Provided by: systemd_245.4-4ubuntu3.24_amd64 
NAME
systemd.netdev - Virtual Network Device configuration
SYNOPSIS
netdev.netdev
DESCRIPTION
A plain ini-style text file that encodes configuration about a virtual network device,
used by systemd-networkd(8). See systemd.syntax(7) for a general description of the
syntax.
The main Virtual Network Device file must have the extension .netdev; other extensions are
ignored. Virtual network devices are created as soon as networkd is started. If a netdev
with the specified name already exists, networkd will use that as-is rather than create
its own. Note that the settings of the pre-existing netdev will not be changed by
networkd.
The .netdev files are read from the files located in the system network directory
/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 in /lib.
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 netdev file foo.netdev, a "drop-in" directory foo.netdev.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 netdev file wherever
located. (Of course, since /run is temporary and /usr/lib is for vendors, it is unlikely
drop-ins should be used in either of those places.)
SUPPORTED NETDEV KINDS
The following kinds of virtual network devices may be configured in .netdev files:
Table 1. Supported kinds of virtual network devices
┌──────────┬──────────────────────────────────┐
│Kind │ Description │
├──────────┼──────────────────────────────────┤
│bond │ A bond device is an aggregation │
│ │ of all its slave devices. See │
│ │ Linux Ethernet Bonding Driver │
│ │ HOWTO[1] for details.Local │
│ │ configuration │
├──────────┼──────────────────────────────────┤
│bridge │ A bridge device is a software │
│ │ switch, and each of its slave │
│ │ devices and the bridge itself │
│ │ are ports of the switch. │
├──────────┼──────────────────────────────────┤
│dummy │ A dummy device drops all packets │
│ │ sent to it. │
├──────────┼──────────────────────────────────┤
│gre │ A Level 3 GRE tunnel over IPv4. │
│ │ See RFC 2784[2] for details. │
├──────────┼──────────────────────────────────┤
│gretap │ A Level 2 GRE tunnel over IPv4. │
├──────────┼──────────────────────────────────┤
│erspan │ ERSPAN mirrors traffic on one or │
│ │ more source ports and delivers │
│ │ the mirrored traffic to one or │
│ │ more destination ports on │
│ │ another switch. The traffic is │
│ │ encapsulated in generic routing │
│ │ encapsulation (GRE) and is │
│ │ therefore routable across a │
│ │ layer 3 network between the │
│ │ source switch and the │
│ │ destination switch. │
├──────────┼──────────────────────────────────┤
│ip6gre │ A Level 3 GRE tunnel over IPv6. │
├──────────┼──────────────────────────────────┤
│ip6tnl │ An IPv4 or IPv6 tunnel over IPv6 │
├──────────┼──────────────────────────────────┤
│ip6gretap │ A Level 2 GRE tunnel over IPv6. │
├──────────┼──────────────────────────────────┤
│ipip │ An IPv4 over IPv4 tunnel. │
├──────────┼──────────────────────────────────┤
│ipvlan │ An ipvlan device is a stacked │
│ │ device which receives packets │
│ │ from its underlying device based │
│ │ on IP address filtering. │
├──────────┼──────────────────────────────────┤
│ipvtap │ An ipvtap device is a stacked │
│ │ device which receives packets │
│ │ from its underlying device based │
│ │ on IP address filtering and can │
│ │ be accessed using the tap user │
│ │ space interface. │
├──────────┼──────────────────────────────────┤
│macvlan │ A macvlan device is a stacked │
│ │ device which receives packets │
│ │ from its underlying device based │
│ │ on MAC address filtering. │
├──────────┼──────────────────────────────────┤
│macvtap │ A macvtap device is a stacked │
│ │ device which receives packets │
│ │ from its underlying device based │
│ │ on MAC address filtering. │
├──────────┼──────────────────────────────────┤
│sit │ An IPv6 over IPv4 tunnel. │
├──────────┼──────────────────────────────────┤
│tap │ A persistent Level 2 tunnel │
│ │ between a network device and a │
│ │ device node. │
├──────────┼──────────────────────────────────┤
│tun │ A persistent Level 3 tunnel │
│ │ between a network device and a │
│ │ device node. │
├──────────┼──────────────────────────────────┤
│veth │ An Ethernet tunnel between a │
│ │ pair of network devices. │
├──────────┼──────────────────────────────────┤
│vlan │ A VLAN is a stacked device which │
│ │ receives packets from its │
│ │ underlying device based on VLAN │
│ │ tagging. See IEEE 802.1Q[3] for │
│ │ details. │
├──────────┼──────────────────────────────────┤
│vti │ An IPv4 over IPSec tunnel. │
├──────────┼──────────────────────────────────┤
│vti6 │ An IPv6 over IPSec tunnel. │
├──────────┼──────────────────────────────────┤
│vxlan │ A virtual extensible LAN │
│ │ (vxlan), for connecting Cloud │
│ │ computing deployments. │
├──────────┼──────────────────────────────────┤
│geneve │ A GEneric NEtwork Virtualization │
│ │ Encapsulation (GENEVE) netdev │
│ │ driver. │
├──────────┼──────────────────────────────────┤
│l2tp │ A Layer 2 Tunneling Protocol │
│ │ (L2TP) is a tunneling protocol │
│ │ used to support virtual private │
│ │ networks (VPNs) or as part of │
│ │ the delivery of services by │
│ │ ISPs. It does not provide any │
│ │ encryption or confidentiality by │
│ │ itself │
├──────────┼──────────────────────────────────┤
│macsec │ Media Access Control Security │
│ │ (MACsec) is an 802.1AE IEEE │
│ │ industry-standard security │
│ │ technology that provides secure │
│ │ communication for all traffic on │
│ │ Ethernet links. MACsec provides │
│ │ point-to-point security on │
│ │ Ethernet links between directly │
│ │ connected nodes and is capable │
│ │ of identifying and preventing │
│ │ most security threats. │
├──────────┼──────────────────────────────────┤
│vrf │ A Virtual Routing and Forwarding │
│ │ (VRF[4]) interface to create │
│ │ separate routing and forwarding │
│ │ domains. │
├──────────┼──────────────────────────────────┤
│vcan │ The virtual CAN driver (vcan). │
│ │ Similar to the network loopback │
│ │ devices, vcan offers a virtual │
│ │ local CAN interface. │
├──────────┼──────────────────────────────────┤
│vxcan │ The virtual CAN tunnel driver │
│ │ (vxcan). Similar to the virtual │
│ │ ethernet driver veth, vxcan │
│ │ implements a local CAN traffic │
│ │ tunnel between two virtual CAN │
│ │ network devices. When creating a │
│ │ vxcan, two vxcan devices are │
│ │ created as pair. When one end │
│ │ receives the packet it appears │
│ │ on its pair and vice versa. The │
│ │ vxcan can be used for cross │
│ │ namespace communication. │
├──────────┼──────────────────────────────────┤
│wireguard │ WireGuard Secure Network Tunnel. │
├──────────┼──────────────────────────────────┤
│netdevsim │ A simulator. This simulated │
│ │ networking device is used for │
│ │ testing various networking APIs │
│ │ and at this time is particularly │
│ │ focused on testing hardware │
│ │ offloading related interfaces. │
├──────────┼──────────────────────────────────┤
│nlmon │ A Netlink monitor device. Use an │
│ │ nlmon device when you want to │
│ │ monitor system Netlink messages. │
├──────────┼──────────────────────────────────┤
│fou │ Foo-over-UDP tunneling. │
├──────────┼──────────────────────────────────┤
│xfrm │ A virtual tunnel interface like │
│ │ vti/vti6 but with several │
│ │ advantages. │
├──────────┼──────────────────────────────────┤
│ifb │ The Intermediate Functional │
│ │ Block (ifb) pseudo network │
│ │ interface acts as a QoS │
│ │ concentrator for multiple │
│ │ different sources of traffic. │
└──────────┴──────────────────────────────────┘
[MATCH] SECTION OPTIONS
A virtual network device is only created if the "[Match]" section matches the current
environment, or if the section is empty. The following keys are accepted:
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.
[NETDEV] SECTION OPTIONS
The "[NetDev]" section accepts the following keys:
Description=
A free-form description of the netdev.
Name=
The interface name used when creating the netdev. This option is compulsory.
Kind=
The netdev kind. This option is compulsory. See the "Supported netdev kinds" section
for the valid keys.
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. For "tun" or "tap" devices,
MTUBytes= setting is not currently supported in "[NetDev]" section. Please specify it
in "[Link]" section of corresponding systemd.network(5) files.
MACAddress=
The MAC address to use for the device. For "tun" or "tap" devices, setting MACAddress=
in the "[NetDev]" section is not supported. Please specify it in "[Link]" section of
the corresponding systemd.network(5) file. If this option is not set, "vlan" devices
inherit the MAC address of the physical interface. For other kind of netdevs, if this
option is not set, then MAC address is generated based on the interface name and the
machine-id(5).
[BRIDGE] SECTION OPTIONS
The "[Bridge]" section only applies for netdevs of kind "bridge", and accepts the
following keys:
HelloTimeSec=
HelloTimeSec specifies the number of seconds between two hello packets sent out by the
root bridge and the designated bridges. Hello packets are used to communicate
information about the topology throughout the entire bridged local area network.
MaxAgeSec=
MaxAgeSec specifies the number of seconds of maximum message age. If the last seen
(received) hello packet is more than this number of seconds old, the bridge in
question will start the takeover procedure in attempt to become the Root Bridge
itself.
ForwardDelaySec=
ForwardDelaySec specifies the number of seconds spent in each of the Listening and
Learning states before the Forwarding state is entered.
AgeingTimeSec=
This specifies the number of seconds a MAC Address will be kept in the forwarding
database after having a packet received from this MAC Address.
Priority=
The priority of the bridge. An integer between 0 and 65535. A lower value means higher
priority. The bridge having the lowest priority will be elected as root bridge.
GroupForwardMask=
A 16-bit bitmask represented as an integer which allows forwarding of link local
frames with 802.1D reserved addresses (01:80:C2:00:00:0X). A logical AND is performed
between the specified bitmask and the exponentiation of 2^X, the lower nibble of the
last octet of the MAC address. For example, a value of 8 would allow forwarding of
frames addressed to 01:80:C2:00:00:03 (802.1X PAE).
DefaultPVID=
This specifies the default port VLAN ID of a newly attached bridge port. Set this to
an integer in the range 1–4094 or "none" to disable the PVID.
MulticastQuerier=
Takes a boolean. This setting controls the IFLA_BR_MCAST_QUERIER option in the kernel.
If enabled, the kernel will send general ICMP queries from a zero source address. This
feature should allow faster convergence on startup, but it causes some multicast-aware
switches to misbehave and disrupt forwarding of multicast packets. When unset, the
kernel's default will be used.
MulticastSnooping=
Takes a boolean. This setting controls the IFLA_BR_MCAST_SNOOPING option in the
kernel. If enabled, IGMP snooping monitors the Internet Group Management Protocol
(IGMP) traffic between hosts and multicast routers. When unset, the kernel's default
will be used.
VLANFiltering=
Takes a boolean. This setting controls the IFLA_BR_VLAN_FILTERING option in the
kernel. If enabled, the bridge will be started in VLAN-filtering mode. When unset, the
kernel's default will be used.
STP=
Takes a boolean. This enables the bridge's Spanning Tree Protocol (STP). When unset,
the kernel's default will be used.
MulticastIGMPVersion=
Allows changing bridge's multicast Internet Group Management Protocol (IGMP) version.
Takes an integer 2 or 3. When unset, the kernel's default will be used.
[VLAN] SECTION OPTIONS
The "[VLAN]" section only applies for netdevs of kind "vlan", and accepts the following
key:
Id=
The VLAN ID to use. An integer in the range 0–4094. This option is compulsory.
GVRP=
Takes a boolean. The Generic VLAN Registration Protocol (GVRP) is a protocol that
allows automatic learning of VLANs on a network. When unset, the kernel's default will
be used.
MVRP=
Takes a boolean. Multiple VLAN Registration Protocol (MVRP) formerly known as GARP
VLAN Registration Protocol (GVRP) is a standards-based Layer 2 network protocol, for
automatic configuration of VLAN information on switches. It was defined in the 802.1ak
amendment to 802.1Q-2005. When unset, the kernel's default will be used.
LooseBinding=
Takes a boolean. The VLAN loose binding mode, in which only the operational state is
passed from the parent to the associated VLANs, but the VLAN device state is not
changed. When unset, the kernel's default will be used.
ReorderHeader=
Takes a boolean. The VLAN reorder header is set VLAN interfaces behave like physical
interfaces. When unset, the kernel's default will be used.
[MACVLAN] SECTION OPTIONS
The "[MACVLAN]" section only applies for netdevs of kind "macvlan", and accepts the
following key:
Mode=
The MACVLAN mode to use. The supported options are "private", "vepa", "bridge", and
"passthru".
[MACVTAP] SECTION OPTIONS
The "[MACVTAP]" section applies for netdevs of kind "macvtap" and accepts the same key as
"[MACVLAN]".
[IPVLAN] SECTION OPTIONS
The "[IPVLAN]" section only applies for netdevs of kind "ipvlan", and accepts the
following key:
Mode=
The IPVLAN mode to use. The supported options are "L2","L3" and "L3S".
Flags=
The IPVLAN flags to use. The supported options are "bridge","private" and "vepa".
[IPVTAP] SECTION OPTIONS
The "[IPVTAP]" section only applies for netdevs of kind "ipvtap" and accepts the same key
as "[IPVLAN]".
[VXLAN] SECTION OPTIONS
The "[VXLAN]" section only applies for netdevs of kind "vxlan", and accepts the following
keys:
VNI=
The VXLAN Network Identifier (or VXLAN Segment ID). Takes a number in the range
1-16777215.
Remote=
Configures destination IP address.
Local=
Configures local IP address.
Group=
Configures VXLAN multicast group IP address. All members of a VXLAN must use the same
multicast group address.
TOS=
The Type Of Service byte value for a vxlan interface.
TTL=
A fixed Time To Live N on Virtual eXtensible Local Area Network packets. Takes
"inherit" or a number in the range 0–255. 0 is a special value meaning inherit the
inner protocol's TTL value. "inherit" means that it will inherit the outer protocol's
TTL value.
MacLearning=
Takes a boolean. When true, enables dynamic MAC learning to discover remote MAC
addresses.
FDBAgeingSec=
The lifetime of Forwarding Database entry learnt by the kernel, in seconds.
MaximumFDBEntries=
Configures maximum number of FDB entries.
ReduceARPProxy=
Takes a boolean. When true, bridge-connected VXLAN tunnel endpoint answers ARP
requests from the local bridge on behalf of remote Distributed Overlay Virtual
Ethernet (DVOE)[5] clients. Defaults to false.
L2MissNotification=
Takes a boolean. When true, enables netlink LLADDR miss notifications.
L3MissNotification=
Takes a boolean. When true, enables netlink IP address miss notifications.
RouteShortCircuit=
Takes a boolean. When true, route short circuiting is turned on.
UDPChecksum=
Takes a boolean. When true, transmitting UDP checksums when doing VXLAN/IPv4 is turned
on.
UDP6ZeroChecksumTx=
Takes a boolean. When true, sending zero checksums in VXLAN/IPv6 is turned on.
UDP6ZeroChecksumRx=
Takes a boolean. When true, receiving zero checksums in VXLAN/IPv6 is turned on.
RemoteChecksumTx=
Takes a boolean. When true, remote transmit checksum offload of VXLAN is turned on.
RemoteChecksumRx=
Takes a boolean. When true, remote receive checksum offload in VXLAN is turned on.
GroupPolicyExtension=
Takes a boolean. When true, it enables Group Policy VXLAN extension security label
mechanism across network peers based on VXLAN. For details about the Group Policy
VXLAN, see the VXLAN Group Policy[6] document. Defaults to false.
GenericProtocolExtension=
Takes a boolean. When true, Generic Protocol Extension extends the existing VXLAN
protocol to provide protocol typing, OAM, and versioning capabilities. For details
about the VXLAN GPE Header, see the Generic Protocol Extension for VXLAN[7] document.
If destination port is not specified and Generic Protocol Extension is set then
default port of 4790 is used. Defaults to false.
DestinationPort=
Configures the default destination UDP port on a per-device basis. If destination port
is not specified then Linux kernel default will be used. Set destination port 4789 to
get the IANA assigned value. If not set or if the destination port is assigned the
empty string the default port of 4789 is used.
PortRange=
Configures VXLAN port range. VXLAN bases source UDP port based on flow to help the
receiver to be able to load balance based on outer header flow. It restricts the port
range to the normal UDP local ports, and allows overriding via configuration.
FlowLabel=
Specifies the flow label to use in outgoing packets. The valid range is 0-1048575.
IPDoNotFragment=
Allows setting the IPv4 Do not Fragment (DF) bit in outgoing packets, or to inherit
its value from the IPv4 inner header. Takes a boolean value, or "inherit". Set to
"inherit" if the encapsulated protocol is IPv6. When unset, the kernel's default will
be used.
[GENEVE] SECTION OPTIONS
The "[GENEVE]" section only applies for netdevs of kind "geneve", and accepts the
following keys:
Id=
Specifies the Virtual Network Identifier (VNI) to use. Ranges [0-16777215]. This field
is mandatory.
Remote=
Specifies the unicast destination IP address to use in outgoing packets.
TOS=
Specifies the TOS value to use in outgoing packets. Ranges [1-255].
TTL=
Accepts the same key in "[VXLAN]" section except when unset or set to 0, the kernel's
default will be used meaning that packets TTL will be set from
/proc/sys/net/ipv4/ip_default_ttl.
UDPChecksum=
Takes a boolean. When true, specifies if UDP checksum is calculated for transmitted
packets over IPv4.
UDP6ZeroChecksumTx=
Takes a boolean. When true, skip UDP checksum calculation for transmitted packets over
IPv6.
UDP6ZeroChecksumRx=
Takes a boolean. When true, allows incoming UDP packets over IPv6 with zero checksum
field.
DestinationPort=
Specifies destination port. Defaults to 6081. If not set or assigned the empty string,
the default port of 6081 is used.
FlowLabel=
Specifies the flow label to use in outgoing packets.
IPDoNotFragment=
Accepts the same key in "[VXLAN]" section.
[L2TP] SECTION OPTIONS
The "[L2TP]" section only applies for netdevs of kind "l2tp", and accepts the following
keys:
TunnelId=
Specifies the tunnel id. The value used must match the "PeerTunnelId=" value being
used at the peer. Ranges a number between 1 and 4294967295). This option is
compulsory.
PeerTunnelId=
Specifies the peer tunnel id. The value used must match the "PeerTunnelId=" value
being used at the peer. Ranges a number between 1 and 4294967295). This option is
compulsory.
Remote=
Specifies the IP address of the remote peer. This option is compulsory.
Local=
Specifies the IP address of the local interface. Takes an IP address, or the special
values "auto", "static", or "dynamic". When an address is set, then the local
interface must have the address. If "auto", then one of the addresses on the local
interface is used. Similarly, if "static" or "dynamic" is set, then one of the static
or dynamic addresses on the local interface is used. Defaults to "auto".
EncapsulationType=
Specifies the encapsulation type of the tunnel. Takes one of "udp" or "ip".
UDPSourcePort=
Specifies the UDP source port to be used for the tunnel. When UDP encapsulation is
selected it's mandotory. Ignored when ip encapsulation is selected.
UDPDestinationPort=
Specifies destination port. When UDP encapsulation is selected it's mandotory. Ignored
when ip encapsulation is selected.
UDPChecksum=
Takes a boolean. When true, specifies if UDP checksum is calculated for transmitted
packets over IPv4.
UDP6ZeroChecksumTx=
Takes a boolean. When true, skip UDP checksum calculation for transmitted packets over
IPv6.
UDP6ZeroChecksumRx=
Takes a boolean. When true, allows incoming UDP packets over IPv6 with zero checksum
field.
[L2TPSESSION] SECTION OPTIONS
The "[L2TPSession]" section only applies for netdevs of kind "l2tp", and accepts the
following keys:
Name=
Specifies the name of the session. This option is compulsory.
SessionId=
Specifies the session id. The value used must match the "SessionId=" value being used
at the peer. Ranges a number between 1 and 4294967295). This option is compulsory.
PeerSessionId=
Specifies the peer session id. The value used must match the "PeerSessionId=" value
being used at the peer. Ranges a number between 1 and 4294967295). This option is
compulsory.
Layer2SpecificHeader=
Specifies layer2specific header type of the session. One of "none" or "default".
Defaults to "default".
[MACSEC] SECTION OPTIONS
The "[MACsec]" section only applies for network devices of kind "macsec", and accepts the
following keys:
Port=
Specifies the port to be used for the MACsec transmit channel. The port is used to
make secure channel identifier (SCI). Takes a value between 1 and 65535. Defaults to
unset.
Encrypt=
Takes a boolean. When true, enable encryption. Defaults to unset.
[MACSECRECEIVECHANNEL] SECTION OPTIONS
The "[MACsecReceiveChannel]" section only applies for network devices of kind "macsec",
and accepts the following keys:
Port=
Specifies the port to be used for the MACsec receive channel. The port is used to make
secure channel identifier (SCI). Takes a value between 1 and 65535. This option is
compulsory, and is not set by default.
MACAddress=
Specifies the MAC address to be used for the MACsec receive channel. The MAC address
used to make secure channel identifier (SCI). This option is compulsory, and is not
set by default.
[MACSECTRANSMITASSOCIATION] SECTION OPTIONS
The "[MACsecTransmitAssociation]" section only applies for network devices of kind
"macsec", and accepts the following keys:
PacketNumber=
Specifies the packet number to be used for replay protection and the construction of
the initialization vector (along with the secure channel identifier [SCI]). Takes a
value between 1-4,294,967,295. Defaults to unset.
KeyId=
Specifies the identification for the key. Takes a number between 0-255. This option is
compulsory, and is not set by default.
Key=
Specifies the encryption key used in the transmission channel. The same key must be
configured on the peer’s matching receive channel. This option is compulsory, and is
not set by default. Takes a 128-bit key encoded in a hexadecimal string, for example
"dffafc8d7b9a43d5b9a3dfbbf6a30c16".
KeyFile=
Takes a absolute path to a file which contains a 128-bit key encoded in a hexadecimal
string, which will be used in the transmission channel. When this option is specified,
Key= is ignored. Note that the file must be readable by the user "systemd-network", so
it should be, e.g., owned by "root:systemd-network" with a "0640" file mode.
Activate=
Takes a boolean. If enabled, then the security association is activated. Defaults to
unset.
UseForEncoding=
Takes a boolean. If enabled, then the security association is used for encoding. Only
one "[MACsecTransmitAssociation]" section can enable this option. When enabled,
Activate=yes is implied. Defaults to unset.
[MACSECRECEIVEASSOCIATION] SECTION OPTIONS
The "[MACsecReceiveAssociation]" section only applies for network devices of kind
"macsec", and accepts the following keys:
Port=
Accepts the same key in "[MACsecReceiveChannel]" section.
MACAddress=
Accepts the same key in "[MACsecReceiveChannel]" section.
PacketNumber=
Accepts the same key in "[MACsecTransmitAssociation]" section.
KeyId=
Accepts the same key in "[MACsecTransmitAssociation]" section.
Key=
Accepts the same key in "[MACsecTransmitAssociation]" section.
KeyFile=
Accepts the same key in "[MACsecTransmitAssociation]" section.
Activate=
Accepts the same key in "[MACsecTransmitAssociation]" section.
[TUNNEL] SECTION OPTIONS
The "[Tunnel]" section only applies for netdevs of kind "ipip", "sit", "gre", "gretap",
"ip6gre", "ip6gretap", "vti", "vti6", "ip6tnl", and "erspan" and accepts the following
keys:
Local=
A static local address for tunneled packets. It must be an address on another
interface of this host, or the special value "any".
Remote=
The remote endpoint of the tunnel. Takes an IP address or the special value "any".
TOS=
The Type Of Service byte value for a tunnel interface. For details about the TOS, see
the Type of Service in the Internet Protocol Suite[8] document.
TTL=
A fixed Time To Live N on tunneled packets. N is a number in the range 1–255. 0 is a
special value meaning that packets inherit the TTL value. The default value for IPv4
tunnels is: inherit. The default value for IPv6 tunnels is 64.
DiscoverPathMTU=
Takes a boolean. When true, enables Path MTU Discovery on the tunnel.
IPv6FlowLabel=
Configures the 20-bit flow label (see RFC 6437[9]) field in the IPv6 header (see RFC
2460[10]), which is used by a node to label packets of a flow. It is only used for
IPv6 tunnels. A flow label of zero is used to indicate packets that have not been
labeled. It can be configured to a value in the range 0–0xFFFFF, or be set to
"inherit", in which case the original flowlabel is used.
CopyDSCP=
Takes a boolean. When true, the Differentiated Service Code Point (DSCP) field will be
copied to the inner header from outer header during the decapsulation of an IPv6
tunnel packet. DSCP is a field in an IP packet that enables different levels of
service to be assigned to network traffic. Defaults to "no".
EncapsulationLimit=
The Tunnel Encapsulation Limit option specifies how many additional levels of
encapsulation are permitted to be prepended to the packet. For example, a Tunnel
Encapsulation Limit option containing a limit value of zero means that a packet
carrying that option may not enter another tunnel before exiting the current tunnel.
(see RFC 2473[11]). The valid range is 0–255 and "none". Defaults to 4.
Key=
The Key= parameter specifies the same key to use in both directions (InputKey= and
OutputKey=). The Key= is either a number or an IPv4 address-like dotted quad. It is
used as mark-configured SAD/SPD entry as part of the lookup key (both in data and
control path) in ip xfrm (framework used to implement IPsec protocol). See ip-xfrm —
transform configuration[12] for details. It is only used for VTI/VTI6, GRE, GRETAP,
and ERSPAN tunnels.
InputKey=
The InputKey= parameter specifies the key to use for input. The format is same as
Key=. It is only used for VTI/VTI6, GRE, GRETAP, and ERSPAN tunnels.
OutputKey=
The OutputKey= parameter specifies the key to use for output. The format is same as
Key=. It is only used for VTI/VTI6, GRE, GRETAP, and ERSPAN tunnels.
Mode=
An "ip6tnl" tunnel can be in one of three modes "ip6ip6" for IPv6 over IPv6, "ipip6"
for IPv4 over IPv6 or "any" for either.
Independent=
Takes a boolean. When true tunnel does not require .network file. Created as
"tunnel@NONE". Defaults to "false".
AssignToLoopback=
Takes a boolean. If set to "yes", the loopback interface "lo" is used as the
underlying device of the tunnel interface. Defaults to "no".
AllowLocalRemote=
Takes a boolean. When true allows tunnel traffic on ip6tnl devices where the remote
endpoint is a local host address. When unset, the kernel's default will be used.
FooOverUDP=
Takes a boolean. Specifies whether FooOverUDP= tunnel is to be configured. Defaults to
false. This takes effects only for IPIP, SIT, GRE, and GRETAP tunnels. For more detail
information see Foo over UDP[13]
FOUDestinationPort=
This setting specifies the UDP destination port for encapsulation. This field is
mandatory when FooOverUDP=yes, and is not set by default.
FOUSourcePort=
This setting specifies the UDP source port for encapsulation. Defaults to 0 — that is,
the source port for packets is left to the network stack to decide.
Encapsulation=
Accepts the same key as in the "[FooOverUDP]" section.
IPv6RapidDeploymentPrefix=
Reconfigure the tunnel for IPv6 Rapid Deployment[14], also known as 6rd. The value is
an ISP-specific IPv6 prefix with a non-zero length. Only applicable to SIT tunnels.
ISATAP=
Takes a boolean. If set, configures the tunnel as Intra-Site Automatic Tunnel
Addressing Protocol (ISATAP) tunnel. Only applicable to SIT tunnels. When unset, the
kernel's default will be used.
SerializeTunneledPackets=
Takes a boolean. If set to yes, then packets are serialized. Only applies for GRE,
GRETAP, and ERSPAN tunnels. When unset, the kernel's default will be used.
ERSPANIndex=
Specifies the ERSPAN index field for the interface, an integer in the range 1-1048575
associated with the ERSPAN traffic's source port and direction. This field is
mandatory.
[FOOOVERUDP] SECTION OPTIONS
The "[FooOverUDP]" section only applies for netdevs of kind "fou" and accepts the
following keys:
Encapsulation=
Specifies the encapsulation mechanism used to store networking packets of various
protocols inside the UDP packets. Supports the following values: "FooOverUDP" provides
the simplest no frills model of UDP encapsulation, it simply encapsulates packets
directly in the UDP payload. "GenericUDPEncapsulation" is a generic and extensible
encapsulation, it allows encapsulation of packets for any IP protocol and optional
data as part of the encapsulation. For more detailed information see Generic UDP
Encapsulation[15]. Defaults to "FooOverUDP".
Port=
Specifies the port number, where the IP encapsulation packets will arrive. Please take
note that the packets will arrive with the encapsulation will be removed. Then they
will be manually fed back into the network stack, and sent ahead for delivery to the
real destination. This option is mandatory.
PeerPort=
Specifies the peer port number. Defaults to unset. Note that when peer port is set
"Peer=" address is mandotory.
Protocol=
The Protocol= specifies the protocol number of the packets arriving at the UDP port.
When Encapsulation=FooOverUDP, this field is mandatory and is not set by default.
Takes an IP protocol name such as "gre" or "ipip", or an integer within the range
1-255. When Encapsulation=GenericUDPEncapsulation, this must not be specified.
Peer=
Configures peer IP address. Note that when peer address is set "PeerPort=" is
mandotory.
Local=
Configures local IP address.
[PEER] SECTION OPTIONS
The "[Peer]" section only applies for netdevs of kind "veth" and accepts the following
keys:
Name=
The interface name used when creating the netdev. This option is compulsory.
MACAddress=
The peer MACAddress, if not set, it is generated in the same way as the MAC address of
the main interface.
[VXCAN] SECTION OPTIONS
The "[VXCAN]" section only applies for netdevs of kind "vxcan" and accepts the following
key:
Peer=
The peer interface name used when creating the netdev. This option is compulsory.
[TUN] SECTION OPTIONS
The "[Tun]" section only applies for netdevs of kind "tun", and accepts the following
keys:
MultiQueue=
Takes a boolean. Configures whether to use multiple file descriptors (queues) to
parallelize packets sending and receiving. Defaults to "no".
PacketInfo=
Takes a boolean. Configures whether packets should be prepended with four extra bytes
(two flag bytes and two protocol bytes). If disabled, it indicates that the packets
will be pure IP packets. Defaults to "no".
VNetHeader=
Takes a boolean. Configures IFF_VNET_HDR flag for a tun or tap device. It allows
sending and receiving larger Generic Segmentation Offload (GSO) packets. This may
increase throughput significantly. Defaults to "no".
User=
User to grant access to the /dev/net/tun device.
Group=
Group to grant access to the /dev/net/tun device.
[TAP] SECTION OPTIONS
The "[Tap]" section only applies for netdevs of kind "tap", and accepts the same keys as
the "[Tun]" section.
[WIREGUARD] SECTION OPTIONS
The "[WireGuard]" section accepts the following keys:
PrivateKey=
The Base64 encoded private key for the interface. It can be generated using the wg
genkey command (see wg(8)). This option or PrivateKeyFile= is mandatory to use
WireGuard. Note that because this information is secret, you may want to set the
permissions of the .netdev file to be owned by "root:systemd-network" with a "0640"
file mode.
PrivateKeyFile=
Takes an absolute path to a file which contains the Base64 encoded private key for the
interface. When this option is specified, then PrivateKey= is ignored. Note that the
file must be readable by the user "systemd-network", so it should be, e.g., owned by
"root:systemd-network" with a "0640" file mode.
ListenPort=
Sets UDP port for listening. Takes either value between 1 and 65535 or "auto". If
"auto" is specified, the port is automatically generated based on interface name.
Defaults to "auto".
FirewallMark=
Sets a firewall mark on outgoing WireGuard packets from this interface. Takes a number
between 1 and 4294967295.
[WIREGUARDPEER] SECTION OPTIONS
The "[WireGuardPeer]" section accepts the following keys:
PublicKey=
Sets a Base64 encoded public key calculated by wg pubkey (see wg(8)) from a private
key, and usually transmitted out of band to the author of the configuration file. This
option is mandatory for this section.
PresharedKey=
Optional preshared key for the interface. It can be generated by the wg genpsk
command. This option adds an additional layer of symmetric-key cryptography to be
mixed into the already existing public-key cryptography, for post-quantum resistance.
Note that because this information is secret, you may want to set the permissions of
the .netdev file to be owned by "root:systemd-networkd" with a "0640" file mode.
PresharedKeyFile=
Takes an absolute path to a file which contains the Base64 encoded preshared key for
the peer. When this option is specified, then PresharedKey= is ignored. Note that the
file must be readable by the user "systemd-network", so it should be, e.g., owned by
"root:systemd-network" with a "0640" file mode.
AllowedIPs=
Sets a comma-separated list of IP (v4 or v6) addresses with CIDR masks from which this
peer is allowed to send incoming traffic and to which outgoing traffic for this peer
is directed. The catch-all 0.0.0.0/0 may be specified for matching all IPv4 addresses,
and ::/0 may be specified for matching all IPv6 addresses.
Endpoint=
Sets an endpoint IP address or hostname, followed by a colon, and then a port number.
This endpoint will be updated automatically once to the most recent source IP address
and port of correctly authenticated packets from the peer at configuration time.
PersistentKeepalive=
Sets a seconds interval, between 1 and 65535 inclusive, of how often to send an
authenticated empty packet to the peer for the purpose of keeping a stateful firewall
or NAT mapping valid persistently. For example, if the interface very rarely sends
traffic, but it might at anytime receive traffic from a peer, and it is behind NAT,
the interface might benefit from having a persistent keepalive interval of 25 seconds.
If set to 0 or "off", this option is disabled. By default or when unspecified, this
option is off. Most users will not need this.
[BOND] SECTION OPTIONS
The "[Bond]" section accepts the following key:
Mode=
Specifies one of the bonding policies. The default is "balance-rr" (round robin).
Possible values are "balance-rr", "active-backup", "balance-xor", "broadcast",
"802.3ad", "balance-tlb", and "balance-alb".
TransmitHashPolicy=
Selects the transmit hash policy to use for slave selection in balance-xor, 802.3ad,
and tlb modes. Possible values are "layer2", "layer3+4", "layer2+3", "encap2+3", and
"encap3+4".
LACPTransmitRate=
Specifies the rate with which link partner transmits Link Aggregation Control Protocol
Data Unit packets in 802.3ad mode. Possible values are "slow", which requests partner
to transmit LACPDUs every 30 seconds, and "fast", which requests partner to transmit
LACPDUs every second. The default value is "slow".
MIIMonitorSec=
Specifies the frequency that Media Independent Interface link monitoring will occur. A
value of zero disables MII link monitoring. This value is rounded down to the nearest
millisecond. The default value is 0.
UpDelaySec=
Specifies the delay before a link is enabled after a link up status has been detected.
This value is rounded down to a multiple of MIIMonitorSec. The default value is 0.
DownDelaySec=
Specifies the delay before a link is disabled after a link down status has been
detected. This value is rounded down to a multiple of MIIMonitorSec. The default value
is 0.
LearnPacketIntervalSec=
Specifies the number of seconds between instances where the bonding driver sends
learning packets to each slave peer switch. The valid range is 1–0x7fffffff; the
default value is 1. This option has an effect only for the balance-tlb and balance-alb
modes.
AdSelect=
Specifies the 802.3ad aggregation selection logic to use. Possible values are
"stable", "bandwidth" and "count".
AdActorSystemPriority=
Specifies the 802.3ad actor system priority. Ranges [1-65535].
AdUserPortKey=
Specifies the 802.3ad user defined portion of the port key. Ranges [0-1023].
AdActorSystem=
Specifies the 802.3ad system mac address. This can not be either NULL or Multicast.
FailOverMACPolicy=
Specifies whether the active-backup mode should set all slaves to the same MAC address
at the time of enslavement or, when enabled, to perform special handling of the bond's
MAC address in accordance with the selected policy. The default policy is none.
Possible values are "none", "active" and "follow".
ARPValidate=
Specifies whether or not ARP probes and replies should be validated in any mode that
supports ARP monitoring, or whether non-ARP traffic should be filtered (disregarded)
for link monitoring purposes. Possible values are "none", "active", "backup" and
"all".
ARPIntervalSec=
Specifies the ARP link monitoring frequency. A value of 0 disables ARP monitoring. The
default value is 0, and the default unit seconds.
ARPIPTargets=
Specifies the IP addresses to use as ARP monitoring peers when ARPIntervalSec is
greater than 0. These are the targets of the ARP request sent to determine the health
of the link to the targets. Specify these values in IPv4 dotted decimal format. At
least one IP address must be given for ARP monitoring to function. The maximum number
of targets that can be specified is 16. The default value is no IP addresses.
ARPAllTargets=
Specifies the quantity of ARPIPTargets that must be reachable in order for the ARP
monitor to consider a slave as being up. This option affects only active-backup mode
for slaves with ARPValidate enabled. Possible values are "any" and "all".
PrimaryReselectPolicy=
Specifies the reselection policy for the primary slave. This affects how the primary
slave is chosen to become the active slave when failure of the active slave or
recovery of the primary slave occurs. This option is designed to prevent flip-flopping
between the primary slave and other slaves. Possible values are "always", "better" and
"failure".
ResendIGMP=
Specifies the number of IGMP membership reports to be issued after a failover event.
One membership report is issued immediately after the failover, subsequent packets are
sent in each 200ms interval. The valid range is 0–255. Defaults to 1. A value of 0
prevents the IGMP membership report from being issued in response to the failover
event.
PacketsPerSlave=
Specify the number of packets to transmit through a slave before moving to the next
one. When set to 0, then a slave is chosen at random. The valid range is 0–65535.
Defaults to 1. This option only has effect when in balance-rr mode.
GratuitousARP=
Specify the number of peer notifications (gratuitous ARPs and unsolicited IPv6
Neighbor Advertisements) to be issued after a failover event. As soon as the link is
up on the new slave, a peer notification is sent on the bonding device and each VLAN
sub-device. This is repeated at each link monitor interval (ARPIntervalSec or
MIIMonitorSec, whichever is active) if the number is greater than 1. The valid range
is 0–255. The default value is 1. These options affect only the active-backup mode.
AllSlavesActive=
Takes a boolean. Specifies that duplicate frames (received on inactive ports) should
be dropped when false, or delivered when true. Normally, bonding will drop duplicate
frames (received on inactive ports), which is desirable for most users. But there are
some times it is nice to allow duplicate frames to be delivered. The default value is
false (drop duplicate frames received on inactive ports).
DynamicTransmitLoadBalancing=
Takes a boolean. Specifies if dynamic shuffling of flows is enabled. Applies only for
balance-tlb mode. Defaults to unset.
MinLinks=
Specifies the minimum number of links that must be active before asserting carrier.
The default value is 0.
For more detail information see Linux Ethernet Bonding Driver HOWTO[1]
[XFRM] SECTION OPTIONS
The "[Xfrm]" section accepts the following keys:
InterfaceId=
Sets the ID/key of the xfrm interface which needs to be associated with a SA/policy.
Can be decimal or hexadecimal, valid range is 0-0xffffffff, defaults to 0.
Independent=
Takes a boolean. If set to "no", the xfrm interface should have an underlying device
which can be used for hardware offloading. Defaults to "no". See systemd.network(5)
for how to configure the underlying device.
For more detail information see Virtual xfrm interfaces[16]
[VRF] SECTION OPTIONS
The "[VRF]" section only applies for netdevs of kind "vrf" and accepts the following key:
Table=
The numeric routing table identifier. This option is compulsory.
EXAMPLES
Example 1. /etc/systemd/network/25-bridge.netdev
[NetDev]
Name=bridge0
Kind=bridge
Example 2. /etc/systemd/network/25-vlan1.netdev
[Match]
Virtualization=no
[NetDev]
Name=vlan1
Kind=vlan
[VLAN]
Id=1
Example 3. /etc/systemd/network/25-ipip.netdev
[NetDev]
Name=ipip-tun
Kind=ipip
MTUBytes=1480
[Tunnel]
Local=192.168.223.238
Remote=192.169.224.239
TTL=64
Example 4. /etc/systemd/network/1-fou-tunnel.netdev
[NetDev]
Name=fou-tun
Kind=fou
[FooOverUDP]
Port=5555
Protocol=4
Example 5. /etc/systemd/network/25-fou-ipip.netdev
[NetDev]
Name=ipip-tun
Kind=ipip
[Tunnel]
Independent=yes
Local=10.65.208.212
Remote=10.65.208.211
FooOverUDP=yes
FOUDestinationPort=5555
Example 6. /etc/systemd/network/25-tap.netdev
[NetDev]
Name=tap-test
Kind=tap
[Tap]
MultiQueue=yes
PacketInfo=yes
Example 7. /etc/systemd/network/25-sit.netdev
[NetDev]
Name=sit-tun
Kind=sit
MTUBytes=1480
[Tunnel]
Local=10.65.223.238
Remote=10.65.223.239
Example 8. /etc/systemd/network/25-6rd.netdev
[NetDev]
Name=6rd-tun
Kind=sit
MTUBytes=1480
[Tunnel]
Local=10.65.223.238
IPv6RapidDeploymentPrefix=2602::/24
Example 9. /etc/systemd/network/25-gre.netdev
[NetDev]
Name=gre-tun
Kind=gre
MTUBytes=1480
[Tunnel]
Local=10.65.223.238
Remote=10.65.223.239
Example 10. /etc/systemd/network/25-ip6gre.netdev
[NetDev]
Name=ip6gre-tun
Kind=ip6gre
[Tunnel]
Key=123
Example 11. /etc/systemd/network/25-vti.netdev
[NetDev]
Name=vti-tun
Kind=vti
MTUBytes=1480
[Tunnel]
Local=10.65.223.238
Remote=10.65.223.239
Example 12. /etc/systemd/network/25-veth.netdev
[NetDev]
Name=veth-test
Kind=veth
[Peer]
Name=veth-peer
Example 13. /etc/systemd/network/25-bond.netdev
[NetDev]
Name=bond1
Kind=bond
[Bond]
Mode=802.3ad
TransmitHashPolicy=layer3+4
MIIMonitorSec=1s
LACPTransmitRate=fast
Example 14. /etc/systemd/network/25-dummy.netdev
[NetDev]
Name=dummy-test
Kind=dummy
MACAddress=12:34:56:78:9a:bc
Example 15. /etc/systemd/network/25-vrf.netdev
Create a VRF interface with table 42.
[NetDev]
Name=vrf-test
Kind=vrf
[VRF]
Table=42
Example 16. /etc/systemd/network/25-macvtap.netdev
Create a MacVTap device.
[NetDev]
Name=macvtap-test
Kind=macvtap
Example 17. /etc/systemd/network/25-wireguard.netdev
[NetDev]
Name=wg0
Kind=wireguard
[WireGuard]
PrivateKey=EEGlnEPYJV//kbvvIqxKkQwOiS+UENyPncC4bF46ong=
ListenPort=51820
[WireGuardPeer]
PublicKey=RDf+LSpeEre7YEIKaxg+wbpsNV7du+ktR99uBEtIiCA=
AllowedIPs=fd31:bf08:57cb::/48,192.168.26.0/24
Endpoint=wireguard.example.com:51820
Example 18. /etc/systemd/network/27-xfrm.netdev
[NetDev]
Name=xfrm0
Kind=xfrm
[Xfrm]
Independent=yes
SEE ALSO
systemd(1), systemd-networkd(8), systemd.link(5), systemd.network(5)
NOTES
1. Linux Ethernet Bonding Driver HOWTO
https://www.kernel.org/doc/Documentation/networking/bonding.txt
2. RFC 2784
https://tools.ietf.org/html/rfc2784
3. IEEE 802.1Q
http://www.ieee802.org/1/pages/802.1Q.html
4. VRF
https://www.kernel.org/doc/Documentation/networking/vrf.txt
5. (DVOE)
https://en.wikipedia.org/wiki/Distributed_Overlay_Virtual_Ethernet
6. VXLAN Group Policy
https://tools.ietf.org/html/draft-smith-vxlan-group-policy
7. Generic Protocol Extension for VXLAN
https://tools.ietf.org/html/draft-ietf-nvo3-vxlan-gpe-07
8. Type of Service in the Internet Protocol Suite
http://tools.ietf.org/html/rfc1349
9. RFC 6437
https://tools.ietf.org/html/rfc6437
10. RFC 2460
https://tools.ietf.org/html/rfc2460
11. RFC 2473
https://tools.ietf.org/html/rfc2473#section-4.1.1
12. ip-xfrm — transform configuration
http://man7.org/linux/man-pages/man8/ip-xfrm.8.html
13. Foo over UDP
https://lwn.net/Articles/614348
14. IPv6 Rapid Deployment
https://tools.ietf.org/html/rfc5569
15. Generic UDP Encapsulation
https://lwn.net/Articles/615044
16. Virtual xfrm interfaces
https://lwn.net/Articles/757391