mdocify and update the traceroute(8) manual page.
Reviewed by: brueffer No objection: ru, uqs
This commit is contained in:
Joel Dahl
parent
f4ae3eee14
commit
49074c51cc
@ -16,113 +16,64 @@
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.\" $Id: traceroute.8,v 1.19 2000/09/21 08:44:19 leres Exp $
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.\" $FreeBSD$
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.\"
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.TH TRACEROUTE 8 "19 February 2008"
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.UC 6
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.SH NAME
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traceroute \- print the route packets take to network host
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.SH SYNOPSIS
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.na
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.B traceroute
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[
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.B \-adDeFISnrvx
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] [
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.B \-f
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.I first_ttl
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] [
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.B \-g
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.I gateway
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]
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.br
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.ti +8
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[
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.B \-i
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.I iface
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] [
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.B \-M
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.I first_ttl
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]
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.br
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.ti +8
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[
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.B \-m
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.I max_ttl
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] [
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.B \-P
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.I proto
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] [
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.B \-p
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.I port
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]
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.br
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.ti +8
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[
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.B \-q
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.I nqueries
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] [
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.B \-s
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.I src_addr
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] [
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.B \-t
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.I tos
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]
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.br
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.ti +8
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[
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.B \-w
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.I waittime
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] [
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.B \-A
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.I as_server
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] [
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.B \-z
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.I pausemsecs
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]
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.br
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.ti +8
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.I host
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[
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.I packetlen
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]
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.ad
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.SH DESCRIPTION
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.Dd June 19, 2012
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.Dt TRACEROUTE 8
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.Os
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.Sh NAME
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.Nm traceroute
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.Nd "print the route packets take to network host"
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.Sh SYNOPSIS
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.Nm
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.Bk -words
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.Op Fl adDeFISnrvx
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.Op Fl f Ar first_ttl
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.Op Fl g Ar gateway
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.Op Fl M Ar first_ttl
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.Op Fl m Ar max_ttl
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.Op Fl P Ar proto
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.Op Fl p Ar port
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.Op Fl q Ar nqueries
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.Op Fl s Ar src_addr
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.Op Fl t Ar tos
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.Op Fl w Ar waittime
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.Op Fl A Ar as_server
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.Op Fl z Ar pausemsecs
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.Ar host
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.Op Ar packetlen
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.Ek
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.Sh DESCRIPTION
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The Internet is a large and complex aggregation of
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network hardware, connected together by gateways.
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Tracking the route one's packets follow (or finding the miscreant
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gateway that's discarding your packets) can be difficult.
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.I Traceroute
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.Nm
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utilizes the IP protocol `time to live' field and attempts to elicit an
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ICMP TIME_EXCEEDED response from each gateway along the path to some
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host.
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.PP
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.Pp
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The only mandatory parameter is the destination host name or IP number.
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The default probe datagram length is 40 bytes, but this may be increased
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by specifying a packet length (in bytes) after the destination host
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name.
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.PP
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.Pp
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Other options are:
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.TP
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.B \-a
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.Bl -tag -width Ds
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.It Fl a
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Turn on AS# lookups for each hop encountered.
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.TP
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.B -A
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.It Fl A Ar as_server
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Turn on AS# lookups and use the given server instead of the
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default.
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.TP
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.B \-e
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.It Fl e
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Firewall evasion mode.
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Use fixed destination ports for UDP and TCP probes.
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The destination port does NOT increment with each packet sent.
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.TP
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.B \-f
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.It Fl f Ar first_ttl
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Set the initial time-to-live used in the first outgoing probe packet.
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.TP
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.B \-F
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.It Fl F
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Set the "don't fragment" bit.
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.TP
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.B \-d
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.It Fl d
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Enable socket level debugging.
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.TP
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.B \-D
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.It Fl D
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When an ICMP response to our probe datagram is received,
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print the differences between the transmitted packet and
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the packet quoted by the ICMP response.
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@ -133,74 +84,66 @@ Bytes that are unchanged in the quoted packet are shown as underscores.
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Note,
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the IP checksum and the TTL of the quoted packet are not expected to match.
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By default, only one probe per hop is sent with this option.
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.TP
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.B \-g
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.It Fl g Ar gateway
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Specify a loose source route gateway (8 maximum).
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.TP
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.B \-i
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.It Fl i Ar iface
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Specify a network interface to obtain the source IP address for
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outgoing probe packets. This is normally only useful on a multi-homed
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host. (See the
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.B \-s
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.Fl s
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flag for another way to do this.)
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.TP
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.B \-I
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.It Fl I
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Use ICMP ECHO instead of UDP datagrams. (A synonym for "-P icmp").
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.TP
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.B \-M
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.It Fl M Ar first_ttl
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Set the initial time-to-live value used in outgoing probe packets.
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The default is 1, i.e., start with the first hop.
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.TP
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.B \-m
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.It Fl m Ar max_ttl
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Set the max time-to-live (max number of hops) used in outgoing probe
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packets. The default is
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.I net.inet.ip.ttl
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hops (the same default used for TCP
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packets. The default is the value of the
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.Va net.inet.ip.ttl
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.Xr sysctl 8
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(the same default used for TCP
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connections).
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.TP
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.B \-n
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.It Fl n
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Print hop addresses numerically rather than symbolically and numerically
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(saves a nameserver address-to-name lookup for each gateway found on the
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path).
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.TP
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.B \-P
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.It Fl P Ar proto
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Send packets of specified IP protocol. The currently supported protocols
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are: UDP, TCP, GRE and ICMP. Other protocols may also be specified (either by
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name or by number), though
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.I traceroute
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.Nm
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does not implement any special knowledge of their packet formats. This
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option is useful for determining which router along a path may be
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blocking packets based on IP protocol number. But see BUGS below.
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.TP
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.B \-p
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.It Fl p Ar port
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Protocol specific. For UDP and TCP, sets
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the base port number used in probes (default is 33434).
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the base
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.Ar port
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number used in probes (default is 33434).
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Traceroute hopes that nothing is listening on UDP ports
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.I base
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.Em base
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to
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.I base + nhops * nprobes - 1
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.Em base + nhops * nprobes - 1
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at the destination host (so an ICMP PORT_UNREACHABLE message will
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be returned to terminate the route tracing). If something is
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listening on a port in the default range, this option can be used
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to pick an unused port range.
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.TP
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.B \-q
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.It Fl q Ar nqueries
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Set the number of probes per hop (default is 3,
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unless
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.B -D
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.Fl D
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is specified,
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when it is 1).
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.TP
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.B \-r
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.It Fl r
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Bypass the normal routing tables and send directly to a host on an attached
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network.
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If the host is not on a directly-attached network,
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an error is returned.
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This option can be used to ping a local host through an interface
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that has no route through it (e.g., after the interface was dropped by
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.IR routed (8C)).
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.TP
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.B \-s
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.Xr routed 8 .
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.It Fl s Ar src_addr
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Use the following IP address (which usually is given as an IP number, not
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a hostname) as the source address in outgoing probe packets. On
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multi-homed hosts (those with more than one IP
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@ -209,15 +152,13 @@ force the source address to be something other than the IP address
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of the interface the probe packet is sent on. If the IP address
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is not one of this machine's interface addresses, an error is
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returned and nothing is sent. (See the
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.B \-i
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.Fl i
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flag for another way to do this.)
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.TP
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.B \-S
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.It Fl S
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Print a summary of how many probes were not answered for each hop.
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.TP
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.B \-t
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.It Fl t Ar tos
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Set the
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.I type-of-service
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.Em type-of-service
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in probe packets to the following value (default zero). The value must be
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a decimal integer in the range 0 to 255. This option can be used to
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see if different types-of-service result in different paths. (If you
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@ -226,72 +167,69 @@ services like telnet and ftp don't let you control the TOS).
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Not all values of TOS are legal or
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meaningful \- see the IP spec for definitions. Useful values are
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probably
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.RB ` -t
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.IR 16 '
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.Fl t Ar 16
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(low delay) and
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.RB ` -t
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.IR 8 '
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.Fl t Ar 8
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(high throughput).
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.TP
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.B \-v
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Verbose output. Received ICMP packets other than TIME_EXCEEDED and
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UNREACHABLEs are listed.
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.TP
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.B \-w
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.It Fl v
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Verbose output. Received ICMP packets other than
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.Dv TIME_EXCEEDED
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and
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.Dv UNREACHABLE Ns s
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are listed.
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.It Fl w Ar waittime
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Set the time (in seconds) to wait for a response to a probe (default 5
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sec.).
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.TP
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.B \-x
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.It Fl x
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Toggle ip checksums. Normally, this prevents traceroute from calculating
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ip checksums. In some cases, the operating system can overwrite parts of
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the outgoing packet but not recalculate the checksum (so in some cases
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the default is to not calculate checksums and using
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.B \-x
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.Fl x
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causes them to be calculated). Note that checksums are usually required
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for the last hop when using ICMP ECHO probes
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.RB ( \-I ).
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.Pq Fl I .
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So they are always calculated when using ICMP.
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.TP
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.B \-z
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.It Fl z Ar pausemsecs
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Set the time (in milliseconds) to pause between probes (default 0).
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Some systems such as Solaris and routers such as Ciscos rate limit
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icmp messages. A good value to use with this this is 500 (e.g. 1/2 second).
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.PP
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.El
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.Pp
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This program attempts to trace the route an IP packet would follow to some
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internet host by launching UDP probe
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packets with a small ttl (time to live) then listening for an
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ICMP "time exceeded" reply from a gateway. We start our probes
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with a ttl of one and increase by one until we get an ICMP "port
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unreachable" (which means we got to "host") or hit a max (which
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defaults to
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.I net.inet.ip.ttl
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hops & can be changed with the
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.B \-m
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defaults to the amount of hops specified by the
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.Va net.inet.ip.ttl
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.Xr sysctl 8
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and can be changed with the
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.Fl m
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flag). Three
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probes (change with
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.B \-q
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.Fl q
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flag) are sent at each ttl setting and a
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line is printed showing the ttl, address of the gateway and
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round trip time of each probe. If the probe answers come from
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different gateways, the address of each responding system will
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be printed. If there is no response within a 5 sec. timeout
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interval (changed with the
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.B \-w
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.Fl w
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flag), a "*" is printed for that
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probe.
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.PP
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.Pp
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We don't want the destination
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host to process the UDP probe packets so the destination port is set to an
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unlikely value (if some clod on the destination is using that
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value, it can be changed with the
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.B \-p
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.Fl p
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flag).
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.PP
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.Pp
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A sample use and output might be:
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.RS
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.nf
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[yak 71]% traceroute nis.nsf.net.
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.Bd -literal -offset 4n
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% traceroute nis.nsf.net.
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traceroute to nis.nsf.net (35.1.1.48), 64 hops max, 38 byte packet
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1 helios.ee.lbl.gov (128.3.112.1) 19 ms 19 ms 0 ms
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2 lilac-dmc.Berkeley.EDU (128.32.216.1) 39 ms 39 ms 19 ms
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@ -304,21 +242,18 @@ traceroute to nis.nsf.net (35.1.1.48), 64 hops max, 38 byte packet
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9 129.140.71.6 (129.140.71.6) 139 ms 239 ms 319 ms
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10 129.140.81.7 (129.140.81.7) 220 ms 199 ms 199 ms
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11 nic.merit.edu (35.1.1.48) 239 ms 239 ms 239 ms
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.fi
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.RE
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.Ed
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.Pp
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Note that lines 2 & 3 are the same. This is due to a buggy
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kernel on the 2nd hop system \- lilac-dmc.Berkeley.EDU \- that forwards
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packets with a zero ttl (a bug in the distributed version
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of 4.3BSD). Note that you have to guess what path
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the packets are taking cross-country since the NSFNet (129.140)
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doesn't supply address-to-name translations for its NSSes.
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.PP
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.Pp
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||||
A more interesting example is:
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.RS
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.nf
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[yak 72]% traceroute allspice.lcs.mit.edu.
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.Bd -literal -offset 4n
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% traceroute allspice.lcs.mit.edu.
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traceroute to allspice.lcs.mit.edu (18.26.0.115), 64 hops max
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1 helios.ee.lbl.gov (128.3.112.1) 0 ms 0 ms 0 ms
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2 lilac-dmc.Berkeley.EDU (128.32.216.1) 19 ms 19 ms 19 ms
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@ -338,15 +273,14 @@ traceroute to allspice.lcs.mit.edu (18.26.0.115), 64 hops max
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16 * * *
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||||
17 * * *
|
||||
18 ALLSPICE.LCS.MIT.EDU (18.26.0.115) 339 ms 279 ms 279 ms
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.fi
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.RE
|
||||
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||||
.Ed
|
||||
.Pp
|
||||
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.
|
||||
.PP
|
||||
.Pp
|
||||
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
|
||||
@ -354,9 +288,7 @@ 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:
|
||||
|
||||
.RS
|
||||
.nf
|
||||
.Bd -literal -offset 4n
|
||||
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
|
||||
@ -370,9 +302,8 @@ when it appears on the destination system:
|
||||
11 * * *
|
||||
12 * * *
|
||||
13 rip.Berkeley.EDU (128.32.131.22) 59 ms ! 39 ms ! 39 ms !
|
||||
.fi
|
||||
.RE
|
||||
|
||||
.Ed
|
||||
.Pp
|
||||
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)
|
||||
@ -383,77 +314,82 @@ 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.
|
||||
Traceroute prints a "!" after the time if the ttl is <= 1.
|
||||
Since vendors ship a lot of obsolete (DEC's Ultrix, Sun 3.x) or
|
||||
non-standard (HPUX) software, expect to see this problem
|
||||
Since vendors ship a lot of obsolete
|
||||
.Pf ( Tn DEC Ns \'s
|
||||
Ultrix, Sun 3.x) or
|
||||
non-standard
|
||||
.Pq Tn HP-UX
|
||||
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
|
||||
.BR !H ,
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||||
.BR !N ,
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||||
or
|
||||
.B !P
|
||||
(host, network or protocol unreachable),
|
||||
.B !S
|
||||
(source route failed),
|
||||
.B !F\-<pmtu>
|
||||
(fragmentation needed \- the RFC1191 Path MTU Discovery value is displayed),
|
||||
.B !U
|
||||
or
|
||||
.B !W
|
||||
(destination network/host unknown),
|
||||
.B !I
|
||||
(source host is isolated),
|
||||
.B !A
|
||||
(communication with destination network administratively prohibited),
|
||||
.B !Z
|
||||
(communication with destination host administratively prohibited),
|
||||
.B !Q
|
||||
(for this ToS the destination network is unreachable),
|
||||
.B !T
|
||||
(for this ToS the destination host is unreachable),
|
||||
.B !X
|
||||
(communication administratively prohibited),
|
||||
.B !V
|
||||
(host precedence violation),
|
||||
.B !C
|
||||
(precedence cutoff in effect), or
|
||||
.B !<num>
|
||||
(ICMP unreachable code <num>).
|
||||
.Pp
|
||||
Other possible annotations after the time are:
|
||||
.Bl -hang -offset indent -width 12n
|
||||
.It Sy !H
|
||||
Host unreachable.
|
||||
.It Sy !N
|
||||
Network unreachable.
|
||||
.It Sy !P
|
||||
Protocol unreachable.
|
||||
.It Sy !S
|
||||
Source route failed.
|
||||
.It Sy !F\-<pmtu>
|
||||
Fragmentation needed.
|
||||
The RFC1191 Path MTU Discovery value is displayed.
|
||||
.It Sy !U
|
||||
Destination network unknown.
|
||||
.It Sy !W
|
||||
Destination host unknown.
|
||||
.It Sy !I
|
||||
Source host is isolated.
|
||||
.It Sy !A
|
||||
Communication with destination network administratively prohibited.
|
||||
.It Sy !Z
|
||||
Communication with destination host administratively prohibited.
|
||||
.It Sy !Q
|
||||
For this ToS the destination network is unreachable.
|
||||
.It Sy !T
|
||||
For this ToS the destination host is unreachable.
|
||||
.It Sy !X
|
||||
Communication administratively prohibited.
|
||||
.It Sy !V
|
||||
Host precedence violation.
|
||||
.It Sy !C
|
||||
Precedence cutoff in effect.
|
||||
.It Sy !<num>
|
||||
ICMP unreachable code <num>.
|
||||
.El
|
||||
.Pp
|
||||
These are defined by RFC1812 (which supersedes RFC1716).
|
||||
If almost all the probes result in some kind of unreachable, traceroute
|
||||
If almost all the probes result in some kind of unreachable,
|
||||
.Nm
|
||||
will give up and exit.
|
||||
.PP
|
||||
.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
|
||||
.I traceroute
|
||||
.Nm
|
||||
during normal operations or from automated scripts.
|
||||
.SH SEE ALSO
|
||||
pathchar(8), netstat(1), ping(8)
|
||||
.SH AUTHOR
|
||||
.Sh SEE ALSO
|
||||
.Xr netstat 1 ,
|
||||
.Xr ping 8 ,
|
||||
.Xr ping6 8 ,
|
||||
.Xr traceroute6 8 .
|
||||
.Sh AUTHORS
|
||||
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.
|
||||
.LP
|
||||
The current version is available via anonymous ftp:
|
||||
.LP
|
||||
.RS
|
||||
.I ftp://ftp.ee.lbl.gov/traceroute.tar.gz
|
||||
.RE
|
||||
.SH BUGS
|
||||
.Sh BUGS
|
||||
When using protocols other than UDP, functionality is reduced.
|
||||
In particular, the last packet will often appear to be lost, because
|
||||
even though it reaches the destination host, there's no way to know
|
||||
that because no ICMP message is sent back.
|
||||
In the TCP case,
|
||||
.I traceroute
|
||||
.Nm
|
||||
should listen for a RST from the destination host (or an intermediate
|
||||
router that's filtering packets), but this is not implemented yet.
|
||||
.PP
|
||||
Please send bug reports to traceroute@ee.lbl.gov.
|
||||
.PP
|
||||
.Pp
|
||||
The AS number capability reports information that may sometimes be
|
||||
inaccurate due to discrepancies between the contents of the
|
||||
routing database server and the current state of the Internet.
|
||||
|
||||
Loading…
Reference in New Issue
Block a user