## ipv6

ipv6 — IPv6 Settings

## Properties

Table 29.

Key Name | Value Type | Default Value | Value Description
--- | --- | --- | ---

    addr-gen-mode

    int32

    3

Configure the method for creating the IPv6 interface identifier of addresses for RFC4862 IPv6 Stateless Address Autoconfiguration and IPv6 Link Local. The permitted values are: 0 (eui64), 1 (stable-privacy). 2 (default-or-eui64) or 3 (default). If the property is set to "eui64", the addresses will be generated using the interface token derived from the hardware address. This makes the host part of the address constant, making it possible to track the host's presence when it changes networks. The address changes when the interface hardware is replaced. If a duplicate address is detected, there is no fallback to generate another address. When configured, the "ipv6.token" is used instead of the MAC address to generate addresses for stateless autoconfiguration. If the property is set to "stable-privacy", the interface identifier is generated as specified by RFC7217. This works by hashing a host specific key (see NetworkManager(8) manual), the interface name, the connection's "connection.stable-id" property and the address prefix. This improves privacy by making it harder to use the address to track the host's presence as every prefix and network has a different identifier. Also, the address is stable when the network interface hardware is replaced. The special values "default" and "default-or-eui64" will fallback to the global connection default as documented in the NetworkManager.conf(5) manual. If the global default is not specified, the fallback value is "stable-privacy" or "eui64", respectively. For libnm, the property defaults to "default" since 1.40. Previously it used to default to "stable-privacy". On D-Bus, the absence of an addr-gen-mode setting equals "default". For keyfile plugin, the absence of the setting on disk means "default-or-eui64" so that the property doesn't change on upgrade from older versions. Note that this setting is distinct from the Privacy Extensions as configured by "ip6-privacy" property and it does not affect the temporary addresses configured with this option.

    address-data

    array of vardict

Array of IPv6 addresses. Each address dictionary contains at least 'address' and 'prefix' entries, containing the IP address as a string, and the prefix length as a uint32. Additional attributes may also exist on some addresses.

    addresses

    array of legacy IPv6 address struct (a(ayuay))

Deprecated in favor of the 'address-data' and 'gateway' properties, but this can be used for backward-compatibility with older daemons. Note that if you send this property the daemon will ignore 'address-data' and 'gateway'. Array of IPv6 address structures. Each IPv6 address structure is composed of an IPv6 address, a prefix length (0 - 128), and an IPv6 gateway address. The gateway may be zeroed out if no gateway exists for that subnet.

    auto-route-ext-gw

    NMTernary (int32)

    -1

VPN connections will default to add the route automatically unless this setting is set to FALSE. For other connection types, adding such an automatic route is currently not supported and setting this to TRUE has no effect.

    dad-timeout

    int32

    -1

Maximum timeout in milliseconds used to check for the presence of duplicate IP addresses on the network. If an address conflict is detected, the activation will fail. The property is currently implemented only for IPv4. A zero value means that no duplicate address detection is performed, -1 means the default value (either the value configured globally in NetworkManger.conf or 200ms). A value greater than zero is a timeout in milliseconds. Note that the time intervals are subject to randomization as per RFC 5227 and so the actual duration can be between half and the full time specified in this property.

    dhcp-dscp

    string

Specifies the value for the DSCP field (traffic class) of the IP header. When empty, the global default value is used; if no global default is specified, it is assumed to be "CS0". Allowed values are: "CS0", "CS4" and "CS6". The property is currently valid only for IPv4, and it is supported only by the "internal" DHCP plugin.

    dhcp-duid

    string

A string containing the DHCPv6 Unique Identifier (DUID) used by the dhcp client to identify itself to DHCPv6 servers (RFC 3315). The DUID is carried in the Client Identifier option. If the property is a hex string ('aa:bb:cc') it is interpreted as a binary DUID and filled as an opaque value in the Client Identifier option. The special value "lease" will retrieve the DUID previously used from the lease file belonging to the connection. If no DUID is found and "dhclient" is the configured dhcp client, the DUID is searched in the system-wide dhclient lease file. If still no DUID is found, or another dhcp client is used, a global and permanent DUID-UUID (RFC 6355) will be generated based on the machine-id. The special values "llt" and "ll" will generate a DUID of type LLT or LL (see RFC 3315) based on the current MAC address of the device. In order to try providing a stable DUID-LLT, the time field will contain a constant timestamp that is used globally (for all profiles) and persisted to disk. The special values "stable-llt", "stable-ll" and "stable-uuid" will generate a DUID of the corresponding type, derived from the connection's stable-id and a per-host unique key. You may want to include the "${DEVICE}" or "${MAC}" specifier in the stable-id, in case this profile gets activated on multiple devices. So, the link-layer address of "stable-ll" and "stable-llt" will be a generated address derived from the stable id. The DUID-LLT time value in the "stable-llt" option will be picked among a static timespan of three years (the upper bound of the interval is the same constant timestamp used in "llt"). When the property is unset, the global value provided for "ipv6.dhcp-duid" is used. If no global value is provided, the default "lease" value is assumed.

    dhcp-hostname

    string

If the "dhcp-send-hostname" property is TRUE, then the specified name will be sent to the DHCP server when acquiring a lease. This property and "dhcp-fqdn" are mutually exclusive and cannot be set at the same time.

    dhcp-hostname-flags

    uint32

    0

Flags for the DHCP hostname and FQDN. Currently, this property only includes flags to control the FQDN flags set in the DHCP FQDN option. Supported FQDN flags are 0x1 (fqdn-serv-update), 0x2 (fqdn-encoded) and 0x4 (fqdn-no-update). When no FQDN flag is set and 0x8 (fqdn-clear-flags) is set, the DHCP FQDN option will contain no flag. Otherwise, if no FQDN flag is set and 0x8 (fqdn-clear-flags) is not set, the standard FQDN flags are set in the request: 0x1 (fqdn-serv-update), 0x2 (fqdn-encoded) for IPv4 and 0x1 (fqdn-serv-update) for IPv6. When this property is set to the default value 0x0 (none), a global default is looked up in NetworkManager configuration. If that value is unset or also 0x0 (none), then the standard FQDN flags described above are sent in the DHCP requests.

    dhcp-iaid

    string

A string containing the "Identity Association Identifier" (IAID) used by the DHCP client. The string can be a 32-bit number (either decimal, hexadecimal or as colon separated hexadecimal numbers). Alternatively it can be set to the special values "mac", "perm-mac", "ifname" or "stable". When set to "mac" (or "perm-mac"), the last 4 bytes of the current (or permanent) MAC address are used as IAID. When set to "ifname", the IAID is computed by hashing the interface name. The special value "stable" can be used to generate an IAID based on the stable-id (see connection.stable-id), a per-host key and the interface name. When the property is unset, the value from global configuration is used; if no global default is set then the IAID is assumed to be "ifname". For DHCPv4, the IAID is only used with "ipv4.dhcp-client-id" values "duid" and "ipv6-duid" to generate the client-id. For DHCPv6, note that at the moment this property is only supported by the "internal" DHCPv6 plugin. The "dhclient" DHCPv6 plugin always derives the IAID from the MAC address. The actually used DHCPv6 IAID for a currently activated interface is exposed in the lease information of the device.

    dhcp-pd-hint

    string

A IPv6 address followed by a slash and a prefix length. If set, the value is sent to the DHCPv6 server as hint indicating the prefix delegation (IA_PD) we want to receive. To only hint a prefix length without prefix, set the address part to the zero address (for example "::/60").

    dhcp-reject-servers

    array of string

Array of servers from which DHCP offers must be rejected. This property is useful to avoid getting a lease from misconfigured or rogue servers. For DHCPv4, each element must be an IPv4 address, optionally followed by a slash and a prefix length (e.g. "192.168.122.0/24"). This property is currently not implemented for DHCPv6.

    dhcp-send-hostname

    boolean

    TRUE

Since 1.52 this property is deprecated and is only used as fallback value for "dhcp-send-hostname-v2" if it's set to 'default'. This is only done to avoid breaking existing configurations, the new property should be used from now on.

    dhcp-send-hostname-v2

    int32

    -1

If TRUE, a hostname is sent to the DHCP server when acquiring a lease. Some DHCP servers use this hostname to update DNS databases, essentially providing a static hostname for the computer. If the "dhcp-hostname" property is NULL and this property is TRUE, the current persistent hostname of the computer is sent. The default value is -1 (default). In this case the global value from NetworkManager configuration is looked up. If it's not set, the value from "dhcp-send-hostname", which defaults to TRUE, is used for backwards compatibility. In the future this will change and, in absence of a global default, it will always fallback to TRUE.

    dhcp-send-release

    NMTernary (int32)

    -1

Whether the DHCP client will send RELEASE message when bringing the connection down. The default value is -1 (default). When the default value is specified, then the global value from NetworkManager configuration is looked up, if not set, it is considered as FALSE.

    dhcp-timeout

    int32

    0

A timeout for a DHCP transaction in seconds. If zero (the default), a globally configured default is used. If still unspecified, a device specific timeout is used (usually 45 seconds). Set to 2147483647 (MAXINT32) for infinity.

    dns

    array of byte array

Array of IP addresses of DNS servers (in network byte order)

    dns-data

    array of strings

Array of DNS name servers. This replaces the deprecated "dns" property. Each name server can also contain a DoT server name.

    dns-options

    array of string

Array of DNS options to be added to resolv.conf. NULL means that the options are unset and left at the default. In this case NetworkManager will use default options. This is distinct from an empty list of properties. The following options are directly added to resolv.conf: "attempts", "debug", "edns0", "inet6", "ip6-bytestring", "ip6-dotint", "ndots", "no-aaaa", "no-check-names", "no-ip6-dotint", "no-reload", "no-tld-query", "rotate", "single-request", "single-request-reopen", "timeout", "trust-ad", "use-vc". See the resolv.conf(5) man page for a detailed description of these options. In addition, NetworkManager supports the special options "_no-add-edns0" and "_no-add-trust-ad". They are not added to resolv.conf, and can be used to prevent the automatic addition of options "edns0" and "trust-ad" when using caching DNS plugins (see below). The "trust-ad" setting is only honored if the profile contributes name servers to resolv.conf, and if all contributing profiles have "trust-ad" enabled. When using a caching DNS plugin (dnsmasq or systemd-resolved in NetworkManager.conf) then "edns0" and "trust-ad" are automatically added, unless "_no-add-edns0" and "_no-add-trust-ad" are present.

    dns-priority

    int32

    0

DNS servers priority. The relative priority for DNS servers specified by this setting. A lower numerical value is better (higher priority). Negative values have the special effect of excluding other configurations with a greater numerical priority value; so in presence of at least one negative priority, only DNS servers from connections with the lowest priority value will be used. To avoid all DNS leaks, set the priority of the profile that should be used to the most negative value of all active connections profiles. Zero selects a globally configured default value. If the latter is missing or zero too, it defaults to 50 for VPNs (including WireGuard) and 100 for other connections. Note that the priority is to order DNS settings for multiple active connections. It does not disambiguate multiple DNS servers within the same connection profile. When multiple devices have configurations with the same priority, VPNs will be considered first, then devices with the best (lowest metric) default route and then all other devices. When using dns=default, servers with higher priority will be on top of resolv.conf. To prioritize a given server over another one within the same connection, just specify them in the desired order. Note that commonly the resolver tries name servers in /etc/resolv.conf in the order listed, proceeding with the next server in the list on failure. See for example the "rotate" option of the dns-options setting. If there are any negative DNS priorities, then only name servers from the devices with that lowest priority will be considered. When using a DNS resolver that supports Conditional Forwarding or Split DNS (with dns=dnsmasq or dns=systemd-resolved settings), each connection is used to query domains in its search list. The search domains determine which name servers to ask, and the DNS priority is used to prioritize name servers based on the domain. Queries for domains not present in any search list are routed through connections having the '~.' special wildcard domain, which is added automatically to connections with the default route (or can be added manually). When multiple connections specify the same domain, the one with the best priority (lowest numerical value) wins. If a sub domain is configured on another interface it will be accepted regardless the priority, unless parent domain on the other interface has a negative priority, which causes the sub domain to be shadowed. With Split DNS one can avoid undesired DNS leaks by properly configuring DNS priorities and the search domains, so that only name servers of the desired interface are configured.

    dns-search

    array of string

List of DNS search domains. Domains starting with a tilde ('~') are considered 'routing' domains and are used only to decide the interface over which a query must be forwarded; they are not used to complete unqualified host names. When using a DNS plugin that supports Conditional Forwarding or Split DNS, then the search domains specify which name servers to query. This makes the behavior different from running with plain /etc/resolv.conf. For more information see also the dns-priority setting. When set on a profile that also enabled DHCP, the DNS search list received automatically (option 119 for DHCPv4 and option 24 for DHCPv6) gets merged with the manual list. This can be prevented by setting "ignore-auto-dns". Note that if no DNS searches are configured, the fallback will be derived from the domain from DHCP (option 15).

    forwarding

    int32

    -1

Whether to configure sysctl interface-specific forwarding. When enabled, the interface will act as a router to forward the packet from one interface to another. When set to -1 (default), the value from global configuration is used; if no global default is defined, 2 (auto) will be used. The "forwarding" property is ignored when "method" is set to "shared", because forwarding is always enabled in this case. The accepted values are: -1 (default): use global default. 0 (no): disabled. 1 (yes): enabled. 2 (auto): enable if any shared connection is active, use kernel default otherwise.

    gateway

    string

The gateway associated with this configuration. This is only meaningful if addresses are also set on the device. Setting the gateway causes NetworkManager to configure a standard default route with the gateway as next hop. This is ignored if "never-default" is set. An alternative is to configure the default route explicitly with a manual route and /0 as prefix length. Note that the gateway usually conflicts with routing that NetworkManager configures for WireGuard interfaces, so usually it should not be set in that case. See "ip4-auto-default-route".

    ignore-auto-dns

    boolean

    FALSE

When "method" is set to "auto" and this property to TRUE, automatically configured name servers and search domains are ignored and only name servers and search domains specified in the "dns" and "dns-search" properties, if any, are used.

    ignore-auto-routes

    boolean

    FALSE

When "method" is set to "auto" and this property to TRUE, automatically configured routes are ignored and only routes specified in the "routes" property, if any, are used.

    ip6-privacy

    NMSettingIP6ConfigPrivacy (int32)

    -1

Configure IPv6 Privacy Extensions for SLAAC, described in RFC4941. If enabled, it makes the kernel generate a temporary IPv6 address in addition to the public one generated from MAC address via modified EUI-64. This enhances privacy, but could cause problems in some applications, on the other hand. The permitted values are: -1: unknown, 0: disabled, 1: enabled (prefer public address), 2: enabled (prefer temporary addresses). Having a per-connection setting set to "-1" (default) means fallback to global configuration "ipv6.ip6-privacy". If it's also unspecified or set to "-1", fallback to read "/proc/sys/net/ipv6/conf/default/use_tempaddr". Note that this setting is distinct from the Stable Privacy addresses that can be enabled with the "addr-gen-mode" property's "stable-privacy" setting as another way of avoiding host tracking with IPv6 addresses.

    may-fail

    boolean

    TRUE

If TRUE, allow overall network configuration to proceed even if the configuration specified by this property times out. Note that at least one IP configuration must succeed or overall network configuration will still fail. For example, in IPv6-only networks, setting this property to TRUE on the NMSettingIP4Config allows the overall network configuration to succeed if IPv4 configuration fails but IPv6 configuration completes successfully.

    method

    string

IP configuration method. NMSettingIP4Config and NMSettingIP6Config both support "disabled", "auto", "manual", and "link-local". See the subclass-specific documentation for other values. In general, for the "auto" method, properties such as "dns" and "routes" specify information that is added on to the information returned from automatic configuration. The "ignore-auto-routes" and "ignore-auto-dns" properties modify this behavior. For methods that imply no upstream network, such as "shared" or "link-local", these properties must be empty. For IPv4 method "shared", the IP subnet can be configured by adding one manual IPv4 address or otherwise 10.42.x.0/24 is chosen. Note that the shared method must be configured on the interface which shares the internet to a subnet, not on the uplink which is shared.

    mtu

    uint32

    0

Maximum transmission unit size, in bytes. If zero (the default), the MTU is set automatically from router advertisements or is left equal to the link-layer MTU. If greater than the link-layer MTU, or greater than zero but less than the minimum IPv6 MTU of 1280, this value has no effect.

    never-default

    boolean

    FALSE

If TRUE, this connection will never be the default connection for this IP type, meaning it will never be assigned the default route by NetworkManager.

    ra-timeout

    int32

    0

A timeout for waiting Router Advertisements in seconds. If zero (the default), a globally configured default is used. If still unspecified, the timeout depends on the sysctl settings of the device. Set to 2147483647 (MAXINT32) for infinity.

    replace-local-rule

    NMTernary (int32)

    -1

Connections will default to keep the autogenerated priority 0 local rule unless this setting is set to TRUE.

    required-timeout

    int32

    -1

The minimum time interval in milliseconds for which dynamic IP configuration should be tried before the connection succeeds. This property is useful for example if both IPv4 and IPv6 are enabled and are allowed to fail. Normally the connection succeeds as soon as one of the two address families completes; by setting a required timeout for e.g. IPv4, one can ensure that even if IP6 succeeds earlier than IPv4, NetworkManager waits some time for IPv4 before the connection becomes active. Note that if "may-fail" is FALSE for the same address family, this property has no effect as NetworkManager needs to wait for the full DHCP timeout. A zero value means that no required timeout is present, -1 means the default value (either configuration ipvx.required-timeout override or zero).

    route-data

    array of vardict

Array of IPv6 routes. Each route dictionary contains at least 'dest' and 'prefix' entries, containing the destination IP address as a string, and the prefix length as a uint32. Most routes will also have a 'next-hop' entry, containing the next hop IP address as a string. If the route has a 'metric' entry (containing a uint32), that will be used as the metric for the route (otherwise NM will pick a default value appropriate to the device). Additional attributes may also exist on some routes.

    route-metric

    int64

    -1

The default metric for routes that don't explicitly specify a metric. The default value -1 means that the metric is chosen automatically based on the device type. The metric applies to dynamic routes, manual (static) routes that don't have an explicit metric setting, address prefix routes, and the default route. Note that for IPv6, the kernel accepts zero (0) but coerces it to 1024 (user default). Hence, setting this property to zero effectively mean setting it to 1024. For IPv4, zero is a regular value for the metric.

    route-table

    uint32

    0

Enable policy routing (source routing) and set the routing table used when adding routes. This affects all routes, including device-routes, IPv4LL, DHCP, SLAAC, default-routes and static routes. But note that static routes can individually overwrite the setting by explicitly specifying a non-zero routing table. If the table setting is left at zero, it is eligible to be overwritten via global configuration. If the property is zero even after applying the global configuration value, policy routing is disabled for the address family of this connection. Policy routing disabled means that NetworkManager will add all routes to the main table (except static routes that explicitly configure a different table). Additionally, NetworkManager will not delete any extraneous routes from tables except the main table. This is to preserve backward compatibility for users who manage routing tables outside of NetworkManager.

    routed-dns

    int32

    -1

Whether to add routes for DNS servers. When enabled, NetworkManager adds a route for each DNS server that is associated with this connection either statically (defined in the connection profile) or dynamically (for example, retrieved via DHCP). The route guarantees that the DNS server is reached via this interface. When set to -1 (default), the value from global configuration is used; if no global default is defined, this feature is disabled.

    routes

    array of legacy IPv6 route struct (a(ayuayu))

Deprecated in favor of the 'route-data' property, but this can be used for backward-compatibility with older daemons. Note that if you send this property the daemon will ignore 'route-data'. Array of IPv6 route structures. Each IPv6 route structure is composed of an IPv6 address, a prefix length (0 - 128), an IPv6 next hop address (which may be zeroed out if there is no next hop), and a metric. If the metric is 0, NM will choose an appropriate default metric for the device.

    routing-rules

    array of 'a{sv}'

Array of dictionaries for routing rules. Each routing rule supports the following options: action (y), dport-end (q), dport-start (q), family (i), from (s), from-len (y), fwmark (u), fwmask (u), iifname (s), invert (b), ipproto (s), oifname (s), priority (u), sport-end (q), sport-start (q), supress-prefixlength (i), table (u), to (s), tos (y), to-len (y), range-end (u), range-start (u).

    shared-dhcp-lease-time

    int32

    0

This option allows you to specify a custom DHCP lease time for the shared connection method in seconds. The value should be either a number between 120 and 31536000 (one year) If this option is not specified, 3600 (one hour) is used. Special values are 0 for default value of 1 hour and 2147483647 (MAXINT32) for infinite lease time.

    shared-dhcp-range

    string

This option allows you to specify a custom DHCP range for the shared connection method. The value is expected to be in `<START_ADDRESS>,<END_ADDRESS>` format. The range should be part of network set by ipv4.address option and it should not contain network address or broadcast address. If this option is not specified, the DHCP range will be automatically determined based on the interface address. The range will be selected to be adjacent to the interface address, either before or after it, with the larger possible range being preferred. The range will be adjusted to fill the available address space, except for networks with a prefix length greater than 24, which will be treated as if they have a prefix length of 24.

    temp-preferred-lifetime

    int32

    0

The preferred lifetime of autogenerated temporary addresses, in seconds. Having a per-connection setting set to "0" (default) means fallback to global configuration "ipv6.temp-preferred-lifetime" setting". If it's also unspecified or set to "0", fallback to read "/proc/sys/net/ipv6/conf/default/temp_prefered_lft".

    temp-valid-lifetime

    int32

    0

The valid lifetime of autogenerated temporary addresses, in seconds. Having a per-connection setting set to "0" (default) means fallback to global configuration "ipv6.temp-valid-lifetime" setting". If it's also unspecified or set to "0", fallback to read "/proc/sys/net/ipv6/conf/default/temp_valid_lft".

    token

    string

Configure the token for draft-chown-6man-tokenised-ipv6-identifiers-02 IPv6 tokenized interface identifiers. Useful with eui64 addr-gen-mode. When set, the token is used as IPv6 interface identifier instead of the hardware address. This only applies to addresses from stateless autoconfiguration, not to IPv6 link local addresses.