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 1800
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
9000. 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.
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.