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examples/synctime.c: remove references to dead URLs and functionality

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This example can use the Date: header of any server so there is no point
in linking to ancient URLs describeing a setup at NIST that no longer
exists.

Closes #15786
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Daniel Stenberg 2024-12-20 08:42:20 +01:00
parent 6a4b4d59a3
commit ed732e3596
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1 changed files with 3 additions and 21 deletions
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24
docs/examples/synctime.c
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@ -26,24 +26,12 @@
* </DESC> * </DESC>
*/ */
/* This example code only builds as-is on Windows. /* This example code only builds as-is on Windows.
*
* While Unix/Linux user, you do not need this software.
* You can achieve the same result as synctime using curl, awk and date.
* Set proxy as according to your network, but beware of proxy Cache-Control.
*
* To set your system clock, root access is required.
* # date -s "`curl -sI https://nist.time.gov/timezone.cgi?UTC/s/0 \
* | awk -F': ' '/Date: / {print $2}'`"
*
* To view remote webserver date and time.
* $ curl -sI https://nist.time.gov/timezone.cgi?UTC/s/0 \
* | awk -F': ' '/Date: / {print $2}'
* *
* Synchronising your computer clock via Internet time server usually relies * Synchronising your computer clock via Internet time server usually relies
* on DAYTIME, TIME, or NTP protocols. These protocols provide good accurate * on DAYTIME, TIME, or NTP protocols. These protocols provide good accurate
* time synchronization but it does not work well through a * time synchronization but it does not work well through a firewall/proxy.
* firewall/proxy. Some adjustment has to be made to the firewall/proxy for * Some adjustment has to be made to the firewall/proxy for these protocols to
* these protocols to work properly. * work properly.
* *
* There is an indirect method. Since most webserver provide server time in * There is an indirect method. Since most webserver provide server time in
* their HTTP header, therefore you could synchronise your computer clock * their HTTP header, therefore you could synchronise your computer clock
@ -64,12 +52,6 @@
* 6. Webserver data should not be cached by the proxy server. Some * 6. Webserver data should not be cached by the proxy server. Some
* webserver provide Cache-Control to prevent caching. * webserver provide Cache-Control to prevent caching.
* *
* References:
* https://web.archive.org/web/20100228012139/ \
* tf.nist.gov/timefreq/service/its.htm
* https://web.archive.org/web/20100409024302/ \
* tf.nist.gov/timefreq/service/firewall.htm
*
* Usage: * Usage:
* This software synchronises your computer clock only when you issue * This software synchronises your computer clock only when you issue
* it with --synctime. By default, it only display the webserver's clock. * it with --synctime. By default, it only display the webserver's clock.