systemd.netdev — Virtual Network Device configuration
netdev.netdev
Network setup is performed by systemd-networkd(8).
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.
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 for details.Local configuration |
bridge | A bridge devcie 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. |
vxlan | A virtual extensible LAN (vxlan), for connecting Cloud computing deployments. |
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.
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.
KernelCommandLine=¶Checks whether a specific kernel command line option
is set (or if prefixed with the exclamation mark unset). See
"ConditionKernelCommandLine=" in
systemd.unit(5)
for details.
Architecture=¶Checks whether the system is running on a specific
architecture. See "ConditionArchitecture=" in
systemd.unit(5)
for details.
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 suported 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-id(5).
This key is not currently suported for
"tun" or "tap" devices.
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.
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".
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".
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.
The "[Tunnel]" section only applies for
netdevs of kind
"ipip",
"sit",
"gre",
"gretap",
"ip6gre",
"ip6gretap",
"vti", 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.
Mode=¶An "ip6tnl" tunnels can have three
modes
"ip6ip6" for IPv6 over IPv6,
"ipip6" for IPv4 over IPv6 or
"any" for either.
The "[Peer]" section only applies for
netdevs of kind "veth" and accepts the
following key:
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 prepened 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".
User=¶User to grant access to the
/dev/net/tun device.
Group=¶Group to grant access to the
/dev/net/tun device.
The "[Tap]" section only applies for
netdevs of kind "tap", and accepts the same keys
as the "[Tun]" section.
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 values 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.
Example 2. /etc/systemd/network/vlan1.netdev
[Match] Virtualization=no [NetDev] Name=vlan1 Kind=vlan [VLAN] Id=1
Example 3. /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
Example 4. /etc/systemd/network/tap.netdev
[NetDev] Name=tap-test Kind=tap [Tap] MultiQueue=true PacketInfo=true
Example 5. /etc/systemd/network/sit.netdev
[NetDev] Name=sit-tun Kind=sit MTUBytes=1480 [Tunnel] Local=10.65.223.238 Remote=10.65.223.239
Example 6. /etc/systemd/network/gre.netdev
[NetDev] Name=gre-tun Kind=gre MTUBytes=1480 [Tunnel] Local=10.65.223.238 Remote=10.65.223.239
Example 7. /etc/systemd/network/vti.netdev
[NetDev] Name=vti-tun Kind=vti MTUBytes=1480 [Tunnel] Local=10.65.223.238 Remote=10.65.223.239
Example 9. /etc/systemd/network/dummy.netdev
[NetDev] Name=dummy-test Kind=dummy MACAddress=12:34:56:78:9a:bc