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RAD.CONF(5) File Formats Manual RAD.CONF(5)

rad.confrouter advertisement daemon configuration file

The rad(8) daemon is an IPv6 router advertisement daemon.

The rad.conf config file is divided into the following main sections:

User-defined variables may be defined and used later, simplifying the configuration file.
Global settings for rad(8). These are used as default values for interface definitions and can be overwritten in an interface block.
rad(8) sends IPv6 router advertisement messages. This section defines on which interfaces to advertise prefix information and their associated parameters.

Additional configuration files can be included with the include keyword.

Macros can be defined that will later be expanded in context. Macro names must start with a letter, digit, or underscore, and may contain any of those characters. Macro names may not be reserved words (for example, interface) Macros are not expanded inside quotes.

The global configuration section sets defaults for router advertisement messages. These can be overwritten in interface blocks.

(yes|no)
Act as a default router or not. The default is yes.
{dns options}
options are as follows:
seconds
The number of seconds the dns options are valid after receiving a router advertisement message. The default is 900 seconds.
(IP|{ nameserver list })
IPv6 address or list of IPv6 addresses of DNS name servers.
Domain or list of domains for the resolv.conf(5) search list.
hops
Specify the diameter of the internet. The default is 0, meaning unspecified by this router.
(yes|no)
If set to yes, indicate that stateless address configuration prefixes are not available and hosts should consult DHCPv6. The default is no.
bytes
The MTU option is used in Router Advertisement messages to ensure that all nodes on a link use the same MTU value in those cases where the link MTU is not well known. The default is 0, meaning unspecified by this router.
prefix [{nat64 options}]
Add a PREF64 router advertisement option to communicate prefixes used for Network Address and Protocol Translation from IPv6 to IPv4 (NAT64). If prefix is specified without a prefix length, its default is 64.

nat64 prefix options are as follows:

seconds
The number of seconds the nat64 prefix option is valid after receiving a router advertisement message. A value of zero indicates to not use the prefix anymore. The maximum is 65528 seconds. The default is 1800 seconds.
(yes|no)
If set to yes, hosts should consult DHCPv6 for additional configuration like NTP servers or DNS name servers.
seconds
The number of seconds this router is a valid default router after receiving a router advertisement message. The default is 1800 seconds.

A list of interfaces or interface groups to send advertisements on:

interface name [{ prefix list }]

Options set in the global section can be overwritten inside an interface block. In addition an interface block can contain a list of prefixes:

[no] auto prefix [{ prefix options }]
prefix prefix [{ prefix options }]

The default is to discover prefixes to announce by inspecting the IPv6 addresses configured on an interface. This can be disabled with no auto prefix. If prefix is specified without a prefix length, its default is 64.

prefix options are as follows:

(yes|no)
This prefix can be used to generate IPv6 addresses. The default is yes.
This prefix is considered on-link. The default is yes.
seconds
The preferred lifetime (pltime) in seconds for addresses generated from this prefix. The default is 604800.
seconds
The valid lifetime (vltime) in seconds for addresses generated from this prefix. The default is 2592000.

/etc/rad.conf
rad(8) configuration file.
/etc/examples/rad.conf
Example configuration file.

With the following example configuration, rad(8) will pick a prefix from the ix1 interface and send router advertisements on it:

interface ix1

ractl(8), rad(8), rc.conf.local(8)

The rad.conf file format first appeared in OpenBSD 6.4.

October 15, 2022 OpenBSD-7.3