Provided by: systemd_245.4-4ubuntu3.24_amd64 
NAME
systemd.network - Network configuration
SYNOPSIS
network.network
DESCRIPTION
A plain ini-style text file that encodes network configuration for matching network
interfaces, used by systemd-networkd(8). See systemd.syntax(7) for a general description
of the syntax.
The main network file must have the extension .network; other extensions are ignored.
Networks are applied to links whenever the links appear.
The .network files are read from the files located in the system network directories
/lib/systemd/network and /usr/local/lib/systemd/network, the volatile runtime network
directory /run/systemd/network and the local administration network directory
/etc/systemd/network. All configuration files are collectively sorted and processed in
lexical order, regardless of the directories in which they live. However, files with
identical filenames replace each other. Files in /etc have the highest priority, files in
/run take precedence over files with the same name under /usr. This can be used to
override a system-supplied configuration file with a local file if needed. As a special
case, an empty file (file size 0) or symlink with the same name pointing to /dev/null
disables the configuration file entirely (it is "masked").
Along with the network file foo.network, a "drop-in" directory foo.network.d/ may exist.
All files with the suffix ".conf" from this directory will be parsed after the file itself
is parsed. This is useful to alter or add configuration settings, without having to modify
the main configuration file. Each drop-in file must have appropriate section headers.
In addition to /etc/systemd/network, drop-in ".d" directories can be placed in
/lib/systemd/network or /run/systemd/network directories. Drop-in files in /etc take
precedence over those in /run which in turn take precedence over those in /lib. Drop-in
files under any of these directories take precedence over the main network file wherever
located.
Note that an interface without any static IPv6 addresses configured, and neither DHCPv6
nor IPv6LL enabled, shall be considered to have no IPv6 support. IPv6 will be
automatically disabled for that interface by writing "1" to
/proc/sys/net/ipv6/conf/ifname/disable_ipv6.
[MATCH] SECTION OPTIONS
The network file contains a "[Match]" section, which determines if a given network file
may be applied to a given device; and a "[Network]" section specifying how the device
should be configured. The first (in lexical order) of the network files that matches a
given device is applied, all later files are ignored, even if they match as well.
A network file is said to match a network interface if all matches specified by the
"[Match]" section are satisfied. When a network file does not contain valid settings in
"[Match]" section, then the file will match all interfaces and systemd-networkd warns
about that. Hint: to avoid the warning and to make it clear that all interfaces shall be
matched, add the following:
Name=*
The following keys are accepted:
MACAddress=
A whitespace-separated list of hardware addresses. Use full colon-, hyphen- or
dot-delimited hexadecimal. See the example below. This option may appear more than
once, in which case the lists are merged. If the empty string is assigned to this
option, the list of hardware addresses defined prior to this is reset.
Example:
MACAddress=01:23:45:67:89:ab 00-11-22-33-44-55 AABB.CCDD.EEFF
PermanentMACAddress=
A whitespace-separated list of hardware's permanent addresses. While MACAddress=
matches the device's current MAC address, this matches the device's permanent MAC
address, which may be different from the current one. Use full colon-, hyphen- or
dot-delimited hexadecimal. This option may appear more than once, in which case the
lists are merged. If the empty string is assigned to this option, the list of hardware
addresses defined prior to this is reset.
Path=
A whitespace-separated list of shell-style globs matching the persistent path, as
exposed by the udev property ID_PATH.
Driver=
A whitespace-separated list of shell-style globs matching the driver currently bound
to the device, as exposed by the udev property ID_NET_DRIVER of its parent device, or
if that is not set, the driver as exposed by ethtool -i of the device itself. If the
list is prefixed with a "!", the test is inverted.
Type=
A whitespace-separated list of shell-style globs matching the device type, as exposed
by networkctl status. If the list is prefixed with a "!", the test is inverted.
Property=
A whitespace-separated list of udev property name with its value after a equal ("=").
If multiple properties are specified, the test results are ANDed. If the list is
prefixed with a "!", the test is inverted. If a value contains white spaces, then
please quote whole key and value pair. If a value contains quotation, then please
escape the quotation with "\".
Example: if a .link file has the following:
Property=ID_MODEL_ID=9999 "ID_VENDOR_FROM_DATABASE=vendor name" "KEY=with \"quotation\""
then, the .link file matches only when an interface has all the above three
properties.
Name=
A whitespace-separated list of shell-style globs matching the device name, as exposed
by the udev property "INTERFACE", or device's alternative names. If the list is
prefixed with a "!", the test is inverted.
WLANInterfaceType=
A whitespace-separated list of wireless network type. Supported values are "ad-hoc",
"station", "ap", "ap-vlan", "wds", "monitor", "mesh-point", "p2p-client", "p2p-go",
"p2p-device", "ocb", and "nan". If the list is prefixed with a "!", the test is
inverted.
SSID=
A whitespace-separated list of shell-style globs matching the SSID of the currently
connected wireless LAN. If the list is prefixed with a "!", the test is inverted.
BSSID=
A whitespace-separated list of hardware address of the currently connected wireless
LAN. Use full colon-, hyphen- or dot-delimited hexadecimal. See the example in
MACAddress=. This option may appear more than one, in which case the lists are merged.
If the empty string is assigned to this option, the list of BSSID defined prior to
this is reset.
Host=
Matches against the hostname or machine ID of the host. See ConditionHost= in
systemd.unit(5) for details. When prefixed with an exclamation mark ("!"), the result
is negated. If an empty string is assigned, then previously assigned value is cleared.
Virtualization=
Checks whether the system is executed in a virtualized environment and optionally test
whether it is a specific implementation. See ConditionVirtualization= in
systemd.unit(5) for details. When prefixed with an exclamation mark ("!"), the result
is negated. If an empty string is assigned, then previously assigned value is cleared.
KernelCommandLine=
Checks whether a specific kernel command line option is set. See
ConditionKernelCommandLine= in systemd.unit(5) for details. When prefixed with an
exclamation mark ("!"), the result is negated. If an empty string is assigned, then
previously assigned value is cleared.
KernelVersion=
Checks whether the kernel version (as reported by uname -r) matches a certain
expression. See ConditionKernelVersion= in systemd.unit(5) for details. When prefixed
with an exclamation mark ("!"), the result is negated. If an empty string is assigned,
then previously assigned value is cleared.
Architecture=
Checks whether the system is running on a specific architecture. See
ConditionArchitecture= in systemd.unit(5) for details. When prefixed with an
exclamation mark ("!"), the result is negated. If an empty string is assigned, then
previously assigned value is cleared.
[LINK] SECTION OPTIONS
The "[Link]" section accepts the following keys:
MACAddress=
The hardware address to set for the device.
MTUBytes=
The maximum transmission unit in bytes to set for the device. The usual suffixes K, M,
G, are supported and are understood to the base of 1024.
Note that if IPv6 is enabled on the interface, and the MTU is chosen below 1280 (the
minimum MTU for IPv6) it will automatically be increased to this value.
ARP=
Takes a boolean. If set to true, the ARP (low-level Address Resolution Protocol) for
this interface is enabled. When unset, the kernel's default will be used.
For example, disabling ARP is useful when creating multiple MACVLAN or VLAN virtual
interfaces atop a single lower-level physical interface, which will then only serve as
a link/"bridge" device aggregating traffic to the same physical link and not
participate in the network otherwise.
Multicast=
Takes a boolean. If set to true, the multicast flag on the device is enabled.
AllMulticast=
Takes a boolean. If set to true, the driver retrieves all multicast packets from the
network. This happens when multicast routing is enabled.
Unmanaged=
Takes a boolean. When "yes", no attempts are made to bring up or configure matching
links, equivalent to when there are no matching network files. Defaults to "no".
This is useful for preventing later matching network files from interfering with
certain interfaces that are fully controlled by other applications.
RequiredForOnline=
Takes a boolean or a minimum operational state and an optional maximum operational
state. Please see networkctl(1) for possible operational states. When "yes", the
network is deemed required when determining whether the system is online when running
systemd-networkd-wait-online. When "no", the network is ignored when checking for
online state. When a minimum operational state and an optional maximum operational
state are set, "yes" is implied, and this controls the minimum and maximum operational
state required for the network interface to be considered online.
Defaults to "yes" when ActivationPolicy= is not set, or set to "up", "always-up", or
"bound". Defaults to "no" when ActivationPolicy= is set to "manual" or "down". This is
forced to "no" when ActivationPolicy= is set to "always-down".
The network will be brought up normally (as configured by ActivationPolicy=), but in
the event that there is no address being assigned by DHCP or the cable is not plugged
in, the link will simply remain offline and be skipped automatically by
systemd-networkd-wait-online if "RequiredForOnline=no".
ActivationPolicy=
Specifies the policy for systemd-networkd managing the link administrative state.
Specifically, this controls how systemd-networkd changes the network device's "IFF_UP"
flag, which is sometimes controlled by system administrators by running e.g., ip set
dev eth0 up or ip set dev eth0 down, and can also be changed with networkctl up eth0
or networkctl down eth0.
Takes one of "up", "always-up", "manual", "always-down", "down", or "bound". When
"manual", systemd-networkd will not change the link's admin state automatically; the
system administrator must bring the interface up or down manually, as desired. When
"up" (the default) or "always-up", or "down" or "always-down", systemd-networkd will
set the link up or down, respectively, when the interface is (re)configured. When
"always-up" or "always-down", systemd-networkd will set the link up or down,
respectively, any time systemd-networkd detects a change in the administrative state.
When BindCarrier= is also set, this is automatically set to "bound" and any other
value is ignored.
When the policy is set to "down" or "manual", the default value of RequiredForOnline=
is "no". When the policy is set to "always-down", the value of RequiredForOnline=
forced to "no".
The administrative state is not the same as the carrier state, so using "always-up"
does not mean the link will never lose carrier. The link carrier depends on both the
administrative state as well as the network device's physical connection. However, to
avoid reconfiguration failures, when using "always-up", IgnoreCarrierLoss= is forced
to true.
[NETWORK] SECTION OPTIONS
The "[Network]" section accepts the following keys:
Description=
A description of the device. This is only used for presentation purposes.
DHCP=
Enables DHCPv4 and/or DHCPv6 client support. Accepts "yes", "no", "ipv4", or "ipv6".
Defaults to "no".
Note that DHCPv6 will by default be triggered by Router Advertisement, if that is
enabled, regardless of this parameter. By enabling DHCPv6 support explicitly, the
DHCPv6 client will be started regardless of the presence of routers on the link, or
what flags the routers pass. See "IPv6AcceptRA=".
Furthermore, note that by default the domain name specified through DHCP, on Ubuntu,
are used for name resolution. See option UseDomains= below.
See the "[DHCPv4]" or "[DHCPv6]" section below for further configuration options for
the DHCP client support.
DHCPServer=
Takes a boolean. If set to "yes", DHCPv4 server will be started. Defaults to "no".
Further settings for the DHCP server may be set in the "[DHCPServer]" section
described below.
LinkLocalAddressing=
Enables link-local address autoconfiguration. Accepts "yes", "no", "ipv4", "ipv6",
"fallback", or "ipv4-fallback". If "fallback" or "ipv4-fallback" is specified, then an
IPv4 link-local address is configured only when DHCPv4 fails. If "fallback", an IPv6
link-local address is always configured, and if "ipv4-fallback", the address is not
configured. Note that, the fallback mechanism works only when DHCPv4 client is
enabled, that is, it requires "DHCP=yes" or "DHCP=ipv4". If Bridge= is set, defaults
to "no", and if not, defaults to "ipv6".
IPv4LLRoute=
Takes a boolean. If set to true, sets up the route needed for non-IPv4LL hosts to
communicate with IPv4LL-only hosts. Defaults to false.
DefaultRouteOnDevice=
Takes a boolean. If set to true, sets up the default route bound to the interface.
Defaults to false. This is useful when creating routes on point-to-point interfaces.
This is equivalent to e.g. the following.
ip route add default dev veth99
IPv6Token=
Specifies an optional address generation mode and a required IPv6 address. If the mode
is present, the two parts must be separated with a colon "mode:address". The address
generation mode may be either prefixstable or static. If not specified, static is
assumed.
When the mode is set to static, or unspecified, the lower bits of the supplied address
are combined with the upper bits of a prefix received in a Router Advertisement
message to form a complete address. Note that if multiple prefixes are received in an
RA message, or in multiple RA messages, addresses will be formed from each of them
using the supplied address. This mode implements SLAAC but uses a static interface
identifier instead of an identifier generated using the EUI-64 algorithm. Because the
interface identifier is static, if Duplicate Address Detection detects that the
computed address is a duplicate (in use by another node on the link), then this mode
will fail to provide an address for that prefix.
When the mode is set to "prefixstable" the RFC 7217 algorithm for generating interface
identifiers will be used, but only when a prefix received in an RA message matches the
supplied address. See RFC 7217[1]. Prefix matching will be attempted against each
prefixstable IPv6Token variable provided in the configuration; if a received prefix
does not match any of the provided addresses, then the EUI-64 algorithm will be used
to form an interface identifier for that prefix. This mode is also SLAAC, but with a
potentially stable interface identifier which does not directly map to the interface's
hardware address. Note that the prefixstable algorithm includes both the interface's
name and MAC address in the hash used to compute the interface identifier, so if
either of those are changed the resulting interface identifier (and address) will
change, even if the prefix received in the RA message has not changed. Note that if
multiple prefixstable IPv6Token variables are supplied with addresses that match a
prefix received in an RA message, only the first one will be used to generate
addresses.
LLMNR=
Takes a boolean or "resolve". When true, enables Link-Local Multicast Name
Resolution[2] on the link. When set to "resolve", only resolution is enabled, but not
host registration and announcement. Defaults to true. This setting is read by systemd-
resolved.service(8).
MulticastDNS=
Takes a boolean or "resolve". When true, enables Multicast DNS[3] support on the link.
When set to "resolve", only resolution is enabled, but not host or service
registration and announcement. Defaults to false. This setting is read by systemd-
resolved.service(8).
DNSOverTLS=
Takes a boolean or "opportunistic". When true, enables DNS-over-TLS[4] support on the
link. When set to "opportunistic", compatibility with non-DNS-over-TLS servers is
increased, by automatically turning off DNS-over-TLS servers in this case. This option
defines a per-interface setting for resolved.conf(5)'s global DNSOverTLS= option.
Defaults to false. This setting is read by systemd-resolved.service(8).
DNSSEC=
Takes a boolean. or "allow-downgrade". When true, enables DNSSEC[5] DNS validation
support on the link. When set to "allow-downgrade", compatibility with non-DNSSEC
capable networks is increased, by automatically turning off DNSSEC in this case. This
option defines a per-interface setting for resolved.conf(5)'s global DNSSEC= option.
Defaults to false. This setting is read by systemd-resolved.service(8).
DNSSECNegativeTrustAnchors=
A space-separated list of DNSSEC negative trust anchor domains. If specified and
DNSSEC is enabled, look-ups done via the interface's DNS server will be subject to the
list of negative trust anchors, and not require authentication for the specified
domains, or anything below it. Use this to disable DNSSEC authentication for specific
private domains, that cannot be proven valid using the Internet DNS hierarchy.
Defaults to the empty list. This setting is read by systemd-resolved.service(8).
LLDP=
Controls support for Ethernet LLDP packet reception. LLDP is a link-layer protocol
commonly implemented on professional routers and bridges which announces which
physical port a system is connected to, as well as other related data. Accepts a
boolean or the special value "routers-only". When true, incoming LLDP packets are
accepted and a database of all LLDP neighbors maintained. If "routers-only" is set
only LLDP data of various types of routers is collected and LLDP data about other
types of devices ignored (such as stations, telephones and others). If false, LLDP
reception is disabled. Defaults to "routers-only". Use networkctl(1) to query the
collected neighbor data. LLDP is only available on Ethernet links. See EmitLLDP= below
for enabling LLDP packet emission from the local system.
EmitLLDP=
Controls support for Ethernet LLDP packet emission. Accepts a boolean parameter or the
special values "nearest-bridge", "non-tpmr-bridge" and "customer-bridge". Defaults to
false, which turns off LLDP packet emission. If not false, a short LLDP packet with
information about the local system is sent out in regular intervals on the link. The
LLDP packet will contain information about the local host name, the local machine ID
(as stored in machine-id(5)) and the local interface name, as well as the pretty
hostname of the system (as set in machine-info(5)). LLDP emission is only available on
Ethernet links. Note that this setting passes data suitable for identification of host
to the network and should thus not be enabled on untrusted networks, where such
identification data should not be made available. Use this option to permit other
systems to identify on which interfaces they are connected to this system. The three
special values control propagation of the LLDP packets. The "nearest-bridge" setting
permits propagation only to the nearest connected bridge, "non-tpmr-bridge" permits
propagation across Two-Port MAC Relays, but not any other bridges, and
"customer-bridge" permits propagation until a customer bridge is reached. For details
about these concepts, see IEEE 802.1AB-2016[6]. Note that configuring this setting to
true is equivalent to "nearest-bridge", the recommended and most restricted level of
propagation. See LLDP= above for an option to enable LLDP reception.
BindCarrier=
A link name or a list of link names. When set, controls the behavior of the current
link. When all links in the list are in an operational down state, the current link is
brought down. When at least one link has carrier, the current interface is brought up.
This forces ActivationPolicy= to be set to "bound".
Address=
A static IPv4 or IPv6 address and its prefix length, separated by a "/" character.
Specify this key more than once to configure several addresses. The format of the
address must be as described in inet_pton(3). This is a short-hand for an [Address]
section only containing an Address key (see below). This option may be specified more
than once.
If the specified address is "0.0.0.0" (for IPv4) or "::" (for IPv6), a new address
range of the requested size is automatically allocated from a system-wide pool of
unused ranges. Note that the prefix length must be equal or larger than 8 for IPv4,
and 64 for IPv6. The allocated range is checked against all current network interfaces
and all known network configuration files to avoid address range conflicts. The
default system-wide pool consists of 192.168.0.0/16, 172.16.0.0/12 and 10.0.0.0/8 for
IPv4, and fd00::/8 for IPv6. This functionality is useful to manage a large number of
dynamically created network interfaces with the same network configuration and
automatic address range assignment.
Gateway=
The gateway address, which must be in the format described in inet_pton(3). This is a
short-hand for a [Route] section only containing a Gateway key. This option may be
specified more than once.
DNS=
A DNS server address, which must be in the format described in inet_pton(3). This
option may be specified more than once. This setting is read by systemd-
resolved.service(8).
Domains=
A whitespace-separated list of domains which should be resolved using the DNS servers
on this link. Each item in the list should be a domain name, optionally prefixed with
a tilde ("~"). The domains with the prefix are called "routing-only domains". The
domains without the prefix are called "search domains" and are first used as search
suffixes for extending single-label host names (host names containing no dots) to
become fully qualified domain names (FQDNs). If a single-label host name is resolved
on this interface, each of the specified search domains are appended to it in turn,
converting it into a fully qualified domain name, until one of them may be
successfully resolved.
Both "search" and "routing-only" domains are used for routing of DNS queries: look-ups
for host names ending in those domains (hence also single label names, if any "search
domains" are listed), are routed to the DNS servers configured for this interface. The
domain routing logic is particularly useful on multi-homed hosts with DNS servers
serving particular private DNS zones on each interface.
The "routing-only" domain "~." (the tilde indicating definition of a routing domain,
the dot referring to the DNS root domain which is the implied suffix of all valid DNS
names) has special effect. It causes all DNS traffic which does not match another
configured domain routing entry to be routed to DNS servers specified for this
interface. This setting is useful to prefer a certain set of DNS servers if a link on
which they are connected is available.
This setting is read by systemd-resolved.service(8). "Search domains" correspond to
the domain and search entries in resolv.conf(5). Domain name routing has no equivalent
in the traditional glibc API, which has no concept of domain name servers limited to a
specific link.
DNSDefaultRoute=
Takes a boolean argument. If true, this link's configured DNS servers are used for
resolving domain names that do not match any link's configured Domains= setting. If
false, this link's configured DNS servers are never used for such domains, and are
exclusively used for resolving names that match at least one of the domains configured
on this link. If not specified defaults to an automatic mode: queries not matching any
link's configured domains will be routed to this link if it has no routing-only
domains configured.
NTP=
An NTP server address. This option may be specified more than once. This setting is
read by systemd-timesyncd.service(8).
IPForward=
Configures IP packet forwarding for the system. If enabled, incoming packets on any
network interface will be forwarded to any other interfaces according to the routing
table. Takes a boolean, or the values "ipv4" or "ipv6", which only enable IP packet
forwarding for the specified address family. This controls the net.ipv4.ip_forward and
net.ipv6.conf.all.forwarding sysctl options of the network interface (see
ip-sysctl.txt[7] for details about sysctl options). Defaults to "no".
Note: this setting controls a global kernel option, and does so one way only: if a
network that has this setting enabled is set up the global setting is turned on.
However, it is never turned off again, even after all networks with this setting
enabled are shut down again.
To allow IP packet forwarding only between specific network interfaces use a firewall.
IPMasquerade=
Configures IP masquerading for the network interface. If enabled, packets forwarded
from the network interface will be appear as coming from the local host. Takes a
boolean argument. Implies IPForward=ipv4. Defaults to "no".
IPv6PrivacyExtensions=
Configures use of stateless temporary addresses that change over time (see RFC
4941[8], Privacy Extensions for Stateless Address Autoconfiguration in IPv6). Takes a
boolean or the special values "prefer-public" and "kernel". When true, enables the
privacy extensions and prefers temporary addresses over public addresses. When
"prefer-public", enables the privacy extensions, but prefers public addresses over
temporary addresses. When false, the privacy extensions remain disabled. When
"kernel", the kernel's default setting will be left in place. Defaults to "no".
IPv6AcceptRA=
Takes a boolean. Controls IPv6 Router Advertisement (RA) reception support for the
interface. If true, RAs are accepted; if false, RAs are ignored. When RAs are
accepted, they may trigger the start of the DHCPv6 client if the relevant flags are
set in the RA data, or if no routers are found on the link. The default is to disable
RA reception for bridge devices or when IP forwarding is enabled, and to enable it
otherwise. Cannot be enabled on bond devices and when link local adressing is
disabled.
Further settings for the IPv6 RA support may be configured in the "[IPv6AcceptRA]"
section, see below.
Also see ip-sysctl.txt[7] in the kernel documentation regarding "accept_ra", but note
that systemd's setting of 1 (i.e. true) corresponds to kernel's setting of 2.
Note that kernel's implementation of the IPv6 RA protocol is always disabled,
regardless of this setting. If this option is enabled, a userspace implementation of
the IPv6 RA protocol is used, and the kernel's own implementation remains disabled,
since systemd-networkd needs to know all details supplied in the advertisements, and
these are not available from the kernel if the kernel's own implementation is used.
IPv6DuplicateAddressDetection=
Configures the amount of IPv6 Duplicate Address Detection (DAD) probes to send. When
unset, the kernel's default will be used.
IPv6HopLimit=
Configures IPv6 Hop Limit. For each router that forwards the packet, the hop limit is
decremented by 1. When the hop limit field reaches zero, the packet is discarded. When
unset, the kernel's default will be used.
IPv4ProxyARP=
Takes a boolean. Configures proxy ARP for IPv4. Proxy ARP is the technique in which
one host, usually a router, answers ARP requests intended for another machine. By
"faking" its identity, the router accepts responsibility for routing packets to the
"real" destination. (see RFC 1027[9]. When unset, the kernel's default will be used.
IPv6ProxyNDP=
Takes a boolean. Configures proxy NDP for IPv6. Proxy NDP (Neighbor Discovery
Protocol) is a technique for IPv6 to allow routing of addresses to a different
destination when peers expect them to be present on a certain physical link. In this
case a router answers Neighbour Advertisement messages intended for another machine by
offering its own MAC address as destination. Unlike proxy ARP for IPv4, it is not
enabled globally, but will only send Neighbour Advertisement messages for addresses in
the IPv6 neighbor proxy table, which can also be shown by ip -6 neighbour show proxy.
systemd-networkd will control the per-interface `proxy_ndp` switch for each configured
interface depending on this option. When unset, the kernel's default will be used.
IPv6ProxyNDPAddress=
An IPv6 address, for which Neighbour Advertisement messages will be proxied. This
option may be specified more than once. systemd-networkd will add the
IPv6ProxyNDPAddress= entries to the kernel's IPv6 neighbor proxy table. This option
implies IPv6ProxyNDP=yes but has no effect if IPv6ProxyNDP has been set to false. When
unset, the kernel's default will be used.
IPv6PrefixDelegation=
Whether to enable or disable Router Advertisement sending on a link. Allowed values
are "static" which distributes prefixes as defined in the "[IPv6PrefixDelegation]" and
any "[IPv6Prefix]" sections, "dhcpv6" which requests prefixes using a DHCPv6 client
configured for another link and any values configured in the "[IPv6PrefixDelegation]"
section while ignoring all static prefix configuration sections, "yes" which uses both
static configuration and DHCPv6, and "false" which turns off IPv6 prefix delegation
altogether. Defaults to "false". See the "[IPv6PrefixDelegation]" and the
"[IPv6Prefix]" sections for more configuration options.
IPv6MTUBytes=
Configures IPv6 maximum transmission unit (MTU). An integer greater than or equal to
1280 bytes. When unset, the kernel's default will be used.
Bridge=
The name of the bridge to add the link to. See systemd.netdev(5).
Bond=
The name of the bond to add the link to. See systemd.netdev(5).
VRF=
The name of the VRF to add the link to. See systemd.netdev(5).
VLAN=
The name of a VLAN to create on the link. See systemd.netdev(5). This option may be
specified more than once.
IPVLAN=
The name of a IPVLAN to create on the link. See systemd.netdev(5). This option may be
specified more than once.
MACVLAN=
The name of a MACVLAN to create on the link. See systemd.netdev(5). This option may be
specified more than once.
VXLAN=
The name of a VXLAN to create on the link. See systemd.netdev(5). This option may be
specified more than once.
Tunnel=
The name of a Tunnel to create on the link. See systemd.netdev(5). This option may be
specified more than once.
MACsec=
The name of a MACsec device to create on the link. See systemd.netdev(5). This option
may be specified more than once.
ActiveSlave=
Takes a boolean. Specifies the new active slave. The "ActiveSlave=" option is only
valid for following modes: "active-backup", "balance-alb" and "balance-tlb". Defaults
to false.
PrimarySlave=
Takes a boolean. Specifies which slave is the primary device. The specified device
will always be the active slave while it is available. Only when the primary is
off-line will alternate devices be used. This is useful when one slave is preferred
over another, e.g. when one slave has higher throughput than another. The
"PrimarySlave=" option is only valid for following modes: "active-backup",
"balance-alb" and "balance-tlb". Defaults to false.
ConfigureWithoutCarrier=
Takes a boolean. Allows networkd to configure a specific link even if it has no
carrier. Defaults to false.
IgnoreCarrierLoss=
Takes a boolean. Allows networkd to retain both the static and dynamic configuration
of the interface even if its carrier is lost. When unset, the value specified with
ConfigureWithoutCarrier= is used.
When ActivationPolicy= is set to "always-up", this is forced to "true".
Xfrm=
The name of the xfrm to create on the link. See systemd.netdev(5). This option may be
specified more than once.
KeepConfiguration=
Takes a boolean or one of "static", "dhcp-on-stop", "dhcp". When "static",
systemd-networkd will not drop static addresses and routes on starting up process.
When set to "dhcp-on-stop", systemd-networkd will not drop addresses and routes on
stopping the daemon. When "dhcp", the addresses and routes provided by a DHCP server
will never be dropped even if the DHCP lease expires. This is contrary to the DHCP
specification, but may be the best choice if, e.g., the root filesystem relies on this
connection. The setting "dhcp" implies "dhcp-on-stop", and "yes" implies "dhcp" and
"static". Defaults to "no".
[ADDRESS] SECTION OPTIONS
An "[Address]" section accepts the following keys. Specify several "[Address]" sections to
configure several addresses.
Address=
As in the "[Network]" section. This key is mandatory. Each "[Address]" section can
contain one Address= setting.
Peer=
The peer address in a point-to-point connection. Accepts the same format as the
Address= key.
Broadcast=
The broadcast address, which must be in the format described in inet_pton(3). This key
only applies to IPv4 addresses. If it is not given, it is derived from the Address=
key.
Label=
An address label.
PreferredLifetime=
Allows the default "preferred lifetime" of the address to be overridden. Only three
settings are accepted: "forever" or "infinity" which is the default and means that the
address never expires, and "0" which means that the address is considered immediately
"expired" and will not be used, unless explicitly requested. A setting of
PreferredLifetime=0 is useful for addresses which are added to be used only by a
specific application, which is then configured to use them explicitly.
Scope=
The scope of the address, which can be "global", "link" or "host" or an unsigned
integer ranges 0 to 255. Defaults to "global".
RouteMetric=
The metric of the prefix route, which is pointing to the subnet of the configured IP
address, taking the configured prefix length into account. Takes an unsigned integer
in the range 0...4294967295. When unset or set to 0, the kernel's default value is
used. This setting will be ignored when AddPrefixRoute= is false.
HomeAddress=
Takes a boolean. Designates this address the "home address" as defined in RFC
6275[10]. Supported only on IPv6. Defaults to false.
DuplicateAddressDetection=
Takes one of "ipv4", "ipv6", "both", "none". When "ipv4", performs IPv4 Duplicate
Address Detection. See RFC 5224[11]. When "ipv6", performs IPv6 Duplicate Address
Detection. See RFC 4862[12]. Defaults to "ipv6".
ManageTemporaryAddress=
Takes a boolean. If true the kernel manage temporary addresses created from this one
as template on behalf of Privacy Extensions RFC 3041[13]. For this to become active,
the use_tempaddr sysctl setting has to be set to a value greater than zero. The given
address needs to have a prefix length of 64. This flag allows using privacy extensions
in a manually configured network, just like if stateless auto-configuration was
active. Defaults to false.
AddPrefixRoute=
Takes a boolean. When true, the prefix route for the address is automatically added.
Defaults to true.
AutoJoin=
Takes a boolean. Joining multicast group on ethernet level via ip maddr command would
not work if we have an Ethernet switch that does IGMP snooping since the switch would
not replicate multicast packets on ports that did not have IGMP reports for the
multicast addresses. Linux vxlan interfaces created via ip link add vxlan or
networkd's netdev kind vxlan have the group option that enables then to do the
required join. By extending ip address command with option "autojoin" we can get
similar functionality for openvswitch (OVS) vxlan interfaces as well as other
tunneling mechanisms that need to receive multicast traffic. Defaults to "no".
[NEIGHBOR] SECTION OPTIONS
A "[Neighbor]" section accepts the following keys. The neighbor section adds a permanent,
static entry to the neighbor table (IPv6) or ARP table (IPv4) for the given hardware
address on the links matched for the network. Specify several "[Neighbor]" sections to
configure several static neighbors.
Address=
The IP address of the neighbor.
LinkLayerAddress=
The link layer address (MAC address or IP address) of the neighbor.
[IPV6ADDRESSLABEL] SECTION OPTIONS
An "[IPv6AddressLabel]" section accepts the following keys. Specify several
"[IPv6AddressLabel]" sections to configure several address labels. IPv6 address labels are
used for address selection. See RFC 3484[14]. Precedence is managed by userspace, and only
the label itself is stored in the kernel
Label=
The label for the prefix (an unsigned integer) ranges 0 to 4294967294. 0xffffffff is
reserved. This key is mandatory.
Prefix=
IPv6 prefix is an address with a prefix length, separated by a slash "/" character.
This key is mandatory.
[ROUTINGPOLICYRULE] SECTION OPTIONS
An "[RoutingPolicyRule]" section accepts the following keys. Specify several
"[RoutingPolicyRule]" sections to configure several rules.
TypeOfService=
Specifies the type of service to match a number between 0 to 255.
From=
Specifies the source address prefix to match. Possibly followed by a slash and the
prefix length.
To=
Specifies the destination address prefix to match. Possibly followed by a slash and
the prefix length.
FirewallMark=
Specifies the iptables firewall mark value to match (a number between 1 and
4294967295).
Table=
Specifies the routing table identifier to lookup if the rule selector matches. Takes
one of "default", "main", and "local", or a number between 1 and 4294967295. Defaults
to "main".
Priority=
Specifies the priority of this rule. Priority= is an unsigned integer. Higher number
means lower priority, and rules get processed in order of increasing number.
IncomingInterface=
Specifies incoming device to match. If the interface is loopback, the rule only
matches packets originating from this host.
OutgoingInterface=
Specifies the outgoing device to match. The outgoing interface is only available for
packets originating from local sockets that are bound to a device.
SourcePort=
Specifies the source IP port or IP port range match in forwarding information base
(FIB) rules. A port range is specified by the lower and upper port separated by a
dash. Defaults to unset.
DestinationPort=
Specifies the destination IP port or IP port range match in forwarding information
base (FIB) rules. A port range is specified by the lower and upper port separated by a
dash. Defaults to unset.
IPProtocol=
Specifies the IP protocol to match in forwarding information base (FIB) rules. Takes
IP protocol name such as "tcp", "udp" or "sctp", or IP protocol number such as "6" for
"tcp" or "17" for "udp". Defaults to unset.
InvertRule=
A boolean. Specifies whether the rule is to be inverted. Defaults to false.
Family=
Takes a special value "ipv4", "ipv6", or "both". By default, the address family is
determined by the address specified in To= or From=. If neither To= nor From= are
specified, then defaults to "ipv4".
User=
Takes a username, a user ID, or a range of user IDs separated by a dash. Defaults to
unset.
SuppressPrefixLength=
Takes a number N in the range 0-128 and rejects routing decisions that have a prefix
length of N or less. Defaults to unset.
[NEXTHOP] SECTION OPTIONS
The "[NextHop]" section accepts the following keys. Specify several "[NextHop]" sections
to configure several nexthop. Nexthop is used to manipulate entries in the kernel's
nexthop tables.
Gateway=
As in the "[Network]" section. This is mandatory.
Id=
The id of the nexthop (an unsigned integer). If unspecified or '0' then automatically
chosen by kernel.
[ROUTE] SECTION OPTIONS
The "[Route]" section accepts the following keys. Specify several "[Route]" sections to
configure several routes.
Gateway=
Takes the gateway address or special value "_dhcp". If "_dhcp", then the gateway
address provided by DHCP (or in the IPv6 case, provided by IPv6 RA) is used.
GatewayOnLink=
Takes a boolean. If set to true, the kernel does not have to check if the gateway is
reachable directly by the current machine (i.e., the kernel does not need to check if
the gateway is attached to the local network), so that we can insert the route in the
kernel table without it being complained about. Defaults to "no".
Destination=
The destination prefix of the route. Possibly followed by a slash and the prefix
length. If omitted, a full-length host route is assumed.
Source=
The source prefix of the route. Possibly followed by a slash and the prefix length. If
omitted, a full-length host route is assumed.
Metric=
The metric of the route (an unsigned integer).
IPv6Preference=
Specifies the route preference as defined in RFC4191[15] for Router Discovery
messages. Which can be one of "low" the route has a lowest priority, "medium" the
route has a default priority or "high" the route has a highest priority.
Scope=
The scope of the route, which can be "global", "site", "link", "host", or "nowhere".
For IPv4 route, defaults to "host" if Type= is "local" or "nat", and "link" if Type=
is "broadcast", "multicast", or "anycast". In other cases, defaults to "global".
PreferredSource=
The preferred source address of the route. The address must be in the format described
in inet_pton(3).
Table=
The table identifier for the route. Takes "default", "main", "local" or a number
between 1 and 4294967295. The table can be retrieved using ip route show table num. If
unset and Type= is "local", "broadcast", "anycast", or "nat", then "local" is used. In
other cases, defaults to "main".
Protocol=
The protocol identifier for the route. Takes a number between 0 and 255 or the special
values "kernel", "boot", "static", "ra" and "dhcp". Defaults to "static".
Type=
Specifies the type for the route. Takes one of "unicast", "local", "broadcast",
"anycast", "multicast", "blackhole", "unreachable", "prohibit", "throw", "nat", and
"xresolve". If "unicast", a regular route is defined, i.e. a route indicating the path
to take to a destination network address. If "blackhole", packets to the defined route
are discarded silently. If "unreachable", packets to the defined route are discarded
and the ICMP message "Host Unreachable" is generated. If "prohibit", packets to the
defined route are discarded and the ICMP message "Communication Administratively
Prohibited" is generated. If "throw", route lookup in the current routing table will
fail and the route selection process will return to Routing Policy Database (RPDB).
Defaults to "unicast".
InitialCongestionWindow=
The TCP initial congestion window is used during the start of a TCP connection. During
the start of a TCP session, when a client requests a resource, the server's initial
congestion window determines how many data bytes will be sent during the initial burst
of data. Takes a size in bytes between 1 and 4294967295 (2^32 - 1). The usual suffixes
K, M, G are supported and are understood to the base of 1024. When unset, the kernel's
default will be used.
InitialAdvertisedReceiveWindow=
The TCP initial advertised receive window is the amount of receive data (in bytes)
that can initially be buffered at one time on a connection. The sending host can send
only that amount of data before waiting for an acknowledgment and window update from
the receiving host. Takes a size in bytes between 1 and 4294967295 (2^32 - 1). The
usual suffixes K, M, G are supported and are understood to the base of 1024. When
unset, the kernel's default will be used.
QuickAck=
Takes a boolean. When true enables TCP quick ack mode for the route. When unset, the
kernel's default will be used.
FastOpenNoCookie=
Takes a boolean. When true enables TCP fastopen without a cookie on a per-route basis.
When unset, the kernel's default will be used.
TTLPropagate=
Takes a boolean. When true enables TTL propagation at Label Switched Path (LSP)
egress. When unset, the kernel's default will be used.
MTUBytes=
The maximum transmission unit in bytes to set for the route. The usual suffixes K, M,
G, are supported and are understood to the base of 1024.
Note that if IPv6 is enabled on the interface, and the MTU is chosen below 1280 (the
minimum MTU for IPv6) it will automatically be increased to this value.
IPServiceType=
Takes string; "CS6" or "CS4". Used to set IP service type to CS6 (network control) or
CS4 (Realtime). Defaults to CS6.
MultiPathRoute=address[@name] [weight]
Configures multipath route. Multipath routing is the technique of using multiple
alternative paths through a network. Takes gateway address. Optionally, takes a
network interface name or index separated with "@", and a weight in 1..256 for this
multipath route separated with whitespace. This setting can be specified multiple
times. If an empty string is assigned, then the all previous assignments are cleared.
[DHCPV4] SECTION OPTIONS
The "[DHCPv4]" section configures the DHCPv4 client, if it is enabled with the DHCP=
setting described above:
UseDNS=
When true (the default), the DNS servers received from the DHCP server will be used
and take precedence over any statically configured ones.
This corresponds to the nameserver option in resolv.conf(5).
RoutesToDNS=
When true, the routes to the DNS servers received from the DHCP server will be
configured. When UseDNS= is disabled, this setting is ignored. Defaults to false.
UseNTP=
When true (the default), the NTP servers received from the DHCP server will be used by
systemd-timesyncd and take precedence over any statically configured ones.
UseSIP=
When true (the default), the SIP servers received from the DHCP server will be saved
at the state files and can be read via sd_network_link_get_sip_servers() function.
UseMTU=
When true, the interface maximum transmission unit from the DHCP server will be used
on the current link. If MTUBytes= is set, then this setting is ignored. Defaults to
false.
Anonymize=
Takes a boolean. When true, the options sent to the DHCP server will follow the RFC
7844[16] (Anonymity Profiles for DHCP Clients) to minimize disclosure of identifying
information. Defaults to false.
This option should only be set to true when MACAddressPolicy= is set to "random" (see
systemd.link(5)).
Note that this configuration will overwrite others. In concrete, the following
variables will be ignored: SendHostname=, ClientIdentifier=, UseRoutes=, UseMTU=,
VendorClassIdentifier=, UseTimezone=.
With this option enabled DHCP requests will mimic those generated by Microsoft
Windows, in order to reduce the ability to fingerprint and recognize installations.
This means DHCP request sizes will grow and lease data will be more comprehensive than
normally, though most of the requested data is not actually used.
SendHostname=
When true (the default), the machine's hostname will be sent to the DHCP server. Note
that the machine's hostname must consist only of 7-bit ASCII lower-case characters and
no spaces or dots, and be formatted as a valid DNS domain name. Otherwise, the
hostname is not sent even if this is set to true.
UseHostname=
When true (the default), the hostname received from the DHCP server will be set as the
transient hostname of the system.
Hostname=
Use this value for the hostname which is sent to the DHCP server, instead of machine's
hostname. Note that the specified hostname must consist only of 7-bit ASCII lower-case
characters and no spaces or dots, and be formatted as a valid DNS domain name.
UseDomains=
Takes a boolean, or the special value "route". When true, the domain name received
from the DHCP server will be used as DNS search domain over this link, similar to the
effect of the Domains= setting. If set to "route", the domain name received from the
DHCP server will be used for routing DNS queries only, but not for searching, similar
to the effect of the Domains= setting when the argument is prefixed with "~". Defaults
to true on Ubuntu.
It is recommended to enable this option only on trusted networks, as setting this
affects resolution of all host names, in particular of single-label names. It is
generally safer to use the supplied domain only as routing domain, rather than as
search domain, in order to not have it affect local resolution of single-label names.
When set to true, this setting corresponds to the domain option in resolv.conf(5).
UseRoutes=
When true (the default), the static routes will be requested from the DHCP server and
added to the routing table with a metric of 1024, and a scope of "global", "link" or
"host", depending on the route's destination and gateway. If the destination is on the
local host, e.g., 127.x.x.x, or the same as the link's own address, the scope will be
set to "host". Otherwise if the gateway is null (a direct route), a "link" scope will
be used. For anything else, scope defaults to "global".
UseGateway=
When true, the gateway will be requested from the DHCP server and added to the routing
table with a metric of 1024, and a scope of "link". When unset, the value specified
with UseRoutes= is used.
UseTimezone=
When true, the timezone received from the DHCP server will be set as timezone of the
local system. Defaults to "no".
ClientIdentifier=
The DHCPv4 client identifier to use. Takes one of "mac", "duid" or "duid-only". If set
to "mac", the MAC address of the link is used. If set to "duid", an RFC4361-compliant
Client ID, which is the combination of IAID and DUID (see below), is used. If set to
"duid-only", only DUID is used, this may not be RFC compliant, but some setups may
require to use this. Defaults to "duid".
VendorClassIdentifier=
The vendor class identifier used to identify vendor type and configuration.
UserClass=
A DHCPv4 client can use UserClass option to identify the type or category of user or
applications it represents. The information contained in this option is a string that
represents the user class of which the client is a member. Each class sets an
identifying string of information to be used by the DHCP service to classify clients.
Takes a whitespace-separated list of strings.
MaxAttempts=
Specifies how many times the DHCPv4 client configuration should be attempted. Takes a
number or "infinity". Defaults to "infinity". Note that the time between retries is
increased exponentially, so the network will not be overloaded even if this number is
high.
DUIDType=
Override the global DUIDType setting for this network. See networkd.conf(5) for a
description of possible values.
DUIDRawData=
Override the global DUIDRawData setting for this network. See networkd.conf(5) for a
description of possible values.
IAID=
The DHCP Identity Association Identifier (IAID) for the interface, a 32-bit unsigned
integer.
RequestBroadcast=
Request the server to use broadcast messages before the IP address has been
configured. This is necessary for devices that cannot receive RAW packets, or that
cannot receive packets at all before an IP address has been configured. On the other
hand, this must not be enabled on networks where broadcasts are filtered out.
RouteMetric=
Set the routing metric for routes specified by the DHCP server.
RouteTable=num
The table identifier for DHCP routes (a number between 1 and 4294967295, or 0 to
unset). The table can be retrieved using ip route show table num.
When used in combination with VRF= the VRF's routing table is used unless this
parameter is specified.
RouteMTUBytes=
Specifies the MTU for the DHCP routes. Please see the [Route] section for further
details.
ListenPort=
Allow setting custom port for the DHCP client to listen on.
SendRelease=
When true, the DHCPv4 client sends a DHCP release packet when it stops. Defaults to
true.
SendDecline=
A boolen. When "true", DHCPv4 clients receives IP address from DHCP server. After new
IP is received, DHCPv4 performs IPv4 Duplicate Address Detection. If duplicate use of
IP is detected the DHCPv4 client rejects the IP by sending a DHCPDECLINE packet DHCP
clients try to obtain an IP address again. See RFC 5224[11]. Defaults to "unset".
BlackList=
A whitespace-separated list of IPv4 addresses. DHCP offers from servers in the list
are rejected.
RequestOptions=
A whitespace-separated list of integers in the range 1–254.
SendOption=
Send an arbitrary option in the DHCPv4 request. Takes a DHCP option number, data type
and data separated with a colon ("option:type:value"). The option number must be an
integer in the range 1..254. The type takes one of "uint8", "uint16", "uint32",
"ipv4address", or "string". Special characters in the data string may be escaped using
C-style escapes[17]. This setting can be specified multiple times. If an empty string
is specified, then all options specified earlier are cleared. Defaults to unset.
[DHCPV6] SECTION OPTIONS
The "[DHCPv6]" section configures the DHCPv6 client, if it is enabled with the DHCP=
setting described above, or invoked by the IPv6 Router Advertisement:
UseDNS=, UseNTP=
As in the "[DHCPv4]" section.
RapidCommit=
Takes a boolean. The DHCPv6 client can obtain configuration parameters from a DHCPv6
server through a rapid two-message exchange (solicit and reply). When the rapid commit
option is enabled by both the DHCPv6 client and the DHCPv6 server, the two-message
exchange is used, rather than the default four-method exchange (solicit, advertise,
request, and reply). The two-message exchange provides faster client configuration and
is beneficial in environments in which networks are under a heavy load. See RFC
3315[18] for details. Defaults to true.
ForceDHCPv6PDOtherInformation=
Takes a boolean that enforces DHCPv6 stateful mode when the 'Other information' bit is
set in Router Advertisement messages. By default setting only the 'O' bit in Router
Advertisements makes DHCPv6 request network information in a stateless manner using a
two-message Information Request and Information Reply message exchange. RFC 7084[19],
requirement WPD-4, updates this behavior for a Customer Edge router so that stateful
DHCPv6 Prefix Delegation is also requested when only the 'O' bit is set in Router
Advertisements. This option enables such a CE behavior as it is impossible to
automatically distinguish the intention of the 'O' bit otherwise. By default this
option is set to 'false', enable it if no prefixes are delegated when the device
should be acting as a CE router.
PrefixDelegationHint=
Takes an IPv6 address with prefix length as Address= in the "[Network]" section.
Specifies the DHCPv6 client for the requesting router to include a prefix-hint in the
DHCPv6 solicitation. Prefix ranges 1-128. Defaults to unset.
[IPV6ACCEPTRA] SECTION OPTIONS
The "[IPv6AcceptRA]" section configures the IPv6 Router Advertisement (RA) client, if it
is enabled with the IPv6AcceptRA= setting described above:
UseDNS=
When true (the default), the DNS servers received in the Router Advertisement will be
used and take precedence over any statically configured ones.
This corresponds to the nameserver option in resolv.conf(5).
UseDomains=
Takes a boolean, or the special value "route". When true, the domain name received via
IPv6 Router Advertisement (RA) will be used as DNS search domain over this link,
similar to the effect of the Domains= setting. If set to "route", the domain name
received via IPv6 RA will be used for routing DNS queries only, but not for searching,
similar to the effect of the Domains= setting when the argument is prefixed with "~".
Defaults to true on Ubuntu.
It is recommended to enable this option only on trusted networks, as setting this
affects resolution of all host names, in particular of single-label names. It is
generally safer to use the supplied domain only as routing domain, rather than as
search domain, in order to not have it affect local resolution of single-label names.
When set to true, this setting corresponds to the domain option in resolv.conf(5).
RouteTable=num
The table identifier for the routes received in the Router Advertisement (a number
between 1 and 4294967295, or 0 to unset). The table can be retrieved using ip route
show table num.
UseAutonomousPrefix=
When true (the default), the autonomous prefix received in the Router Advertisement
will be used and take precedence over any statically configured ones.
UseOnLinkPrefix=
When true (the default), the onlink prefix received in the Router Advertisement will
be used and take precedence over any statically configured ones.
BlackList=
A whitespace-separated list of IPv6 prefixes. IPv6 prefixes supplied via router
advertisements in the list are ignored.
[DHCPSERVER] SECTION OPTIONS
The "[DHCPServer]" section contains settings for the DHCP server, if enabled via the
DHCPServer= option described above:
PoolOffset=, PoolSize=
Configures the pool of addresses to hand out. The pool is a contiguous sequence of IP
addresses in the subnet configured for the server address, which does not include the
subnet nor the broadcast address. PoolOffset= takes the offset of the pool from the
start of subnet, or zero to use the default value. PoolSize= takes the number of IP
addresses in the pool or zero to use the default value. By default, the pool starts at
the first address after the subnet address and takes up the rest of the subnet,
excluding the broadcast address. If the pool includes the server address (the
default), this is reserved and not handed out to clients.
DefaultLeaseTimeSec=, MaxLeaseTimeSec=
Control the default and maximum DHCP lease time to pass to clients. These settings
take time values in seconds or another common time unit, depending on the suffix. The
default lease time is used for clients that did not ask for a specific lease time. If
a client asks for a lease time longer than the maximum lease time, it is automatically
shortened to the specified time. The default lease time defaults to 1h, the maximum
lease time to 12h. Shorter lease times are beneficial if the configuration data in
DHCP leases changes frequently and clients shall learn the new settings with shorter
latencies. Longer lease times reduce the generated DHCP network traffic.
EmitDNS=, DNS=
Takes a boolean. Configures whether the DHCP leases handed out to clients shall
contain DNS server information. Defaults to "yes". The DNS servers to pass to clients
may be configured with the DNS= option, which takes a list of IPv4 addresses. If the
EmitDNS= option is enabled but no servers configured, the servers are automatically
propagated from an "uplink" interface that has appropriate servers set. The "uplink"
interface is determined by the default route of the system with the highest priority.
Note that this information is acquired at the time the lease is handed out, and does
not take uplink interfaces into account that acquire DNS or NTP server information at
a later point. DNS server propagation does not take /etc/resolv.conf into account.
Also, note that the leases are not refreshed if the uplink network configuration
changes. To ensure clients regularly acquire the most current uplink DNS server
information, it is thus advisable to shorten the DHCP lease time via MaxLeaseTimeSec=
described above.
EmitNTP=, NTP=
Similar to the EmitDNS= and DNS= settings described above, these settings configure
whether and what NTP server information shall be emitted as part of the DHCP lease.
The same syntax, propagation semantics and defaults apply as for EmitDNS= and DNS=.
EmitSIP=, SIP=
Similar to the EmitDNS= and DNS= settings described above, these settings configure
whether and what SIP server information shall be emitted as part of the DHCP lease.
The same syntax, propagation semantics and defaults apply as for EmitDNS= and DNS=.
EmitRouter=
Similar to the EmitDNS= setting described above, this setting configures whether the
DHCP lease should contain the router option. The same syntax, propagation semantics
and defaults apply as for EmitDNS=.
EmitTimezone=, Timezone=
Takes a boolean. Configures whether the DHCP leases handed out to clients shall
contain timezone information. Defaults to "yes". The Timezone= setting takes a
timezone string (such as "Europe/Berlin" or "UTC") to pass to clients. If no explicit
timezone is set, the system timezone of the local host is propagated, as determined by
the /etc/localtime symlink.
SendOption=
Send a raw option with value via DHCPv4 server. Takes a DHCP option number, data type
and data ("option:type:value"). The option number is an integer in the range 1..254.
The type takes one of "uint8", "uint16", "uint32", "ipv4address", or "string". Special
characters in the data string may be escaped using C-style escapes[17]. This setting
can be specified multiple times. If an empty string is specified, then all options
specified earlier are cleared. Defaults to unset.
[IPV6PREFIXDELEGATION] SECTION OPTIONS
The "[IPv6PrefixDelegation]" section contains settings for sending IPv6 Router
Advertisements and whether to act as a router, if enabled via the IPv6PrefixDelegation=
option described above. IPv6 network prefixes are defined with one or more "[IPv6Prefix]"
sections.
Managed=, OtherInformation=
Takes a boolean. Controls whether a DHCPv6 server is used to acquire IPv6 addresses on
the network link when Managed= is set to "true" or if only additional network
information can be obtained via DHCPv6 for the network link when OtherInformation= is
set to "true". Both settings default to "false", which means that a DHCPv6 server is
not being used.
RouterLifetimeSec=
Takes a timespan. Configures the IPv6 router lifetime in seconds. If set, this host
also announces itself in Router Advertisements as an IPv6 router for the network link.
When unset, the host is not acting as a router.
RouterPreference=
Configures IPv6 router preference if RouterLifetimeSec= is non-zero. Valid values are
"high", "medium" and "low", with "normal" and "default" added as synonyms for "medium"
just to make configuration easier. See RFC 4191[15] for details. Defaults to "medium".
EmitDNS=, DNS=
DNS= specifies a list of recursive DNS server IPv6 addresses that are distributed via
Router Advertisement messages when EmitDNS= is true. DNS= also takes special value
"_link_local"; in that case the IPv6 link local address is distributed. If DNS= is
empty, DNS servers are read from the "[Network]" section. If the "[Network]" section
does not contain any DNS servers either, DNS servers from the uplink with the highest
priority default route are used. When EmitDNS= is false, no DNS server information is
sent in Router Advertisement messages. EmitDNS= defaults to true.
EmitDomains=, Domains=
A list of DNS search domains distributed via Router Advertisement messages when
EmitDomains= is true. If Domains= is empty, DNS search domains are read from the
"[Network]" section. If the "[Network]" section does not contain any DNS search
domains either, DNS search domains from the uplink with the highest priority default
route are used. When EmitDomains= is false, no DNS search domain information is sent
in Router Advertisement messages. EmitDomains= defaults to true.
DNSLifetimeSec=
Lifetime in seconds for the DNS server addresses listed in DNS= and search domains
listed in Domains=.
[IPV6PREFIX] SECTION OPTIONS
One or more "[IPv6Prefix]" sections contain the IPv6 prefixes that are announced via
Router Advertisements. See RFC 4861[20] for further details.
AddressAutoconfiguration=, OnLink=
Takes a boolean to specify whether IPv6 addresses can be autoconfigured with this
prefix and whether the prefix can be used for onlink determination. Both settings
default to "true" in order to ease configuration.
Prefix=
The IPv6 prefix that is to be distributed to hosts. Similarly to configuring static
IPv6 addresses, the setting is configured as an IPv6 prefix and its prefix length,
separated by a "/" character. Use multiple "[IPv6Prefix]" sections to configure
multiple IPv6 prefixes since prefix lifetimes, address autoconfiguration and onlink
status may differ from one prefix to another.
PreferredLifetimeSec=, ValidLifetimeSec=
Preferred and valid lifetimes for the prefix measured in seconds.
PreferredLifetimeSec= defaults to 604800 seconds (one week) and ValidLifetimeSec=
defaults to 2592000 seconds (30 days).
[IPV6ROUTEPREFIX] SECTION OPTIONS
One or more "[IPv6RoutePrefix]" sections contain the IPv6 prefix routes that are announced
via Router Advertisements. See RFC 4191[15] for further details.
Route=
The IPv6 route that is to be distributed to hosts. Similarly to configuring static
IPv6 routes, the setting is configured as an IPv6 prefix routes and its prefix route
length, separated by a"/" character. Use multiple "[IPv6PrefixRoutes]" sections to
configure multiple IPv6 prefix routes.
LifetimeSec=
Lifetime for the route prefix measured in seconds. LifetimeSec= defaults to 604800
seconds (one week).
[BRIDGE] SECTION OPTIONS
The "[Bridge]" section accepts the following keys.
UnicastFlood=
Takes a boolean. Controls whether the bridge should flood traffic for which an FDB
entry is missing and the destination is unknown through this port. When unset, the
kernel's default will be used.
MulticastFlood=
Takes a boolean. Controls whether the bridge should flood traffic for which an MDB
entry is missing and the destination is unknown through this port. When unset, the
kernel's default will be used.
MulticastToUnicast=
Takes a boolean. Multicast to unicast works on top of the multicast snooping feature
of the bridge. Which means unicast copies are only delivered to hosts which are
interested in it. When unset, the kernel's default will be used.
NeighborSuppression=
Takes a boolean. Configures whether ARP and ND neighbor suppression is enabled for
this port. When unset, the kernel's default will be used.
Learning=
Takes a boolean. Configures whether MAC address learning is enabled for this port.
When unset, the kernel's default will be used.
HairPin=
Takes a boolean. Configures whether traffic may be sent back out of the port on which
it was received. When this flag is false, and the bridge will not forward traffic back
out of the receiving port. When unset, the kernel's default will be used.
UseBPDU=
Takes a boolean. Configures whether STP Bridge Protocol Data Units will be processed
by the bridge port. When unset, the kernel's default will be used.
FastLeave=
Takes a boolean. This flag allows the bridge to immediately stop multicast traffic on
a port that receives an IGMP Leave message. It is only used with IGMP snooping if
enabled on the bridge. When unset, the kernel's default will be used.
AllowPortToBeRoot=
Takes a boolean. Configures whether a given port is allowed to become a root port.
Only used when STP is enabled on the bridge. When unset, the kernel's default will be
used.
ProxyARP=
Takes a boolean. Configures whether proxy ARP to be enabled on this port. When unset,
the kernel's default will be used.
ProxyARPWiFi=
Takes a boolean. Configures whether proxy ARP to be enabled on this port which meets
extended requirements by IEEE 802.11 and Hotspot 2.0 specifications. When unset, the
kernel's default will be used.
MulticastRouter=
Configures this port for having multicast routers attached. A port with a multicast
router will receive all multicast traffic. Takes one of "no" to disable multicast
routers on this port, "query" to let the system detect the presence of routers,
"permanent" to permanently enable multicast traffic forwarding on this port, or
"temporary" to enable multicast routers temporarily on this port, not depending on
incoming queries. When unset, the kernel's default will be used.
Cost=
Sets the "cost" of sending packets of this interface. Each port in a bridge may have a
different speed and the cost is used to decide which link to use. Faster interfaces
should have lower costs. It is an integer value between 1 and 65535.
Priority=
Sets the "priority" of sending packets on this interface. Each port in a bridge may
have a different priority which is used to decide which link to use. Lower value means
higher priority. It is an integer value between 0 to 63. Networkd does not set any
default, meaning the kernel default value of 32 is used.
[BRIDGEFDB] SECTION OPTIONS
The "[BridgeFDB]" section manages the forwarding database table of a port and accepts the
following keys. Specify several "[BridgeFDB]" sections to configure several static MAC
table entries.
MACAddress=
As in the "[Network]" section. This key is mandatory.
Destination=
Takes an IP address of the destination VXLAN tunnel endpoint.
VLANId=
The VLAN ID for the new static MAC table entry. If omitted, no VLAN ID information is
appended to the new static MAC table entry.
VNI=
The VXLAN Network Identifier (or VXLAN Segment ID) to use to connect to the remote
VXLAN tunnel endpoint. Takes a number in the range 1-16777215. Defaults to unset.
AssociatedWith=
Specifies where the address is associated with. Takes one of "use", "self", "master"
or "router". "use" means the address is in use. User space can use this option to
indicate to the kernel that the fdb entry is in use. "self" means the address is
associated with the port drivers fdb. Usually hardware. "master" means the address is
associated with master devices fdb. "router" means the destination address is
associated with a router. Note that it's valid if the referenced device is a VXLAN
type device and has route shortcircuit enabled. Defaults to "self".
[CAN] SECTION OPTIONS
The "[CAN]" section manages the Controller Area Network (CAN bus) and accepts the
following keys.
BitRate=
The bitrate of CAN device in bits per second. The usual SI prefixes (K, M) with the
base of 1000 can be used here.
SamplePoint=
Optional sample point in percent with one decimal (e.g. "75%", "87.5%") or permille
(e.g. "875‰").
RestartSec=
Automatic restart delay time. If set to a non-zero value, a restart of the CAN
controller will be triggered automatically in case of a bus-off condition after the
specified delay time. Subsecond delays can be specified using decimals (e.g. "0.1s")
or a "ms" or "us" postfix. Using "infinity" or "0" will turn the automatic restart
off. By default automatic restart is disabled.
TripleSampling=
Takes a boolean. When "yes", three samples (instead of one) are used to determine the
value of a received bit by majority rule. When unset, the kernel's default will be
used.
[QDISC] SECTION OPTIONS
The "[QDisc]" section manages the traffic control queueing discipline (qdisc).
Parent=
Specifies the parent Queueing Discipline (qdisc). Takes one of "clsact" or "ingress".
This is mandatory.
Handle=
Specifies the major number of unique identifier of the qdisc, known as the handle.
Takes a number in hexadecimal ranges 1 to ffff. Defaults to unset.
[NETWORKEMULATOR] SECTION OPTIONS
The "[NetworkEmulator]" section manages the queueing discipline (qdisc) of the network
emulator. It can be used to configure the kernel packet scheduler and simulate packet
delay and loss for UDP or TCP applications, or limit the bandwidth usage of a particular
service to simulate internet connections.
Parent=
Specifies the parent Queueing Discipline (qdisc). Takes one of "root", "clsact" or
"ingress". Defaults to "root".
Handle=
Specifies the major number of unique identifier of the qdisc, known as the handle.
Takes a number in hexadecimal ranges 1 to ffff. Defaults to unset.
DelaySec=
Specifies the fixed amount of delay to be added to all packets going out of the
interface. Defaults to unset.
DelayJitterSec=
Specifies the chosen delay to be added to the packets outgoing to the network
interface. Defaults to unset.
PacketLimit=
Specifies the maximum number of packets the qdisc may hold queued at a time. An
unsigned integer ranges 0 to 4294967294. Defaults to 1000.
LossRate=
Specifies an independent loss probability to be added to the packets outgoing from the
network interface. Takes a percentage value, suffixed with "%". Defaults to unset.
DuplicateRate=
Specifies that the chosen percent of packets is duplicated before queuing them. Takes
a percentage value, suffixed with "%". Defaults to unset.
[TOKENBUCKETFILTER] SECTION OPTIONS
The "[TokenBucketFilter]" section manages the queueing discipline (qdisc) of token bucket
filter (tbf).
Parent=
Specifies the parent Queueing Discipline (qdisc). Takes one of "root", "clsact" or
"ingress". Defaults to "root".
Handle=
Specifies the major number of unique identifier of the qdisc, known as the handle.
Takes a number in hexadecimal ranges 1 to ffff. Defaults to unset.
LatencySec=
Specifies the latency parameter, which specifies the maximum amount of time a packet
can sit in the Token Bucket Filter (TBF). Defaults to unset.
LimitSize=
Takes the number of bytes that can be queued waiting for tokens to become available.
When the size is suffixed with K, M, or G, it is parsed as Kilobytes, Megabytes, or
Gigabytes, respectively, to the base of 1000. Defaults to unset.
Burst=
Specifies the size of the bucket. This is the maximum amount of bytes that tokens can
be available for instantaneous transfer. When the size is suffixed with K, M, or G, it
is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of 1000.
Defaults to unset.
Rate=
Specifies the device specific bandwidth. When suffixed with K, M, or G, the specified
bandwidth is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
1000. Defaults to unset.
MPUBytes=
The Minimum Packet Unit (MPU) determines the minimal token usage (specified in bytes)
for a packet. When suffixed with K, M, or G, the specified size is parsed as
Kilobytes, Megabytes, or Gigabytes, respectively, to the base of 1000. Defaults to
zero.
PeakRate=
Takes the maximum depletion rate of the bucket. When suffixed with K, M, or G, the
specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base
of 1000. Defaults to unset.
MTUBytes=
Specifies the size of the peakrate bucket. When suffixed with K, M, or G, the
specified size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the
base of 1000. Defaults to unset.
[STOCHASTICFAIRNESSQUEUEING] SECTION OPTIONS
The "[StochasticFairnessQueueing]" section manages the queueing discipline (qdisc) of
stochastic fairness queueing (sfq).
Parent=
Specifies the parent Queueing Discipline (qdisc). Takes one of "root", "clsact" or
"ingress". Defaults to "root".
Handle=
Specifies the major number of unique identifier of the qdisc, known as the handle.
Takes a number in hexadecimal ranges 1 to ffff. Defaults to unset.
PerturbPeriodSec=
Specifies the interval in seconds for queue algorithm perturbation. Defaults to unset.
[CONTROLLEDDELAY] SECTION OPTIONS
The "[ControlledDelay]" section manages the queueing discipline (qdisc) of controlled
delay (CoDel).
Parent=
Specifies the parent Queueing Discipline (qdisc). Takes one of "root", "clsact" or
"ingress". Defaults to "root".
Handle=
Specifies the major number of unique identifier of the qdisc, known as the handle.
Takes a number in hexadecimal ranges 1 to ffff. Defaults to unset.
PacketLimit=
Specifies the hard limit on the queue size in number of packets. When this limit is
reached, incoming packets are dropped. An unsigned integer ranges 0 to 4294967294.
Defaults to unset and kernel's default is used.
TargetSec=
Takes a timespan. Specifies the acceptable minimum standing/persistent queue delay.
Defaults to unset and kernel's default is used.
IntervalSec=
Takes a timespan. This is used to ensure that the measured minimum delay does not
become too stale. Defaults to unset and kernel's default is used.
ECN=
Takes a boolean. This can be used to mark packets instead of dropping them. Defaults
to unset and kernel's default is used.
CEThresholdSec=
Takes a timespan. This sets a threshold above which all packets are marked with ECN
Congestion Experienced (CE). Defaults to unset and kernel's default is used.
[FAIRQUEUEINGCONTROLLEDDELAY] SECTION OPTIONS
The "[FairQueueingControlledDelay]" section manages the queueing discipline (qdisc) of
fair queuing controlled delay (FQ-CoDel).
Parent=
Specifies the parent Queueing Discipline (qdisc). Takes one of "root", "clsact" or
"ingress". Defaults to "root".
Handle=
Specifies the major number of unique identifier of the qdisc, known as the handle.
Takes a number in hexadecimal ranges 1 to ffff. Defaults to unset.
PacketLimit=
Specifies the hard limit on the real queue size. When this limit is reached, incoming
packets are dropped. Defaults to unset and kernel's default is used.
MemoryLimit=
Specifies the limit on the total number of bytes that can be queued in this FQ-CoDel
instance. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
Megabytes, or Gigabytes, respectively, to the base of 1024. Defaults to unset and
kernel's default is used.
Flows=
Specifies the number of flows into which the incoming packets are classified. Defaults
to unset and kernel's default is used.
TargetSec=
Takes a timespan. Specifies the acceptable minimum standing/persistent queue delay.
Defaults to unset and kernel's default is used.
IntervalSec=
Takes a timespan. This is used to ensure that the measured minimum delay does not
become too stale. Defaults to unset and kernel's default is used.
Quantum=
Specifies the number of bytes used as 'deficit' in the fair queuing algorithmtimespan.
When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes,
or Gigabytes, respectively, to the base of 1024. Defaults to unset and kernel's
default is used.
ECN=
Takes a boolean. This can be used to mark packets instead of dropping them. Defaults
to unset and kernel's default is used.
CEThresholdSec=
Takes a timespan. This sets a threshold above which all packets are marked with ECN
Congestion Experienced (CE). Defaults to unset and kernel's default is used.
[FAIRQUEUEING] SECTION OPTIONS
The "[FairQueueing]" section manages the queueing discipline (qdisc) of fair queue traffic
policing (FQ).
Parent=
Specifies the parent Queueing Discipline (qdisc). Takes one of "root", "clsact" or
"ingress". Defaults to "root".
Handle=
Specifies the major number of unique identifier of the qdisc, known as the handle.
Takes a number in hexadecimal ranges 1 to ffff. Defaults to unset.
PacketLimit=
Specifies the hard limit on the real queue size. When this limit is reached, incoming
packets are dropped. Defaults to unset and kernel's default is used.
FlowLimit=
Specifies the hard limit on the maximum number of packets queued per flow. Defaults to
unset and kernel's default is used.
Quantum=
Specifies the credit per dequeue RR round, i.e. the amount of bytes a flow is allowed
to dequeue at once. When suffixed with K, M, or G, the specified size is parsed as
Kilobytes, Megabytes, or Gigabytes, respectively, to the base of 1024. Defaults to
unset and kernel's default is used.
InitialQuantum=
Specifies the initial sending rate credit, i.e. the amount of bytes a new flow is
allowed to dequeue initially. When suffixed with K, M, or G, the specified size is
parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of 1024.
Defaults to unset and kernel's default is used.
MaximumRate=
Specifies the maximum sending rate of a flow. When suffixed with K, M, or G, the
specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base
of 1000. Defaults to unset and kernel's default is used.
Buckets=
Specifies the size of the hash table used for flow lookups. Defaults to unset and
kernel's default is used.
OrphanMask=
Takes an unsigned integer. For packets not owned by a socket, fq is able to mask a
part of hash and reduce number of buckets associated with the traffic. Defaults to
unset and kernel's default is used.
Pacing=
Takes a boolean, and enables or disables flow pacing. Defaults to unset and kernel's
default is used.
CEThresholdSec=
Takes a timespan. This sets a threshold above which all packets are marked with ECN
Congestion Experienced (CE). Defaults to unset and kernel's default is used.
[TRIVIALLINKEQUALIZER] SECTION OPTIONS
The "[TrivialLinkEqualizer]" section manages the queueing discipline (qdisc) of trivial
link equalizer (teql).
Parent=
Specifies the parent Queueing Discipline (qdisc). Takes one of "root", "clsact" or
"ingress". Defaults to "root".
Handle=
Specifies the major number of unique identifier of the qdisc, known as the handle.
Takes a number in hexadecimal ranges 1 to ffff. Defaults to unset.
Id=
Specifies the interface ID "N" of teql. Defaults to "0". Note that when teql is used,
currently, the module sch_teql with max_equalizers=N+1 option must be loaded before
systemd-networkd is started.
[BRIDGEVLAN] SECTION OPTIONS
The "[BridgeVLAN]" section manages the VLAN ID configuration of a bridge port and accepts
the following keys. Specify several "[BridgeVLAN]" sections to configure several VLAN
entries. The VLANFiltering= option has to be enabled, see "[Bridge]" section in
systemd.netdev(5).
VLAN=
The VLAN ID allowed on the port. This can be either a single ID or a range M-N. VLAN
IDs are valid from 1 to 4094.
EgressUntagged=
The VLAN ID specified here will be used to untag frames on egress. Configuring
EgressUntagged= implicates the use of VLAN= above and will enable the VLAN ID for
ingress as well. This can be either a single ID or a range M-N.
PVID=
The Port VLAN ID specified here is assigned to all untagged frames at ingress. PVID=
can be used only once. Configuring PVID= implicates the use of VLAN= above and will
enable the VLAN ID for ingress as well.
EXAMPLES
Example 1. Static network configuration
# /etc/systemd/network/50-static.network
[Match]
Name=enp2s0
[Network]
Address=192.168.0.15/24
Gateway=192.168.0.1
This brings interface "enp2s0" up with a static address. The specified gateway will be
used for a default route.
Example 2. DHCP on ethernet links
# /etc/systemd/network/80-dhcp.network
[Match]
Name=en*
[Network]
DHCP=yes
This will enable DHCPv4 and DHCPv6 on all interfaces with names starting with "en" (i.e.
ethernet interfaces).
Example 3. IPv6 Prefix Delegation
# /etc/systemd/network/55-ipv6-pd-upstream.network
[Match]
Name=enp1s0
[Network]
DHCP=ipv6
# /etc/systemd/network/56-ipv6-pd-downstream.network
[Match]
Name=enp2s0
[Network]
IPv6PrefixDelegation=dhcpv6
This will enable IPv6 PD on the interface enp1s0 as an upstream interface where the DHCPv6
client is running and enp2s0 as a downstream interface where the prefix is delegated to.
Example 4. A bridge with two enslaved links
# /etc/systemd/network/25-bridge-static.network
[Match]
Name=bridge0
[Network]
Address=192.168.0.15/24
Gateway=192.168.0.1
DNS=192.168.0.1
# /etc/systemd/network/25-bridge-slave-interface-1.network
[Match]
Name=enp2s0
[Network]
Bridge=bridge0
# /etc/systemd/network/25-bridge-slave-interface-2.network
[Match]
Name=wlp3s0
[Network]
Bridge=bridge0
This creates a bridge and attaches devices "enp2s0" and "wlp3s0" to it. The bridge will
have the specified static address and network assigned, and a default route via the
specified gateway will be added. The specified DNS server will be added to the global list
of DNS resolvers.
Example 5.
# /etc/systemd/network/20-bridge-slave-interface-vlan.network
[Match]
Name=enp2s0
[Network]
Bridge=bridge0
[BridgeVLAN]
VLAN=1-32
PVID=42
EgressUntagged=42
[BridgeVLAN]
VLAN=100-200
[BridgeVLAN]
EgressUntagged=300-400
This overrides the configuration specified in the previous example for the interface
"enp2s0", and enables VLAN on that bridge port. VLAN IDs 1-32, 42, 100-400 will be
allowed. Packets tagged with VLAN IDs 42, 300-400 will be untagged when they leave on this
interface. Untagged packets which arrive on this interface will be assigned VLAN ID 42.
Example 6. Various tunnels
/etc/systemd/network/25-tunnels.network
[Match]
Name=ens1
[Network]
Tunnel=ipip-tun
Tunnel=sit-tun
Tunnel=gre-tun
Tunnel=vti-tun
/etc/systemd/network/25-tunnel-ipip.netdev
[NetDev]
Name=ipip-tun
Kind=ipip
/etc/systemd/network/25-tunnel-sit.netdev
[NetDev]
Name=sit-tun
Kind=sit
/etc/systemd/network/25-tunnel-gre.netdev
[NetDev]
Name=gre-tun
Kind=gre
/etc/systemd/network/25-tunnel-vti.netdev
[NetDev]
Name=vti-tun
Kind=vti
This will bring interface "ens1" up and create an IPIP tunnel, a SIT tunnel, a GRE tunnel,
and a VTI tunnel using it.
Example 7. A bond device
# /etc/systemd/network/30-bond1.network
[Match]
Name=bond1
[Network]
DHCP=ipv6
# /etc/systemd/network/30-bond1.netdev
[NetDev]
Name=bond1
Kind=bond
# /etc/systemd/network/30-bond1-dev1.network
[Match]
MACAddress=52:54:00:e9:64:41
[Network]
Bond=bond1
# /etc/systemd/network/30-bond1-dev2.network
[Match]
MACAddress=52:54:00:e9:64:42
[Network]
Bond=bond1
This will create a bond device "bond1" and enslave the two devices with MAC addresses
52:54:00:e9:64:41 and 52:54:00:e9:64:42 to it. IPv6 DHCP will be used to acquire an
address.
Example 8. Virtual Routing and Forwarding (VRF)
Add the "bond1" interface to the VRF master interface "vrf1". This will redirect routes
generated on this interface to be within the routing table defined during VRF creation.
For kernels before 4.8 traffic won't be redirected towards the VRFs routing table unless
specific ip-rules are added.
# /etc/systemd/network/25-vrf.network
[Match]
Name=bond1
[Network]
VRF=vrf1
Example 9. MacVTap
This brings up a network interface "macvtap-test" and attaches it to "enp0s25".
# /lib/systemd/network/25-macvtap.network
[Match]
Name=enp0s25
[Network]
MACVTAP=macvtap-test
Example 10. A Xfrm interface with physical underlying device.
# /etc/systemd/network/27-xfrm.netdev
[NetDev]
Name=xfrm0
[Xfrm]
InterfaceId=7
# /etc/systemd/network/27-eth0.network
[Match]
Name=eth0
[Network]
Xfrm=xfrm0
This creates a "xfrm0" interface and binds it to the "eth0" device. This allows hardware
based ipsec offloading to the "eth0" nic. If offloading is not needed, xfrm interfaces can
be assigned to the "lo" device.
SEE ALSO
systemd(1), systemd-networkd.service(8), systemd.link(5), systemd.netdev(5), systemd-
resolved.service(8)
NOTES
1. RFC 7217
https://tools.ietf.org/html/rfc7217
2. Link-Local Multicast Name Resolution
https://tools.ietf.org/html/rfc4795
3. Multicast DNS
https://tools.ietf.org/html/rfc6762
4. DNS-over-TLS
https://tools.ietf.org/html/rfc7858
5. DNSSEC
https://tools.ietf.org/html/rfc4033
6. IEEE 802.1AB-2016
https://standards.ieee.org/findstds/standard/802.1AB-2016.html
7. ip-sysctl.txt
https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt
8. RFC 4941
https://tools.ietf.org/html/rfc4941
9. RFC 1027
https://tools.ietf.org/html/rfc1027
10. RFC 6275
https://tools.ietf.org/html/rfc6275
11. RFC 5224
https://tools.ietf.org/html/rfc5227
12. RFC 4862
https://tools.ietf.org/html/rfc4862
13. RFC 3041
https://tools.ietf.org/html/rfc3041
14. RFC 3484
https://tools.ietf.org/html/rfc3484
15. RFC4191
https://tools.ietf.org/html/rfc4191
16. RFC 7844
https://tools.ietf.org/html/rfc7844
17. C-style escapes
https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences
18. RFC 3315
https://tools.ietf.org/html/rfc3315#section-17.2.1
19. RFC 7084
https://tools.ietf.org/html/rfc7084
20. RFC 4861
https://tools.ietf.org/html/rfc4861