xref: /freebsd/usr.sbin/rtadvd/rtadvd.8 (revision 1e413cf93298b5b97441a21d9a50fdcd0ee9945e)
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30.\" $FreeBSD$
31.\"
32.Dd May 17, 1998
33.Dt RTADVD 8
34.Os
35.Sh NAME
36.Nm rtadvd
37.Nd router advertisement daemon
38.Sh SYNOPSIS
39.Nm
40.Op Fl dDfMRs
41.Op Fl c Ar configfile
42.Ar interface ...
43.Sh DESCRIPTION
44.Nm
45sends router advertisement packets to the specified
46.Ar interfaces .
47.Pp
48The program will daemonize itself on invocation.
49It will then send router advertisement packets periodically, as well
50as in response to router solicitation messages sent by end hosts.
51.Pp
52Router advertisements can be configured on a per-interface basis, as
53described in
54.Xr rtadvd.conf 5 .
55.Pp
56If there is no configuration file entry for an interface,
57or if the configuration file does not exist altogether,
58.Nm
59sets all the parameters to their default values.
60In particular,
61.Nm
62reads all the interface routes from the routing table and advertises
63them as on-link prefixes.
64.Pp
65.Nm
66also watches the routing table.
67If an interface direct route is
68added on an advertising interface and no static prefixes are
69specified by the configuration file,
70.Nm
71adds the corresponding prefix to its advertising list.
72.Pp
73Similarly, when an interface direct route is deleted,
74.Nm
75will start advertising the prefixes with zero valid and preferred
76lifetimes to help the receiving hosts switch to a new prefix when
77renumbering.
78Note, however, that the zero valid lifetime cannot invalidate the
79autoconfigured addresses at a receiving host immediately.
80According to the specification, the host will retain the address
81for a certain period, which will typically be two hours.
82The zero lifetimes rather intend to make the address deprecated,
83indicating that a new non-deprecated address should be used as the
84source address of a new connection.
85This behavior will last for two hours.
86Then
87.Nm
88will completely remove the prefix from the advertising list,
89and succeeding advertisements will not contain the prefix information.
90.Pp
91Moreover, if the status of an advertising interface changes,
92.Nm
93will start or stop sending router advertisements according
94to the latest status.
95.Pp
96The
97.Fl s
98option may be used to disable this behavior;
99.Nm
100will not watch the routing table and the whole functionality described
101above will be suppressed.
102.Pp
103Basically, hosts MUST NOT send Router Advertisement messages at any
104time (RFC 2461, Section 6.2.3).
105However, it would sometimes be useful to allow hosts to advertise some
106parameters such as prefix information and link MTU.
107Thus,
108.Nm
109can be invoked if router lifetime is explicitly set zero on every
110advertising interface.
111.Pp
112The command line options are:
113.Bl -tag -width indent
114.\"
115.It Fl c
116Specify an alternate location,
117.Ar configfile ,
118for the configuration file.
119By default,
120.Pa /etc/rtadvd.conf
121is used.
122.It Fl d
123Print debugging information.
124.It Fl D
125Even more debugging information is printed.
126.It Fl f
127Foreground mode (useful when debugging).
128Log messages will be dumped to stderr when this option is specified.
129.It Fl M
130Specify an interface to join the all-routers site-local multicast group.
131By default,
132.Nm
133tries to join the first advertising interface appearing on the command
134line.
135This option has meaning only with the
136.Fl R
137option, which enables routing renumbering protocol support.
138.It Fl R
139Accept router renumbering requests.
140If you enable it, certain IPsec setup is suggested for security reasons.
141This option is currently disabled, and is ignored by
142.Nm
143with a warning message.
144.It Fl s
145Do not add or delete prefixes dynamically.
146Only statically configured prefixes, if any, will be advertised.
147.El
148.Pp
149Upon receipt of signal
150.Dv SIGUSR1 ,
151.Nm
152will dump the current internal state into
153.Pa /var/run/rtadvd.dump .
154.Pp
155Use
156.Dv SIGTERM
157to kill
158.Nm
159gracefully.
160In this case,
161.Nm
162will transmit router advertisement with router lifetime 0
163to all the interfaces
164.Pq in accordance with RFC2461 6.2.5 .
165.Sh RETURN VALUES
166The
167.Nm
168program exits 0 on success, and >0 on failures.
169.Sh FILES
170.Bl -tag -width Pa -compact
171.It Pa /etc/rtadvd.conf
172The default configuration file.
173.It Pa /var/run/rtadvd.pid
174contains the pid of the currently running
175.Nm .
176.It Pa /var/run/rtadvd.dump
177The file in which
178.Nm
179dumps its internal state.
180.El
181.Sh SEE ALSO
182.Xr rtadvd.conf 5 ,
183.Xr rtsol 8
184.Sh HISTORY
185The
186.Nm
187command first appeared in the WIDE Hydrangea IPv6 protocol stack kit.
188.Sh BUGS
189There used to be some text that recommended users not to let
190.Nm
191advertise Router Advertisement messages on an upstream link to avoid
192undesirable
193.Xr icmp6 4
194redirect messages.
195However, based on the later discussion in the IETF ipng working group,
196all routers should rather advertise the messages regardless of
197the network topology, in order to ensure reachability.
198