105 lines
3.8 KiB
Groff
105 lines
3.8 KiB
Groff
|
.\" This manpage has been automatically generated by docbook2man
|
||
|
|
.\" from a DocBook document. This tool can be found at:
|
||
|
|
.\" <http://shell.ipoline.com/~elmert/comp/docbook2X/>
|
||
|
|
.\" Please send any bug reports, improvements, comments, patches,
|
||
|
|
.\" etc. to Steve Cheng <steve@ggi-project.org>.
|
||
|
|
.TH "TRACEPATH" "8" "07 May 2014" "iputils-121221" "System Manager's Manual: iputils"
|
||
|
|
.SH NAME
|
||
|
|
tracepath, tracepath6 \- traces path to a network host discovering MTU along this path
|
||
|
|
.SH SYNOPSIS
|
||
|
|
|
||
|
|
\fBtracepath\fR [\fB-n\fR] [\fB-b\fR] [\fB-l \fIpktlen\fB\fR] [\fB-m \fImax_hops\fB\fR] [\fB-p \fIport\fB\fR] \fB\fIdestination\fB\fR
|
||
|
|
|
||
|
|
.SH "DESCRIPTION"
|
||
|
|
.PP
|
||
|
|
It traces path to \fIdestination\fR discovering MTU along this path.
|
||
|
|
It uses UDP port \fIport\fR or some random port.
|
||
|
|
It is similar to \fBtraceroute\fR, only does not require superuser
|
||
|
|
privileges and has no fancy options.
|
||
|
|
.PP
|
||
|
|
\fBtracepath6\fR is good replacement for \fBtraceroute6\fR
|
||
|
|
and classic example of application of Linux error queues.
|
||
|
|
The situation with IPv4 is worse, because commercial
|
||
|
|
IP routers do not return enough information in ICMP error messages.
|
||
|
|
Probably, it will change, when they will be updated.
|
||
|
|
For now it uses Van Jacobson's trick, sweeping a range
|
||
|
|
of UDP ports to maintain trace history.
|
||
|
|
.SH "OPTIONS"
|
||
|
|
.TP
|
||
|
|
\fB-n\fR
|
||
|
|
Print primarily IP addresses numerically.
|
||
|
|
.TP
|
||
|
|
\fB-b\fR
|
||
|
|
Print both of host names and IP addresses.
|
||
|
|
.TP
|
||
|
|
\fB-l\fR
|
||
|
|
Sets the initial packet length to \fIpktlen\fR instead of
|
||
|
|
65535 for \fBtracepath\fR or 128000 for \fBtracepath6\fR.
|
||
|
|
.TP
|
||
|
|
\fB-m/term> \fR
|
||
|
|
Set maximum hops (or maximum TTLs) to \fImax_hops\fR
|
||
|
|
instead of 30.
|
||
|
|
.TP
|
||
|
|
\fB-p\fR
|
||
|
|
Sets the initial destination port to use.
|
||
|
|
.SH "OUTPUT"
|
||
|
|
.PP
|
||
|
|
|
||
|
|
.nf
|
||
|
|
root@mops:~ # tracepath6 3ffe:2400:0:109::2
|
||
|
|
1?: [LOCALHOST] pmtu 1500
|
||
|
|
1: dust.inr.ac.ru 0.411ms
|
||
|
|
2: dust.inr.ac.ru asymm 1 0.390ms pmtu 1480
|
||
|
|
2: 3ffe:2400:0:109::2 463.514ms reached
|
||
|
|
Resume: pmtu 1480 hops 2 back 2
|
||
|
|
.fi
|
||
|
|
.PP
|
||
|
|
The first column shows TTL of the probe, followed by colon.
|
||
|
|
Usually value of TTL is obtained from reply from network,
|
||
|
|
but sometimes reply does not contain necessary information and
|
||
|
|
we have to guess it. In this case the number is followed by ?.
|
||
|
|
.PP
|
||
|
|
The second column shows the network hop, which replied to the probe.
|
||
|
|
It is either address of router or word [LOCALHOST], if
|
||
|
|
the probe was not sent to the network.
|
||
|
|
.PP
|
||
|
|
The rest of line shows miscellaneous information about path to
|
||
|
|
the correspinding network hop. As rule it contains value of RTT.
|
||
|
|
Additionally, it can show Path MTU, when it changes.
|
||
|
|
If the path is asymmetric
|
||
|
|
or the probe finishes before it reach prescribed hop, difference
|
||
|
|
between number of hops in forward and backward direction is shown
|
||
|
|
following keyword async. This information is not reliable.
|
||
|
|
F.e. the third line shows asymmetry of 1, it is because the first probe
|
||
|
|
with TTL of 2 was rejected at the first hop due to Path MTU Discovery.
|
||
|
|
.PP
|
||
|
|
The last line summarizes information about all the path to the destination,
|
||
|
|
it shows detected Path MTU, amount of hops to the destination and our
|
||
|
|
guess about amount of hops from the destination to us, which can be
|
||
|
|
different when the path is asymmetric.
|
||
|
|
.SH "SEE ALSO"
|
||
|
|
.PP
|
||
|
|
\fBtraceroute\fR(8),
|
||
|
|
\fBtraceroute6\fR(8),
|
||
|
|
\fBping\fR(8).
|
||
|
|
.SH "AUTHOR"
|
||
|
|
.PP
|
||
|
|
\fBtracepath\fR was written by
|
||
|
|
Alexey Kuznetsov
|
||
|
|
<kuznet@ms2.inr.ac.ru>.
|
||
|
|
.SH "SECURITY"
|
||
|
|
.PP
|
||
|
|
No security issues.
|
||
|
|
.PP
|
||
|
|
This lapidary deserves to be elaborated.
|
||
|
|
\fBtracepath\fR is not a privileged program, unlike
|
||
|
|
\fBtraceroute\fR, \fBping\fR and other beasts of this kind.
|
||
|
|
\fBtracepath\fR may be executed by everyone who has some access
|
||
|
|
to network, enough to send UDP datagrams to investigated destination
|
||
|
|
using given port.
|
||
|
|
.SH "AVAILABILITY"
|
||
|
|
.PP
|
||
|
|
\fBtracepath\fR is part of \fIiputils\fR package
|
||
|
|
and the latest versions are available in source form at
|
||
|
|
http://www.skbuff.net/iputils/iputils-current.tar.bz2.
|