A tool to synchronize system time from web servers, for linux, windows and macos.

Go to file

Bob Wen 8ee35d8541 fix bug: windows shell command Strange permission requirements invalidate the wmic command, so when adjusting the time, user need to specify the time format for their region, default command is '[time ]HH[:]mm[:]ss[.]SS[ && date ]MM[-]DD[-]YY', which means 'time HH:mm:ss.SS && date MM-DD-YY'		2021-11-04 13:31:33 +08:00
.gitignore	1.0.2	2021-11-03 18:07:10 +08:00
LICENSE	Initial commit	2021-01-25 11:55:04 +08:00
README.md	Update README.md	2021-11-04 11:31:31 +08:00
adjust_time.coffee	fix bug: windows shell command	2021-11-04 13:31:33 +08:00
argv.coffee	1.0.2	2021-11-03 18:07:10 +08:00
dayjs_format_ms.coffee	Change source files attributes	2021-01-25 13:02:04 +08:00
index.coffee	bug fix	2021-11-03 22:32:30 +08:00
median.coffee	Change source files attributes	2021-01-25 13:02:04 +08:00
package.json	upgrade dayjs	2021-11-03 23:49:23 +08:00

README.md

htpdate

A tool to synchronize system time from web servers, for linux, windows and macos. Download

htpdate provides time calibration with second-level accuracy.

But, why not NTP?

There are always cases where the device cannot connect to the NTP server.

Examples

Synchronize time from multiple URLs

C:\> htpdate -s www.pool.ntp.org www.openssl.org nodejs.org
HEAD https://www.pool.ntp.org
    #1: +367325 ms
    #2: +366966 ms
    #3: +367462 ms
    #4: +366960 ms
HEAD https://www.openssl.org
    #1: +367258 ms
    #2: +366983 ms
    #3: +367487 ms
    #4: +366986 ms
HEAD https://nodejs.org
    #1: +367647 ms
    #2: +367278 ms
    #3: +367670 ms
    #4: +367516 ms
Median: 367301.5 ms
Adjust time...
>
$ wmic os set localdatetime=20211103143426.513000+000
> Updating property(s) of '\\TESTDEVICE\ROOT\CIMV2:Win32_OperatingSystem=@'
$ exit
> Property(s) update successful.
>
>
Done

Query from multiple URLs

$ htpdate -c 5 -v www.pool.ntp.org www.openssl.org
HEAD https://www.pool.ntp.org
    #1:    -419 ms  DNS:   95 TCP:   27 TSL:   43 Send:    3 Recv:   38
    #2:    +403 ms  DNS:    0 TCP:    0 TSL:    0 Send:    1 Recv:   26
    #3:     -94 ms  DNS:    0 TCP:    0 TSL:    0 Send:    1 Recv:   24
    #4:    +372 ms  DNS:    0 TCP:    0 TSL:    0 Send:    1 Recv:   46
    #5:     -97 ms  DNS:    0 TCP:    0 TSL:    0 Send:    1 Recv:   24
HEAD https://www.openssl.org
    #1:    +251 ms  DNS:   38 TCP:   27 TSL:   67 Send:    1 Recv:   33
    #2:    -107 ms  DNS:    0 TCP:    0 TSL:    0 Send:    1 Recv:   28
    #3:    +396 ms  DNS:    0 TCP:    0 TSL:    0 Send:    1 Recv:   25
    #4:    -113 ms  DNS:    0 TCP:    0 TSL:    0 Send:    1 Recv:   30
    #5:    +385 ms  DNS:    0 TCP:    0 TSL:    0 Send:    0 Recv:   31
Median:    78.5 ms

Change default protocol to 'http'

htpdate -s -p http www.pool.ntp.org

Mix http and https URLs

htpdate -s http://www.pool.ntp.org https://www.openssl.org

Access through a http proxy

export http_proxy=http://127.0.0.1:8118
htpdate -s www.pool.ntp.org

Usage

htpdate [options...] URLs...

Options

 -c, --count            The number of requests for each URL
                        Default: 4

 -C, --command          Command to adjust system time, in https://day.js.org/ UTC format
                        Default(Linux/Mac): '[date --utc -s ]YYYY[-]MM[-]DDTHH[:]mm[:]ss[.]SSS'
                        Default(Windows): '[wmic os set localdatetime=]YYYYMMDDHHmmss[.]SSS[000][+000]'

 -h, --help             This help text
                        Default: false

     --http2            Try to choose either HTTP/1.1 or HTTP/2 depending on the ALPN protocol
                        Default: false

 -i, --interval         The minimum milliseconds between requests
                        Default: 500

 -k, --insecure         Allow insecure server connections when using https
                        Default: false

 -m, --method           HTTP method
                        Default: 'HEAD'

 -p, --protocol         Use this protocol when no protocol is specified in the URL
                        Default: 'https'

 -r, --retry
                        Default: 0

 -R, --redirect         If redirect responses should be followed
                        Default: false

 -s, --set              Adjust system time if necessary
                        Default: false

 -t, --threshold        At least how many milliseconds are considered to adjust system time
                        Default: 1500

 -T, --timeout
                        Default: 6000

 -u, --user-agent
                        Type: string

 -V, --version          display the version of htpdate and exit
                        Default: false

 -v, --verbose          Make the operation more talkative
                        Default: false

Install Precompiled package

Download the precompiled binary package from Releases page, uncompress it, and run it independently as an executable.

Compile

git clone https://github.com/bobwen-dev/htpdate
cd htpdate
npm install
npm run build

The principle

Website returns a header Date in each response, like this:

HTTP/2 200
Content-Type: text/html; charset=utf-8
Date: Wed, 03 Nov 2021 11:46:19 GMT
...

This Date: Wed, 03 Nov 2021 11:46:19 GMT is the moment the website was processing the request, which is between the time we sent the request and the time we received the response. Simply assuming that the period to send request and receive is equal, we can calculate that the difference between local time and website time:

duration = received_at - sent_at
delta = server_time - received_at - duration / 2

There is one more thing: the precision of Date. Imagine you get a Date end with :23 GMT, which could be 23.000 seconds, or 23.999 seconds. So we give +0.5s as a compensation.

License

Licensed under the GNU Affero General Public License v3.0 or later.