.TH sntpclock 1
.SH NAME
sntpclock \- check a system's clock through NTP
.SH SYNOPSIS
.B sntpclock
.I host
.SH DESCRIPTION
.B sntpclock
connects to an NTP server on
.IR host .
.I host
must be a dotted-decimal IP address.

.B sntpclock
prints a 16-byte TAI64NA adjustment that,
when added to the local UNIX clock,
will produce the TAI clock on
.IR host .
.B sntpclock
limits the adjustment to 2 days.

.B sntpclock
does not bind to port 123;
this means that it does not need to run as root.
Note that some firewalls will not permit
.B sntpclock
requests.
.SH NOTES
An NTP timestamp is a count of non-leap seconds.
.B sntpclock
uses a local leap-second table to
convert the NTP timestamp to TAI with an epoch of
1970-01-01 00:00:10 TAI.
For a discussion of the difference between UTC and TAI see
.BR http://pobox.com/~djb/proto/utctai.html .

The current NTP time scale will break down in 2036.
.SH "SEE ALSO"
clockspeed(1),
clockadd(1),
clockview(1),
taiclock(1),
leapsecs(3),
xntpd(8)