SYSTEMD.NETDEV(5)



SYSTEMD.NETDEV(5)               systemd.network              SYSTEMD.NETDEV(5)

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(5) 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

systemd 245                                                  SYSTEMD.NETDEV(5)

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