional IP addresses
Contents of /etc/network/interfaces
Since Alpine 3.13 (and only if you have ifupdown-ng
installed) must be:
Contents of /etc/network/interfaces
IPv6 DHCP Configuration
Alpine's use of ifupdown-ng supports three DHCP clients: udhcpc, dhclient, and dhcpcd. Of these, only dhcpcd can interact with both DHCP and DHCPv6 from the same process, which ifupdown-ng requires. Thus the IPv4 DHCP configuration given above will also result in the use of DHCPv6, but only if you install the dhcpcd package. (The ifupdown-ng scripts prioritize dhclient over udhcpc, and they prioritize dhcpcd over dhclient; see /usr/libexec/ifupdown-ng/dhcp.)
IPv6 Stateless Autoconfiguration
Add the following to the file /etc/network/interfaces, below the auto eth0
definition:
Contents of /etc/network/interfaces
IPv6 Static Address Configuration
Add the following to the file /etc/network/interfaces, below the auto eth0
definition:
Contents of /etc/network/interfaces
Since Alpine Linux 3.13 (and only if you have ifupdown-ng
installed) must be as:
Contents of /etc/network/interfaces
Example: Dual-Stack Configuration
This example shows a dual-stack configuration.
Contents of /etc/network/interfaces
Take care since Alpine 3.13 (and only if you have ifupdown-ng
installed) must be as:
Contents of /etc/network/interfaces
Firewalling with iptables and ip6tables
See also: Alpine Wall - How-To Alpine Wall - Alpine Wall User's Guide
Install iptables/ip6tables
- To install iptables (includes ip6tables in alpine 3.19 and up):
# apk add iptables
- To install ip6tables (Alpine older than 3.19 only):
# 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
# rc-service 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
# rc-service 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:
# rc-service 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 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
Additional Utilities
iproute2
You may wish to install the 'iproute2' package (note that this will also install iptables if not yet installed)
# apk add iproute2
This provides the 'ss' command which is IMHO a 'better' version of netstat.
Show listening tcp ports:
$ ss -tl
Show listening tcp ports and associated processes:
$ ss -ptl
Show listening and established tcp connections:
$ ss -ta
Show socket usage summary:
$ ss -s
Show more options:
$ ss -h
drill
You may also wish to install 'drill' (it will also install the 'ldns' package) which is a superior (IMHO) replacement for nslookup and dig etc:
# apk add drill
Then use it as you would for dig:
$ drill alpinelinux.org @8.8.8.8
To perform a reverse lookup (get a name from an IP) use the following syntax:
$ drill -x 8.8.8.8 @208.67.222.222
Related articles
You may also wish to review the following network related articles: