systemd.netdev - Virtual Network Device configuration
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.)
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. |
| 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. |
| 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. |
| bareudp |
Bare UDP tunnels provide a generic L3 encapsulation support for
tunnelling different L3 protocols like MPLS, IP etc. inside of an UDP
tunnel. |
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.
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
setting is compulsory.
Kind=
The netdev kind. This setting 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).
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.
VLANProtocol=
Allows setting the protocol used for VLAN filtering.
Takes 802.1q or, 802.1ad, and defaults to unset and kernel's
default is 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.
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 setting 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. When enabled, the VLAN reorder header is
used and VLAN interfaces behave like physical interfaces. When unset, the
kernel's default will be used.
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",
"passthru", and "source".
SourceMACAddress=
A whitespace-separated list of remote hardware addresses
allowed on the MACVLAN. This option only has an effect in source mode. 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.
Defaults to unset.
The [MACVTAP] section applies for netdevs of kind
"macvtap" and accepts the same keys as [MACVLAN].
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".
The [IPVTAP] section only applies for netdevs of kind
"ipvtap" and accepts the same keys as [IPVLAN].
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. If the
destination port is not specified then Linux kernel default will be used. Set
to 4789 to get the IANA assigned value.
PortRange=
Configures the source port range for the VXLAN. The
kernel assigns the source UDP port based on the flow to help the receiver to
do load balancing. When this option is not set, the normal range of local UDP
ports is used.
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.
The [GENEVE] section only applies for netdevs of kind
"geneve", and accepts the following keys:
Id=
Specifies the Virtual Network Identifier (VNI) to use, a
number between 0 and 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. Takes
a number between 1 and 255.
TTL=
Accepts the same values as in the [VXLAN] section, except
that when unset or set to 0, the kernel's default will be used, meaning that
packet TTL will be set from /proc/sys/net/ipv4/ip_default_ttl.
UDPChecksum=
Takes a boolean. When true, specifies that 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 as in [VXLAN] section.
Independent=
Takes a boolean. When true, the vxlan interface is
created without any underlying network interface. Defaults to false, which
means that a .network file that requests this tunnel using Tunnel= is
required for the tunnel to be created.
The [BareUDP] section only applies for netdevs of kind
"bareudp", and accepts the following keys:
DestinationPort=
Specifies the destination UDP port (in range 1...65535).
This is mandatory.
EtherType=
Specifies the L3 protocol. Takes one of "ipv4",
"ipv6", "mpls-uc" or "mpls-mc". This is
mandatory.
The [L2TP] section only applies for netdevs of kind
"l2tp", and accepts the following keys:
TunnelId=
Specifies the tunnel identifier. Takes an number in the
range 1–4294967295. The value used must match the
"PeerTunnelId=" value being used at the peer. This setting is
compulsory.
PeerTunnelId=
Specifies the peer tunnel id. Takes a number in the range
1—4294967295. The value used must match the "TunnelId=" value
being used at the peer. This setting is compulsory.
Remote=
Specifies the IP address of the remote peer. This setting
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 mandatory. Ignored when IP
encapsulation is selected.
UDPDestinationPort=
Specifies destination port. When UDP encapsulation is
selected it's mandatory. Ignored when IP encapsulation is selected.
UDPChecksum=
Takes a boolean. When true, specifies that 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.
The [L2TPSession] section only applies for netdevs of kind
"l2tp", and accepts the following keys:
Name=
Specifies the name of the session. This setting is
compulsory.
SessionId=
Specifies the session identifier. Takes an number in the
range 1–4294967295. The value used must match the
"SessionId=" value being used at the peer. This setting is
compulsory.
PeerSessionId=
Specifies the peer session identifier. Takes an number in
the range 1–4294967295. The value used must match the
"PeerSessionId=" value being used at the peer. This setting is
compulsory.
Layer2SpecificHeader=
Specifies layer2specific header type of the session. One
of "none" or "default". Defaults to
"default".
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.
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 setting is compulsory, and is not set by default.
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 setting 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. If the path refers to an AF_UNIX stream socket in the file
system a connection is made to it and the key read from it.
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.
The [MACsecReceiveAssociation] section only applies for network
devices of kind "macsec", and accepts the following keys:
Port=
Accepts the same key as in [MACsecReceiveChannel]
section.
MACAddress=
Accepts the same key as in [MACsecReceiveChannel]
section.
PacketNumber=
Accepts the same key as in [MACsecTransmitAssociation]
section.
KeyId=
Accepts the same key as in [MACsecTransmitAssociation]
section.
Key=
Accepts the same key as in [MACsecTransmitAssociation]
section.
KeyFile=
Accepts the same key as in [MACsecTransmitAssociation]
section.
Activate=
Accepts the same key as in [MACsecTransmitAssociation]
section.
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 0 (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 false (the default), the tunnel is
always created over some network device, and a .network file that requests
this tunnel using Tunnel= is required for the tunnel to be created.
When true, the tunnel is created independently of any network as
"tunnel@NONE".
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.
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 encapsulated packets
will arrive. Those packets will be removed and manually fed back into the
network stack with the encapsulation removed to be sent 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 mandatory.
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 mandatory.
Local=
Configures local IP address.
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
setting is compulsory.
MACAddress=
The peer MACAddress, if not set, it is generated in the
same way as the MAC address of the main interface.
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 setting is compulsory.
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.
The [Tap] section only applies for netdevs of kind
"tap", and accepts the same keys as the [Tun] section.
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. If the
path refers to an AF_UNIX stream socket in the file system a connection
is made to it and the key read from it.
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.
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-network" 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. If the
path refers to an AF_UNIX stream socket in the file system a connection
is made to it and the key read from it.
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.
Note that this only affects "routing inside the network
interface itself", as in, which wireguard peer packets with a specific
destination address are sent to, and what source addresses are accepted from
which peer.
To cause packets to be sent via wireguard in first place, a route
needs to be added, as well - either in the "[Routes]" section on
the ".network" matching the wireguard interface, or outside of
networkd.
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.
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. Takes a
number in the range 1—65535.
AdUserPortKey=
Specifies the 802.3ad user defined portion of the port
key. Takes a number in the range 0–1023.
AdActorSystem=
Specifies the 802.3ad system MAC address. This cannot be
a null or multicast address.
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]
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 false (the default), the xfrm
interface must have an underlying device which can be used for hardware
offloading.
For more detail information see Virtual XFRM
Interfaces[16].
The [VRF] section only applies for netdevs of kind "vrf"
and accepts the following key:
Table=
The numeric routing table identifier. This setting is
compulsory.
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
- 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