SYSTEMD.NETWORK(5) systemd.network SYSTEMD.NETWORK(5) (NAME) systemd.network - systemd-networkd (SYNOPSIS) network.network (DESCRIPTION) ini systemd- networkd(8) . systemd.syntax(7) . .network . (links) . .network systemd.link(5) systemd.netdev(5) .network . .network /usr/lib/systemd/network /usr/local/lib/systemd/network [1] /run/systemd/network /etc/systemd/network . - . . "70" ( 10-eth0.network). .network systemd- network-generator.service(8) . /etc/ /run/ /usr/ . . ( ) /dev/null ( "" ). foo.network ("drop-in") foo.network.d/ . ".conf" - . . drop-in . /etc/systemd/network ".d" /usr/lib/systemd/network /run/systemd/network . /etc/ /run/ /usr/lib/ . . [MATCH] ([MATCH] SECTION OPTIONS) [Match] [Network] . ( -) . udev ID_NET_MANAGED_BY= .network - "io.systemd.Network" - [Match] . systemd-networkd(8) [Match] . ID_NET_MANAGED_BY= . [Match] . [Match] systemd-networkd . : : Name=* : MACAddress= (whitespace). : . "12:34:56:78:90:ab" "AA:BB:CC:DD:EE:FF". 250. . "12-34-56-78-90-ab" "AA-BB-CC-DD-EE-FF". 250. . "1234.5678.90ab" "AABB.CCDD.EEFF". 250. IPv4 "127.0.0.1" "192.168.0.1". 250. IPv6 "2001:0db8:85a3::8a2e:0370:7334" "::1". 250. MAC ( IPv4) ( ) ( IPv6) ( InfiniBand) . . . . 211 . PermanentMACAddress= . MACAddress= MAC MAC . IPv4 IPv6 . . . . 245 . Path= (shell-style globs) udev ID_PATH . 211 . Driver= udev ID_NET_DRIVER ethtool -i . "!" . 211 . Type= networkctl list . "!" . "ether" "loopback" "wlan" "wwan". "DEVTYPE" udev "ARPHRD_" linux/if_arp.h . 211 . Kind= (kind) networkctl status INTERFACE ip -d link show INTERFACE . "!" . "bond" "bridge" "gre" "tun" "veth". "IFLA_INFO_KIND" netlink . 251 . Property= udev ("="). AND . "!" . . "\" (escape) . : .link : Property=ID_MODEL_ID=9999 "ID_VENDOR_FROM_DATABASE=vendor name" "KEY=with \"quotation\"" .link . 243 . Name= udev "INTERFACE" . "!" . 211 . WLANInterfaceType= . "ad-hoc" "station" "ap" "ap-vlan" "wds" "monitor" "mesh-point" "p2p-client" "p2p-go" "p2p-device" "ocb" "nan". "!" . 244 . SSID= SSID LAN . "!" . 244 . BSSID= LAN . . MACAddress= . . . 244 . Host= (machine ID) . ConditionHost= systemd.unit(5) . ("!") . . 211 . Virtualization= . ConditionVirtualization= systemd.unit(5) . ("!") . . 211 . KernelCommandLine= . ConditionKernelCommandLine= systemd.unit(5) . ("!") . . 211 . KernelVersion= ( uname -r ) . ConditionKernelVersion= systemd.unit(5) . ("!") . . 237 . Credential= (credential) systemd-udevd.service . [2] . ("!") . . 252 . Architecture= . ConditionArchitecture= systemd.unit(5) . ("!") . . 211 . Firmware= . ConditionFirmware= systemd.unit(5) . ("!") . . 249 . [LINK] ([LINK] SECTION OPTIONS) [Link] : MACAddress= . 218 . MTUBytes= (MTU) . K M G 1024 . IPv6 MTU 1280 ( MTU IPv6) . 218 . ARP= . true IPv4 ARP ( ) IPv6 NDP ( ) . . ARP MACVLAN VLAN /"" . . 232 . Multicast= . true (multicast) . . IPv6AcceptRA= IPv6SendRA= . 239 . AllMulticast= . true . . . 239 . Promiscuous= . true (promiscuous mode) . . MACVLAN/MACVTAP "passthru" false "nopromisc" . 248 . Unmanaged= . "yes" . "no" . . 233 . Group= . . 0...2147483647 . . 246 . RequiredForOnline= ( "carrier") ( "degraded:routable") . networkctl(1) . "yes" ( systemd-networkd-wait-online) . "no" . systemd-networkd-wait-online . ActivationPolicy= "up" "always-up" "bound" "yes" . ActivationPolicy= "manual" "down" "no" . ActivationPolicy= "always-down" "no" . ( ActivationPolicy= ) DHCP "RequiredForOnline=no" systemd-networkd-wait-online . "yes" : CAN "carrier" 256 . (Master) bond bridge "degraded-carrier" RequiredFamilyForOnline=any 256 . Bonding "enslaved" 256 . "degraded". 236 . systemd-networkd-wait-online . systemd- networkd-wait-online.service(8) . 236 . RequiredFamilyForOnline= . IP ( systemd-networkd-wait-online) . "ipv4" "ipv6" "both" "any" . "no" . "RequiredForOnline=no" . 249 . ActivationPolicy= systemd-networkd . "IFF_UP" systemd-networkd ip link set dev eth0 up ip link set dev eth0 down networkctl up eth0 networkctl down eth0 . "up" "always-up" "manual" "always-down" "down" "bound" . "manual" systemd-networkd . "up" () "always-up" "down" "always-down" systemd-networkd () . "always-up" "always-down" systemd-networkd . BindCarrier= "bound" . "down" "manual" RequiredForOnline= "no" . "always-down" RequiredForOnline= "no" . (carrier) "always-up" . . "always-up" IgnoreCarrierLoss= true . 248 . [SR-IOV] ([SR-IOV] SECTION OPTIONS) SR-IOV PCI PCI (VM) . VF SR-IOV CPU - ( ) . [SR-IOV] .link . .network . SR-IOV [SR-IOV] . [SR-IOV] : VirtualFunction= (VF) PCIe . 0...2147483646 . . 251 . VLANId= VLAN . 1...4095 . 251 . QualityOfService= (QoS) . 1...4294967294 . 251 . VLANProtocol= VLAN . "802.1Q" "802.1ad" . 251 . MACSpoofCheck= . MAC (spoof checking) . . 251 . QueryReceiveSideScaling= . (RSS) (VF) . RSS VF RSS VF (PF) . . 251 . Trust= . (trust mode) (VF) . VF / . . 251 . LinkState= (VF) . "auto" . "auto" (PF) "yes" VF PF (down) VF "no" VF . . 251 . MACAddress= MAC . 251 . [NETWORK] ([NETWORK] SECTION OPTIONS) [Network] : Description= . . 211 . DHCP= DHCPv4 / DHCPv6 . "yes" "no" "ipv4" "ipv6" . "no" . DHCPv6 (Router Advertisements) . DHCPv6 DHCPv6 WithoutRA= [DHCPv6] . IPv6AcceptRA= . DHCP . UseDomains= . DHCP [DHCPv4] [DHCPv6] . 211 . DHCPServer= . "yes" DHCPv4 . "no" . DHCP [DHCPServer] . DHCP / RelayTarget= PersistLeases=no [DHCPServer] . systemd-networkd-persistent-storage.service networkctl persistent-storage yes . networkctl(1) . 215 . LinkLocalAddressing= (link-local) . ipv4 ipv6 . IPv6 yes ipv6 . IPv4 yes ipv4 DHCPv4 . ( IPv4 DHCPv4 ). KeepMaster= Bridge= MACVLAN=/MACVTAP= Mode=passthru no ipv6 . 219 . IPv6LinkLocalAddressGenerationMode= IPv6 . "eui64" "none" "stable-privacy" "random" . IPv6StableSecretAddress= "stable-privacy" "eui64" . LinkLocalAddressing= "no" "ipv4" IPv6LinkLocalAddressGenerationMode= . LinkLocalAddressing= "yes" "ipv6" IPv6LinkLocalAddressGenerationMode=none IPv6 . 246 . IPv6StableSecretAddress= IPv6 . (stable secret) IPv6 . IPv6LinkLocalAddressGenerationMode= IPv6LinkLocalAddressGenerationMode=stable-privacy . "stable-privacy" IPv6LinkLocalAddressGenerationMode= . 249 . IPv4LLStartAddress= IPv4 . IPv4 169.254.1.2 : 169.254.0.0/16 169.254.0.0/24 169.254.255.0/24 . . . . 252 . IPv4LLRoute= . true -IPv4LL -IPv4LL . false . 216 . DefaultRouteOnDevice= . true IPv4 . false . -- (point-to-point) . : ip route add default dev veth99 : [Route] Gateway=0.0.0.0 . : [Route] Gateway=0.0.0.0 Table=1234 IPv6 : [Route] Gateway=:: Table=1234 243 . LLMNR= "resolve" . true (LLMNR)[3] . "resolve" . true . systemd-resolved.service(8) . 216 . MulticastDNS= "resolve" . true (mDNS)[4] . "resolve" . false . systemd-resolved.service(8) . 229 . DNSOverTLS= "opportunistic" . true DNS-over-TLS[5] . "opportunistic" DNS-over-TLS DNS-over-TLS . DNSOverTLS= resolved.conf(5) . . systemd-resolved.service(8) . 239 . DNSSEC= "allow-downgrade" . true DNS DNSSEC[6] . "allow-downgrade" DNSSEC DNSSEC . DNSSEC= resolved.conf(5) . . systemd-resolved.service(8) . 229 . DNSSECNegativeTrustAnchors= DNSSEC . DNSSEC DNS . DNSSEC DNS . . systemd-resolved.service(8) . 229 . LLDP= LLDP . LLDP . "routers-only" . true LLDP LLDP . "routers-only" LLDP LLDP ( ) . false LLDP . "routers-only" . networkctl(1) . LLDP . LLDP EmitLLDP= . 219 . EmitLLDP= LLDP . "nearest-bridge" "non-tpmr-bridge" "customer-bridge" . false LLDP . false LLDP . LLDP ( machine-id(5) ) ( machine-info(5) ) . LLDP . . . LLDP : "nearest-bridge" "non-tpmr-bridge" Two-Port MAC "customer-bridge" . IEEE 802.1AB-2016[7] . true "nearest-bridge" . LLDP LLDP= . 230 . BindCarrier= . . (down) . . ActivationPolicy= "bound" . 220 . Address= IPv4 IPv6 "/". . inet_pton(3) . [Address] Address ( ). . "0.0.0.0" ( IPv4) "::" ( IPv6) . IPv4 IPv6 . . 192.168.0.0/16 172.16.0.0/12 10.0.0.0/8 IPv4 fd00::/8 IPv6 . . IPv4 (169.254.0.0/16) IPv4 ( RFC 5227[8]) . IPv4 [Address] DuplicateAddressDetection= : [Address] Address=169.254.10.1/24 DuplicateAddressDetection=none [Network] [Address] . 211 . Gateway= (gateway) inet_pton(3) . [Route] Gateway= . . [Network] [Route] . 211 . DNS= DNS inet_pton(3) . . ":" "%" (SNI) "#" . IPv6 () . : "111.222.333.444:9953%ifname#example.com" IPv4 "[1111:2222::3333]:9953%ifname#example.com" IPv6. . systemd-resolved.service(8) . 211 . UseDomains= [IPv6AcceptRA] [DHCPv4] [DHCPv6] . route . [DHCPv4] . . 256 . Domains= DNS . ("~") . " -" (routing-only domains) . " " (search domains) ( ) (FQDN) . FQDN . "" "-" DNS : ( " " ) DNS . (multi-homed) DNS DNS . - "~." ( DNS DNS ) . DNS DNS . DNS . systemd-resolved.service(8) . " " domain search resolv.conf(5) . API glibc . 216 . DNSDefaultRoute= . true DNS Domains= . false DNS . : - . 240 . NTP= NTP ( IP ). . systemd-timesyncd.service(8) . 216 . IPv4Forwarding= IPv4 . . sysctl net.ipv4.conf.INTERFACE.forwarding . sysctl IP Sysctl[9] . IPMasquerade= IPv4 true networkd.conf(5) . sysctl . networkd.conf(5) . 256 . IPv6Forwarding= / . . sysctl net.ipv6.conf.INTERFACE.forwarding . sysctl IP Sysctl[9] . IPMasquerade= IPv6 IPv6SendRA= true networkd.conf(5) . sysctl . networkd.conf(5) . IPv4Forwarding= IPv6Forwarding= IPv6 . sysctl sysctl . IPv6 networkd.conf(5) . 256 . IPMasquerade= IP (IP masquerading) . . . "ipv4" "ipv6" "both" "no" . "no" . "yes" "true" . . "ipv4" "both" IPv4Forwarding= .network networkd.conf(5) . IPv6Forwarding= "ipv6" "both" . IPv4Forwarding=/IPv6Forwarding= networkd.conf(5) . 219 . IPv6PrivacyExtensions= ( RFC 4941[10] IPv6 ). "prefer-public" "kernel" . true . "prefer-public" . false . "kernel" . networkd.conf(5) "no" . 222 . IPv6AcceptRA= . IPv6 (RA) . true false . RA DHCPv6 . (bond) IPv6 ( LinkLocalAddressing= ) ( Multicast= ) . . Multicast= . IPv6SendRA= IPv6Forwarding= IPMasquerade= . IPv6Forwarding= IPMasquerade= . IPv6Forwarding= IPMasquerade= . . IPv6 RA [IPv6AcceptRA] . IP Sysctl[9] "accept_ra" 1 ( true) systemd 2 . IPv6 RA . IPv6 RA systemd-networkd . 231 . IPv6DuplicateAddressDetection= (DAD) IPv6 . . 228 . IPv6HopLimit= (Hop Limit) IPv6 . 1...255 . . . . 228 . IPv6RetransmissionTimeSec= IPv6 . (Neighbor Solicitation) . . . . 256 . IPv4ReversePathFilter= (Reverse Path Filtering) IPv4 . IPv4 source () . . "no" "strict" "loose" . "no" . "strict" FIB . . "loose" FIB . . RFC 3704[11] . . 255 . MulticastIGMPVersion= IGMP IPv4 /proc/sys/net/ipv4/conf/INTERFACE/force_igmp_version . "no" "v1" "v2" "v3" . "no" IGMP . IGMPv1/v2 systemd-networkd IGMPv1/v2 Querier Present IGMPv3 . "v1" IGMP . IGMPv2/v3 IGMPv1 . "v2" IGMP . IGMPv2/v3 IGMPv2 . systemd-networkd IGMPv1 IGMPv1 . "v3" IGMP "no" . -- sysctl . 257 . IPv4AcceptLocal= . . . . 246 . IPv4RouteLocalnet= . true loopback (martian) . 127.0.0.0/8 . . 248 . IPv4ProxyARP= . ARP IPv4 . ARP ARP . "" "" . RFC 1027[11] . . 233 . IPv4ProxyARPPrivateVLAN= . ARP VLAN IPv4 VLAN aggregation private VLAN source-port filtering port-isolation MAC-forced forwarding . ARP ARP . RFC 3069[12] . . 256 . IPv6ProxyNDP= . NDP IPv6 . NDP ( ) IPv6 . MAC . ARP IPv4 IPv6 ip -6 neighbour show proxy . systemd-networkd `proxy_ndp` . . 234 . IPv6ProxyNDPAddress= IPv6 . . systemd-networkd IPv6ProxyNDPAddress= IPv6 . IPv6ProxyNDP=yes IPv6ProxyNDP= false . . 233 . IPv6SendRA= (Router Advertisement) . . [IPv6Prefix] [IPv6RoutePrefix] [IPv6SendRA] . DHCPPrefixDelegation= . DHCPPrefixDelegation= [IPv6SendRA] [IPv6Prefix] [IPv6RoutePrefix] [DHCPPrefixDelegation] . IPv6Forwarding= . IPv6Forwarding= . 247 . DHCPPrefixDelegation= . DHCPv6 6RD DHCPv4 . IPv6SendRA= IPv6 . [DHCPPrefixDelegation] . . 250 . IPv6MTUBytes= (MTU) IPv6 . 1280 . . 239 . KeepMaster= . BatmanAdvanced= Bond= Bridge= VRF= . netdev systemd- nspawn(1) . false . 250 . BatmanAdvanced=, Bond=, Bridge=, VRF= B.A.T.M.A.N. Advanced bond bridge VRF . systemd.netdev(5) . 211 . IPoIB=, IPVLAN=, IPVTAP=, MACsec=, MACVLAN=, MACVTAP=, Tunnel=, VLAN=, VXLAN=, Xfrm= IPoIB IPVLAN IPVTAP MACsec MACVLAN MACVTAP tunnel VLAN VXLAN Xfrm . systemd.netdev(5) . . 211 . ActiveSlave= . . "ActiveSlave=" : "active-backup" "balance-alb" "balance-tlb". false . 235 . PrimarySlave= . () . . . . "PrimarySlave=" : "active-backup" "balance-alb" "balance-tlb". false . 235 . ConfigureWithoutCarrier= . systemd-networkd (carrier) . false . IgnoreCarrierLoss= . "configured" systemd-networkd-wait-online DHCP= IPv6AcceptRA= ( ) . DuplicateAddressDetection= ( IPv4 IPv6 ) . "configuring" systemd-networkd-wait-online . RequiredForOnline=no-carrier systemd-networkd-wait-online . 235 . IgnoreCarrierLoss= . true systemd-networkd . false systemd-networkd . systemd-networkd . "no" "infinite" "yes" . : o SSID . o bond . o MTU . Bond= . DHCPv4 UseMTU= [DHCPv4] . ConfigureWithoutCarrier= . ActivationPolicy= "always-up" "yes" . 242 . KeepConfiguration= "static" "dynamic-on-stop" "dynamic" . "static" systemd-networkd . "dynamic-on-stop" DHCPv4 DHCPv6 SLAAC IPv4 systemd-networkd . "dynamic" DHCPv4 . DHCP . "dynamic" "dynamic-on-stop" "yes" "dynamic" "static" . systemd-networkd initrd "dynamic-on-stop" "yes" "no" . 257 . [ADDRESS] ([ADDRESS] SECTION OPTIONS) [Address] . [Address] . Address= [Network]. . [Address] Address= . 211 . Peer= (peer) -- (point-to-point). Address= . 216 . Broadcast= IPv4 . inet_pton(3) . true (broadcast) IPv4 Address= . false . wireguard false true . 211 . Label= IPv4 . ASCII . . 211 . PreferredLifetime= " " (preferred lifetime) . : "forever" "infinity" "0" "" . PreferredLifetime=0 . 230 . Scope= (scope) "global" ( ) "link" ( ) "host" ( 127.0.0.1) 0...255 . "global" . IPv4 - IPv6 . 235 . RouteMetric= IP . 0...4294967295 . . AddPrefixRoute= false . 246 . HomeAddress= . " " (home address) RFC 6275[13] . IPv6 . false . 232 . DuplicateAddressDetection= "ipv4" "ipv6" "both" "none" . "ipv4" IPv4 . RFC 5227[8] . "ipv6" IPv6 . RFC 4862[14] . IPv4 (169.254.0.0/16) "ipv4" IPv6 "ipv6" "none" . 232 . ManageTemporaryAddress= . true (Privacy Extensions) RFC 3041[15] . sysctl use_tempaddr . . . false . 232 . AddPrefixRoute= . true . true . 245 . AutoJoin= . ip maddr IGMP snooping IGMP . vxlan ip link add vxlan vxlan netdev systemd-networkd group . ip address "autojoin" vxlan openvswitch (OVS) . "no" . 232 . NetLabel= NetLabel[16] (LSM)[17] . LSM ( ) . SELinux . NetLabel netlabelctl(8) systemd-networkd . SELinux . NetLabel . LSM . IP NetLabel Fallback Peer Labeling[18] . . . LSM . LSM . netlabelctl(8) . : [Address] NetLabel=system_u:object_r:localnet_peer_t:s0 "eth0" IPv4 10.0.0.123/8 systemd-networkd netlabelctl : netlabelctl unlbl add interface eth0 address:10.0.0.0/8 label:system_u:object_r:localnet_peer_t:s0 IPv4 . LSM SELinux SELinux "peer" SELinux. : type localnet_peer_t; allow my_server_t localnet_peer_t:peer recv; ( ) "my_server_t" ( ) 10.0.0.0/8 "eth0" . 252 . NFTSet=source:family:table:set NFT[19] . ( ) NFT . . IP DHCP . NFT . ( "address" "prefix" "ifindex") NFT ( "arp" "bridge" "inet" "ip" "ip6" "netdev") . NFT . NFT ("address" "prefix" "ifindex") (IPv4 IPv6) . 1. source type +-------------+-----------------------+---------------------+ | | | | | | | NFT | | | | | +-------------+-----------------------+---------------------+ |"address" | IP | "ipv4_addr" | | | | "ipv6_addr" | +-------------+-----------------------+---------------------+ |"prefix" | | "ipv4_addr" | | | | "ipv6_addr" | | | | "flags | | | | interval" | +-------------+-----------------------+---------------------+ |"ifindex" | | "iface_index" | | | | | +-------------+-----------------------+---------------------+ IP NFT . . systemd-networkd ( ) NFT . . : [Address] NFTSet=prefix:netdev:filter:eth_ipv4_prefix NFT : table netdev filter { set eth_ipv4_prefix { type ipv4_addr flags interval } chain eth_ingress { type filter hook ingress device "eth0" priority filter; policy drop; ip daddr != @eth_ipv4_prefix drop accept } } 255 . [NEIGHBOR] ([NEIGHBOR] SECTION OPTIONS) [Neighbor] . neighbor (IPv6) ARP (IPv4) . [Neighbor] . Address= IP . 240 . LinkLayerAddress= ( MAC IP) . 243 . [IPV6ADDRESSLABEL] ([IPV6ADDRESSLABEL] SECTION OPTIONS) [IPv6AddressLabel] . [IPv6AddressLabel] . IPv6 . RFC 3484[20] . . Label= . 0...4294967294 (0xfffffffe) . 4294967295 (0xffffffff) . . 234 . Prefix= IPv6 "/" . . 234 . [ROUTINGPOLICYRULE] ([ROUTINGPOLICYRULE] SECTION OPTIONS) [RoutingPolicyRule] . [RoutingPolicyRule] . TypeOfService= (Type of Service ToS) 0...255 . ( ) ToS ( ) . (DSCP) ( ) (ECN) ( ) . (Type of Service)[21] (Differentiated services)[22] . 235 . From= . . 235 . To= . . 235 . FirewallMark= iptables ( 0...4294967295). ( 0...4294967295) ("/") "7/255". . 235 . Table= . "default" "main" "local" RouteTable= networkd.conf(5) 4294967295 . "main" . L3MasterDevice= true . 235 . Priority= . Priority= 0...4294967295 . . . 235 . GoTo= "goto" . 1...4294967295 . Priority= . Type=goto . Type=goto . 257 . IncomingInterface= . loopback . 236 . OutgoingInterface= . . 236 . L3MasterDevice= . ( VRF ) . (VRF)[23] . false . 256 . SourcePort= IP IP (FIB) . . . 240 . DestinationPort= IP IP (FIB) . . . 240 . IPProtocol= IP (FIB) . IP "tcp" "udp" "sctp" IP "6" "tcp" "17" "udp" . . 240 . InvertRule= . . false . 240 . Family= "ipv4" "ipv6" "both" . To= From= . To= From= "ipv4" . 243 . User= (UID) . . 245 . SuppressPrefixLength= N 0...128 N . . 245 . SuppressInterfaceGroup= 0...2147483647 . suppress_ifgroup ip rule . . 250 . Type= (RPDB) . "table" "goto" "nop" "blackhole" "unreachable" "prohibit" . "goto" GoTo= . "table" . 248 . [NEXTHOP] ([NEXTHOP] SECTION OPTIONS) [NextHop] "nexthop" ( ) . [NextHop] . [NextHop] . Id= . 1...4294967295 . ManageForeignNextHops=no networkd.conf(5) . . 244 . Gateway= [Network]. 244 . Family= "ipv4" "ipv6" . Gateway= . Gateway= "ipv4" . 248 . OnLink= . true ( ) nexthop . "no" . 248 . Blackhole= . Gateway= . "no" . 248 . Group= nexthop . 1...4294967295 . nexthop ("id[:weight]"). 1...255 . . Gateway= Family= Blackhole= . . . . 249 . [ROUTE] ([ROUTE] SECTION OPTIONS) [Route] . [Route] . Gateway= "_dhcp4" "_ipv6ra" . "_dhcp4" "_ipv6ra" DHCPv4 IPv6 RA . 211 . GatewayOnLink= . true ( ) . "no" . 234 . Destination= . . . 211 . Source= . . . 218 . Metric= . 0...4294967295 . . 216 . IPv6Preference= RFC 4191[24] . "low" ( ) "medium" ( ) "high" ( ) . 234 . Scope= (scope) IPv4 "global" "site" "link" "host" "nowhere" : o "global" . o "site" (autonomous system) . o "link" ( ) . o "host" ( 127.0.0.1 ). o "nowhere" . IPv4 Type= "local" "nat" "host" Type= "broadcast" "multicast" "anycast" "unicast" "link" . "global" . IPv6 . 219 . PreferredSource= . inet_pton(3) . 227 . Table= . "default" "main" "local" RouteTable= networkd.conf(5) 4294967295 . ip route show table num . Type= "local" "broadcast" "anycast" "nat" "local" . "main" . 230 . HopLimit= . 1...255 . IPv6HopLimit= . 255 . Protocol= . "kernel" "boot" "static" "ra" "dhcp" . "static" . 234 . Type= . "unicast" "local" "broadcast" "anycast" "multicast" "blackhole" "unreachable" "prohibit" "throw" "nat" "xresolve" . "unicast" . "blackhole" . "unreachable" ICMP "Host Unreachable" . "prohibit" ICMP "Communication Administratively Prohibited" . "throw" (RPDB) . "unicast" . 235 . InitialCongestionWindow= TCP TCP . TCP . . . ( ) . 237 . InitialAdvertisedReceiveWindow= TCP ( ) . . . . . 237 . QuickAck= . true ACK TCP . . 237 . FastOpenNoCookie= . true TCP fastopen . . 243 . MTUBytes= (MTU) . K M G 1024 . 239 . TCPAdvertisedMaximumSegmentSize= Path MSS ( ) TCP . K M G 1024 . 1...4294967294. . 248 . TCPCongestionControlAlgorithm= TCP . "bbr" "dctcp" "vegas". . 252 . TCPRetransmissionTimeoutSec= TCP (RTO) . . TCP . . 255 . MultiPathRoute=address[@name] [weight] (multipath route) . . . "@" . . . 245 . NextHop= nexthop . 1...4294967295 . [NextHop] . . 248 . [DHCPV4] ([DHCPV4] SECTION OPTIONS) [DHCPv4] DHCPv4 DHCP= : RequestAddress= IPv4 . Requested IP Address ( ) DHCPDISCOVER DHCP . . 255 . SendHostname= true () ( Hostname= ) DHCP . ASCII DNS . DHCP ( Host Name RFC 2132[25]) (FQDN) DHCP ( Client FQDN RFC 4702[26]) . true . 215 . Hostname= DHCP . ASCII DNS . (FQDN) SendHostname= . 223 . MUDURL= URL (MUD) DHCPv4 . URL . URL . DHCPv4 URL MUD . RFC 8520[27] . MUD IETF IoT . . 246 . ClientIdentifier= DHCPv4 . mac duid . mac MAC . duid RFC4361 IAID DUID . IAID IAID= . DUID DUIDType= DUIDRawData= . duid . 220 . VendorClassIdentifier= (Vendor Class Identifier) . 216 . UserClass= DHCPv4 UserClass . . DHCP . . 239 . DUIDType= DUIDType= . networkd.conf(5) . 230 . DUIDRawData= DUIDRawData= . networkd.conf(5) . 230 . IAID= DHCP ( IAID) . 230 . RapidCommit= . DHCPv4 DHCPv4 (discover ack) . DHCPv4 . (discover offer request ack) . . RFC 4039[28] . Anonymize=no AllowList= DenyList= true false . 255 . Anonymize= . true DHCP RFC 7844[29] ( DHCP) . false . true MACAddressPolicy= random ( systemd.link(5) ). true ClientIdentifier=mac RapidCommit=no SendHostname=no Use6RD=no UseCaptivePortal=no UseMTU=no UseNTP=no UseSIP=no UseTimezone=no .network . Hostname= MUDURL= RequestAddress= RequestOptions= SendOption= SendVendorOption= UserClass= VendorClassIdentifier= . DHCP . DHCP . 235 . RequestOptions= DHCPv4 . 1...254. . 244 . SendOption= DHCPv4 . DHCP ("option:type:value"). 1...254 . "uint8" "uint16" "uint32" "ipv4address" "string" . C[30] . . . . 244 . SendVendorOption= DHCPv4 . DHCP ("option:type:value"). 1...254 . "uint8" "uint16" "uint32" "ipv4address" "string" . C[30] . . . . 246 . IPServiceType= "none" "CS6" "CS4" . "none" IP DHCPv4 . "CS6" ( ) "CS4" () . "CS6" . 244 . SocketPriority= SO_PRIORITY IP DHCPv4 . . . SO_PRIORITY socket(7) . EgressQOSMaps= [VLAN] .netdev 802.1Q VLAN systemd.netdev(5) . 253 . Label= IPv4 DHCP . ASCII . . 250 . UseDNS= true () DNS DHCP . nameserver resolv.conf(5) . 211 . RoutesToDNS= true DNS DHCP . UseDNS= . true . 243 . UseNTP= true () NTP DHCP systemd-timesyncd.service . 220 . RoutesToNTP= true NTP DHCP . UseNTP= . true . 249 . UseSIP= true () SIP DHCP . 244 . UseCaptivePortal= true () (captive portal) DHCP networkctl(1) . 254 . UseDNR= true (designated resolvers) DHCP DNS . RFC 9463[31] . UseDNS= . 257 . UseMTU= true (MTU) DHCP . MTUBytes= . false . MTU . IgnoreCarrierLoss= "3 seconds" . 211 . UseHostname= true () DHCP (transient) . 211 . UseDomains= route . true DHCP DNS Domains=. route DHCP DNS Domains= "~" . [Network] . [DHCPv4] networkd.conf(5) . [Network] networkd.conf(5) . "no" . . . true domain resolv.conf(5) . 216 . UseRoutes= true () DHCP 1024 (scope) global link host . ( 127.x.x.x ) host . ( ) link . global . 215 . RouteMetric= DHCP ( ) . 0...4294967295 . 1024 . 217 . RouteTable=num DHCP. "default" "main" "local" RouteTable= networkd.conf(5) 1...4294967295 . VRF= VRF . 232 . RouteMTUBytes= MTU DHCP . [Route] . 245 . QuickAck= . true ACK TCP DHCPv4 . . 253 . InitialCongestionWindow= [Route]. 255 . InitialAdvertisedReceiveWindow= [Route]. 255 . UseGateway= true DHCP Router . UseRoutes= . Router Classless Static Routes UseRoutes= Router . RFC 3442[32] . 246 . UseTimezone= true DHCP . false . 226 . Use6RD= true IPv6 DHCPPrefixDelegation= . DHCPPrefixDelegation= [Network] [DHCPPrefixDelegation] RFC 5969[33] . false . 250 . UnassignedSubnetPolicy= "none" (reject) : "unreachable" "prohibit" "blackhole" "throw" . 6RD . "unreachable" : unreachable 2001:db8::/56 dev lo proto dhcp metric 1024 pref medium . RFC 7084[34] . "none" . . "unreachable" . 257 . IPv6OnlyMode= true DHCPv4 DHCP IPv6 IPv4 . RFC 8925[35] . false . 255 . FallbackLeaseLifetimeSec= DHCPv4 DHCPv4 . "forever" "infinity" . . . 246 . RequestBroadcast= IP (broadcast) . (RAW) IP . . 216 . MaxAttempts= DHCPv4 . "infinity" . "infinity" . . . 243 . ListenPort= DHCP . 233 . ServerPort= DHCP . 256 . DenyList= IPv4 . "/" . DHCP . AllowList= DenyList= . DHCP RapidCommit= . RapidCommit= . 246 . AllowList= IPv4 . "/" . DHCP . DHCP RapidCommit= . RapidCommit= . 246 . SendRelease= true DHCPv4 DHCP ( release) . true . 243 . SendDecline= . true systemd-networkd IPv4 DHCPv4 . DHCPv4 DHCPDECLINE DHCP IP . RFC 5227[8] . false . 245 . NetLabel= NetLabel DHCP NetLabel= [Address] . NetLabel= [Address] . 252 . NFTSet= NFT DHCP NFTSet= [Address] . NFTSet= [Address] . "address" "prefix" NFT "ipv4_addr" . 255 . [DHCPV6] ([DHCPV6] SECTION OPTIONS) [DHCPv6] DHCPv6 DHCP= IPv6 : MUDURL=, IAID=, DUIDType=, DUIDRawData=, RequestOptions= [DHCPv4]. 246 . SendOption= [DHCPv4] DHCPv6 1...65536 . 246 . SendVendorOption= DHCPv6 . (enterprise identifier) DHCP ("enterprise identifier:option:type:value"). 1...4294967294 . 1...254 . "uint8" "uint16" "uint32" "ipv4address" "ipv6address" "string" . C[30] . . . . 246 . UserClass= DHCPv6 User Class . . DHCP . C[30] . . . . NUL . 246 . VendorClass= DHCPv6 VendorClass . (opaque) . . 246 . PrefixDelegationHint= IPv6 Address= [Network] . DHCPv6 (prefix hint) DHCPv6 . 1...128 . . 244 . UnassignedSubnetPolicy= "none" (reject) : "unreachable" "prohibit" "blackhole" "throw" . . "unreachable" : unreachable 2001:db8::/56 dev lo proto dhcp metric 1024 pref medium . RFC 7084[34] . "none" . . "unreachable" . 257 . RapidCommit= . DHCPv6 DHCPv6 (solicit reply) . DHCPv6 . (solicit advertise request reply) . . RFC 3315[36] . true . 252 . SendHostname= true () ( Hostname= ) DHCPv6 . ASCII DNS . true . 255 . Hostname= DHCPv6 . ASCII DNS . 255 . UseAddress= true () IP DHCPv6 . 248 . UseCaptivePortal= true () DHCPv6 networkctl(1) . 254 . UseDelegatedPrefix= true () DHCPv6 . DHCPPrefixDelegation=yes . DHCPPrefixDelegation= [Network] [DHCPPrefixDelegation] RFC 8415[37] . 250 . UseDNS=, UseDNR=, UseNTP=, UseHostname=, UseDomains=, NetLabel=, SendRelease= [DHCPv4]. 243 . NFTSet= NFT DHCP NFTSet= [Address] . NFTSet= [Address] . "address" "prefix" NFT "ipv6_addr" . 255 . WithoutRA= DHCPv6 "managed" "other configuration" . "no" "solicit" "information-request" . DHCPPrefixDelegation= UplinkInterface=:self [DHCPPrefixDelegation] "solicit" . "no" DHCPv6 RA . DHCPv6Client= [IPv6AcceptRA] . 246 . [DHCPPREFIXDELEGATION] ([DHCPPREFIXDELEGATION] SECTION OPTIONS) [DHCPPrefixDelegation] DHCPv6 DHCPv4 6RD . DHCPPrefixDelegation= [Network] . UplinkInterface= (uplink) ":self" ":auto" . ":self" WithoutRA=solicit . ":auto" DHCPv6 DHCPv4 . ":auto" . 250 . SubnetId= (subnet ID) () . "auto" () ( RFC 4291[38] .. ) 0x7fffffffffffffff . 246 . Announce= . IPv6SendRA= [Network] IPv6 . DHCPPrefixDelegation= . yes . 247 . Assign= . WAN DHCPv6 . true ( LAN) EUI-64 . Token= . yes . 246 . Token= . Token= [IPv6AcceptRA] . Assign= false . EUI-64 . 246 . ManageTemporaryAddress= [Address] true . 248 . RouteMetric= . 0...4294967295 . . 256 . 249 . NetLabel= NetLabel DHCP NetLabel= [Address] . NetLabel= [Address] . 252 . NFTSet= NFT DHCP NFTSet= [Address] . NFTSet= [Address] . "address" "prefix" NFT "ipv6_addr" . 255 . [IPV6ACCEPTRA] ([IPV6ACCEPTRA] SECTION OPTIONS) [IPv6AcceptRA] IPv6 (RA) IPv6AcceptRA= : UseRedirect= true () Redirect . 256 . Token= (SLAAC) . : eui64 EUI-64 . InfiniBand . 250 . static:ADDRESS IPv6 (":") (RA) . RA RA . SLAAC EUI-64 . ( ) . IPv6 "static" . 250 . prefixstable[:ADDRESS][,UUID] RFC 7217[39] . IPv6 (":") . IPv6 RA . UUID sd_id128_from_string() "86b123b969ba4b7eb8b3d8605123525a" "86b123b9-69ba-4b7e-b8b3-d8605123525a". UUID . . sd-id128(3) sd_id128_from_string(3) sd_id128_get_machine(3) . "prefixstable" MAC ( ) RA . 250 . ( ) "prefixstable" EUI-64 InfiniBand "prefixstable" . . . : Token=eui64 Token=::1a:2b:3c:4d Token=static:::1a:2b:3c:4d Token=prefixstable Token=prefixstable:2002:da8:1:: 250 . UseDNS= true () DNS . nameserver resolv.conf(5) . 231 . UseDNR= true DNR . UseDNS= . 257 . UseDomains= "route" . true IPv6 (RA) DNS Domains=. "route" IPv6 RA DNS Domains= "~" . false . . . true domain resolv.conf(5) . 231 . RouteTable=num . "default" "main" "local" RouteTable= networkd.conf(5) 1...4294967295 . VRF= VRF . 232 . RouteMetric= . 0...4294967295 ":" (high) (medium) (low) ("high:medium:low"). "512:1024:2048" . 249 . QuickAck= . true ACK TCP RA . . 253 . UseMTU= . true MTU . true . 250 . UseHopLimit= . true . IPv6HopLimit= . true . 255 . UseReachableTime= . true . . true . 256 . UseRetransmissionTime= . true . Neighbor Solicitation . true . 256 . UseGateway= true () . 250 . UseRoutePrefix= true () . 250 . UseCaptivePortal= true () networkctl(1) . 254 . UsePREF64= true IPv6 PREF64 ( NAT64) networkctl(1) . RFC 8781[40] . false . 255 . UseAutonomousPrefix= true () . 242 . UseOnLinkPrefix= true () onlink . 242 . RouterDenyList= IPv6 . "/" . . 248 . RouterAllowList= IPv6 . "/" . . RouterAllowList= RouterDenyList= . 248 . PrefixDenyList= IPv6 . "/" . IPv6 . 248 . PrefixAllowList= IPv6 . "/" . IPv6 . PrefixAllowList= PrefixDenyList= . 248 . RouteDenyList= IPv6 . "/" . IPv6 . 248 . RouteAllowList= IPv6 . "/" . IPv6 . RouteAllowList= RouteDenyList= . 248 . DHCPv6Client= "always" . true DHCPv6 "managed" RA "solicit" "managed" "other configuration" "information-request" . "always" DHCPv6 RA "solicit" "managed" "other configuration" RA . WithoutRA= [DHCPv6] UplinkInterface=:self [DHCPPrefixDelegation] . true . 246 . NetLabel= NetLabel RA NetLabel= [Address] . NetLabel= [Address] . 252 . NFTSet= NFT RA NFTSet= [Address] . NFTSet= [Address] . "address" "prefix" NFT "ipv6_addr" . 255 . [DHCPSERVER] ([DHCPSERVER] SECTION OPTIONS) [DHCPServer] DHCP DHCPServer= : ServerAddress= DHCP . IPv4 "192.168.0.1/24". IPv4 [Network] [Address] . DHCP IPv4 . Address= [Network] [Address] . : [Network] DHCPServer=yes Address=192.168.0.1/24 Address=192.168.0.2/24 [DHCPServer] ServerAddress=192.168.0.1/24 : [Network] DHCPServer=yes [Address] Address=192.168.0.1/24 [Address] Address=192.168.0.2/24 [DHCPServer] ServerAddress=192.168.0.1/24 : [Network] DHCPServer=yes Address=192.168.0.2/24 [DHCPServer] ServerAddress=192.168.0.1/24 255 Address= [Network] [Address] (null) "0.0.0.0/24" . Address= [Network] . 249 . PoolOffset=, PoolSize= (pool) . IP . PoolOffset= . PoolSize= IP . . ( ) . 226 . DefaultLeaseTimeSec=, MaxLeaseTimeSec= DHCP . . . . 1h ( ) 12h ( ) . DHCP . DHCP . 226 . UplinkInterface= (uplink) ":none" ":auto" . DNS NTP SIP . ":auto" . ":none" . ":auto" . 249 . EmitDNS=, DNS= EmitDNS= . DHCP DNS . "yes" . DNS DNS= IPv4 "_server_address" DHCP . EmitDNS= "" . "" . DNS . DNS /etc/resolv.conf . . DNS DHCP MaxLeaseTimeSec= . . DNS . 226 . EmitNTP=, NTP=, EmitSIP=, SIP=, EmitPOP3=, POP3=, EmitSMTP=, SMTP=, EmitLPR=, LPR= EmitDNS= DNS= DHCP . EmitDNS= DNS= . 226 . EmitRouter=, Router= EmitRouter= DHCP router . Router= IPv4 . Router= router . EmitRouter= Router= . EmitRouter= true Router= . 230 . EmitTimezone=, Timezone= . DHCP . "yes" . Timezone= ( "Asia/Tehran" "Europe/Berlin" "UTC") . /etc/localtime . 226 . BootServerAddress= IPv4 PXE . siaddr DHCP . RFC 2131[41] . . 251 . BootServerName= PXE . DHCP ( "TFTP server name") . RFC 2132[42] . . BootServerName= BootServerAddress= . 251 . BootFilename= URL PXE . DHCP ( "Bootfile name") . RFC 2132[42] . . 251 . IPv6OnlyPreferredSec= . IPv6-Only Preferred RFC 8925[35] . DHCPv4 -IPv6 IPv6 IPv4 . . . 255 . SendOption= DHCPv4 . DHCP ("option:type:value"). 1...254 . "uint8" "uint16" "uint32" "ipv4address" "ipv6address" "string" . C[30] . . . . 244 . SendVendorOption= DHCPv4 . DHCP ("option:type:value"). 1...254 . "uint8" "uint16" "uint32" "ipv4address" "string" . C[30] . . . . 246 . BindToInterface= . "yes" DHCP . "yes" RelayTarget= ( ) "no" . 249 . RelayTarget= IPv4 inet_pton(3) . DHCP DHCP . RFC 1542[43] . DHCP DHCP . 249 . RelayAgentCircuitId= Agent Circuit ID Relay Agent Information . "string:value" "value" . ( Agent Circuit ID ). RelayTarget= . 249 . RelayAgentRemoteId= Agent Remote ID Relay Agent Information . "string:value" "value" . ( Agent Remote ID ). RelayTarget= . 249 . RapidCommit= . true RFC 4039[44] . DHCPDISCOVER Rapid Commit DHCPOFFER DHCPACK . true . 255 . PersistLeases= . true DHCP . false DHCP . networkctl reconfigure systemd-networkd.service(8) . . . networkd.conf(5) "yes" . 256 . [DHCPSERVERSTATICLEASE] ([DHCPSERVERSTATICLEASE] SECTION OPTIONS) "[DHCPServerStaticLease]" DHCP IPv4 MAC . . MACAddress= . . 249 . Address= IPv4 MACAddress= . . 249 . [IPV6SENDRA] ([IPV6SENDRA] SECTION OPTIONS) [IPv6SendRA] IPv6 IPv6SendRA= . IPv6 [IPv6Prefix] [IPv6RoutePrefix] . Managed=, OtherInformation= . DHCPv6 IPv6 Managed= "true" DHCPv6 OtherInformation= "true" . "false" DHCPv6 . 235 . RouterLifetimeSec= . IPv6 . . . ( ) . 235 . ReachableTimeSec= . 0...4294967295 . . . 256 . RetransmitSec= . 0...4294967295 . . . 255 . RouterPreference= IPv6 RouterLifetimeSec= . "high" "medium" "low" "normal" "default" "medium" . RFC 4191[24] . "medium" . 235 . HopLimit= . 0...255 . IPv6HopLimit= . 255 . UplinkInterface= (uplink) ":none" ":auto" . DNS . ":auto" DHCPPrefixDelegation= [DHCPPrefixDelegation] . ":none" . ":auto" . 250 . EmitDNS=, DNS= DNS= IPv6 DNS true EmitDNS= . DNS= "_link_local" IPv6 . DNS= DNS [Network] . [Network] DNS DNS UplinkInterface= . EmitDNS= false DNS . EmitDNS= true . 235 . EmitDomains=, Domains= DNS true EmitDomains= . Domains= DNS [Network] . [Network] DNS DNS UplinkInterface= . EmitDomains= false DNS . EmitDomains= true . 235 . DNSLifetimeSec= DNS DNS= Domains=. ( ) . 235 . HomeAgent= . IPv6 (Home Agent) Home Agent . false . RFC 6275[13] . 255 . HomeAgentLifetimeSec= . . 1...65535. RouterLifetimeSec= . 255 . HomeAgentPreference= IPv6 . 0...65535 . . 255 . [IPV6PREFIX] ([IPV6PREFIX] SECTION OPTIONS) [IPv6Prefix] IPv6 . RFC 4861[45] . AddressAutoconfiguration=, OnLink= IPv6 onlink . "true" . 235 . Prefix= IPv6 . IPv6 IPv6 "/" . [IPv6Prefix] IPv6 onlink . 235 . PreferredLifetimeSec=, ValidLifetimeSec= . PreferredLifetimeSec= ( ) ValidLifetimeSec= ( ) . 235 . Assign= . true . false . 246 . Token= . Token= [IPv6AcceptRA] . Assign= false . EUI-64 . 250 . RouteMetric= . 0...4294967295 . . Assign= false . 249 . [IPV6ROUTEPREFIX] ([IPV6ROUTEPREFIX] SECTION OPTIONS) [IPv6RoutePrefix] IPv6 . RFC 4191[24] . Route= IPv6 . IPv6 IPv6 "/" . [IPv6RoutePrefix] IPv6 . 244 . LifetimeSec= . LifetimeSec= ( ) . 244 . [IPV6PREF64PREFIX] ([IPV6PREF64PREFIX] SECTION OPTIONS) [IPv6PREF64Prefix] IPv6 PREF64 ( NAT64) . RFC 8781[40] . Prefix= IPv6 PREF64 ( NAT64) . IPv6 NAT64 (PLAT) 464XLAT . [IPv6PREF64Prefix] IPv6 . "/" . NAT64 . 255 . LifetimeSec= . RouterLifetimeSec= . LifetimeSec= . 255 . [BRIDGE] ([BRIDGE] SECTION OPTIONS) [Bridge] : UnicastFlood= . FDB (flood) . . 223 . MulticastFlood= . MDB . . 242 . MulticastToUnicast= . (multicast to unicast) multicast snooping . . . 240 . NeighborSuppression= . ARP ND . . 242 . Learning= . MAC . . 242 . HairPin= . . false . . 223 . Isolated= . . . true Isolated false . false . . 251 . UseBPDU= . STP ( BPDU) . . 223 . FastLeave= . IGMP Leave . IGMP snooping . . 223 . AllowPortToBeRoot= . (root port) . STP . . 223 . ProxyARP= . ARP . . 243 . ProxyARPWiFi= . ARP IEEE 802.11 Hotspot 2.0 . . 243 . MulticastRouter= . . "no" "query" "permanent" "temporary" . . 243 . Cost= "" (cost) . . . . 218 . Priority= "" (priority) . . . . systemd-networkd . 234 . [BRIDGEFDB] ([BRIDGEFDB] SECTION OPTIONS) [BridgeFDB] (FDB) . MAC [BridgeFDB] . MACAddress= [Network]. . 219 . Destination= IP VXLAN . 243 . VLANId= VLAN MAC . VLAN MAC . 219 . VNI= VXLAN ( VXLAN) VXLAN . 1...16777215 . . 243 . AssociatedWith= . "use" "self" "master" "router" . "use" . fdb . "self" fdb ( ). "master" fdb (master) . "router" . VXLAN . "self" . 243 . OutgoingInterface= VXLAN VXLAN . . 249 . [BRIDGEMDB] ([BRIDGEMDB] SECTION OPTIONS) [BridgeMDB] . [BridgeMDB] . MulticastGroupAddress= IPv4 IPv6 L2 MAC . . 247 . VLANId= VLAN . ( VLAN) . . 247 . [LLDP] ([LLDP] SECTION OPTIONS) [LLDP] (LLDP) : MUDURL= URL (MUD) LLDP . MUDURL= [DHCPv4] . MUD LLDP sd_lldp_neighbor_get_mud_url() . 246 . [CAN] ([CAN] SECTION OPTIONS) [CAN] ( CAN) : BitRate= CAN . SI (K, M) . 1...4294967295 . 239 . SamplePoint= ( "75%" "87.5%") ( "875"). BitRate= . 239 . TimeQuantaNSec=, PropagationSegment=, PhaseBufferSegment1=, PhaseBufferSegment2=, SyncJumpWidth= (time quanta) (propagation segment) CAN Bosch CAN 2.0 . TimeQuantaNSec= . PropagationSegment= PhaseBufferSegment1= PhaseBufferSegment2= SyncJumpWidth= TimeQuantaNSec= 0...4294967295 . SyncJumpWidth= BitRate= . 250 . DataBitRate=, DataSamplePoint= CAN-FD . BitRate= SamplePoint= . 246 . DataTimeQuantaNSec=, DataPropagationSegment=, DataPhaseBufferSegment1=, DataPhaseBufferSegment2=, DataSyncJumpWidth= CAN-FD . TimeQuantaNSec= . 250 . FDMode= . "yes" CAN-FD . CAN-FD DataBitRate= DataSamplePoint= DataTimeQuanta= . 246 . FDNonISO= . "yes" -ISO CAN-FD . . 246 . RestartSec= . (bus-off) CAN . ( "0.1s") "ms" "us" . "infinity" "0" . . 239 . Termination= (termination resistor) 0...65535 . "yes" . "no" "0" . . 246 . TripleSampling= . "yes" ( ) . . 242 . BusErrorReporting= . "yes" CAN ( ). . : CAN CAN CAN CAN . 248 . ListenOnly= . "yes" - (listen-only) . - CAN ACK . - CAN CAN . . 246 . Loopback= . "yes" (loopback) . . CAN . . 250 . OneShot=?R . "yes" (one-shot) . . 250 . PresumeAck=?R . "yes" ACK CAN . . 250 . ClassicDataLengthCode=?R . "yes" (DLC) . . 250 . [IPOIB] ([IPOIB] SECTION OPTIONS) [IPoIB] IP Infiniband : Mode= "datagram" "connected" . . "datagram" (UD) MTU IB L2 MTU IPoIB ( ) . IB MTU 2K MTU IPoIB 2048 - 4 = 2044 . "connected" (RC) . IB MTU IP 64K IP UDP TCP . 250 . IgnoreUserspaceMulticastGroup= . true . . 250 . [QDISC] ([QDISC] SECTION OPTIONS) [QDisc] (qdisc) . Parent= (qdisc) . "clsact" "ingress" . . 244 . Handle= qdisc (handle) . 0x1-0xffff . . [NETWORKEMULATOR] ([NETWORKEMULATOR] SECTION OPTIONS) [NetworkEmulator] (qdisc) . UDP TCP . Parent= (qdisc) . "root" "clsact" "ingress" . 0x1-0xffff ("major:minor"). "root" . Handle= qdisc handle . 0x1-0xffff . . DelaySec= . . 245 . DelayJitterSec= (jitter) . . 245 . PacketLimit= qdisc . 0...4294967294. . 245 . LossRate= . "%" . . 245 . DuplicateRate= . "%" . . 245 . [TOKENBUCKETFILTER] ([TOKENBUCKETFILTER] SECTION OPTIONS) [TokenBucketFilter] (qdisc) (tbf) . Parent= (qdisc) . "root" "clsact" "ingress" . 0x1-0xffff ("major:minor"). "root" . Handle= qdisc handle . 0x1-0xffff . . LatencySec= (TBF) . . 245 . LimitBytes= . K M G . . 246 . BurstBytes= . . K M G . . 246 . Rate= . K M G . . 245 . MPUBytes= (MPU) ( ) . K M G . . 245 . PeakRate= . K M G . . 245 . MTUBytes= peakrate . K M G . . 245 . [PIE] ([PIE] SECTION OPTIONS) [PIE] (qdisc) - (PIE) . Parent= (qdisc) . "root" "clsact" "ingress" . 0x1-0xffff ("major:minor"). "root" . Handle= qdisc handle . 0x1-0xffff . . PacketLimit= . . 1...4294967294. . 246 . [FLOWQUEUEPIE] ([FLOWQUEUEPIE] SECTION OPTIONS) "[FlowQueuePIE]" (qdisc) - (fq_pie) . Parent= (qdisc) . "root" "clsact" "ingress" . 0x1-0xffff ("major:minor"). "root" . Handle= qdisc handle . 0x1-0xffff . . PacketLimit= . . 4294967294. . 247 . [STOCHASTICFAIRBLUE] ([STOCHASTICFAIRBLUE] SECTION OPTIONS) [StochasticFairBlue] (qdisc) (sfb) . Parent= (qdisc) . "root" "clsact" "ingress" . 0x1-0xffff ("major:minor"). "root" . Handle= qdisc handle . 0x1-0xffff . . PacketLimit= . . 0...4294967294. . 246 . [STOCHASTICFAIRNESSQUEUEING] ([STOCHASTICFAIRNESSQUEUEING] SECTION OPTIONS) [StochasticFairnessQueueing] (qdisc) (sfq) . Parent= (qdisc) . "root" "clsact" "ingress" . 0x1-0xffff ("major:minor"). "root" . Handle= qdisc handle . 0x1-0xffff . . PerturbPeriodSec= (perturbation) . . 245 . [BFIFO] ([BFIFO] SECTION OPTIONS) [BFIFO] (qdisc) (bfifo) . Parent= (qdisc) . "root" "clsact" "ingress" . 0x1-0xffff ("major:minor"). "root" . Handle= qdisc handle . 0x1-0xffff . . LimitBytes= FIFO . . . K M G . . 246 . [PFIFO] ([PFIFO] SECTION OPTIONS) [PFIFO] (qdisc) (pfifo) . Parent= (qdisc) . "root" "clsact" "ingress" . 0x1-0xffff ("major:minor"). "root" . Handle= qdisc handle . 0x1-0xffff . . PacketLimit= FIFO . . . 0...4294967294. . 246 . [PFIFOHEADDROP] ([PFIFOHEADDROP] SECTION OPTIONS) [PFIFOHeadDrop] (qdisc) (pfifo_head_drop) . Parent= (qdisc) . "root" "clsact" "ingress" . 0x1-0xffff ("major:minor"). "root" . Handle= qdisc handle . 0x1-0xffff . . PacketLimit= [PFIFO]. 246 . [PFIFOFAST] ([PFIFOFAST] SECTION OPTIONS) [PFIFOFast] (qdisc) (pfifo_fast) . Parent= (qdisc) . "root" "clsact" "ingress" . 0x1-0xffff ("major:minor"). "root" . Handle= qdisc handle . 0x1-0xffff . . [CAKE] ([CAKE] SECTION OPTIONS) [CAKE] (qdisc) (CAKE) . Parent= (qdisc) . "root" "clsact" "ingress" . 0x1-0xffff ("major:minor"). "root" . Handle= qdisc handle . 0x1-0xffff . . Bandwidth= (shaper) . K M G . . 246 . AutoRateIngress= . qdisc . . Bandwidth= . . 250 . OverheadBytes= . . -64...256 . . 246 . MPUBytes= ( ) . 1...256 . . 250 . CompensationMode= "none" "atm" "ptm" . . "none" . "atm" ATM ADSL . "ptm" PTM VDSL2 64b/65b . . 250 . UseRawPacketSize= . true IP . . 250 . FlowIsolationMode= CAKE . . : none . 250 . src-host . "srchost" tc qdisc . tc-cake(8) . 250 . dst-host . "dsthost" tc qdisc . tc-cake(8) . 250 . hosts - . tc qdisc . tc-cake(8) . 250 . flows - . tc qdisc . tc-cake(8) . 250 . dual-src-host - ( "flows" ) . "dual-srchost" tc qdisc . tc-cake(8) . 250 . dual-dst-host - ( "flows" ) . "dual-dsthost" tc qdisc . tc-cake(8) . 250 . triple - ( "flows" ) . "triple-isolate" tc qdisc . tc-cake(8) . 250 . . 250 . NAT= . true CAKE NAT NAT . FlowIsolationMode= "none" "flows" NAT . . 250 . PriorityQueueingPreset= CAKE "" (tins) tin . tin . : besteffort tin . 250 . precedence "Precedence" TOS . . 250 . diffserv8 Differentiated Service ("DiffServ") tin : Background Traffic High Throughput Best Effort Video Streaming Low Latency Transactions Interactive Shell Minimum Latency Network Control. 250 . diffserv4 Differentiated Service ("DiffServ") tin : Background Traffic Best Effort Streaming Media Latency Sensitive. 250 . diffserv3 Differentiated Service ("DiffServ") tin : Background Traffic Best Effort Latency Sensitive. 250 . . 250 . FirewallMark= 1...4294967295 . tin CAKE . . 250 . Wash= . true CAKE DSCP ECN CAKE . . 250 . SplitGSO= . true CAKE General Segmentation Offload (GSO) . . 250 . RTTSec= (RTT) . . 100us 10GigE+ 1ms LAN 100ms . . 253 . AckFilter= "aggressive" . ACK ACK . yes ACK "aggressive" ACK . . . 253 . [CONTROLLEDDELAY] ([CONTROLLEDDELAY] SECTION OPTIONS) [ControlledDelay] (qdisc) (CoDel) . Parent= (qdisc) . "root" "clsact" "ingress" . 0x1-0xffff ("major:minor"). "root" . Handle= qdisc handle . 0x1-0xffff . . PacketLimit= . . 0...4294967294. . 245 . TargetSec= . / . . 245 . IntervalSec= . . . 245 . ECN= . . . 245 . CEThresholdSec= . ECN Congestion Experienced (CE) . . 245 . [DEFICITROUNDROBINSCHEDULER] ([DEFICITROUNDROBINSCHEDULER] SECTION OPTIONS) [DeficitRoundRobinScheduler] (qdisc) (DRR) . Parent= (qdisc) . "root" "clsact" "ingress" . 0x1-0xffff ("major:minor"). "root" . Handle= qdisc handle . 0x1-0xffff . . [DEFICITROUNDROBINSCHEDULERCLASS] ([DEFICITROUNDROBINSCHEDULERCLASS] SECTION OPTIONS) [DeficitRoundRobinSchedulerClass] (DRR) . Parent= (qdisc) . "root" qdisc . qdisc 0x1-0xffff ("major:minor"). "root" . ClassId= . 0x1-0xffff ("major:minor"). . QuantumBytes= . K M G . MTU . 246 . [ENHANCEDTRANSMISSIONSELECTION] ([ENHANCEDTRANSMISSIONSELECTION] SECTION OPTIONS) [EnhancedTransmissionSelection] (qdisc) (ETS) . Parent= (qdisc) . "root" "clsact" "ingress" . 0x1-0xffff ("major:minor"). "root" . Handle= qdisc handle . 0x1-0xffff . . Bands= . 1...16. StrictBands= QuantumBytes= . 246 . StrictBands= . 1...16. 246 . QuantumBytes= . K M G . . . 246 . PriorityMap= . . . . . 0...255 . . . 246 . [GENERICRANDOMEARLYDETECTION] ([GENERICRANDOMEARLYDETECTION] SECTION OPTIONS) [GenericRandomEarlyDetection] (qdisc) (GRED) . Parent= (qdisc) . "root" "clsact" "ingress" . 0x1-0xffff ("major:minor"). "root" . Handle= qdisc handle . 0x1-0xffff . . VirtualQueues= . 1...16 . . 246 . DefaultVirtualQueue= . VirtualQueue= . . 246 . GenericRIO= . RIO . . 246 . [FAIRQUEUEINGCONTROLLEDDELAY] ([FAIRQUEUEINGCONTROLLEDDELAY] SECTION OPTIONS) [FairQueueingControlledDelay] (qdisc) (FQ-CoDel) . Parent= (qdisc) . "root" "clsact" "ingress" . 0x1-0xffff ("major:minor"). "root" . Handle= qdisc handle . 0x1-0xffff . . PacketLimit= . . . 245 . MemoryLimitBytes= FQ-CoDel . K M G . . 246 . Flows= . . 245 . TargetSec= . / . . 245 . IntervalSec= . . . 245 . QuantumBytes= "" . K M G . . 246 . ECN= . . . 245 . CEThresholdSec= . ECN Congestion Experienced (CE) . . 245 . [FAIRQUEUEING] ([FAIRQUEUEING] SECTION OPTIONS) [FairQueueing] (qdisc) (FQ) . Parent= (qdisc) . "root" "clsact" "ingress" . 0x1-0xffff ("major:minor"). "root" . Handle= qdisc handle . 0x1-0xffff . . PacketLimit= . . . 245 . FlowLimit= . . 245 . QuantumBytes= RR . K M G . . 246 . InitialQuantumBytes= . K M G . . 245 . MaximumRate= . K M G . . 245 . Buckets= . . 245 . OrphanMask= . fq . . 245 . Pacing= (flow pacing) . . 245 . CEThresholdSec= . ECN Congestion Experienced (CE) . . 245 . [TRIVIALLINKEQUALIZER] ([TRIVIALLINKEQUALIZER] SECTION OPTIONS) [TrivialLinkEqualizer] (qdisc) (teql) . Parent= (qdisc) . "root" "clsact" "ingress" . 0x1-0xffff ("major:minor"). "root" . Handle= qdisc handle . 0x1-0xffff . . Id= "N" teql . "0" . teql sch_teql max_equalizers=N+1 systemd-networkd . 245 . [HIERARCHYTOKENBUCKET] ([HIERARCHYTOKENBUCKET] SECTION OPTIONS) [HierarchyTokenBucket] (qdisc) (htb) . Parent= (qdisc) . "root" "clsact" "ingress" . 0x1-0xffff ("major:minor"). "root" . Handle= qdisc handle . 0x1-0xffff . . DefaultClass= . . . 246 . RateToQuantum= . DRR Rate= RateToQuantum= . 246 . [HIERARCHYTOKENBUCKETCLASS] ([HIERARCHYTOKENBUCKETCLASS] SECTION OPTIONS) [HierarchyTokenBucketClass] (htb) . Parent= (qdisc) . "root" qdisc . qdisc 0x1-0xffff ("major:minor"). "root" . ClassId= . 0x1-0xffff ("major:minor"). . Priority= . (round-robin) . 246 . QuantumBytes= (leaf) . K M G . 246 . MTUBytes= . K M G . 246 . OverheadBytes= . K M G . 246 . Rate= . K M G . . 246 . CeilRate= . K M G . Rate= . 246 . BufferBytes= . K M G . 246 . CeilBufferBytes= ceil . K M G . 246 . [CLASSFULMULTIQUEUEING] ([CLASSFULMULTIQUEUEING] SECTION OPTIONS) [ClassfulMultiQueueing] (qdisc) (mq) . Parent= (qdisc) . "root" "clsact" "ingress" . 0x1-0xffff ("major:minor"). "root" . Handle= qdisc handle . 0x1-0xffff . . [BANDMULTIQUEUEING] ([BANDMULTIQUEUEING] SECTION OPTIONS) [BandMultiQueueing] (qdisc) (multiq) . Parent= (qdisc) . "root" "clsact" "ingress" . 0x1-0xffff ("major:minor"). "root" . Handle= qdisc handle . 0x1-0xffff . . [HEAVYHITTERFILTER] ([HEAVYHITTERFILTER] SECTION OPTIONS) [HeavyHitterFilter] (qdisc) (hhf) . Parent= (qdisc) . "root" "clsact" "ingress" . 0x1-0xffff ("major:minor"). "root" . Handle= qdisc handle . 0x1-0xffff . . PacketLimit= . . 0...4294967294. . 246 . [QUICKFAIRQUEUEING] ([QUICKFAIRQUEUEING] SECTION OPTIONS) [QuickFairQueueing] (qdisc) (QFQ) . Parent= (qdisc) . "root" "clsact" "ingress" . 0x1-0xffff ("major:minor"). "root" . Handle= qdisc handle . 0x1-0xffff . . [QUICKFAIRQUEUEINGCLASS] ([QUICKFAIRQUEUEINGCLASS] SECTION OPTIONS) [QuickFairQueueingClass] (qfq) . Parent= (qdisc) . "root" qdisc . qdisc 0x1-0xffff ("major:minor"). "root" . ClassId= . 0x1-0xffff ("major:minor"). . Weight= . 1...1023 . . 246 . MaxPacketBytes= . K M G . . 246 . [BRIDGEVLAN] ([BRIDGEVLAN] SECTION OPTIONS) [BridgeVLAN] VLAN . VLANFiltering= [Bridge] systemd.netdev(5) VLAN [BridgeVLAN] . VLAN .network . VLAN .network VLANFiltering= . VLAN= VLAN . M-N . 1...4094 . . . 231 . EgressUntagged= VLAN (untag) . EgressUntagged= VLAN= VLAN . M-N . . . 231 . PVID= VLAN . VLAN ( "no") . false VLAN . PVID= VLAN= VLAN . VLAN . 231 . (EXAMPLES) 1. # /etc/systemd/network/50-static.network [Match] Name=enp2s0 [Network] Address=192.168.0.15/24 Gateway=192.168.0.1 "enp2s0" . . 2. DHCP # /etc/systemd/network/60-dhcp.network [Match] Name=en* [Network] DHCP=yes DHCPv4 DHCPv6 "en" ( ) . 3. IPv6 ( DHCPv6 PD) # /etc/systemd/network/55-dhcpv6-pd-upstream.network [Match] Name=enp1s0 [Network] DHCP=ipv6 # # . . #[Network] #DHCPPrefixDelegation=yes #[DHCPPrefixDelegation] #UplinkInterface=:self #SubnetId=0 #Announce=no # (RA) # DHCPv6 . #[Network] #IPv6AcceptRA=no #[DHCPv6] #WithoutRA=solicit # (RA) Managed # DHCPv6 RA . #[DHCPv6] #UseAddress=no #[IPv6AcceptRA] #DHCPv6Client=always # /etc/systemd/network/55-dhcpv6-pd-downstream.network [Match] Name=enp2s0 [Network] DHCPPrefixDelegation=yes IPv6SendRA=yes # . # . IPv6AcceptRA=no [DHCPPrefixDelegation] UplinkInterface=enp1s0 SubnetId=1 Announce=yes DHCPv6-PD enp1s0 DHCPv6 enp2s0 . IPv6 . 4. IPv6 ( DHCPv4 6RD) # /etc/systemd/network/55-dhcpv4-6rd-upstream.network [Match] Name=enp1s0 [Network] DHCP=ipv4 # DHCPv4-6RD IPv6 . # . IPv6AcceptRA=no [DHCPv4] Use6RD=yes # /etc/systemd/network/55-dhcpv4-6rd-downstream.network [Match] Name=enp2s0 [Network] DHCPPrefixDelegation=yes IPv6SendRA=yes # . # . IPv6AcceptRA=no [DHCPPrefixDelegation] UplinkInterface=enp1s0 SubnetId=1 Announce=yes DHCPv4-6RD enp1s0 DHCPv4 enp2s0 . IPv6 . 5. # /etc/systemd/network/25-bridge-static.netdev [NetDev] Name=bridge0 Kind=bridge # /etc/systemd/network/25-bridge-static.network [Match] Name=bridge0 [Network] Address=192.168.0.15/24 Gateway=192.168.0.1 DNS=192.168.0.1 # /etc/systemd/network/25-bridge-slave-interface-1.network [Match] Name=enp2s0 [Network] Bridge=bridge0 # /etc/systemd/network/25-bridge-slave-interface-2.network [Match] Name=wlp3s0 [Network] Bridge=bridge0 "enp2s0" "wlp3s0" . . DNS DNS . 6. VLAN # /etc/systemd/network/25-bridge-slave-interface-1.network [Match] Name=enp2s0 [Network] Bridge=bridge0 [BridgeVLAN] VLAN=1-32 PVID=42 EgressUntagged=42 [BridgeVLAN] VLAN=100-299 [BridgeVLAN] EgressUntagged=300-400 "enp2s0" VLAN . VLAN 1 32 42 100 400 . VLAN 42 300 400 . VLAN 42 . 7. /etc/systemd/network/25-tunnels.network [Match] Name=ens1 [Network] Tunnel=ipip-tun Tunnel=sit-tun Tunnel=gre-tun Tunnel=vti-tun /etc/systemd/network/25-tunnel-ipip.netdev [NetDev] Name=ipip-tun Kind=ipip /etc/systemd/network/25-tunnel-sit.netdev [NetDev] Name=sit-tun Kind=sit /etc/systemd/network/25-tunnel-gre.netdev [NetDev] Name=gre-tun Kind=gre /etc/systemd/network/25-tunnel-vti.netdev [NetDev] Name=vti-tun Kind=vti "ens1" IPIP SIT GRE VTI . 8. (Bond) # /etc/systemd/network/30-bond1.network [Match] Name=bond1 [Network] DHCP=ipv6 # /etc/systemd/network/30-bond1.netdev [NetDev] Name=bond1 Kind=bond # /etc/systemd/network/30-bond1-dev1.network [Match] MACAddress=52:54:00:e9:64:41 [Network] Bond=bond1 # /etc/systemd/network/30-bond1-dev2.network [Match] MACAddress=52:54:00:e9:64:42 [Network] Bond=bond1 bond "bond1" MAC 52:54:00:e9:64:41 52:54:00:e9:64:42 . IPv6 DHCP . 9. (VRF) "bond1" VRF "vrf1" . VRF . . VRF ip- rules . # /etc/systemd/network/25-vrf.network [Match] Name=bond1 [Network] VRF=vrf1 10. MacVTap "macvtap-test" "enp0s25" . # /usr/lib/systemd/network/25-macvtap.network [Match] Name=enp0s25 [Network] MACVTAP=macvtap-test 11. Xfrm # /etc/systemd/network/27-xfrm.netdev [NetDev] Name=xfrm0 Kind=xfrm [Xfrm] InterfaceId=7 # /etc/systemd/network/27-eth0.network [Match] Name=eth0 [Network] Xfrm=xfrm0 "xfrm0" "eth0" . ipsec "eth0" . xfrm "lo" . (SEE ALSO) systemd(1), systemd-networkd.service(8), systemd.link(5), systemd.netdev(5), systemd-network-generator.service(8), systemd- resolved.service(8) (NOTES) 1. . /usr/local/ . 2. https://systemd.io/CREDENTIALS 3. (LLMNR) https://tools.ietf.org/html/rfc4795 4. (mDNS) https://tools.ietf.org/html/rfc6762 5. DNS-over-TLS https://tools.ietf.org/html/rfc7858 6. DNSSEC https://tools.ietf.org/html/rfc4033 7. IEEE 802.1AB-2016 https://standards.ieee.org/findstds/standard/802.1AB-2016.html 8. RFC 5227 https://tools.ietf.org/html/rfc5227 9. IP Sysctl https://docs.kernel.org/networking/ip-sysctl.html 10. RFC 4941 https://tools.ietf.org/html/rfc4941 11. RFC 3704 https://tools.ietf.org/html/rfc1027 12. RFC 3069 https://tools.ietf.org/html/rfc3069 13. RFC 6275 https://tools.ietf.org/html/rfc6275 14. RFC 4862 https://tools.ietf.org/html/rfc4862 15. RFC 3041 https://tools.ietf.org/html/rfc3041 16. NetLabel https://docs.kernel.org/netlabel/index.html 17. (LSM) https://en.wikipedia.org/wiki/Linux_Security_Modules 18. NetLabel Fallback Peer Labeling https://github.com/SELinuxProject/selinux- notebook/blob/main/src/network_support.md 19. NFT https://netfilter.org/projects/nftables/index.html 20. RFC 3484 https://tools.ietf.org/html/rfc3484 21. (Type of Service) https://en.wikipedia.org/wiki/Type_of_service 22. (Differentiated services) https://en.wikipedia.org/wiki/Differentiated_services 23. (VRF) https://docs.kernel.org/networking/vrf.html 24. RFC 4191 https://tools.ietf.org/html/rfc4191 25. RFC 2132 https://tools.ietf.org/html/rfc2132 26. RFC 4702 https://tools.ietf.org/html/rfc4702 27. RFC 8520 https://tools.ietf.org/html/rfc8520 28. RFC 4039 https://tools.ietf.org/html/rfc4039 29. RFC 7844 https://tools.ietf.org/html/rfc7844 30. C https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences 31. RFC 9463 https://datatracker.ietf.org/doc/html/rfc9463 32. RFC 3442 https://datatracker.ietf.org/doc/html/rfc3442 33. RFC 5969 https://tools.ietf.org/html/rfc5969 34. RFC 7084 https://datatracker.ietf.org/doc/html/rfc7084 35. RFC 8925 https://tools.ietf.org/html/rfc8925 36. RFC 3315 https://tools.ietf.org/html/rfc3315#section-17.2.1 37. RFC 8415 https://www.rfc-editor.org/rfc/rfc8415.html#section-6.3 38. RFC 4291 https://tools.ietf.org/html/rfc4291#section-2.5.4 39. RFC 7217 https://tools.ietf.org/html/rfc7217 40. RFC 8781 https://tools.ietf.org/html/rfc8781 41. RFC 2131 https://www.rfc-editor.org/rfc/rfc2131.html 42. RFC 2132 https://www.rfc-editor.org/rfc/rfc2132.html 43. RFC 1542 https://tools.ietf.org/html/rfc1542 44. RFC 4039 https://datatracker.ietf.org/doc/html/rfc4039 45. RFC 4861 https://tools.ietf.org/html/rfc4861 systemd 257.13 SYSTEMD.NETWORK(5)