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Under GNU General Public License
2012-05-26 04:11 @38.107.179.239 Crawled by CCBot/1.0 (+http://www.commoncrawl.org/bot.html)
TRACEROUTE(8) TRACEROUTE(8)
NAME
traceroute - print route IP packets follow going to a remote host
SYNOPSIS
traceroute [ options ] host [ size ]
DESCRIPTION
Traceroute attempts to trace the route an IP packet follows to some internet host. It
finds out intermediate hops by launching probe packets with a small time-to-live (TTL)
value, and then listens for an ICMP reply of time exceeded from an intermediate router.
Traceroute starts probing with a TTL of one, and increments by one until an ICMP port
unreachable reply is received. This means the probe either got through to host, or hit
the maximum TTL.
host is the only mandatory argument, and specifies the target system, either as an IP
address, or as a host name. Parameter size determines the size of the probe packets in
bytes.
OPTIONS
-a Abort after 10 consecutive hops without an answer.
-d Turn on socket level debugging. This option is only available to the super-user
(root).
-m max_ttl
Set the maximum time-to-live (TTL) value that will be used for probing. Hosts that
are farther than max_ttl hops away will not be traced (default 30).
-n Report only IP addresses, but no hostnames.
-p port
Start probing at an alternate UDP port (default 33434). Traceroute by default
sends out UDP packets with increasing port numbers starting at port, and listens
for ICMP errors returned from remote hosts. This scheme only works if there are no
UDP servers listening on the probed hosts in the range from port to port + max_ttl.
-q n Send out n queries for each TTL (each intermediate host) (default 3).
-r Set Dont Route option, advising routers to drop the packets. In other words, only
probe within the local subnet.
-s addr
Set source address of outgoing packets to addr, given either as numeric IP address,
or as hostname.
-t tos Set the type-of-service field in the outgoing IP packets (default 0). tos is valid
in the range of 0 to 255.
-u Use microsecond timestamps.
-v Turn on verbose output.
-w wait
Set timeout for replies to wait seconds (default 5 sec). If no ICMP reply is
received within wait after a packet has been sent out, the probe is considered as
failed.
-A Report the Autonomous System Number (ASN) at each hop. Roughly speaking, the ASN
tells which administration a router is subject to. See RFC 1930 for all the
details, and section ENVIRONMENT below on how to fine tune the lookup.
-I proto
Send out probe packets using IP protocol proto, given either as name or numerical
value (default UDP). Some features like parallel probing are only available when
using UDP.
-M Determine the maximum transfer unit (MTU) along the path. See RFC 1191 for
details.
-O At each hop, perform a DNS lookup and report the owner as listed in the SOA record.
-P Send out multiple probes in parallel. The default behaviour probes each hop in
turn, starting from the nearest. Parallel mode is faster, but less reliable. Many
routers rate limit ICMP packets from a single host, so dropouts are much more
likely in parallel mode, and need not indicate a networking problem.
-Q Report detailed statistics on the round trip times at each hop (minimum / average
+- standard deviation / maximum). The values are given in milli seconds.
-S min_ttl
Set the time-to-live (TTL) value in the first packet sent out to min_ttl (default
1). This option determines the first (nearest) host that will show up in the
trace.
-T t End each line with t instead of a newline. This comes in handy, for example, when
including traceroute's output in an HTML page.
-U Move on to probing the next hop as soon as the first successful probe arrives.
-$ Send out nothing but a single ping with a very large time-to-live.
DIAGNOSTICS
Usually the round trip time is printed for each probe at each hop. Special symbols denote
when something went wrong:
* No reply received within wait seconds.
! Reply arrived with a time-to-live value of one or lower.
!H Received a reply telling that the destination host is unreachable.
!N Received a reply telling that the destination network is unreachable.
!P Received a reply telling that the desired protocol is unavailable.
!S Received a reply telling that source routing failed. Should never occur--unless
the probed gateway is screwed.
!F Received a reply telling that fragmentation is needed. Should never occur--unless
the probed gateway is screwed.
EXAMPLES
(This section is taken almost verbatim from the documentation in the traceroute source-
code.)
[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
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 more interesting example is:
[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
(I start to see why I'm having so much trouble with mail to MIT.) Note that the gateways
12, 14, 15, 16 & 17 hops away either don't send ICMP "time exceeded" messages or send them
with a TTL too small to reach us. 14 - 17 are running the MIT C Gateway code that doesn't
send "time exceeded"s. God only knows what's going on with 12.
The silent gateway 12 in the above may be the result of a bug in the 4.[23]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
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:
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 !
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 icmp reply. So, the
reply will time out on the return path until we probe with a TTL that's at least twice the
path length. I.e., rip is really only 7 hops away.
ENVIRONMENT
The lookup process of Autonomous System Numbers (ASN, see option -A above) can be config-
ured via several environment variables. By default, traceroute issues a whois query on the
Routing Assets Database (RADB) at whois.ra.net, which should be sufficient in most cases.
Chances are that you don't want to change anything here, unless you know very well what
you are doing.
The contents of the following environment variables are limited to 100 characters at most.
Any trailing characters are silently ignored. If unset, compiled-in defaults are used.
RA_SERVER
Server to issue a RADB whois query on, given either as hostname, or dotted-quad IP
address. Defaults to whois.ra.net.
RA_SERVICE
TCP port to connect to on the whois server, given either as name or port number.
Defaults to whois.
The following variables determine how traceroute attempts to extract an ASN from the whois
reply.
DATA_DELIMITER
Each line containing an ASN starts with this tag. Defaults to origin:.
The RADB may contain more than one entry for a given IP address. To find out the correct
entry, traceroute has to look up the subnet that is the most specific to this IP.
ROUTE_DELIMITER
Each line containing a subnet entry starts with this tag. Defaults to route:.
PREFIX_DELIMITER
The network IP and the prefix are separated by this tag. Defaults to /.
NOTES
This is not the standard version of traceroute (as included in the netkit package), but an
alternative implementation maintained by Ehud Gavron. It is based on the Van Jacobson/BSD
traceroute, and includes additional features including AS lookup, TOS support, microsecond
timestamps, path MTU discovery, and parallel probing. It is known as trACESroute or
traceroute-nanog.
SEE ALSO
mtr(8), netstat(8), pchar(8), ping(8)
BUGS
Please send any bugs to Ehud Gavron <gavron AT wetwork.net> and/or report them to the Debian
Bug Tracking System at http://bugs.debian.org/traceroute-nanog.
AUTHORS
TrACESroute is maintained by Ehud Gavron <ehud.gavron AT login.com>.
The first man page was written by Brian Russo for use with Debian/GNU, and was later
rewritten by Daniel Kobras <kobras AT debian.org> and Martin A. Godisch <martin AT godisch.de>.
Some parts are taken from the documentation in the source code. Still, this man page may
be used by others.
NANOG traceroute 6.3.10 March 2004 TRACEROUTE(8)
Generated by $Id: phpMan.php,v 4.49 2006/02/26 13:18:18 chedong Exp $ Author: Che Dong
On Apache
Under GNU General Public License
2012-05-26 04:11 @38.107.179.239 Crawled by CCBot/1.0 (+http://www.commoncrawl.org/bot.html)