RADVD.CONF(5)RADVD.CONF(5)NAMEradvd.conf - configuration file of the router advertisement daemon
radvd
DESCRIPTION
This file describes the information which is included in the router
advertisement (RA) of a specific interface.
The file contains one or more interface definitions of the form:
interface name {
list of interface specific options
list of prefix definitions
list of clients (IPv6 addresses) to advertise to
list of route definitions
list of RDNSS definitions
list of DNSSL definitions
};
All the possible interface specific options are detailed below. Each
option has to be terminated by a semicolon.
Prefix definitions are of the form:
prefix prefix/length {
list of prefix specific options
};
Prefix can be network prefix or the address of the inferface. The
address of interface should be used when using Mobile IPv6 extensions.
Special prefix "::/64" is also supported on systems that implement
getifaddrs() (on other systems, configuration activation fails and
radvd exits). When configured, radvd picks all non-link-local prefix
assigned to the interface and starts advertising it. This may be
applicable in non-6to4 scenarios where the upstream prefix might
change. This option is incompatible with Base6to4Interface option.
AdvRouterAddr option is always enabled when this configuration is used.
All the possible prefix specific options are described below. Each
option has to be terminated by a semicolon.
Decimal values are allowed only for MinDelayBetweenRAs, MaxRtrAdvInter‐
val and MinRtrAdvInterval. Decimal values should be used only when
using Mobile IPv6 extensions.
Route definitions are of the form:
route prefix/length {
list of route specific options
};
The prefix of a route definition should be network prefix; it can be
used to advertise more specific routes to the hosts.
RDNSS (Recursive DNS server) definitions are of the form:
RDNSS ip [ip] [ip] {
list of rdnss specific options
};
DNSSL (DNS Search List) definitions are of the form:
DNSSL suffix [suffix] [suffix] [...] {
list of dnssl specific options
};
By default radvd will send route advertisements so that every node on
the link can use them. The list of clients (IPv6 address) to advertise
to, and accept route solicitations from can be configured. If done,
radvd does not send send messages to the multicast addresses but to the
configured unicast addresses only. Solicitations from other addresses
are refused. This is similar to UnicastOnly but includes periodic mes‐
sages and incoming client access configuration. See examples section
for a use case of this.
The definitions are of the form:
clients {
list of IPv6 addresses
};
INTERFACE SPECIFIC OPTIONS
IgnoreIfMissing on|off
A flag indicating whether or not the interface is ignored if it
does not exist at start-up. By default, radvd exits.
This is useful for dynamic interfaces which are not active when
radvd starts or which are dynamically disabled and re-enabled
during the time radvd runs.
Current versions of radvd automatically try to re-enable inter‐
faces.
Enabling IgnoreIfMissing also quenches certain warnings in log
messages relating to missing interfaces.
Default: on
AdvSendAdvert on|off
A flag indicating whether or not the router sends periodic
router advertisements and responds to router solicitations.
This option no longer has to be specified first, but it needs to
be on to enable advertisement on this interface.
Default: off
UnicastOnly on|off
Indicates that the interface link type only supports unicast.
This will prevent unsolicited advertisements from being sent,
and will cause solicited advertisements to be unicast to the
soliciting node. This option is necessary for non-broadcast,
multiple-access links, such as ISATAP.
Default: off
MaxRtrAdvInterval seconds
The maximum time allowed between sending unsolicited multicast
router advertisements from the interface, in seconds.
Must be no less than 4 seconds and no greater than 1800 seconds.
Minimum when using Mobile IPv6 extensions: 0.07.
For values less than 0.2 seconds, 0.02 seconds is added to
account for scheduling granularities as specified in RFC3775.
Default: 600 seconds
MinRtrAdvInterval seconds
The minimum time allowed between sending unsolicited multicast
router advertisements from the interface, in seconds.
Must be no less than 3 seconds and no greater than 0.75 * MaxR‐
trAdvInterval.
Minimum when using Mobile IPv6 extensions: 0.03.
Default: 0.33 * MaxRtrAdvInterval
MinDelayBetweenRAs seconds
The minimum time allowed between sending multicast router adver‐
tisements from the interface, in seconds.
This applies to solicited multicast RAs. This is defined as the
protocol constant MIN_DELAY_BETWEEN_RAS in RFC4861. MIPv6 rede‐
fines this parameter to have a minimum of 0.03 seconds.
Minimum when using Mobile IPv6 extensions: 0.03.
Default: 3
AdvManagedFlag on|off
When set, hosts use the administered (stateful) protocol for
address autoconfiguration in addition to any addresses autocon‐
figured using stateless address autoconfiguration. The use of
this flag is described in RFC 4862.
Default: off
AdvOtherConfigFlag on|off
When set, hosts use the administered (stateful) protocol for
autoconfiguration of other (non-address) information. The use
of this flag is described in RFC 4862.
Default: off
AdvLinkMTU integer
The MTU option is used in router advertisement messages to
insure that all nodes on a link use the same MTU value in those
cases where the link MTU is not well known.
If specified, i.e. not 0, must not be smaller than 1280 and not
greater than the maximum MTU allowed for this link (e.g. ether‐
net has a maximum MTU of 1500. See RFC 4864).
Default: 0
AdvReachableTime milliseconds
The time, in milliseconds, that a node assumes a neighbor is
reachable after having received a reachability confirmation.
Used by the Neighbor Unreachability Detection algorithm (see
Section 7.3 of RFC 4861). A value of zero means unspecified (by
this router).
Must be no greater than 3,600,000 milliseconds (1 hour).
Default: 0
AdvRetransTimer milliseconds
The time, in milliseconds, between retransmitted Neighbor Solic‐
itation messages. Used by address resolution and the Neighbor
Unreachability Detection algorithm (see Sections 7.2 and 7.3 of
RFC 4861). A value of zero means unspecified (by this router).
Default: 0
AdvCurHopLimit integer
The default value that should be placed in the Hop Count field
of the IP header for outgoing (unicast) IP packets. The value
should be set to the current diameter of the Internet. The
value zero means unspecified (by this router).
Default: 64
AdvDefaultLifetime seconds
The lifetime associated with the default router in units of sec‐
onds. The maximum value corresponds to 18.2 hours. A lifetime
of 0 indicates that the router is not a default router and
should not appear on the default router list. The router life‐
time applies only to the router's usefulness as a default
router; it does not apply to information contained in other mes‐
sage fields or options. Options that need time limits for their
information include their own lifetime fields.
Must be either zero or between MaxRtrAdvInterval and 9000 sec‐
onds.
Default: 3 * MaxRtrAdvInterval (Minimum 1 second).
AdvDefaultPreference low|medium|high
The preference associated with the default router, as either
"low", "medium", or "high".
Default: medium
AdvSourceLLAddress on|off
When set, the link-layer address of the outgoing interface is
included in the RA.
Default: on
AdvHomeAgentFlag on|off
When set, indicates that sending router is able to serve as
Mobile IPv6 Home Agent. When set, minimum limits specified by
Mobile IPv6 are used for MinRtrAdvInterval and MaxRtrAdvInter‐
val.
Default: off
AdvHomeAgentInfo on|off
When set, Home Agent Information Option (specified by Mobile
IPv6) is included in Router Advertisements. AdvHomeAgentFlag
must also be set when using this option.
Default: off
HomeAgentLifetime seconds
The length of time in seconds (relative to the time the packet
is sent) that the router is offering Mobile IPv6 Home Agent ser‐
vices. A value 0 must not be used. The maximum lifetime is
65520 seconds (18.2 hours). This option is ignored, if AdvHome‐
AgentInfo is not set.
If both HomeAgentLifetime and HomeAgentPreference are set to
their default values, Home Agent Information Option will not be
sent.
Default: AdvDefaultLifetime
HomeAgentPreference integer
The preference for the Home Agent sending this Router Advertise‐
ment. Values greater than 0 indicate more preferable Home
Agent, values less than 0 indicate less preferable Home Agent.
This option is ignored, if AdvHomeAgentInfo is not set.
If both HomeAgentLifetime and HomeAgentPreference are set to
their default values, Home Agent Information Option will not be
sent.
Default: 0
AdvMobRtrSupportFlag on|off
When set, the Home Agent signals it supports Mobile Router reg‐
istrations (specified by NEMO Basic). AdvHomeAgentInfo must
also be set when using this option.
Default: off
AdvIntervalOpt on|off
When set, Advertisement Interval Option (specified by Mobile
IPv6) is included in Router Advertisements. When set, minimum
limits specified by Mobile IPv6 are used for MinRtrAdvInterval
and MaxRtrAdvInterval.
The advertisement interval is based on the configured MaxRtrAdv‐
Interval parameter except where this is less than 200ms. In
this case, the advertised interval is ( MaxRtrAdvInterval + 20ms
).
Default: off
PREFIX SPECIFIC OPTIONS
AdvOnLink on|off
When set, indicates that this prefix can be used for on-link
determination. When not set the advertisement makes no state‐
ment about on-link or off-link properties of the prefix. For
instance, the prefix might be used for address configuration
with some of the addresses belonging to the prefix being on-link
and others being off-link.
Default: on
AdvAutonomous on|off
When set, indicates that this prefix can be used for autonomous
address configuration as specified in RFC 4862.
Default: on
AdvRouterAddr on|off
When set, indicates that the address of interface is sent
instead of network prefix, as is required by Mobile IPv6. When
set, minimum limits specified by Mobile IPv6 are used for MinR‐
trAdvInterval and MaxRtrAdvInterval.
Default: off
AdvValidLifetime seconds|infinity
The length of time in seconds (relative to the time the packet
is sent) that the prefix is valid for the purpose of on-link
determination. The symbolic value infinity represents infinity
(i.e. a value of all one bits (0xffffffff)). The valid lifetime
is also used by RFC 4862.
Note that clients will ignore AdvValidLifetime of an existing
prefix if the lifetime is below two hours, as required in RFC
4862 Section 5.5.3 point e).
Note: RFC4861's suggested default value is significantly longer:
30 days.
Default: 86400 seconds (1 day)
AdvPreferredLifetime seconds|infinity
The length of time in seconds (relative to the time the packet
is sent) that addresses generated from the prefix via stateless
address autoconfiguration remain preferred. The symbolic value
infinity represents infinity (i.e. a value of all one bits
(0xffffffff)). See RFC 4862.
Note: RFC4861's suggested default value is significantly longer:
7 days.
Default: 14400 seconds (4 hours)
DeprecatePrefix on|off
Upon shutdown, this option will cause radvd to deprecate the
prefix by announcing it in the radvd shutdown RA with a zero
preferred lifetime and a valid lifetime slightly greater than 2
hours. This will encourage end-nodes using this prefix to depre‐
cate any associated addresses immediately. Note that this option
should only be used when only one router is announcing the pre‐
fix onto the link, otherwise end-nodes will deprecate associated
addresses despite the prefix still being valid for preferred
use.
See RFC4862, section 5.5.3., "Router Advertisement Processing",
part (e).
Default: off
DecrementLifetimes on|off
This option causes radvd to decrement the values of the pre‐
ferred and valid lifetimes for the prefix over time. The life‐
times are decremented by the number of seconds since the last
RA. If radvd receives a SIGUSR1 signal, it will reset the values
of the preferred and valid lifetimes back to the initial values
used by radvd when it started. If radvd never receives a SIGUSR1
signal, it will continue to decrement the lifetimes until the
preferred lifetime reaches zero. After a final RA with a zero
value preferred lifetime, radvd will cease to announce the pre‐
fix. If a SIGUSR1 signal then causes the lifetimes to be reset,
the prefix will then re-appear in the RAs.
This option is intended to be used in conjunction with a DHCPv6
client that is using the Identity Association for Prefix Delega‐
tion (IA_PD) option to acquire a prefix from a Delegating Router
for use by a Requesting Router. In this scenario, the prefix(es)
from within the delegated prefix that are announced by radvd
would age in parallel with and at the same rate as the delegated
prefix, and expire at approximately the same time, if the dele‐
gated prefix's life isn't extended.
See RFC3633, "IPv6 Prefix Options for Dynamic Host Configuration
Protocol (DHCP) version 6".
Default: off
Base6Interface name
If this options is specified, this prefix will be combined with
the IPv6 address of the interface specified by name. The
resulting prefix length will be 64.
Base6to4Interface name
If this option is specified, this prefix will be combined with
the IPv4 address of interface name to produce a valid 6to4 pre‐
fix. The first 16 bits of this prefix will be replaced by 2002
and the next 32 bits of this prefix will be replaced by the IPv4
address assigned to interface name at configuration time. The
remaining 80 bits of the prefix (including the SLA ID) will be
advertised as specified in the configuration file. See the next
section for an example.
If interface name is not available at configuration time, a
warning will be written to the log and this prefix will be dis‐
abled until radvd is reconfigured.
This option enables systems with dynamic IPv4 addresses to
update their advertised 6to4 prefixes simply by restarting radvd
or sending a SIGHUP signal to cause radvd to reconfigure itself.
Note that 6to4 prefixes derived from dynamically-assigned IPv4
addresses should be advertised with a significantly shorter
lifetime (see the AdvValidLifetime and AdvPreferredLifetime
options).
For more information on 6to4, see RFC 3056.
Default: 6to4 is not used
ROUTE SPECIFIC OPTIONS
AdvRouteLifetime seconds|infinity
The lifetime associated with the route in units of seconds. The
symbolic value infinity represents infinity (i.e. a value of all
one bits (0xffffffff)).
Default: 3 * MaxRtrAdvInterval
AdvRoutePreference low|medium|high
The preference associated with the default router, as either
"low", "medium", or "high".
Default: medium
RemoveRoute on|off
Upon shutdown, announce this route with a zero second lifetime.
This should cause the route to be immediately removed from the
receiving end-nodes' route table.
Default: on
RDNSS SPECIFIC OPTIONS
AdvRDNSSLifetime seconds|infinity
The maximum duration how long the RDNSS entries are used for
name resolution. A value of 0 means the nameserver must no
longer be used. The value, if not 0, must be at least MaxRtrAdv‐
Interval. To ensure stale RDNSS info gets removed in a timely
fashion, this should not be greater than 2*MaxRtrAdvInterval.
Default: 2*MaxRtrAdvInterval
FlushRDNSS on|off
Upon shutdown, announce the RDNSS entries with a zero second
lifetime. This should cause the RDNSS addresses to be immedi‐
ately removed from the end-nodes' list of Recursive DNS Servers.
Default: on
DNSSL SPECIFIC OPTIONS
AdvDNSSLLifetime seconds|infinity;
The maximum duration how long the DNSSL entries are used for
name resolution. A value of 0 means the suffix should no longer
be used. The value, if not 0, must be at least MaxRtrAdvInter‐
val. To ensure stale DNSSL info gets removed in a timely fash‐
ion, this should not be greater than 2*MaxRtrAdvInterval.
Default: 2*MaxRtrAdvInterval
FlushDNSSL on|off
Upon shutdown, announce the DNSSL entries with a zero second
lifetime. This should cause the DNSSL entries to be immediately
removed from the end-nodes' DNS search list.
Default: on
EXAMPLES
interface eth0
{
AdvSendAdvert on;
prefix 2001:db8:0:1::/64
{
AdvOnLink on;
AdvAutonomous on;
};
};
It says that router advertisement daemon should advertise (AdvSendAd‐
vert on;) the prefix 2001:db8:0:1:: which has a lenght of 64 on the
interface eth0. Also the prefix should be marked as autonomous (AdvAu‐
tonomous on;) and as on-link (AdvOnLink on;). All the other options
are left on their default values.
To support movement detection of Mobile IPv6 Mobile Nodes, the address
of interface should be used instead of network prefix:
interface eth0
{
AdvSendAdvert on;
prefix 2001:db8:0:1::4/64
{
AdvOnLink on;
AdvAutonomous on;
AdvRouterAddr on;
};
};
For 6to4 support, include the Base6to4Interface option in each prefix
section. When using a dynamic IPv4 address, set small prefix lifetimes
to prevent hosts from retaining unreachable prefixes after a new IPv4
address has been assigned. When advertising to on a dynamic interface
(e.g., Bluetooth), skip the interface if it is not active yet.
interface bnep0
{
IgnoreIfMissing on;
AdvSendAdvert on;
# Advertise at least every 30 seconds
MaxRtrAdvInterval 30;
prefix 0:0:0:5678::/64
{
AdvOnLink on;
AdvAutonomous on;
Base6to4Interface ppp0;
# Very short lifetimes for dynamic addresses
AdvValidLifetime 300;
AdvPreferredLifetime 120;
};
};
Since 6to4 is enabled, the prefix will be advertised as
2002:WWXX:YYZZ:5678::/64, where WW.XX.YY.ZZ is the IPv4 address of ppp0
at configuration time. (IPv6 addresses are written in hexadecimal
whereas IPv4 addresses are written in decimal, so the IPv4 address
WW.XX.YY.ZZ in the 6to4 prefix will be represented in hex.)
In this specific case, the configuration scripts may send HUP signal to
radvd when taking bnep0 up or down to notify about the status; in the
current radvd releases, sending HUP is no longer mandatory when the
link comes back up.
interface eth0
{
AdvSendAdvert on;
prefix 2001:db8:0:1::/64
{
AdvOnLink on;
AdvAutonomous on;
};
clients
{
fe80::21f:16ff:fe06:3aab;
fe80::21d:72ff:fe96:aaff;
};
};
This configuration would only announce the prefix to
fe80::21f:16ff:fe06:3aab and fe80::21d:72ff:fe96:aaff. Furthermore,
all RA requests of other clients are denied.
This may come in handy if you want to roll out IPv6 only partially
because some clients are broken or untested.
FILES
/usr/sbin/radvd
/etc/radvd.conf
/var/run/radvd/radvd.pid
/var/log/radvd.log
CREDIT
The description of the different flags and variables is in large parts
taken from RFC 4861.
RFCS
Narten, T., Nordmark, E., Simpson, W., and H. Soliman, "Neighbor Dis‐
covery for IP Version 6 (IPv6)", RFC 4861, September 2007.
Thomson, S., Narten, T., T. Jinmei, "IPv6 Stateless Address Autoconfig‐
uration", RFC 4862, September 2007.
Deering, S., and R. Hinden, "IP Version 6 Addressing Architecture", RFC
4291, February 2006.
Conta, A., Deering, S., and M. Gupta "Internet Control Message Protocol
(ICMPv6) for the Internet Protocol Version 6 (IPv6)", RFC 4443, March
2006.
Crawford, M., "Transmission of IPv6 Packets over Ethernet Networks",
RFC 2464, December 1998.
Carpenter B., K. Moore, "Connection of IPv6 Domains via IPv4 Clouds",
RFC 3056, February 2001. (6to4 specification)
Draves, R., D. Thaler, "Default Router Preferences and More-Specific
Routes", RFC 4191, November 2005.
Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in IPv6", RFC
3775, June 2004.
Devarapalli, V., Wakikawa, R., Petrescu, A., and P. Thubert "Network
Mobility (NEMO) Basic Support Protocol", RFC 3963, January 2005.
J. Jeong, S. Park, L. Beloeil, and S. Madanapalli, "IPv6 Router Adver‐
tisement Options for DNS Configuration", RFC 6106, November 2010.
SEE ALSOradvd(8), radvdump(8)BUGS
radvd does not support splitting up RAs to multiple packets (RFC4861
6.2.3 last paragraph). In practise this limits advertising to ~45 pre‐
fixes on a link, but there is no reason to be able to so.
radvd 1.8.2 4 Jan 2011 RADVD.CONF(5)
