systemd.network
systemd
Developer
Tom
Gundersen
teg@jklm.no
systemd.netdev
5
systemd.netdev
Virtual Network Device configuration
netdev.netdev
Description
Network setup is performed by
systemd-networkd8.
Virtual Network Device files 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
/usr/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 /usr/lib. This can be used to
override a system-supplied configuration file with a local file if
needed; a symlink in /etc with the same name
as a configuration file in /usr/lib, pointing
to /dev/null, disables the configuration file
entirely.
Supported netdev kinds
The following kinds of virtual network devices may be
configured in .netdev files:
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 for details.Local configuration
bridge
A bridge device is a software switch, 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 for details.
gretap
A Level 2 GRE tunnel over IPv4.
ip6gre
A Level 3 GRE tunnel over IPv6.
ip6tnl
An IPv4 or IPv6 tunnel over IPv6
ip6gretap
An 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.
macvlan
A macvlan 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 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.
[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.unit5
for details.
Virtualization=
Checks whether the system is executed in a virtualized
environment and optionally test whether it is a specific
implementation. See
ConditionVirtualization= in
systemd.unit5
for details.
KernelCommandLine=
Checks whether a specific kernel command line option
is set (or if prefixed with the exclamation mark unset). See
ConditionKernelCommandLine= in
systemd.unit5
for details.
Architecture=
Checks whether the system is running on a specific
architecture. See ConditionArchitecture= in
systemd.unit5
for details.
[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. This key is not
currently supported for tun or
tap devices.
MACAddress=
The MAC address to use for the device. If none is
given, one is generated based on the interface name and
the
machine-id5.
This key is not currently supported for
tun or tap devices.
[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.
[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.
[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 and L3.
[VXLAN] Section Options
The [VXLAN] section only applies for
netdevs of kind vxlan, and accepts the
following keys:
Id=
The VXLAN ID to use.
Group=
An assigned multicast group IP 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. N is a number in the range 1-255. 0
is a special value meaning that packets inherit the TTL
value.
MacLearning=
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.
ARPProxy=
A boolean. When true, enables ARP proxy.
L2MissNotification=
A boolean. When true, enables netlink LLADDR miss
notifications.
L3MissNotification=
A boolean. When true, enables netlink IP ADDR miss
notifications.
RouteShortCircuit=
A boolean. When true route short circuit is turned
on.
UDPCheckSum=
A boolean. When true transmitting UDP checksums when doing VXLAN/IPv4 is turned on.
UDP6ZeroChecksumTx=
A boolean. When true sending zero checksums in VXLAN/IPv6 is turned on.
UDP6ZeroCheckSumRx=
A boolean. When true receiving zero checksums in VXLAN/IPv6 is turned on.
[Tunnel] Section Options
The [Tunnel] section only applies for
netdevs of kind
ipip,
sit,
gre,
gretap,
ip6gre,
ip6gretap,
vti,
vti6, and
ip6tnl and accepts
the following keys:
Local=
A static local address for tunneled packets. It must
be an address on another interface of this host.
Remote=
The remote endpoint of the tunnel.
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 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=
A boolean. When true, enables Path MTU Discovery on
the tunnel.
IPv6FlowLabel=
Configures The 20-bit Flow Label (see
RFC 6437) field in the IPv6 header (see
RFC 2460), is used by a node to label packets of a flow.
It's only used for IPv6 Tunnels.
A Flow Label of zero is used to indicate packets that have
not been labeled. Takes following values.
When inherit it uses the original flowlabel,
or can be configured to any value between 0 to 0xFFFFF.
CopyDSCP=
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.
Mode=
An ip6tnl tunnels can have three
modes
ip6ip6 for IPv6 over IPv6,
ipip6 for IPv4 over IPv6 or
any for either.
[Peer] Section Options
The [Peer] section only applies for
netdevs of kind veth and accepts the
following key:
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.
[Tun] Section Options
The [Tun] section only applies for
netdevs of kind tun, and accepts the following
keys:
OneQueue=
Takes a boolean argument. Configures whether
all packets are queued at the device (enabled), or a fixed
number of packets are queued at the device and the rest at the
qdisc. Defaults to
no.
MultiQueue=
Takes a boolean argument. Configures whether
to use multiple file descriptors (queues) to parallelize
packets sending and receiving. Defaults to
no.
PacketInfo=
Takes a boolean argument. 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 argument. Configures
IFF_VNET_HDR flag for a 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.
[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,
802.3ad, 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 slaves peer switch.
The valid range is 1 - 0x7fffffff; the default value is 1. This Option
has effect only in balance-tlb and balance-alb modes.
AdSelect=
Specifies the 802.3ad aggregation selection logic to use. Possible values are
stable,
bandwidth,
count
FailOverMACPolicy=
Specifies whether active-backup mode should set all slaves to
the same MAC address at enslavement or, when enabled, 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,
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,
all
ARPIntervalSec=
Specifies the ARP link monitoring frequency in milliseconds.
A value of 0 disables ARP monitoring. The default value is 0.
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,
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,
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
has effect only 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). Default value is 1.
These options affect only the active-backup mode.
AllSlavesActive=
A boolean. Specifies that duplicate frames (received on inactive ports)
should be dropped false or delivered 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).
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
Example
/etc/systemd/network/bridge.netdev
[NetDev]
Name=bridge0
Kind=bridge
/etc/systemd/network/vlan1.netdev
[Match]
Virtualization=no
[NetDev]
Name=vlan1
Kind=vlan
[VLAN]
Id=1
/etc/systemd/network/ipip.netdev
[NetDev]
Name=ipip-tun
Kind=ipip
MTUBytes=1480
[Tunnel]
Local=192.168.223.238
Remote=192.169.224.239
TTL=64
/etc/systemd/network/tap.netdev
[NetDev]
Name=tap-test
Kind=tap
[Tap]
MultiQueue=true
PacketInfo=true
/etc/systemd/network/sit.netdev
[NetDev]
Name=sit-tun
Kind=sit
MTUBytes=1480
[Tunnel]
Local=10.65.223.238
Remote=10.65.223.239
/etc/systemd/network/gre.netdev
[NetDev]
Name=gre-tun
Kind=gre
MTUBytes=1480
[Tunnel]
Local=10.65.223.238
Remote=10.65.223.239
/etc/systemd/network/vti.netdev
[NetDev]
Name=vti-tun
Kind=vti
MTUBytes=1480
[Tunnel]
Local=10.65.223.238
Remote=10.65.223.239
/etc/systemd/network/veth.netdev
[NetDev]
Name=veth-test
Kind=veth
[Peer]
Name=veth-peer
/etc/systemd/network/dummy.netdev
[NetDev]
Name=dummy-test
Kind=dummy
MACAddress=12:34:56:78:9a:bc
See Also
systemd1,
systemd-networkd8,
systemd.link5,
systemd.network5