HTTP Time Protocol (HTP)?

HTP is not really a protocol, but uses a feature from HTTP, aka web traffic. According the specifications of HTTP (RFC 2616) a web server needs to put a timestamp in a response to a web browser request. In web browsers you don't see the HTTP headers, but these headers contain a timestamp in Greenwich Mean Time (GMT), accurate in seconds.

These timestamps, from various web servers which you may specify, can be used to extract a pretty good time.

If you have the Perl module LWP installed you can see the HTTP headers, especially the line which contains Date:

# HEAD -e www.microsoft.com
200 OK
Cache-Control: private
Date: Wed, 25 Aug 2004 18:38:58 GMT
Server: Microsoft-IIS/6.0
Content-Length: 39445
Content-Type: text/html
Expires: Wed, 25 Aug 2004 18:38:58 GMT
Client-Date: Wed, 25 Aug 2004 18:38:54 GMT
Client-Peer: 207.46.156.252:80
Client-Response-Num: 1
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