.TH MTR 8 "@VERSION@" "mtr" "System Administration"
.SH NAME
mtr \- a network diagnostic tool
.SH SYNOPSIS
.B mtr
[\c
.BR \-4 |\c
.B \-6\c
]
[\c
.BI \-F \ FILENAME\c
]
[\c
.B \-\-report\c
]
[\c
.B \-\-report-wide\c
]
[\c
.B \-\-xml\c
]
[\c
.B \-\-gtk\c
]
[\c
.B \-\-curses\c
]
[\c
.BI \--displaymode \ MODE\c
]
[\c
.B \-\-raw\c
]
[\c
.B \-\-csv\c
]
[\c
.B \-\-json\c
]
[\c
.B \-\-split\c
]
[\c
.B \-\-no-dns\c
]
[\c
.B \-\-show-ips\c
]
[\c
.BI \-o \ FIELDS\c
]
[\c
.BI \-y \ IPINFO\c
]
[\c
.B \-\-aslookup\c
]
[\c
.BI \-i \ INTERVAL\c
]
[\c
.BI \-c \ COUNT\c
]
[\c
.BI \-s \ PACKETSIZE\c
]
[\c
.BI \-B \ BITPATTERN\c
]
[\c
.BI \-G \ GRACEPERIOD\c
]
[\c
.BI \-Q \ TOS\c
]
[\c
.B \-\-mpls\c
]
[\c
.BI \-a \ ADDRESS\c
]
[\c
.BI \-f \ FIRST\-TTL\c
]
[\c
.BI \-m \ MAX\-TTL\c
]
[\c
.BI \-U \ MAX\-UNKNOWN\c
]
[\c
.B \-\-udp\c
]
[\c
.B \-\-tcp\c
]
[\c
.BI \-\-sctp\c
]
[\c
.BI \-P \ PORT\c
]
[\c
.BI \-L \ LOCALPORT\c
]
[\c
.BI \-Z \ TIMEOUT\c
]
[\c
.BI \-M \ MARK\c
]
.I HOSTNAME
.SH DESCRIPTION
.B mtr 
combines the functionality of the 
.B traceroute
and 
.B ping
programs in a single network diagnostic tool.
.PP
As 
.B mtr 
starts, it investigates the network connection between the host 
.B mtr
runs on and 
.BR HOSTNAME
by sending packets with purposely low TTLs.  It continues to send
packets with low TTL, noting the response time of the intervening
routers.  This allows 
.B mtr 
to print the response percentage and response times of the internet
route to 
.BR HOSTNAME . 
A sudden increase in packet loss or response time is often an indication
of a bad (or simply overloaded) link. 
.PP
The results are usually reported as round-trip-response times in milliseconds
and the percentage of packetloss. 
.SH OPTIONS
.TP
.B \-h\fR, \fB\-\-help
Print the summary of command line argument options.
.TP
.B \-v\fR, \fB\-\-version
Print the installed version of mtr.  
.TP
.B \-4
Use IPv4 only.
.TP
.B \-6
Use IPv6 only.  (IPV4 may be used for DNS lookups.)
.TP
.B \-F \fIFILENAME\fR, \fB\-\-filename \fIFILENAME
Reads the list of hostnames from the specified file.
.TP
.B \-r\fR, \fB\-\-report
This option puts 
.B mtr
into 
.B report
mode.  When in this mode,
.B mtr
will run for the number of cycles specified by the 
.B \-c
option, and then print statistics and exit.  
.TP
\c
This mode is useful for generating statistics about network quality.  
Note that each running instance of 
.B mtr
generates a significant amount of network traffic.  Using 
.B mtr
to measure the quality of your network may result in decreased
network performance.  
.TP
.B \-w\fR, \fB\-\-report\-wide
This option puts 
.B mtr
into 
.B wide report
mode.  When in this mode,
.B mtr
will not cut hostnames in the report. 
.TP
.B \-x\fR, \fB\-\-xml
Use this option to tell
.B mtr
to use the xml output format.  This format is better suited for
automated processing of the measurement results.
.TP
.B \-t\fR, \fB\-\-curses
Use this option to force 
.B mtr 
to use the curses based terminal
interface (if available).
In case the list of hops exceeds the 
height of your terminal, you can use the 
.B +
and
.B -
keys to scroll up and down half a page.

.B Ctrl\fR-\fPL
clears spurious error messages that may overwrite other parts of the display.

.TP
.B -\-displaymode \fIMODE
Use this option to select the initial display mode: 0 (default)
selects statistics, 1 selects the stripchart without latency
information, and 2 selects the stripchart with latency
information.
.TP
.B \-g\fR, \fB\-\-gtk
Use this option to force
.B mtr 
to use the GTK+ based X11 window interface (if available).  
GTK+ must have been available on the system when 
.B mtr 
was built for this to work.  See the GTK+ web page at 
.UR http://\:www.\:gtk.\:org/
.UE
for more information about GTK+.
.TP
.B \-l\fR, \fB\-\-raw
Use the raw output format.  This format is better suited for
archival of the measurement results.  It could be parsed to 
be presented into any of the other display methods. 
.IP
Example of the raw output format:
.nf
h 0 10.1.1.1
p 0 339
h 1 46.149.16.4
p 1 530
h 2 172.31.1.16
p 2 531
h 3 82.221.168.236
p 3 1523
h 5 195.130.211.8
p 5 1603
h 6 193.4.58.17
p 6 1127
h 7 193.4.58.17
d 7 www.isnic.is
.fi
.TP
.B \-C\fR, \fB\-\-csv
Use the Comma-Separated-Value (CSV) output format.
(Note: The separator is actually a semi-colon ';'.)
.IP
Example of the CSV output format:
.nf
MTR.0.86+git:16e39fc0;1435562787;OK;nic.is;1;r-76520-PROD.greenqloud.internal;288
MTR.0.86+git:16e39fc0;1435562787;OK;nic.is;2;46.149.16.4;2086
MTR.0.86+git:16e39fc0;1435562787;OK;nic.is;3;172.31.1.16;600
MTR.0.86+git:16e39fc0;1435562787;OK;nic.is;4;82.221.168.236;1163
MTR.0.86+git:16e39fc0;1435562787;OK;nic.is;5;???;0
MTR.0.86+git:16e39fc0;1435562787;OK;nic.is;6;rix-k2-gw.isnic.is;1654
MTR.0.86+git:16e39fc0;1435562787;OK;nic.is;7;www.isnic.is;1036
.fi
.TP
.B \-j\fR, \fB\-\-json
Use this option to tell
.B mtr
to use the JSON output format.  This format is better suited for
automated processing of the measurement results.
.TP
.B \-p\fR, \fB\-\-split
Use this option to set
.B mtr 
to spit out a format that is suitable for a split-user interface.
.TP
.B \-n\fR, \fB\-\-no\-dns
Use this option to force 
.B mtr 
to display numeric IP numbers and not try to resolve the
host names. 
.TP
.B \-b\fR, \fB\-\-show\-ips
Use this option to tell
.B mtr
to display both the host names and numeric IP numbers.  In split mode
this adds an extra field to the output.  In report mode, there is usually
too little space to add the IPs, and they will be truncated.  Use the
wide report (-w) mode to see the IPs in report mode. 
.TP
.B \-o \fIFIELDS\fR, \fB\-\-order \fIFIELDS
Use this option to specify which fields to display and in which order.
You may use one or more space characters to separate fields.
.br
Available fields:
.TS
center allbox tab(%);
ll.
L%Loss ratio
D%Dropped packets
R%Received packets
S%Sent Packets
N%Newest RTT(ms)
B%Min/Best RTT(ms)
A%Average RTT(ms)
W%Max/Worst RTT(ms)
V%Standard Deviation
G%Geometric Mean
J%Current Jitter
M%Jitter Mean/Avg.
X%Worst Jitter
I%Interarrival Jitter
.TE
.br

Example:
-o "LSD NBAW  X"
.TP
.B \-y \fIn\fR, \fB\-\-ipinfo \fIn
Displays information about each IP hop.  Valid values for \fIn\fR are:
.TS
tab(%);
ll.
0%Display AS number (equivalent to \fB-z\fR)
1%Display IP prefix
2%Display country code of the origin AS
3%Display RIR (ripencc, arin, ...)
4%Display the allocation date of the IP prefix
.TE
.br

It is possible to cycle between these fields at runtime (using the \fBy\fR key).
.TP
.B \-z\fR, \fB\-\-aslookup
Displays the Autonomous System (AS) number alongside each hop.  Equivalent to \fB\-\-ipinfo 0\fR.
.IP
Example (columns to the right not shown for clarity):
.nf
1. AS???   r-76520-PROD.greenqloud.internal
2. AS51969 46.149.16.4
3. AS???   172.31.1.16
4. AS30818 82.221.168.236
5. ???
6. AS???   rix-k2-gw.isnic.is
7. AS1850  www.isnic.is
.fi
.TP
.B \-i \fISECONDS\fR, \fB\-\-interval \fISECONDS
Use this option to specify the positive number of seconds between ICMP
ECHO requests.  The default value for this parameter is one second.  The
root user may choose values between zero and one.
.TP
.B \-c \fICOUNT\fR, \fB\-\-report\-cycles \fICOUNT
Use this option to set the number of pings sent to determine
both the machines on the network and the reliability of 
those machines.  Each cycle lasts one second.
.TP
.B \-s \fIPACKETSIZE\fR, \fB\-\-psize \fIPACKETSIZE
This option sets the packet size used for probing.  It is in bytes,
inclusive IP and ICMP headers.

If set to a negative number, every iteration will use a different, random
packet size up to that number.
.TP
.B \-B \fINUM\fR, \fB\-\-bitpattern \fINUM
Specifies bit pattern to use in payload.  Should be within range 0 - 255.  If
.I NUM
is greater than 255, a random pattern is used.
.TP
.B \-G \fISECONDS\fR, \fB\-\-gracetime \fISECONDS
Use this option to specify the positive number of seconds to wait for responses
after the final request. The default value is five seconds.
.TP
.B \-Q \fINUM\fR, \fB\-\-tos \fINUM
Specifies value for type of service field in IP header.  Should be within range 0
- 255.
.TP
.B \-e\fR, \fB\-\-mpls
Use this option to tell 
.B mtr 
to display information from ICMP extensions for MPLS (RFC 4950)
that are encoded in the response packets.
.TP
.B \-a \fIADDRESS\fR, \fB\-\-address \fIADDRESS
Use this option to bind the outgoing socket to
.IR ADDRESS ,
so that all packets will be sent with
.I ADDRESS
as source address.  NOTE that this option doesn't apply to DNS requests
(which could be and could not be what you want).
.TP
.B \-f \fINUM\fR, \fB\-\-first-ttl \fINUM
Specifies with what TTL to start.  Defaults to 1.
.TP
.B \-m \fINUM\fR, \fB\-\-max-ttl \fINUM
Specifies the maximum number of hops (max time-to-live value) traceroute will
probe.  Default is 30.
.TP
.B \-U \fINUM\fR, \fB\-\-max-unknown \fINUM
Specifies the maximum unknown host. Default is 5.
.TP
.B \-u\fR, \fB\-\-udp
Use UDP datagrams instead of ICMP ECHO.
.TP
.B \-T\fR, \fB\-\-tcp
Use TCP SYN packets instead of ICMP ECHO.
.I PACKETSIZE
is ignored, since SYN packets can not contain data.
.TP
.B \-S\fR, \fB\-\-sctp
Use Stream Control Transmission Protocol packets instead of ICMP ECHO.
.TP
.B \-P \fIPORT\fR, \fB\-\-port \fIPORT
The target port number for TCP/SCTP/UDP traces.
.TP
.B \-L \fILOCALPORT\fR, \fB\-\-localport \fILOCALPORT
The source port number for UDP traces.
.TP
.B \-Z \fISECONDS\fR, \fB\-\-timeout \fISECONDS
The number of seconds to keep probe sockets open before giving up on
the connection.  Using large values for this, especially combined with
a short interval, will use up a lot of file descriptors.
.TP
.B \-M \fIMARK\fR, \fB\-\-mark \fIMARK
Set the mark for each packet sent through this socket similar to the
netfilter MARK target but socket-based.
.I MARK
is 32 unsigned integer.  See
.BR socket (7)
for full description of this socket option.
.SH ENVIRONMENT
.B mtr
recognizes a few environment variables.
.TP
.B MTR_OPTIONS
This environment variable allows to specify options, as if they were
passed on the command line.  It is parsed before reading the actual
command line options, so that options specified in
.B MTR_OPTIONS
are overridden by command-line options.

Example:

.BI MTR_OPTIONS ="-4\ -c\ 1"
.B mtr
.I \-6\ localhost

would send one probe (because of
.I -c\ 1\c
) towards
.B ::1
(because of
.IR -6 ,
which overrides the
.I -4
passed in
.B MTR_OPTIONS\c
).
.TP
.B MTR_PACKET
A path to the
.I mtr-packet
executable, to be used for sending and receiving network probes.  If
.B MTR_PACKET
is unset, the
.B PATH
will be used to search for an
.I mtr-packet
executable.
.TP
.B DISPLAY
Specifies an X11 server for the GTK+ frontend.
.SH BUGS
Some modern routers give a lower priority to ICMP ECHO packets than 
to other network traffic.  Consequently, the reliability of these
routers reported by 
.B mtr
will be significantly lower than the actual reliability of 
these routers.  
.SH CONTACT INFORMATION
.PP
For the latest version, see the mtr web page at 
.UR http://\:www.\:bitwizard.\:nl/\:mtr/
.UE
.PP
For patches, bug reports, or feature requests, please open an issue on
GitHub at:
.UR https://\:github\:.com/\:traviscross/\:mtr
.UE .
.SH "SEE ALSO"
.BR mtr-packet (8),
.BR traceroute (8),
.BR ping (8),
.BR socket (7),
TCP/IP Illustrated (Stevens, ISBN 0201633469).