362 lines
12 KiB
Groff
362 lines
12 KiB
Groff
.\" Copyright (c) 1990, 1991, 1993
|
|
.\" The Regents of the University of California. All rights reserved.
|
|
.\"
|
|
.\" This code is derived from software contributed to Berkeley by
|
|
.\" Van Jacobson.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\" 3. All advertising materials mentioning features or use of this software
|
|
.\" must display the following acknowledgement:
|
|
.\" This product includes software developed by the University of
|
|
.\" California, Berkeley and its contributors.
|
|
.\" 4. Neither the name of the University nor the names of its contributors
|
|
.\" may be used to endorse or promote products derived from this software
|
|
.\" without specific prior written permission.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\" @(#)traceroute.8 8.1 (Berkeley) 6/6/93
|
|
.\" $Id: traceroute.8,v 1.4 1995/01/04 04:28:18 mycroft Exp $
|
|
.\"
|
|
.Dd June 6, 1993
|
|
.Dt TRACEROUTE 8
|
|
.Os BSD 4.3
|
|
.Sh NAME
|
|
.Nm traceroute
|
|
.Nd print the route packets take to network host
|
|
.Sh SYNOPSIS
|
|
.Nm traceroute
|
|
.Op Fl d
|
|
.Op Fl D
|
|
.Op Fl g Ar gateway_addr
|
|
.Op Fl m Ar max_ttl
|
|
.Op Fl n
|
|
.Op Fl p Ar port
|
|
.Op Fl q Ar nqueries
|
|
.Op Fl r
|
|
.Bk -words
|
|
.Op Fl s Ar src_addr
|
|
.Ek
|
|
.Op Fl t Ar tos
|
|
.Op Fl w Ar waittime
|
|
.Ar host
|
|
.Op Ar packetsize
|
|
.Sh DESCRIPTION
|
|
The Internet is a large and complex aggregation of
|
|
network hardware, connected together by gateways.
|
|
Tracking the route one's packets follow (or finding the miscreant
|
|
gateway that's discarding your packets) can be difficult.
|
|
.Nm Traceroute
|
|
utilizes the IP protocol `time to live' field and attempts to elicit an
|
|
.Tn ICMP
|
|
.Dv TIME_EXCEEDED
|
|
response from each gateway along the path to some
|
|
host.
|
|
.Pp
|
|
The only mandatory parameter is the destination host name or IP number.
|
|
The default probe datagram length is 38 bytes, but this may be increased
|
|
by specifying a packet size (in bytes) after the destination host
|
|
name.
|
|
.Pp
|
|
Other options are:
|
|
.Bl -tag -width Ds
|
|
.It Fl d
|
|
Turn on socket-level debugging.
|
|
.It Fl D
|
|
Dump the packet data to standard error before transmitting it.
|
|
.It Fl g Ar gateway_addr
|
|
Add
|
|
.Ar gateway_addr
|
|
to the list of addresses in the IP Loose Source Record Route (LSRR)
|
|
option. If no gateways are specified, the LSRR option is omitted.
|
|
.It Fl m Ar max_ttl
|
|
Set the max time-to-live (max number of hops) used in outgoing probe
|
|
packets. The default is 30 hops (the same default used for
|
|
.Tn TCP
|
|
connections).
|
|
.It Fl n
|
|
Print hop addresses numerically rather than symbolically and numerically
|
|
(saves a nameserver address-to-name lookup for each gateway found on the
|
|
path).
|
|
.It Fl p Ar port
|
|
Set the base
|
|
.Tn UDP
|
|
.Ar port
|
|
number used in probes (default is 33434).
|
|
.Nm Traceroute
|
|
hopes that nothing is listening on
|
|
.Tn UDP
|
|
ports
|
|
.Em base
|
|
to
|
|
.Em base+nhops-1
|
|
at the destination host (so an
|
|
.Tn ICMP
|
|
.Dv PORT_UNREACHABLE
|
|
message will
|
|
be returned to terminate the route tracing). If something is
|
|
listening on a port in the default range, this option can be used
|
|
to pick an unused port range.
|
|
.It Fl q Ar nqueries
|
|
Set the number of probes per ``ttl'' to
|
|
.Ar nqueries
|
|
(default is three probes).
|
|
.It Fl r
|
|
Bypass the normal routing tables and send directly to a host on an attached
|
|
network.
|
|
If the host is not on a directly-attached network,
|
|
an error is returned.
|
|
This option can be used to ping a local host through an interface
|
|
that has no route through it (e.g., after the interface was dropped by
|
|
.Xr routed 8 ) .
|
|
.It Fl s Ar src_addr
|
|
Use the following IP address
|
|
(which must be given as an IP number, not
|
|
a hostname) as the source address in outgoing probe packets. On
|
|
hosts with more than one IP address, this option can be used to
|
|
force the source address to be something other than the IP address
|
|
of the interface the probe packet is sent on. If the IP address
|
|
is not one of this machine's interface addresses, an error is
|
|
returned and nothing is sent.
|
|
.It Fl t Ar tos
|
|
Set the
|
|
.Em type-of-service
|
|
in probe packets to the following value (default zero). The value must be
|
|
a decimal integer in the range 0 to 255. This option can be used to
|
|
see if different types-of-service result in different paths. (If you
|
|
are not running a
|
|
.Bx 4.3 tahoe
|
|
or later system, this may be academic since the normal network
|
|
services like telnet and ftp don't let you control the
|
|
.Dv TOS ) .
|
|
Not all values of
|
|
.Dv TOS
|
|
are legal or
|
|
meaningful \- see the IP spec for definitions. Useful values are
|
|
probably
|
|
.Ql \-t 16
|
|
(low delay) and
|
|
.Ql \-t 8
|
|
(high throughput).
|
|
.It Fl v
|
|
Verbose output. Received
|
|
.Tn ICMP
|
|
packets other than
|
|
.Dv TIME_EXCEEDED
|
|
and
|
|
.Dv UNREACHABLE Ns s
|
|
are listed.
|
|
.It Fl w
|
|
Set the time (in seconds) to wait for a response to a probe (default 3
|
|
sec.).
|
|
.El
|
|
.Pp
|
|
This program attempts to trace the route an IP packet would follow to some
|
|
internet host by launching
|
|
.Tn UDP
|
|
probe
|
|
packets with a small ttl (time to live) then listening for an
|
|
.Tn ICMP
|
|
"time exceeded" reply from a gateway. We start our probes
|
|
with a ttl of one and increase by one until we get an
|
|
.Tn ICMP
|
|
"port unreachable"
|
|
(which means we got to "host") or hit a max (which
|
|
defaults to 30 hops & can be changed with the
|
|
.Fl m
|
|
flag). Three
|
|
probes (changed with
|
|
.Fl q
|
|
flag) are sent at each ttl setting and a
|
|
line is printed showing the ttl, address of the gateway and
|
|
round trip time of each probe. If the probe answers come from
|
|
different gateways, the address of each responding system will
|
|
be printed. If there is no response within a 3 sec. timeout
|
|
interval (changed with the
|
|
.Fl w
|
|
flag), a "*" is printed for that
|
|
probe.
|
|
.Pp
|
|
We don't want the destination
|
|
host to process the
|
|
.Tn UDP
|
|
probe packets so the destination port is set to an
|
|
unlikely value (if some clod on the destination is using that
|
|
value, it can be changed with the
|
|
.Fl p
|
|
flag).
|
|
.Pp
|
|
A sample use and output might be:
|
|
.Bd -literal
|
|
[yak 71]% traceroute nis.nsf.net.
|
|
traceroute to nis.nsf.net (35.1.1.48), 30 hops max, 56 byte packet
|
|
1 helios.ee.lbl.gov (128.3.112.1) 19 ms 19 ms 0 ms
|
|
2 lilac-dmc.Berkeley.EDU (128.32.216.1) 39 ms 39 ms 19 ms
|
|
3 lilac-dmc.Berkeley.EDU (128.32.216.1) 39 ms 39 ms 19 ms
|
|
4 ccngw-ner-cc.Berkeley.EDU (128.32.136.23) 39 ms 40 ms 39 ms
|
|
5 ccn-nerif22.Berkeley.EDU (128.32.168.22) 39 ms 39 ms 39 ms
|
|
6 128.32.197.4 (128.32.197.4) 40 ms 59 ms 59 ms
|
|
7 131.119.2.5 (131.119.2.5) 59 ms 59 ms 59 ms
|
|
8 129.140.70.13 (129.140.70.13) 99 ms 99 ms 80 ms
|
|
9 129.140.71.6 (129.140.71.6) 139 ms 239 ms 319 ms
|
|
10 129.140.81.7 (129.140.81.7) 220 ms 199 ms 199 ms
|
|
11 nic.merit.edu (35.1.1.48) 239 ms 239 ms 239 ms
|
|
|
|
.Ed
|
|
Note that lines 2 & 3 are the same. This is due to a buggy
|
|
kernel on the 2nd hop system \- lbl-csam.arpa \- that forwards
|
|
packets with a zero ttl (a bug in the distributed version
|
|
of 4.3
|
|
.Tn BSD ) .
|
|
Note that you have to guess what path
|
|
the packets are taking cross-country since the
|
|
.Tn NSFNet
|
|
(129.140)
|
|
doesn't supply address-to-name translations for its
|
|
.Tn NSS Ns es .
|
|
.Pp
|
|
A more interesting example is:
|
|
.Bd -literal
|
|
[yak 72]% traceroute allspice.lcs.mit.edu.
|
|
traceroute to allspice.lcs.mit.edu (18.26.0.115), 30 hops max
|
|
1 helios.ee.lbl.gov (128.3.112.1) 0 ms 0 ms 0 ms
|
|
2 lilac-dmc.Berkeley.EDU (128.32.216.1) 19 ms 19 ms 19 ms
|
|
3 lilac-dmc.Berkeley.EDU (128.32.216.1) 39 ms 19 ms 19 ms
|
|
4 ccngw-ner-cc.Berkeley.EDU (128.32.136.23) 19 ms 39 ms 39 ms
|
|
5 ccn-nerif22.Berkeley.EDU (128.32.168.22) 20 ms 39 ms 39 ms
|
|
6 128.32.197.4 (128.32.197.4) 59 ms 119 ms 39 ms
|
|
7 131.119.2.5 (131.119.2.5) 59 ms 59 ms 39 ms
|
|
8 129.140.70.13 (129.140.70.13) 80 ms 79 ms 99 ms
|
|
9 129.140.71.6 (129.140.71.6) 139 ms 139 ms 159 ms
|
|
10 129.140.81.7 (129.140.81.7) 199 ms 180 ms 300 ms
|
|
11 129.140.72.17 (129.140.72.17) 300 ms 239 ms 239 ms
|
|
12 * * *
|
|
13 128.121.54.72 (128.121.54.72) 259 ms 499 ms 279 ms
|
|
14 * * *
|
|
15 * * *
|
|
16 * * *
|
|
17 * * *
|
|
18 ALLSPICE.LCS.MIT.EDU (18.26.0.115) 339 ms 279 ms 279 ms
|
|
|
|
.Ed
|
|
Note that the gateways 12, 14, 15, 16 & 17 hops away
|
|
either don't send
|
|
.Tn ICMP
|
|
"time exceeded" messages or send them
|
|
with a ttl too small to reach us. 14 \- 17 are running the
|
|
.Tn MIT
|
|
C Gateway code that doesn't send "time exceeded"s. God
|
|
only knows what's going on with 12.
|
|
.Pp
|
|
The silent gateway 12 in the above may be the result of a bug in
|
|
the 4.[23]
|
|
.Tn BSD
|
|
network code (and its derivatives): 4.x (x <= 3)
|
|
sends an unreachable message using whatever ttl remains in the
|
|
original datagram. Since, for gateways, the remaining ttl is
|
|
zero, the
|
|
.Tn ICMP
|
|
"time exceeded" is guaranteed to not make it back
|
|
to us. The behavior of this bug is slightly more interesting
|
|
when it appears on the destination system:
|
|
.Bd -literal
|
|
1 helios.ee.lbl.gov (128.3.112.1) 0 ms 0 ms 0 ms
|
|
2 lilac-dmc.Berkeley.EDU (128.32.216.1) 39 ms 19 ms 39 ms
|
|
3 lilac-dmc.Berkeley.EDU (128.32.216.1) 19 ms 39 ms 19 ms
|
|
4 ccngw-ner-cc.Berkeley.EDU (128.32.136.23) 39 ms 40 ms 19 ms
|
|
5 ccn-nerif35.Berkeley.EDU (128.32.168.35) 39 ms 39 ms 39 ms
|
|
6 csgw.Berkeley.EDU (128.32.133.254) 39 ms 59 ms 39 ms
|
|
7 * * *
|
|
8 * * *
|
|
9 * * *
|
|
10 * * *
|
|
11 * * *
|
|
12 * * *
|
|
13 rip.Berkeley.EDU (128.32.131.22) 59 ms ! 39 ms ! 39 ms !
|
|
|
|
.Ed
|
|
Notice that there are 12 "gateways" (13 is the final
|
|
destination) and exactly the last half of them are "missing".
|
|
What's really happening is that rip (a Sun-3 running Sun OS3.5)
|
|
is using the ttl from our arriving datagram as the ttl in its
|
|
.Tn ICMP
|
|
reply. So, the reply will time out on the return path
|
|
(with no notice sent to anyone since
|
|
.Tn ICMP's
|
|
aren't sent for
|
|
.Tn ICMP's )
|
|
until we probe with a ttl that's at least twice the path
|
|
length. I.e., rip is really only 7 hops away. A reply that
|
|
returns with a ttl of 1 is a clue this problem exists.
|
|
.Nm Traceroute
|
|
prints a "!" after the time if the ttl is <= 1.
|
|
Since vendors ship a lot of obsolete
|
|
.Pf ( Tn DEC Ns \'s
|
|
Ultrix, Sun 3.x) or
|
|
non-standard
|
|
.Pq Tn HPUX
|
|
software, expect to see this problem
|
|
frequently and/or take care picking the target host of your
|
|
probes.
|
|
Other possible annotations after the time are
|
|
.Sy !H ,
|
|
.Sy !N ,
|
|
.Sy !P
|
|
(got a host, network or protocol unreachable, respectively),
|
|
.Sy !S
|
|
or
|
|
.Sy !F
|
|
(source route failed or fragmentation needed \- neither of these should
|
|
ever occur and the associated gateway is busted if you see one). If
|
|
almost all the probes result in some kind of unreachable,
|
|
.Nm traceroute
|
|
will give up and exit.
|
|
.Pp
|
|
.Bd -literal
|
|
traceroute \-g 10.3.0.5 128.182.0.0
|
|
|
|
.Ed
|
|
will show the path from the Cambridge Mailbridge to PSC, while
|
|
.Bd -literal
|
|
traceroute \-g 192.5.146.4 \-g 10.3.0.5 35.0.0.0
|
|
|
|
.Ed
|
|
will show the path from the Cambridge Mailbridge to Merit, using PSC to
|
|
reach the Mailbridge.
|
|
.Pp
|
|
This program is intended for use in network testing, measurement
|
|
and management.
|
|
It should be used primarily for manual fault isolation.
|
|
Because of the load it could impose on the network, it is unwise to use
|
|
.Nm traceroute
|
|
during normal operations or from automated scripts.
|
|
.Sh AUTHOR
|
|
Implemented by Van Jacobson from a suggestion by Steve Deering. Debugged
|
|
by a cast of thousands with particularly cogent suggestions or fixes from
|
|
C. Philip Wood, Tim Seaver and Ken Adelman.
|
|
.Sh SEE ALSO
|
|
.Xr netstat 1 ,
|
|
.Xr ping 8
|
|
.Sh HISTORY
|
|
The
|
|
.Nm
|
|
command
|
|
.Bt
|