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121 lines
3.3 KiB
Groff
121 lines
3.3 KiB
Groff
.\"
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.\" $FreeBSD$
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.\"
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.Dd January 13, 2000
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.Dt NTP.KEYS 5
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.Os
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.Sh NAME
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.Nm ntp.keys
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.Nd NTP daemon key file format
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.Sh SYNOPSIS
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.Nm /etc/ntp.keys
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.Sh DESCRIPTION
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Following is a description of the format of NTP key files.
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For a description of the use of these files, see the
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.Qq Authentication Support
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section of the
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.Xr ntp.conf 5
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page.
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.Pp
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In the case of DES, the keys are 56 bits long with,
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depending on type, a parity check on each byte.
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In the case of MD5, the keys are 64 bits (8 bytes).
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.Xr ntpd 8
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reads its keys from a file specified using the
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.Fl k
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command line option or the
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.Ic keys
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statement in the configuration file.
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While key number 0 is fixed by the NTP standard
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(as 56 zero bits)
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and may not be changed,
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one or more of the keys numbered 1 through 15
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may be arbitrarily set in the keys file.
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.Pp
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The key file uses the same comment conventions
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as the configuration file.
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Key entries use a fixed format of the form
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.Pp
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.D1 Ar keyno type key
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.Pp
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where
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.Ar keyno
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is a positive integer,
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.Ar type
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is a single character which defines the key format,
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and
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.Ar key
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is the key itself.
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.Pp
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The
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.Ar key
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may be given in one of four different formats,
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controlled by the
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.Ar type
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character.
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The four key types, and corresponding formats,
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are listed following.
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.Bl -tag -width X
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.It Li S
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The key is a 64-bit hexadecimal number in the format
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specified in the DES specification;
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that is, the high order seven bits of each octet are used
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to form the 56-bit key
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while the low order bit of each octet is given a value
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such that odd parity is maintained for the octet.
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Leading zeroes must be specified
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(i.e., the key must be exactly 16 hex digits long)
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and odd parity must be maintained.
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Hence a zero key, in standard format, would be given as
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.Ql 0101010101010101 .
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.It Li N
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The key is a 64-bit hexadecimal number in the format
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specified in the NTP standard.
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This is the same as the DES format,
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except the bits in each octet have been rotated one bit right
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so that the parity bit is now the high order bit of the octet.
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Leading zeroes must be specified and odd parity must be maintained.
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A zero key in NTP format would be specified as
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.Ql 8080808080808080 .
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.It Li A
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The key is a 1-to-8 character ASCII string.
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A key is formed from this by using the low order 7 bits
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of each ASCII character in the string,
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with zeroes added on the right
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when necessary to form a full width 56-bit key,
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in the same way that encryption keys are formed from
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.Ux
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passwords.
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.It Li M
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The key is a 1-to-8 character ASCII string,
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using the MD5 authentication scheme.
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Note that both the keys and the authentication schemes (DES or MD5)
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must be identical between a set of peers sharing the same key number.
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.El
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.Pp
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Note that the keys used by the
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.Xr ntpq 8
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and
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.Xr ntpdc 8
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programs are checked against passwords
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requested by the programs and entered by hand,
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so it is generally appropriate to specify these keys in ASCII format.
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.Sh FILES
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.Bl -tag -width /etc/ntp.drift -compact
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.It Pa /etc/ntp.keys
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the default name of the configuration file
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.El
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.Sh SEE ALSO
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.Xr ntp.conf 5 ,
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.Xr ntpd 8 ,
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.Xr ntpdate 8 ,
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.Xr ntpdc 8
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.Sh BUGS
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.Xr ntpd 8
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has gotten rather fat.
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While not huge, it has gotten larger than might
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be desireable for an elevated-priority daemon running on a workstation,
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particularly since many of the fancy features which consume the space
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were designed more with a busy primary server, rather than a high
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stratum workstation, in mind.
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