1.\"	$KAME: traceroute6.8,v 1.10 2004/06/06 12:35:15 suz Exp $
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30.\" $FreeBSD$
31.\"
32.Dd September 13, 2020
33.Dt TRACEROUTE6 8
34.Os
35.\"
36.Sh NAME
37.Nm traceroute6
38.Nd "print the route IPv6 packets will take to a network node"
39.\"
40.Sh SYNOPSIS
41.Nm
42.Bk -words
43.Op Fl adIlnNrSTUv
44.Ek
45.Bk -words
46.Op Fl f Ar firsthop
47.Ek
48.Bk -words
49.Op Fl g Ar gateway
50.Ek
51.Bk -words
52.Op Fl m Ar hoplimit
53.Ek
54.Bk -words
55.Op Fl p Ar port
56.Ek
57.Bk -words
58.Op Fl q Ar probes
59.Ek
60.Bk -words
61.Op Fl s Ar src
62.Ek
63.Bk -words
64.Op Fl t Ar tclass
65.Ek
66.Bk -words
67.Op Fl w Ar waittime
68.Ek
69.Bk -words
70.Op Fl A Ar as_server
71.Ek
72.Bk -words
73.Ar target
74.Op Ar datalen
75.Ek
76.\"
77.Sh DESCRIPTION
78The
79.Nm
80utility
81uses the IPv6 protocol hop limit field to elicit an ICMPv6 TIME_EXCEEDED
82response from each gateway along the path to some host.
83.Pp
84The only mandatory parameter is the destination host name or IPv6 address.
85The default probe datagram carries 20 bytes of payload,
86in addition to the IPv6 header.
87The size of the payload can be specified by giving a length
88(in bytes)
89after the destination host name.
90.Pp
91Other options are:
92.Bl -tag -width Ds
93.It Fl a
94Turn on AS# lookups for each hop encountered.
95.It Fl A Ar as_server
96Turn on AS# lookups and use the given server instead of the default.
97.It Fl d
98Debug mode.
99.It Fl f Ar firsthop
100Specify how many hops to skip in trace.
101.It Fl g Ar gateway
102Specify intermediate gateway.
103Please note that
104.Nm
105tries to use routing headers.
106.It Fl I
107Use ICMP6 ECHO instead of UDP datagrams.
108.It Fl l
109Print both host hostnames and numeric addresses.
110Normally
111.Nm
112prints only hostnames if
113.Fl n
114is not specified, and only numeric addresses if
115.Fl n
116is specified.
117.It Fl m Ar hoplimit
118Specify maximum hoplimit, up to 255.
119The default is the value of the
120.Va net.inet6.ip6.hlim
121.Xr sysctl 8
122(the same default used for TCP connections).
123.It Fl n
124Do not resolve numeric address to hostname.
125.It Fl N
126Use a packet with no upper layer header for the probes,
127instead of UDP datagrams.
128.It Fl p Ar port
129Set SCTP/TCP/UDP port number to
130.Ar port .
131.It Fl q Ar probes
132Set the number of probe per hop count to
133.Ar probes .
134.It Fl r
135Bypass the normal routing tables and send directly to a host
136on an attached network.
137If the host is not on a directly-connected network,
138an error is returned.
139This option corresponds to the
140.Dv SO_DONTROUTE
141socket option;
142it can be used to ping a local host through an interface
143that has no route through it
144(e.g., after the interface was dropped by a routing daemon).
145.It Fl s Ar src
146.Ar Src
147specifies the source IPv6 address to be used.
148.It Fl S
149Use SCTP packets for the probes.
150The size of probe packets must be a multiple of 4.
151If
152.Ar datalen
153is up to 28, probe packets consist of a SHUTDOWN-ACK chunk possibly bundled
154with a PAD chunk.
155For larger probe packets, an INIT chunk is used.
156.It Fl t Ar tclass
157.Ar tclass
158specifies the
159.Em traffic class
160used when sending probe packets.
161The value must be a decimal integer in the range 0 to 255.
162The default is 0.
163.It Fl T
164Use TCP segments for the probes.
165.It Fl U
166Use UDP datagrams for the probes.
167This is the default.
168.It Fl v
169Be verbose.
170.It Fl w Ar waittime
171Specify the delay time between probes.
172.El
173.Pp
174This program prints the route to the given destination and the round-trip
175time to each gateway, in the same manner as traceroute.
176.Pp
177Here is a list of possible annotations after the round-trip time for each gateway:
178.Bl -hang -offset indent
179.It !N
180Destination Unreachable - No Route to Host.
181.It !P
182Destination Unreachable - Administratively Prohibited.
183.It !S
184Destination Unreachable - Not a Neighbour.
185.It !A
186Destination Unreachable - Address Unreachable.
187.It !H
188Parameter Problem - Unrecognized Next Header Type.
189.It !\&
190This is printed if the hop limit is <= 1 on a port unreachable message.
191This means that the packet got to the destination,
192but that the reply had a hop limit that was just large enough to
193allow it to get back to the source of the traceroute6.
194This was more interesting in the IPv4 case,
195where some IP stack bugs could be identified by this behaviour.
196.El
197.\"
198.Sh EXIT STATUS
199The
200.Nm
201utility will exit with 0 on success, and non-zero on errors.
202.\"
203.Sh SEE ALSO
204.Xr ping 8 ,
205.Xr ping6 8 ,
206.Xr traceroute 8
207.\"
208.Sh HISTORY
209The
210.Nm
211utility first appeared in WIDE hydrangea IPv6 protocol stack kit.
212