Updated: 2022/Sep/29
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RTADVD.CONF(5) File Formats Manual RTADVD.CONF(5)
NAME
rtadvd.conf - config file for router advertisement daemon
DESCRIPTION
This file describes how the router advertisement packets must be
constructed for each of the interfaces.
As described in rtadvd(8), you do not have to set this configuration file
up at all, unless you need some special configurations. You may even
omit the file as a whole. In such cases, the rtadvd daemon will
automatically configure itself using default values specified in the
specification.
It obeys the famous capfile(5) file format. Each line in the file
describes a network interface. Fields are separated by a colon (`:'),
and each field contains one capability description. Lines may be
concatenated by the `\' character. The comment marker is the `#'
character.
CAPABILITIES
Capabilities describe the value to be filled into ICMPv6 router
advertisement messages and to control rtadvd(8) behavior. Therefore, you
are encouraged to read IETF neighbor discovery documents if you would
like to modify the sample configuration file.
Note that almost all items have default values. If you omit an item, the
default value of the item will be used.
There are two items which control the interval of sending router
advertisements. These items can be omitted, then rtadvd will use the
default values.
maxinterval
(num) The maximum time allowed between sending unsolicited
multicast router advertisements (unit: seconds). The default
value is 600. Its value must be no less than 4 seconds and no
greater than 65535 seconds.
mininterval
(num) The minimum time allowed between sending unsolicited
multicast router advertisements (unit: seconds). The default
value is the one third of value of maxinterval. Its value must
be no less than 3 seconds and no greater than .75 * the value of
maxinterval.
The following items are for ICMPv6 router advertisement message header.
These items can be omitted, then rtadvd will use the default values.
chlim (num) The value for Cur Hop Limit field. The default value is
64.
raflags
(str or num) A 8-bit flags field in router advertisement message
header. This field can be specified either as a case-sensitive
string or as an integer. A sting consists of characters each of
which corresponds to a particular flag bit(s). An integer should
be the logical OR of all enabled bits. Bit 7 ('m' or 0x80) means
Managed address configuration flag bit, and Bit 6 ('o' or 0x40)
means Other stateful configuration flag bit. Bit 4 (0x10) and
Bit 3 (0x08) are used to encode router preference. Bits 01 (or
'h') means high, 00 means medium, and 11 (or 'l') means low.
Bits 10 is reserved, and must not be specified. There is no
character to specify the medium preference explicitly. The
default value of the entire flag is 0 (or a null string), which
means no additional configuration methods, and the medium router
preference.
rltime (num) Router lifetime field (unit: seconds). The value must be
either zero or between the value of maxinterval and 65535. When
rtadvd runs on a host, this value must explicitly set 0 on all
the advertising interfaces as described in rtadvd(8). The
default value is 1800.
rtime (num) Reachable time field (unit: milliseconds). The default
value is 0, which means unspecified by this router.
retrans
(num) Retrans Timer field (unit: milliseconds). The default
value is 0, which means unspecified by this router.
The following items are for ICMPv6 prefix information option, which will
be attached to router advertisement header. These items can be omitted,
then rtadvd will automatically get appropriate prefixes from the kernel's
routing table, and advertise the prefixes with the default parameters,
unless the noifprefix flag is specified. Keywords other than clockskew
and noifprefix can be augmented with a number, like "prefix2", to specify
multiple prefixes.
noifprefix
(bool) Specified whether rtadvd should gather prefix information
from the interface if no addr is specified. If no addr is given,
and noifprefix is set, rtadvd will send RA packets with no prefix
information.
clockskew
(num) Time skew to adjust link propagation delays and clock skews
between routers on the link (unit: seconds). This value is used
in consistency check for locally-configured and advertised prefix
lifetimes, and has its meaning when the local router configures a
prefix on the link with a lifetime that decrements in real time.
If the value is 0, it means the consistency check will be skipped
for such prefixes. The default value is 0.
prefixlen
(num) Prefix length field. The default value is 64.
pinfoflags
(str or num) A 8-bit flags field in prefix information option.
This field can be specified either as a case-sensitive string or
as an integer. A sting consists of characters each of which
corresponds to a particular flag bit(s). An integer should be
the logical OR of all enabled bits. Bit 7 ('l' or 0x80) means
On-link flag bit, and Bit 6 ('a' or 0x40) means Autonomous
address-configuration flag bit. The default value is "la" or
0xc0, i.e., both bits are set.
addr (str) The address filled into Prefix field. Since ":" is used
for capfile(5) file format as well as IPv6 numeric address, the
field MUST be quoted by doublequote character.
vltime (num) Valid lifetime field (unit: seconds). The default value is
2592000 (30 days).
vltimedecr
(bool) This item means the advertised valid lifetime will
decrement in real time, which is disabled by default.
pltime (num) Preferred lifetime field (unit: seconds). The default
value is 604800 (7 days).
pltimedecr
(bool) This item means the advertised preferred lifetime will
decrement in real time, which is disabled by default.
The following item is for ICMPv6 MTU option, which will be attached to
router advertisement header. This item can be omitted, then rtadvd will
use the default value.
mtu (num or str) MTU (maximum transmission unit) field. If 0 is
specified, it means that the option will not be included. The
default value is 0. If the special string "auto" is specified
for this item, MTU option will be included and its value will be
set to the interface MTU automatically.
The following item controls ICMPv6 source link-layer address option,
which will be attached to router advertisement header. As noted above,
you can just omit the item, then rtadvd will use the default value.
nolladdr
(bool) By default (if nolladdr is not specified), rtadvd(8) will
try to get link-layer address for the interface from the kernel,
and attach that in source link-layer address option. If this
capability exists, rtadvd(8) will not attach source link-layer
address option to router advertisement packets.
The following items are for ICMPv6 route information option, which will
be attached to router advertisement header. These items are optional.
Each items can be augmented with number, like "rtplen2", to specify
multiple routes.
rtprefix
(str) The prefix filled into the Prefix field of route
information option. Since ":" is used for capfile(5) file format
as well as IPv6 numeric address, the field MUST be quoted by
doublequote character.
rtplen (num) Prefix length field in route information option. The
default value is 64.
rtflags
(str or num) A 8-bit flags field in route information option.
Currently only the preference values are defined. The notation
is same as that of the raflags field. Bit 4 (0x10) and Bit 3
(0x08) are used to encode the route preference for the route.
The default value is 0x00, i.e. medium preference.
rtltime
(num) route lifetime field in route information option. (unit:
seconds). Since the specification does not define the default
value of this item, the value for this item should be specified
by hand. However, rtadvd allows this item to be unspecified, and
uses the router lifetime as the default value in such a case,
just for compatibility with an old version of the program.
In the above list, each keyword beginning with "rt" could be replaced
with the one beginning with "rtr" for backward compatibility reason. For
example, rtrplen is accepted instead of rtplen. However, keywords that
start with "rtr" have basically been obsoleted, and should not be used
any more.
The following items are for ICMPv6 Recursive DNS Server Option and DNS
Search List Option (RFC 6106), which will be attached to router
advertisement header. These items are optional.
rdnss (str) The IPv6 address of one or more recursive DNS servers. The
argument must be inside double quotes. Multiple DNS servers can
be specified in a comma-separated string. If different lifetimes
are needed for different servers, separate entries can be given
by using rdnss, rdnss0, rdnss1, rdnss2 ... options with
corresponding rdnssltime, rdnssltime0, rdnssltime1, rdnssltime2
... entries. Note that the maximum number of servers depends on
the receiver side. See also the resolv.conf(5) manual page for
the resolver implementation.
rdnssltime
The lifetime of the rdnss DNS server entries. The default value
is 3/2 of the interval time.
dnssl (str) One or more domain names in a comma-separated string.
These domain names will be used when making DNS queries on a non-
fully-qualified domain name. If different lifetimes are needed
for different domains, separate entries can be given by using
dnssl, dnssl0, dnssl1, dnssl2 ... options with corresponding
dnsslltime, dnsslltime0, dnsslltime1, dnsslltime2 ... entries.
Note that the maximum number of names depends on the receiver
side. See also the resolv.conf(5) manual page for the resolver
implementation.
dnsslltime
The lifetime of the dnssl DNS search list entries. The default
value is 3/2 of the interval time.
You can also refer one line from another by using tc capability. See
capfile(5) for details on the capability.
EXAMPLES
As presented above, all of the advertised parameters have default values
defined in specifications, and hence you usually do not have to set them
by hand, unless you need special non-default values. It can cause
interoperability problem if you use an ill-configured parameter.
To override a configuration parameter, you can specify the parameter
alone. With the following configuration, rtadvd(8) overrides the router
lifetime parameter for the ne0 interface.
ne0:\
:rltime#0:
The following example manually configures prefixes advertised from the
ef0 interface. The configuration must be used with the -s option to
rtadvd(8).
ef0:\
:addr="2001:db8:ffff:1000::":prefixlen#64:
The following example configures the wlan0 interface and adds two DNS
servers and a DNS domain search options using the default option lifetime
values.
wlan0:\
:addr="2001:db8:ffff:1000::":prefixlen#64:\
:rdnss="2001:db8:ffff::10,2001:db8:ffff::2:43":\
:dnssl="example.com":
The following example presents the default values in an explicit manner.
The configuration is provided just for reference purposes; YOU DO NOT
NEED TO HAVE IT AT ALL.
default:\
:chlim#64:raflags#0:rltime#1800:rtime#0:retrans#0:\
:pinfoflags="la":vltime#2592000:pltime#604800:mtu#0:
ef0:\
:addr="2001:db8:ffff:1000::":prefixlen#64:tc=default:
SEE ALSO
capfile(5), rtadvd(8), rtsol(8)
Thomas Narten, Erik Nordmark and W. A. Simpson, "Neighbor Discovery for
IP version 6 (IPv6)", RFC 2461
Richard Draves, "Default Router Preferences and More-Specific Routes",
RFC 4191
J. Jeong, S. Park, L. Beloeil, S. Madanapalli "IPv6 Router Advertisement
Options for DNS Configuration", RFC 6106
HISTORY
The rtadvd(8) and the configuration file rtadvd.conf first appeared in
WIDE Hydrangea IPv6 protocol stack kit.
NetBSD 10.99 April 20, 2018 NetBSD 10.99