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These are the definitions for the various log format components:
The time when the request is completed (socket closed). The format is "Unix time" (seconds since Jan 1, 1970) with millisecond resolution.
When the request is completed (Day/Month/CenturyYear:Hour:Minute:Second GMT-Offset)
The elapsed time of the request, in milliseconds. This is the time between the accept() and close() of the client socket.
The IP address of the connecting client, or the FQDN if the 'log_fqdn' option is enabled in the config file.
The Action describes how the request was treated locally (hit, miss, etc). All the tags are described below.
The HTTP reply code taken from the first line of the HTTP reply header. For ICP requests this is always "000." If the reply code was not given, it will be logged as "555."
For TCP requests, the amount of data written to the client. For UDP requests, the size of the request. (in bytes)
The HTTP request method (GET, POST, etc), or ICP_QUERY for ICP requests.
The result of the RFC931/ident lookup of the client username. If RFC931/ident lookup is disabled (default: `ident_lookup off'), it is logged as - .
A description of how and where the requested object was fetched.
Hostname of the machine where we got the object.
You can use any HTTP Header Field, this is just a list of the most commonly used with definitions. For a complete list, check Hypertext Transfer Protocol -- http/1.1.
The MIME types which the client will accept, as given by HTTP headers. Other protocols may need to get this information from elsewhere. Each item in this list should be separated by commas as per the HTTP spec.
Format: type/subtype, type/subtype
The browser the client is using to send the request. General format: software/version library/version.
The server sends back to the client:
A status code that indicates whether the request was successful or not. Typical error codes indicate that the requested file was not found, that the request was malformed, or that authentication is required to access the file.
The data itself. Since HTTP is liberal about sending documents of any format, it is ideal for transmitting multimedia such as graphics, audio, and video files.
It also sends back information about the object being returned.
Indicates the media type of the data sent to the recipient or, in the case of the HEAD method, the media type that would have been sent had the request been a GET. Content-Type: text/html
The date and time at which the message was originated.
Date: Tue, 15 Nov 1994 08:12:31 GMT
The date after which the information in the document ceases to be valid. Caching clients, including proxies, must not cache this copy of the resource beyond the date given, unless its status has been updated by a later check of the origin server.
Expires: Thu, 01 Dec 1994 16:00:00 GMT
An Internet e-mail address for the human user who controls the requesting user agent.
The request is being performed on behalf of the person given, who accepts responsibility for the method performed. Robot agents should include this header so that the person responsible for running the robot can be contacted if problems occur on the receiving end.
Used with the GET method to make it conditional: if the requested resource has not been modified since the time specified in this field, a copy of the resource will not be returned from the server; instead, a 304 (not modified) response will be returned without any data.
If-Modified-Since: Sat, 29 Oct 1994 19:43:31 GMT
Indicates the date and time at which the sender believes the resource was last modified. Useful for clients that eliminate unnecessary transfers by using caching.
Last-Modified: Tue, 15 Nov 1994 12:45:26 GMT
The Location response header field defines the exact location of the resource that was identified by the request URI. If the value is a full URL, the server returns a "redirect" to the client to retrieve the specified object directly.
Location: http://WWW.Stars.com/Tutorial/HTTP/index.html
If you want to reference another file on your own server, you should output a partial URL, such as the following:
Location: /Tutorial/HTTP/index.html
Allows the client to specify, for the server's benefit, the address (URI) of the resource from which the request URI was obtained. This allows a server to generate lists of back-links to resources for interest, logging, optimized caching, etc. It also allows obsolete or mistyped links to be traced for maintenance.
Referer: http://WWW.Stars.com/index.html
The Server response header field contains information about the software used by the origin server to handle the request.
Information about the user agent originating the request. This is for statistical purposes, the tracing of protocol violations, and automated recognition of user agents for the sake of tailoring responses to avoid particular user agent limitations - such as the inability to support HTML tables.