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doc: improve description of key option in chrony.conf man page

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Miroslav Lichvar 2018-03-26 19:00:50 +02:00
parent e3f840aae9
commit 94822d5156
1 changed files with 7 additions and 4 deletions
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doc/chrony.conf.adoc
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@ -91,16 +91,19 @@ to keep the average interval at or above the minimum interval, i.e. the current
interval needs to be at least two times longer than the minimum interval in interval needs to be at least two times longer than the minimum interval in
order to allow a burst with two requests. order to allow a burst with two requests.
*key* _ID_::: *key* _ID_:::
The NTP protocol supports the inclusion of checksums in the packets, to prevent The NTP protocol supports a message authentication code (MAC) to prevent
computers having their system time upset by rogue packets being sent to them. computers having their system time upset by rogue packets being sent to them.
The checksums are generated as a function of a password, using the The MAC is generated as a function of a password specified in the key file,
cryptographic hash function set in the key file, which is specified by the which is specified by the <<keyfile,*keyfile*>> directive.
<<keyfile,*keyfile*>> directive.
+ +
The *key* option specifies which key (with an ID in the range 1 through 2^32-1) The *key* option specifies which key (with an ID in the range 1 through 2^32-1)
should *chronyd* use to authenticate requests sent to the server and verify its should *chronyd* use to authenticate requests sent to the server and verify its
responses. The server must have the same key for this number configured, responses. The server must have the same key for this number configured,
otherwise no relationship between the computers will be possible. otherwise no relationship between the computers will be possible.
+
If the server is running *ntpd* and the output size of the hash function used
by the key is longer than 160 bits (e.g. SHA256), the *version* option needs to
be set to 4 for compatibility.
*maxdelay* _delay_::: *maxdelay* _delay_:::
*chronyd* uses the network round-trip delay to the server to determine how *chronyd* uses the network round-trip delay to the server to determine how
accurate a particular measurement is likely to be. Long round-trip delays accurate a particular measurement is likely to be. Long round-trip delays