Provided by: ntpsec_1.2.3+dfsg1-3_amd64 
NAME
ntpmon - real-time NTP status monitor
SYNOPSIS
ntpmon [-dhnuV] [-D lvl] [-l logfile] [host]
DESCRIPTION
This program is a real-time status monitor for NTP. It presents the same information as
the peers, mrulist, rv, and cv commands of ntpq(1), but using a split-window display that
also includes a status summary bar, and updates at intervals guaranteed to show status
changes almost as soon as they occur.
(Specifically, the display begins updating once per second and adjusts itself to poll at
twice the frequency of the shortest polling interval reported in the last peers response.)
The status bar includes the version string of the server being watched, the (local) time
at which it was last updated, and the current query interval in parens following the date.
There is a detail-display mode that dumps full information about a single selected peer in
a tabular format that makes it relatively easy to see changing values. However, note that
a default-sized terminal emulator window (usually 25 lines) doesn’t have enough room for
the clock variables portion. The only fix for this is to resize your terminal.
^C cleanly terminates the program. Any keystroke will trigger a poll and update. A few
single-keystroke commands are also interpreted as commands.
If no hostname is specified on the command line, localhost is monitored.
Here’s a breakdown of the peers display in the top window:
┌─────────┬──────────────────────────────────┐
│ │ │
│Variable │ Description │
├─────────┼──────────────────────────────────┤
│ │ │
│tally │ single-character code indicating │
│ │ current value of the select │
│ │ field of the peer status word │
│ │ <decode.html#peer> │
├─────────┼──────────────────────────────────┤
│ │ │
│remote │ host name (or IP address) of │
│ │ server │
├─────────┼──────────────────────────────────┤
│ │ │
│refid │ association ID or kiss code │
│ │ <decode.html#kiss> │
├─────────┼──────────────────────────────────┤
│ │ │
│st │ stratum │
├─────────┼──────────────────────────────────┤
│ │ │
│t │ u: server (u for unicast), l: │
│ │ local (reference clock), p: Pool │
│ │ name, 1-8 NTS server with this │
│ │ number of cookies stored. │
├─────────┼──────────────────────────────────┤
│ │ │
│when │ sec/min/hr since last received │
│ │ packet │
├─────────┼──────────────────────────────────┤
│ │ │
│poll │ poll interval (log2 s) │
├─────────┼──────────────────────────────────┤
│ │ │
│reach │ reach shift register (octal) │
├─────────┼──────────────────────────────────┤
│ │ │
│delay │ roundtrip delay │
├─────────┼──────────────────────────────────┤
│ │ │
│offset │ offset of server relative to │
│ │ this host │
├─────────┼──────────────────────────────────┤
│ │ │
│jitter │ jitter │
└─────────┴──────────────────────────────────┘
The t column has strange encodings due to historical use by old code. If you are looking
at an old server, you might also see: s: symmetric (peer), server, B: broadcast server,
The tally code is one of the following:
┌─────┬──────────────────────────────────┐
│ │ │
│Code │ Description │
├─────┼──────────────────────────────────┤
│ │ │
│ │ discarded as not valid │
├─────┼──────────────────────────────────┤
│ │ │
│x │ discarded by intersection │
│ │ algorithm │
├─────┼──────────────────────────────────┤
│ │ │
│. │ discarded by table overflow (not │
│ │ used) │
├─────┼──────────────────────────────────┤
│ │ │
│- │ discarded by the cluster │
│ │ algorithm │
├─────┼──────────────────────────────────┤
│ │ │
│+ │ included by the combine │
│ │ algorithm │
├─────┼──────────────────────────────────┤
│ │ │
│# │ backup (more than tos maxclock │
│ │ sources) │
├─────┼──────────────────────────────────┤
│ │ │
│* │ system peer │
├─────┼──────────────────────────────────┤
│ │ │
│o │ PPS peer (when the prefer peer │
│ │ is valid) │
└─────┴──────────────────────────────────┘
And the MRU list in the bottom window:
┌───────────────┬──────────────────────────────────┐
│ │ │
│Column │ Description │
├───────────────┼──────────────────────────────────┤
│ │ │
│lstint │ Interval in s between the │
│ │ receipt of the most recent │
│ │ packet from this address and the │
│ │ completion of the retrieval of │
│ │ the MRU list by ntpq. │
├───────────────┼──────────────────────────────────┤
│ │ │
│avgint │ Average interval in s between │
│ │ packets from this address. │
├───────────────┼──────────────────────────────────┤
│ │ │
│rstr │ Restriction flags associated │
│ │ with this address. Most are │
│ │ copied unchanged from the │
│ │ matching restrict command, │
│ │ however 0x400 (kod) and 0x20 │
│ │ (limited) flags are cleared │
│ │ unless the last packet from this │
│ │ address triggered a rate control │
│ │ response. │
├───────────────┼──────────────────────────────────┤
│ │ │
│r │ Rate control indicator, either a │
│ │ period, L or K for no rate │
│ │ control response, rate limiting │
│ │ by discarding, or rate limiting │
│ │ with a KoD response, │
│ │ respectively. │
├───────────────┼──────────────────────────────────┤
│ │ │
│m │ Packet mode. │
├───────────────┼──────────────────────────────────┤
│ │ │
│v │ Packet version number. │
├───────────────┼──────────────────────────────────┤
│ │ │
│count │ Packets received from this │
│ │ address. │
├───────────────┼──────────────────────────────────┤
│ │ │
│score │ Packets per second (averaged │
│ │ with exponential decay). │
├───────────────┼──────────────────────────────────┤
│ │ │
│drop │ Packets dropped (or KoDed) from │
│ │ this address. │
├───────────────┼──────────────────────────────────┤
│ │ │
│rport │ Source port of last packet from │
│ │ this address. │
├───────────────┼──────────────────────────────────┤
│ │ │
│remote address │ DNS name, numeric address, or │
│ │ address followed by claimed DNS │
│ │ name which could not be verified │
│ │ in parentheses. │
└───────────────┴──────────────────────────────────┘
The refid field is as described under "Event Messages and Status Words" in the NTP
documentation on the Web.
COMMANDS
a
Change peer display to apeers mode, showing association IDs.
d
Toggle detail mode (some peer will be reverse-video highlighted when on).
h
Display help screen
j
Select next peer (in select mode); arrow down also works.
k
Select previous peer (in select mode); arrow up also works.
m
Toggle MRUlist-only mode; suppresses peer display when on.
n
Toggle display of hostnames vs. IP addresses vs ntpd supplied names plus IP addresses
or ntpd supplied names and hostnames (default is hostnames).
o
Change peer display to opeers mode, showing destination address.
p
Change peer display to default mode, showing refid.
q
Cleanly terminate the program.
r
Change to dextral mode, identical to p save that the refid, tally \ and remote clock
are on the right.
s
Toggle display of only reachable hosts (default is all hosts).
u
Toggle display of units for time values. (default is off)
w
Toggle wide mode.
x
Cleanly terminate the program.
<space>
Rotate through a/n/o/p display modes.
+
Increase debugging level. Output goes to ntpmon.log
-
Decrease debugging level.
?
Display help screen
OPTIONS
-d
Increase output debug message level
• may appear multiple times
-D
Set the output debug message level
• may appear multiple times
-h
Print a usage message.
-l
Logs debug messages to the provided filename
-n
Show IP addresses (vs. hostnames)
-s, --srcname
Show srchost first then names and numbers
-S, --srcnumber
Show srchost first then numbers
-u
Show units
-V
Display version and exit.
KNOWN BUGS
When run in a terminal that does not allow UTF-8 ntpmon will downgrade its unit display to
a non-unicode version. ntpmon has to interact with the curses and locale libraries, which
prevents it from forcing the use of UTF-8.
When querying a version of ntpd older than NTPsec 0.9.6, ntpmon will appear to hang when
monitoring hosts with extremely long MRU lists - in particular, public pool hosts. Correct
behavior requires a Mode 6 protocol extension not yet present in those versions.
Even with this extension, monitoring a sufficiently high-traffic server sometimes fails.
When using the -u option, very old xterms may fail to render μ correctly. If this
happens, be sure your xterm is started with the -u8 option, or the utf8 resource', and
that your console font contains the UTF-8 μ character. Also confirm your LANG
environment variable is set to a UTF-8 language, like this: "export LANG=en_US.utf8".
Timestamp interpretation in this program is likely to fail in flaky ways if the local
system clock has not already been approximately synchronized to UTC. Querying a server
based in a different NTP era than the current one is especially likely to fail.
This program will behave in apparently buggy and only semi-predictable ways when fetching
MRU lists from any server with sufficiently high traffic.
The problem is fundamental. The Mode 6 protocol can’t ship (and your client cannot accept)
MRU records as fast as the daemon accepts incoming traffic. Under these circumstances, the
daemon will repeatedly fail to ship an entire report, leading to long hangs as your client
repeatedly re-sends the request. Eventually the Mode 6 client library will throw an error
indicating that a maximum number of restarts has been exceeded.
To avoid this problem, avoid monitoring over links that don’t have enough capacity to
handle the monitored server’s entire NTP load.
EXIT STATUS
Always returns 0.