System Administration Commands traceroute(1M)
NAME
traceroute - print the route packets take to network host
SYNOPSIS
traceroute [-adFIlnSvx] [-A addrfamily] [-c trafficclass]
[-f firsthop] [-g gateway [-g gateway...] -r]
[-i iface] [-L flowlabel] [-m maxhop]
[-P pausesec] [-p port] [-Q maxtimeout]
[-q nqueries] [-s srcaddr] [-t tos] [-w waittime] host
[packetlen]
DESCRIPTION
The Internet is a large and complex aggregation of network
hardware, connected by gateways. Tracking the route a packet
follows can be difficult. The utility traceroute traces the
route that an IP packet follows to another internet host.
The traceroute utility utilizes the both the IPv4 and IPv6
protocols. Use the -A option to override the default
behavior. traceroute uses the IPv4 protocol ttl (time to
live) field or the IPv6 field hop limit. It attempts to eli-
cit an ICMP or ICMP6 TIMEXCEDED response from each gate-
way along the path, and a PORTUNREACHABLE(or ECHOREPLY if
-I is used) response from the destination host. It starts by
sending probes with a ttl or hop limit of 1 and increases by
1 until it either gets to the host, or it hits the maximum
maxhop. The default maximum maxhop is 30 hops, but this
can be set by the -m option.
Three probes are sent at each ttl (hop limit) setting, and a
line is printed showing the ttl (hop limit), the hostname
and the address of the gateway, and the rtt (round trip
time) of each probe. The number of probes may be specifi-
cally set using the -q option. If the probe answers come
from different gateways, the hostname and the address of
each responding system will be printed. If there is no
response within a 5 second timeout interval, an asterisk (*)
is displayed for that probe. The -w option may be used to
set the timeout interval. Other possible annotations that
may appear after the time are:
!
the ttl (hop limit) value in the received packet is <=
1.
!H
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System Administration Commands traceroute(1M)
host unreachable.
!X
communication administratively prohibited.
ICMP (ICMP6) unreachable code N.
The following annotations appear only for IPv4:
!F
fragmentation needed. This should never occur. If this
is seen, the associated gateway is broken.
!N
network unreachable.
!P
protocol unreachable.
!S
source route failed. It is likely that the gateway does
not support source routing.
!T
unreachable for the specified tos (type-of-service).
!U
source host isolated or precedence problem.
The following annotations appear only for IPv6:
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System Administration Commands traceroute(1M)
!A
host unreachable for a reason other than lack of an
entry in the routing table.
!B
packet too big.
!E
destination is not a neighbor.
!R
unrecognized next header.
If almost all the probes result in some kind of unreachable
code, then traceroute gives up and exits.
The destination host is not supposed to process the UDP
probe packets, so the destination port default is set to an
unlikely value. However, if some application on the destina-
tion is using that value, the value of port can be changed
with the -p option.
The only mandatory parameter is the destination host name or
IP number. The default probe datagram length is 40 bytes (60
bytes for IPv6), but this may be increased by specifying a
packet length (in bytes) after the destination host name.
All integer arguments to traceroute can be specified in
either decimal or hexadecimal notation. For example, pack-
etlen can be specified either as 256 or 0x100.
OPTIONS
-A addrfamily
Specify the address family of the target host.
addrfamily can be either inet or inet6. Address family
determines which protocol to use. For an argument of
inet, IPv4 is used. For inet6, IPv6 is used.
By default, if the name of a host is provided, not the
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System Administration Commands traceroute(1M)
literal IP address, and a valid IPv6 address exists in
the name service database, traceroute will use this
address. Otherwise, if the name service database con-
tains an IPv4 address, it will try the IPv4 address.
Specify the address family inet or inet6 to override the
default behavior. If the argument specified is inet,
traceroute will use the IPv4 address associated with the
hostname. If none exists, traceroute will state that the
host is unknown and exit. It will not try to determine
if an IPv6 address exists in the name service database.
If the specified argument is inet6, traceroute will use
the IPv6 address that is associated with the hostname.
If none exists, traceroute will state that the host is
unknown and exit.
-a
Probe all of the addresses of a multi-homed destination.
The output looks like traceroute has been run once for
each IP address of the destination. If this option is
used together with -A, traceroute probes only the
addresses that are of the specified address family.
While probing one of the addresses of the destination,
user can skip to the next address by sending a SIGINT,
or exit traceroute by sending a SIGQUIT signal. See
signal(3C)
-c trafficclass
Specify the traffic class of probe packets. The value
must be an integer in the range from 0 to 255. Gateways
along the path may route the probe packet differently
depending upon the value of trafficclass set in the
probe packet. This option is valid only on IPv6.
-d
Set the SODEBUG socket option.
-F
Set the "don't fragment" bit. This option is valid only
on IPv4. When specified from within a shared-IP zone,
this option has no effect as the "don't fragment" bit is
always set in this case.
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-f firsthop
Set the starting ttl ( hop limit) value to firsthop, to
override the default value 1. traceroute skips process-
ing for those intermediate gateways which are less than
firsthop hops away.
-g gateway
Specify a loose source route gateway. The user can
specify more than one gateway by using -g for each gate-
way. The maximum number of gateways is 8 for IPv4 and
127 for IPv6. Note that some factors such as the link
MTU can further limit the number of gateways for IPv6.
This option cannot be used with the -r option.
Only users with the {PRIVNETRAWACES} privilege can
specify a loose source route with this option.
-I
Use ICMP (ICMP6) ECHO instead of UDP datagrams.
-i iface
For IPv4, this option specifies a network interface to
obtain the source IP address. This is normally only use-
ful on a multi-homed host. The -s option is also another
way to do this. For IPv6, it specifies the network
interface on which probe packets are transmitted. The
argument can be either an interface index, for example,
1, 2, or an interface name, for example, eri0, hme0.
-L flowlabel
Specify the flow label of probe packets. The value must
be an integer in the range from 0 to 1048575. This
option is valid only on IPv6.
-l
Print the value of the ttl (hop limit) field in each
packet received.
-m maxhop
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Set the maximum ttl (hop limit) used in outgoing probe
packets. The default is 30 hops, which is the same
default used for TCP connections.
-n
Print hop addresses numerically rather than symbolically
and numerically. This saves a nameserver address-to-name
lookup for each gateway found on the path.
-P pausesec
Specify a delay, in seconds, to pause between probe
packets. This may be necessary if the final destination
does not accept undeliverable packets in bursts. By
default, traceroute sends the next probe as soon as it
has received a reply. Note that pausesec is a real
number.
-p port
Set the base UDP port number used in probes.The default
is 33434. traceroute hopes that nothing is listening on
UDP ports (base](nhops-1)*nqueries) to
(base](nhops*nqueries)-1)at the destination host, so
that an ICMP (ICMP6) PORTUNREACHABLE 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 select an unused port range. nhops is
defined as the number of hops between the source and the
destination.
-Q maxtimeout
Stop probing this hop after maxtimeout consecutive
timeouts are detected. The default value is 5. Useful in
combination with the -q option if you have specified a
large nqueries probe count.
-q nqueries
Set the desired number of probe queries. The default is
3.
-r
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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 send probes to a local host
through an interface that has been dropped by the router
deamon. See in.routed(1M). You cannot use this option if
the -g option is used.
-S
Display a summary of how many probes were not answered
for each hop.
-s srcaddr
Use the following address, which usually is given as a
literal IP address, not a hostname, as the source
address in outgoing probe packets. On multi-homed hosts,
those with more than one IP address, this option can be
used to force the source address to be something other
than the IP address traceroute picks by default. If the
IP address is not one of this machine's interface
addresses, an error is returned and nothing is sent. For
IPv4, when used together with the -i option, the given
IP address should be configured on the specified inter-
face. Otherwise, an error will be returned. In the case
of IPv6, the interface name and the source address do
not have to match.
-t tos
Set the tos(type-of-service) in probe packets to the
specified value. The default is zero. The value must be
an integer in the range from 0 to 255. Gateways along
the path may route the probe packet differently depend-
ing upon the tos value set in the probe packet. This
option is valid only on IPv4.
-v
Verbose output. For each hop, the size and the destina-
tion of the response packets is displayed. Also ICMP
(ICMP6) packets received other than TIMEXCEDED and
UNREACHABLE are listed as well.
-w waittime
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Set the time, in seconds, to wait for a response to a
probe. The default is 5 seconds.
-x
Prevent traceroute from calculating checksums. Checksums
are usually required for the last hop when using ICMP
ECHO probes. This option is valid only on IPv4. See the
-I option.
When specified from within a shared-IP zone, this option
has no effect as the checksum is always calculated by
the operating system in this case.
OPERANDS
The following operands are supported:
host
The network host.
EXAMPLES
Example 1 Sample Output From the traceroute Utility
Some sample output from the traceroute utility might be:
istanbul% traceroute london
traceroute: Warning: london has multiple addresses; \
using 4::114:a00:20ff:ab3d:83ed
traceroute: Warning: Multiple interfaces found; \
using 4::56:a00:20ff:fe93:8dde @ eri0:2
traceroute to london (4::114:a00:20ff:ab3d:83ed), 30 hops max, \
60 byte packets
1 frbldg7c-86 (4::56:a00:20ff:fe1f:65a1) 1.786 ms 1.544 ms 1.719 ms
2 frbldg7b-77 (4::255:0:0:c0a8:517) 2.587 ms 3.001 ms 2.988 ms
3 london (4::114:a00:20ff:ab3d:83ed) 3.122 ms 2.744 ms 3.356 ms
The target host, london, has both IPv4 and IPv6 addresses in
the name service database. According to the default
behavior, traceroute uses IPv6 address of the destination
host.
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Example 2 Using the traceroute Utility For a Host Which has
Only IPv4 Addresses
In the following examples, traceroute is tracking the route
to host sanfrancisco, which has only IPv4 addresses in the
name service database. Therefore traceroute uses only IPv4
addresses. The following shows the 7-hop path that a packet
would follow from the host istanbul to the host sanfran-
cisco.
istanbul% traceroute sanfrancisco
traceroute: Warning: Multiple interfaces found; using 172.31.86.247 @eri0
traceroute to sanfrancisco (172.29.64.39), 30 hops max, 40 byte packets
1 frbldg7c-86 (172.31.86.1) 1.516 ms 1.283 ms 1.362 ms
2 bldg1a-001 (172.31.1.211) 2.277 ms 1.773 ms 2.186 ms
3 bldg4-bldg1 (172.30.4.42) 1.978 ms 1.986 ms 13.996 ms
4 bldg6-bldg4 (172.30.4.49) 2.655 ms 3.042 ms 2.344 ms
5 ferbldg11a-001 (172.29.1.236) 2.636 ms 3.432 ms 3.830 ms
6 frbldg12b-153 (172.29.153.72) 3.452 ms 3.146 ms 2.962 ms
7 sanfrancisco (172.29.64.39) 3.430 ms 3.312 ms 3.451 ms
Example 3 Using the traceroute Utility With Source Routing
The following example shows the path of a packet that goes
from istanbul to sanfrancisco through the hosts cairo and
paris, as specified by the -g option. The -I option makes
traceroute send ICMP ECHO probes to the host sanfrancisco.
The -i options sets the source address to the IP address
configured on the interface qe0.
istanbul% traceroute -g cairo -g paris -i qe0 -q 1 -I sanfrancisco
traceroute to sanfrancisco (172.29.64.39), 30 hops max, 56 byte packets
1 frbldg7c-86 (172.31.86.1) 2.012 ms
2 flrbldg7u (172.31.17.131) 4.960 ms
3 cairo (192.168.163.175) 4.894 ms
4 flrbldg7u (172.31.17.131) 3.475 ms
5 frbldg7c-017 (172.31.17.83) 4.126 ms
6 paris (172.31.86.31) 4.086 ms
7 frbldg7b-82 (172.31.82.1) 6.454 ms
8 bldg1a-001 (172.31.1.211) 6.541 ms
9 bldg6-bldg4 (172.30.4.49) 6.518 ms
10 ferbldg11a-001 (172.29.1.236) 9.108 ms
11 frbldg12b-153 (172.29.153.72) 9.634 ms
12 sanfrancisco (172.29.64.39) 14.631 ms
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EXIT STATUS
The following exit values are returned:
0
Successful operation.
>0
An error occurred.
ATRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
ATRIBUTE TYPE ATRIBUTE VALUE
Availability SUNWcsu
SEE ALSO
netstat(1M), signal(3C), ping(1M), attributes(5),
privileges(5), zones(5)
WARNINGS
This utility is intended for use in network testing, meas-
urement 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 traceroute(1M) during
normal operations or from automated scripts.
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