Configure Networking: Difference between revisions

From Alpine Linux
m (updated links)
(included setup-interfaces from Ethernet page moved out Iptables reformatted headings)
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* <code>setup-ntp</code>
* <code>setup-ntp</code>


All the above utilities are interactive. When <code>setup-interfaces</code> is invoked as follows,
All the above utilities are interactive.  
{{:Ethernet}}


{{Cmd|# setup-interfaces}}
For a versatile networking front end refer [[NetworkManager]]. If you're needs are more advanced, you have to refer to the following detailed guides for manual configuration.


it helps to configure wireless and ethernet interfaces in addition to other types. The above scripts will satisfy most trivial configurations. For a versatile networking front end, refer [[NetworkManager]]. If you're needs are more advanced, you've to refer to the following detailed guides..
== Setting hostname ==


== Setting System Hostname ==
To set the system hostname:{{Cmd|# echo "shortname" > /etc/hostname}}
To set the system hostname:
{{Cmd|# echo "shortname" > /etc/hostname}}


Then, to activate the change:
Then, to activate the change: {{Cmd|# hostname -F /etc/hostname}}
{{Cmd|# hostname -F /etc/hostname}}


If you're using IPv6, you should also add the following special IPv6 addresses to your {{path|/etc/hosts}} file:
If you're using IPv6, you should also add the following special IPv6 addresses to your {{path|/etc/hosts}} file:{{cat|/etc/hosts|...
{{cat|/etc/hosts|...
::1            localhost ipv6-localhost ipv6-loopback
::1            localhost ipv6-localhost ipv6-loopback
fe00::0        ipv6-localnet
fe00::0        ipv6-localnet
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For a static IP configuration, it's common to also add the machine's hostname you just set (above) to the {{path|/etc/hosts}} file.
For a static IP configuration, it's common to also add the machine's hostname you just set (above) to the {{path|/etc/hosts}} file.


Here's an IPv4 example:
Here's an IPv4 example:{{cat|/etc/hosts|...
{{cat|/etc/hosts|...
192.168.1.150  shortname.domain.com
192.168.1.150  shortname.domain.com
...
...
}}
}}


And here's an IPv6 example:
And here's an IPv6 example:{{cat|/etc/hosts|...
{{cat|/etc/hosts|...
2001:470:ffff:ff::2  shortname.domain.com
2001:470:ffff:ff::2  shortname.domain.com
...
...
Line 53: Line 48:


== Configuring DNS ==
== Configuring DNS ==
{{Tip|'''For users of IPv4 DHCP:''' Please note that {{path|/etc/resolv.conf}} will be completely overwritten with any nameservers provided by DHCP.
{{Tip|'''For users of IPv4 DHCP:''' Please note that {{path|/etc/resolv.conf}} will be completely overwritten with any nameservers provided by DHCP.
If DHCP does not provide any nameservers, then {{path|/etc/resolv.conf}} will still be overwritten, but will not contain any nameservers!}}
If DHCP does not provide any nameservers, then {{path|/etc/resolv.conf}} will still be overwritten, but will not contain any nameservers!}}
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{{Tip|If you decide to use Hurricane Electric's nameserver, be aware that it is 'Google-whitelisted'. What does this mean?  It allows you access to many of Google's services via IPv6. (Just don't add other, non-whitelisted, nameservers to {{path|/etc/resolv.conf}} — ironically, such as Google's Public DNS Servers.) Read [https://www.google.com/intl/en/ipv6/ here] for more information.}}
{{Tip|If you decide to use Hurricane Electric's nameserver, be aware that it is 'Google-whitelisted'. What does this mean?  It allows you access to many of Google's services via IPv6. (Just don't add other, non-whitelisted, nameservers to {{path|/etc/resolv.conf}} — ironically, such as Google's Public DNS Servers.) Read [https://www.google.com/intl/en/ipv6/ here] for more information.}}


== Interface Configuration ==
== Interface configuration ==


=== Loopback Configuration (Required) ===
=== Loopback configuration  ===
{{Note|The loopback configuration must appear first in {{path|/etc/network/interfaces}} to prevent networking issues.}}
 
To configure loopback, add the following to a new file {{path|/etc/network/interfaces}}:
{{Note|The loopback configuration is mandatory and must appear first in {{path|/etc/network/interfaces}} to prevent networking issues.}}
{{cat|/etc/network/interfaces|...
 
To configure loopback, add the following to a new file {{path|/etc/network/interfaces}}: {{cat|/etc/network/interfaces|...
auto lo
auto lo
iface lo inet loopback
iface lo inet loopback
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The above works to set up the IPv4 loopback address (127.0.0.1), and the IPv6 loopback address (<code>::1</code>) — if you enabled IPv6.
The above works to set up the IPv4 loopback address (127.0.0.1), and the IPv6 loopback address (<code>::1</code>) — if you enabled IPv6.


=== Wireless Configuration ===
=== Wireless configuration ===


Alpine Linux supports two wireless daemons i.e [[iwd]] and [[Wi-Fi#wpa_supplicant|wpa_supplicant]]. Using both may lead to conflicts.
Alpine Linux supports two wireless daemons i.e [[Wi-Fi#wpa_supplicant|wpa_supplicant]] and [[iwd]]. <code>setup-interfaces</code> script uses  [[Wi-Fi#wpa_supplicant|wpa_supplicant]] to configure wireless interface.  
 
{{Note| Using both wireless daemons simultaneously lead to conflicts.}}
 
=== Ethernet configuration ===


=== Ethernet Configuration ===
For the following Ethernet configuration examples, we will assume that you are using Ethernet device <code>eth0</code>.
For the following Ethernet configuration examples, we will assume that you are using Ethernet device <code>eth0</code>.


==== Initial Configuration ====
==== Initial configuration ====
Add the following to the file {{path|/etc/network/interfaces}}, above any IP configuration for <code>eth0</code>:
Add the following to the file {{path|/etc/network/interfaces}}, above any IP configuration for <code>eth0</code>:
{{cat|/etc/network/interfaces|...
{{cat|/etc/network/interfaces|...
Line 98: Line 98:
}}
}}


==== IPv4 DHCP Configuration ====
==== IPv4 DHCP configuration ====
Add the following to the file {{path|/etc/network/interfaces}}, below the <code>auto eth0</code> definition:
Add the following to the file {{path|/etc/network/interfaces}}, below the <code>auto eth0</code> definition:
{{cat|/etc/network/interfaces|...
{{cat|/etc/network/interfaces|...
Line 132: Line 132:
...
...
}}
}}


===== Additional IP addresses =====
===== Additional IP addresses =====
Line 161: Line 160:
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 {{path|/usr/libexec/ifupdown-ng/dhcp}}.)
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 {{path|/usr/libexec/ifupdown-ng/dhcp}}.)


=== IPv6 Stateless Autoconfiguration ===
==== IPv6 Stateless Autoconfiguration ====
Add the following to the file {{path|/etc/network/interfaces}}, below the <code>auto eth0</code> definition:
Add the following to the file {{path|/etc/network/interfaces}}, below the <code>auto eth0</code> definition:
{{cat|/etc/network/interfaces|...
{{cat|/etc/network/interfaces|...
Line 228: Line 227:
}}
}}


== Firewalling with iptables and ip6tables ==
Changes made to {{path|/etc/network/interfaces}} can be activated by running: {{Cmd|# rc-service networking restart}}
 
See also: [[Alpine Wall]] - [[How-To Alpine Wall]] - [https://git.alpinelinux.org/awall/about/ Alpine Wall User's Guide].
 
=== Install iptables/ip6tables ===
* To install iptables (includes ip6tables in alpine 3.19 and up):
: {{Cmd|# apk add {{pkg|iptables|arch=}}}}
 
* To install ip6tables (Alpine older than 3.19 only):
: {{Cmd|# apk add {{pkg|ip6tables|branch=v3.18|arch=}}}}


* To install the man pages for iptables and ip6tables:
== Firewall==
: {{Cmd|# apk add {{pkg|iptables-doc|arch=}}}}


=== Configure iptables/ip6tables ===
Alpine Linux provides multiple firewall software. Some of the prominent ones are listed below:
* [https://git.alpinelinux.org/awall/about/ Alpine Wall User's Guide]
* [[Iptables]]
* [[nftables]]
* [[Uncomplicated Firewall]]


== Troubleshooting ==


=== Save Firewall Rules ===
=== Connectivity testing ===


=== For iptables ===
Test if networking is configured properly by attempting to ping out:
# Set iptables to start on reboot
#* {{ Cmd|# rc-update add iptables }}
# Write the firewall rules to disk
#* {{ Cmd|# rc-service iptables save}}
# If you use Alpine Local Backup:
<!-- Not needed on Alpine > 2.3
## Add the firewall rules to Alpine Local Backup
##* {{ Cmd|# lbu add /var/lib/iptables/rules-save }}
-->
## Save the configuration
##* {{ Cmd|# lbu ci }}
 
=== For ip6tables ===
# Set ip6tables to start on reboot
#* {{ Cmd|# rc-update add ip6tables }}
# Write the firewall rules to disk
#* {{ Cmd|# rc-service ip6tables save}}
# If you use Alpine Local Backup:
<!-- Not needed on Alpine > 2.3
## Add the firewall rules to Alpine Local Backup
##* {{ Cmd|# lbu add /var/lib/ip6tables/rules-save }}
-->
## Save the configuration
##* {{ Cmd|# lbu ci }}
 
== Activating Changes and Testing Connectivity ==
Changes made to {{path|/etc/network/interfaces}} can be activated by running:
{{Cmd|# 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:
{{Cmd|<nowiki>$ ping www.google.com
{{Cmd|<nowiki>$ ping www.google.com
PING www.l.google.com (74.125.47.103) 56(84) bytes of data.
PING www.l.google.com (74.125.47.103) 56(84) bytes of data.
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  9  yw-in-x67.1e100.net (2001:4860:8009::67)  101.545 ms  109.675 ms  99.431 ms
  9  yw-in-x67.1e100.net (2001:4860:8009::67)  101.545 ms  109.675 ms  99.431 ms
}}
}}
== Additional Utilities ==


=== iproute2 ===
=== iproute2 ===


You may wish to install the 'iproute2' package (note that this will also install iptables if not yet installed)
Install the {{pkg|iproute2}} package which provides the 'ss' command which is IMHO a 'better' version of netstat.: {{Cmd|# apk add iproute2}}


{{Cmd|# apk add iproute2}}
Show listening tcp ports:{{Cmd|$ ss -tl}}


This provides the 'ss' command which is IMHO a 'better' version of netstat.
Show listening tcp ports and associated processes:{{Cmd|$ ss -ptl}}


Show listening tcp ports:
Show listening and established tcp connections:{{Cmd|$ ss -ta}}
{{Cmd|$ ss -tl}}


Show listening tcp ports and associated processes:
Show socket usage summary:{{Cmd|$ ss -s}}
{{Cmd|$ ss -ptl}}


Show listening and established tcp connections:
Show more options:{{Cmd|$ ss -h}}
{{Cmd|$ ss -ta}}
 
Show socket usage summary:
{{Cmd|$ ss -s}}
 
Show more options:
{{Cmd|$ ss -h}}


=== drill ===
=== 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:
Install {{pkg|drill}} (it will also install the 'ldns' package) which is a superior (IMHO) replacement for nslookup and dig etc: {{Cmd|# apk add drill}}
 
{{Cmd|# apk add drill}}


Then use it as you would for dig:
Then use it as you would for dig: {{Cmd|$ drill alpinelinux.org @8.8.8.8}}


{{Cmd|$ drill alpinelinux.org @8.8.8.8}}
To perform a reverse lookup (get a name from an IP) use the following syntax: {{Cmd|$ drill -x 8.8.8.8 @208.67.222.222}}


To perform a reverse lookup (get a name from an IP) use the following syntax:
=== Missing interface ===


{{Cmd|$ drill -x 8.8.8.8 @208.67.222.222}}
Sometimes networking interface will not be detected by the installation media. In this case, you may have to use an alternate interface for installation (e.g. a usb to ethernet adapter) upon which after install / reboot the interface will display. You may also try installing any missing packages that contain the drivers.


== Related articles ==
== See also ==


You may also wish to review the following network related articles:
You may also wish to review the following network related articles:
* [[NetworkManager]] - Front-end to Networking
* [[VLAN|VLAN setup]]
* [[VLAN|VLAN setup]]
* [[Bonding|Bonding setup]]
* [[Bonding|Bonding setup]]
* [[Bridge|Network bridge setup]]
* [[Bridge|Network bridge setup]]
* [[udhcpc|udhcpc configuration]]
* [[udhcpc|udhcpc configuration]]
* [[NetworkManager]] - Front-end to Networking
* [[Wifi#wpa_supplicant|wpa_supplicant]] - Default wifi daemon
* [[Wifi#wpa_supplicant|wpa_supplicant]] - Default wifi daemon
* [[Iwd|iwd]] - An alternate to wpa_supplicant
* [[Iwd|iwd]] - An alternate wifi daemon


[[Category:Networking]]
[[Category:Networking]]

Revision as of 06:02, 10 January 2025

This page will assist you in setting up networking on Alpine Linux.

Note: You must be logged in as root in order to perform the actions on this page.

Network setup-scripts

Among the alpine setup scripts that are installed as part of alpine-conf, the following network related scripts are available.

  • setup-hostname
  • setup-interfaces
  • setup-dns
  • setup-proxy
  • setup-ntp

All the above utilities are interactive. This page will assist you in setting up networking on Alpine Linux.

Note: You must be logged in as root in order to perform the actions on this page.

Network setup-scripts

Among the alpine setup scripts that are installed as part of alpine-conf, the following network related scripts are available.

  • setup-hostname
  • setup-interfaces
  • setup-dns
  • setup-proxy
  • setup-ntp

All the above utilities are interactive. Template loop detected: Ethernet

For a versatile networking front end refer NetworkManager. If you're needs are more advanced, you have to refer to the following detailed guides for manual configuration.

Setting 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

... ::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
Tip: If you're going to use automatic IP configuration, such as IPv4 DHCP or IPv6 Stateless Autoconfiguration, you can skip ahead to Configuring DNS. Otherwise, if you're going to use a static IPv4 or IPv6 address, continue below.

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

... 192.168.1.150 shortname.domain.com ...

And here's an IPv6 example:

Contents of /etc/hosts

... 2001:470:ffff:ff::2 shortname.domain.com ...

Configuring DNS

Tip: For users of IPv4 DHCP: Please note that /etc/resolv.conf will be completely overwritten with any nameservers provided by DHCP. If DHCP does not provide any nameservers, then /etc/resolv.conf will still be overwritten, but will not contain any nameservers!

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

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.

Contents of /etc/resolv.conf

nameserver 2001:470:20::2

You can also use Hurricane Electric's public IPv4 DNS server:

Contents of /etc/resolv.conf

nameserver 74.82.42.42
Tip: If you decide to use Hurricane Electric's nameserver, be aware that it is 'Google-whitelisted'. What does this mean? It allows you access to many of Google's services via IPv6. (Just don't add other, non-whitelisted, nameservers to /etc/resolv.conf — ironically, such as Google's Public DNS Servers.) Read here for more information.

Interface configuration

Loopback configuration

Note: The loopback configuration is mandatory and must appear first in /etc/network/interfaces to prevent networking issues.

To configure loopback, add the following to a new file /etc/network/interfaces:

Contents of /etc/network/interfaces

... auto lo iface lo inet loopback

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

Alpine Linux supports two wireless daemons i.e wpa_supplicant and iwd. setup-interfaces script uses wpa_supplicant to configure wireless interface.

Note: Using both wireless daemons simultaneously lead to conflicts.

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

... auto eth0 ...

IPv4 DHCP configuration

Add the following to the file /etc/network/interfaces, below the auto eth0 definition:

Contents of /etc/network/interfaces

... iface eth0 inet dhcp ...

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

... iface eth0 inet dhcp udhcpc_opts -O search ...

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

... iface eth0 inet static address 192.168.1.150 netmask 255.255.255.0 gateway 192.168.1.1 ...

Since Alpine 3.13 (and only if you have ifupdown-ng installed) must be:

Contents of /etc/network/interfaces

... iface eth0 inet static address 192.168.1.150/24 gateway 192.168.1.1 ...
Additional IP addresses

Contents of /etc/network/interfaces

... iface eth0 inet static address 192.168.1.150 netmask 255.255.255.0 iface eth0 inet static address 192.168.1.151/24 ...

Since Alpine 3.13 (and only if you have ifupdown-ng installed) must be:

Contents of /etc/network/interfaces

... iface eth0 inet static address 192.168.1.150/24 gateway 192.168.1.1 iface eth0 inet static address 192.168.1.151/24 ...

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

... iface eth0 inet6 auto ...

IPv6 Static Address Configuration

Add the following to the file /etc/network/interfaces, below the auto eth0 definition:

Contents of /etc/network/interfaces

... 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 ...

Since Alpine Linux 3.13 (and only if you have ifupdown-ng installed) must be as:

Contents of /etc/network/interfaces

... iface eth0 inet6 static address 2001:470:ffff:ff::2/64 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.

Contents of /etc/network/interfaces

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

Take care since Alpine 3.13 (and only if you have ifupdown-ng installed) must be as:

Contents of /etc/network/interfaces

auto lo iface lo inet loopback auto eth0 iface eth0 inet static address 192.168.1.150/24 gateway 192.168.1.1 iface eth0 inet6 static address 2001:470:ffff:ff::2/64 gateway 2001:470:ffff:ff::1 pre-up echo 0 > /proc/sys/net/ipv6/conf/eth0/accept_ra

Changes made to /etc/network/interfaces can be activated by running:

# rc-service networking restart

Firewall

Alpine Linux provides multiple firewall software. Some of the prominent ones are listed below:

Troubleshooting

Connectivity testing

Test if 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

iproute2

Install the iproute2 package which provides the 'ss' command which is IMHO a 'better' version of netstat.:

# apk add iproute2

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

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

Missing interface

Sometimes networking interface will not be detected by the installation media. In this case, you may have to use an alternate interface for installation (e.g. a usb to ethernet adapter) upon which after install / reboot the interface will display. You may also try installing any missing packages that contain the drivers.

See also

You may also wish to review the following network related articles:

For a versatile networking front end refer NetworkManager. If you're needs are more advanced, you have to refer to the following detailed guides for manual configuration.

Setting 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

... ::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
Tip: If you're going to use automatic IP configuration, such as IPv4 DHCP or IPv6 Stateless Autoconfiguration, you can skip ahead to Configuring DNS. Otherwise, if you're going to use a static IPv4 or IPv6 address, continue below.

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

... 192.168.1.150 shortname.domain.com ...

And here's an IPv6 example:

Contents of /etc/hosts

... 2001:470:ffff:ff::2 shortname.domain.com ...

Configuring DNS

Tip: For users of IPv4 DHCP: Please note that /etc/resolv.conf will be completely overwritten with any nameservers provided by DHCP. If DHCP does not provide any nameservers, then /etc/resolv.conf will still be overwritten, but will not contain any nameservers!

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

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.

Contents of /etc/resolv.conf

nameserver 2001:470:20::2

You can also use Hurricane Electric's public IPv4 DNS server:

Contents of /etc/resolv.conf

nameserver 74.82.42.42
Tip: If you decide to use Hurricane Electric's nameserver, be aware that it is 'Google-whitelisted'. What does this mean? It allows you access to many of Google's services via IPv6. (Just don't add other, non-whitelisted, nameservers to /etc/resolv.conf — ironically, such as Google's Public DNS Servers.) Read here for more information.

Interface configuration

Loopback configuration

Note: The loopback configuration is mandatory and must appear first in /etc/network/interfaces to prevent networking issues.

To configure loopback, add the following to a new file /etc/network/interfaces:

Contents of /etc/network/interfaces

... auto lo iface lo inet loopback

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

Alpine Linux supports two wireless daemons i.e wpa_supplicant and iwd. setup-interfaces script uses wpa_supplicant to configure wireless interface.

Note: Using both wireless daemons simultaneously lead to conflicts.

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

... auto eth0 ...

IPv4 DHCP configuration

Add the following to the file /etc/network/interfaces, below the auto eth0 definition:

Contents of /etc/network/interfaces

... iface eth0 inet dhcp ...

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

... iface eth0 inet dhcp udhcpc_opts -O search ...

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

... iface eth0 inet static address 192.168.1.150 netmask 255.255.255.0 gateway 192.168.1.1 ...

Since Alpine 3.13 (and only if you have ifupdown-ng installed) must be:

Contents of /etc/network/interfaces

... iface eth0 inet static address 192.168.1.150/24 gateway 192.168.1.1 ...
Additional IP addresses

Contents of /etc/network/interfaces

... iface eth0 inet static address 192.168.1.150 netmask 255.255.255.0 iface eth0 inet static address 192.168.1.151/24 ...

Since Alpine 3.13 (and only if you have ifupdown-ng installed) must be:

Contents of /etc/network/interfaces

... iface eth0 inet static address 192.168.1.150/24 gateway 192.168.1.1 iface eth0 inet static address 192.168.1.151/24 ...

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

... iface eth0 inet6 auto ...

IPv6 Static Address Configuration

Add the following to the file /etc/network/interfaces, below the auto eth0 definition:

Contents of /etc/network/interfaces

... 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 ...

Since Alpine Linux 3.13 (and only if you have ifupdown-ng installed) must be as:

Contents of /etc/network/interfaces

... iface eth0 inet6 static address 2001:470:ffff:ff::2/64 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.

Contents of /etc/network/interfaces

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

Take care since Alpine 3.13 (and only if you have ifupdown-ng installed) must be as:

Contents of /etc/network/interfaces

auto lo iface lo inet loopback auto eth0 iface eth0 inet static address 192.168.1.150/24 gateway 192.168.1.1 iface eth0 inet6 static address 2001:470:ffff:ff::2/64 gateway 2001:470:ffff:ff::1 pre-up echo 0 > /proc/sys/net/ipv6/conf/eth0/accept_ra

Changes made to /etc/network/interfaces can be activated by running:

# rc-service networking restart

Firewall

Alpine Linux provides multiple firewall software. Some of the prominent ones are listed below:

Troubleshooting

Connectivity testing

Test if 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

iproute2

Install the iproute2 package which provides the 'ss' command which is IMHO a 'better' version of netstat.:

# apk add iproute2

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

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

Missing interface

Sometimes networking interface will not be detected by the installation media. In this case, you may have to use an alternate interface for installation (e.g. a usb to ethernet adapter) upon which after install / reboot the interface will display. You may also try installing any missing packages that contain the drivers.

See also

You may also wish to review the following network related articles:

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