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22<h1 class="settitle">NTP Symmetric Key</h1>
23<div class="node">
24<p><hr>
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30
31<h2 class="unnumbered">NTP's Symmetric Key File User Manual</h2>
32
33<p>This document describes the symmetric key file for the NTP Project's
34<code>ntpd</code> program.
35
36  <p>This document applies to version 4.2.8p11 of <code>ntp.keys</code>.
37
38  <div class="shortcontents">
39<h2>Short Contents</h2>
40<ul>
41<a href="#Top">NTP's Symmetric Key File User Manual</a>
42</ul>
43</div>
44
45<ul class="menu">
46<li><a accesskey="1" href="#ntp_002ekeys-Description">ntp.keys Description</a>
47<li><a accesskey="2" href="#ntp_002ekeys-Notes">ntp.keys Notes</a>
48</ul>
49
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58<h3 class="section">Description</h3>
59
60<p>The name and location of the symmetric key file for <code>ntpd</code> can
61be specified in a configuration file, by default <code>/etc/ntp.keys</code>.
62
63<div class="node">
64<p><hr>
65<a name="ntp_002ekeys-Notes"></a>
66<br>
67</div>
68
69<h3 class="section">Notes about ntp.keys</h3>
70
71<p><a name="index-ntp_002ekeys-1"></a><a name="index-NTP-symmetric-key-file-format-2"></a>
72
73  <p>This document describes the format of an NTP symmetric key file.
74For a description of the use of this type of file, see the
75"Authentication Support"
76section of the
77<code>ntp.conf(5)</code>
78page.
79
80  <p><code>ntpd(8)</code>
81reads its keys from a file specified using the
82<code>-k</code>
83command line option or the
84<code>keys</code>
85statement in the configuration file.
86While key number 0 is fixed by the NTP standard
87(as 56 zero bits)
88and may not be changed,
89one or more keys numbered between 1 and 65534
90may be arbitrarily set in the keys file.
91
92  <p>The key file uses the same comment conventions
93as the configuration file.
94Key entries use a fixed format of the form
95
96<pre class="example">     <kbd>keyno</kbd> <kbd>type</kbd> <kbd>key</kbd> <kbd>opt_IP_list</kbd>
97</pre>
98  <p>where
99<kbd>keyno</kbd>
100is a positive integer (between 1 and 65534),
101<kbd>type</kbd>
102is the message digest algorithm,
103<kbd>key</kbd>
104is the key itself, and
105<kbd>opt_IP_list</kbd>
106is an optional comma-separated list of IPs
107where the
108<kbd>keyno</kbd>
109should be trusted.
110that are allowed to serve time.
111Each IP in
112<kbd>opt_IP_list</kbd>
113may contain an optional
114<code>/subnetbits</code>
115specification which identifies the number of bits for
116the desired subnet of trust.
117If
118<kbd>opt_IP_list</kbd>
119is empty,
120any properly-authenticated message will be
121accepted.
122
123  <p>The
124<kbd>key</kbd>
125may be given in a format
126controlled by the
127<kbd>type</kbd>
128field.
129The
130<kbd>type</kbd>
131<code>MD5</code>
132is always supported.
133If
134<code>ntpd</code>
135was built with the OpenSSL library
136then any digest library supported by that library may be specified.
137However, if compliance with FIPS 140-2 is required the
138<kbd>type</kbd>
139must be either
140<code>SHA</code>
141or
142<code>SHA1</code>.
143
144  <p>What follows are some key types, and corresponding formats:
145
146     <dl>
147<dt><code>MD5</code><dd>The key is 1 to 16 printable characters terminated by
148an EOL,
149whitespace,
150or
151a
152<code>#</code>
153(which is the "start of comment" character).
154
155     <br><dt><code>SHA</code><br><dt><code>SHA1</code><br><dt><code>RMD160</code><dd>The key is a hex-encoded ASCII string of 40 characters,
156which is truncated as necessary.
157</dl>
158
159  <p>Note that the keys used by the
160<code>ntpq(8)</code>
161and
162<code>ntpdc(8)</code>
163programs are checked against passwords
164requested by the programs and entered by hand,
165so it is generally appropriate to specify these keys in ASCII format.
166
167  <p>This section was generated by <strong>AutoGen</strong>,
168using the <code>agtexi-cmd</code> template and the option descriptions for the <code>ntp.keys</code> program.
169This software is released under the NTP license, &lt;http://ntp.org/license&gt;.
170
171<ul class="menu">
172<li><a accesskey="1" href="#ntp_002ekeys-Files">ntp.keys Files</a>:                   Files
173<li><a accesskey="2" href="#ntp_002ekeys-See-Also">ntp.keys See Also</a>:                See Also
174<li><a accesskey="3" href="#ntp_002ekeys-Notes">ntp.keys Notes</a>:                   Notes
175</ul>
176
177<div class="node">
178<p><hr>
179<a name="ntp_002ekeys-Files"></a>Next:&nbsp;<a rel="next" accesskey="n" href="#ntp_002ekeys-See-Also">ntp.keys See Also</a>,
180Up:&nbsp;<a rel="up" accesskey="u" href="#ntp_002ekeys-Notes">ntp.keys Notes</a>
181<br>
182</div>
183
184<h4 class="subsection">ntp.keys Files</h4>
185
186     <dl>
187<dt><span class="file">/etc/ntp.keys</span><dd>the default name of the configuration file
188</dl>
189<div class="node">
190<p><hr>
191<a name="ntp_002ekeys-See-Also"></a>Next:&nbsp;<a rel="next" accesskey="n" href="#ntp_002ekeys-Notes">ntp.keys Notes</a>,
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193Up:&nbsp;<a rel="up" accesskey="u" href="#ntp_002ekeys-Notes">ntp.keys Notes</a>
194<br>
195</div>
196
197<h4 class="subsection">ntp.keys See Also</h4>
198
199<p><code>ntp.conf(5)</code>,
200<code>ntpd(1ntpdmdoc)</code>,
201<code>ntpdate(1ntpdatemdoc)</code>,
202<code>ntpdc(1ntpdcmdoc)</code>,
203<code>sntp(1sntpmdoc)</code>
204<div class="node">
205<p><hr>
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207Up:&nbsp;<a rel="up" accesskey="u" href="#ntp_002ekeys-Notes">ntp.keys Notes</a>
208<br>
209</div>
210
211<h4 class="subsection">ntp.keys Notes</h4>
212
213<p>This document was derived from FreeBSD.
214
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