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Asked: 2026-06-07T16:54:42+00:00

I am trying to write a torrent downloader and needed to work out how

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I am trying to write a torrent downloader and needed to work out how to contact a tracker. I used the Fiddler2 program to intercept a tracker request sent from Vuze to it’s tracker.

In the message sent (shown below), the Connection header is declared twice with different values.

Is this a correct use of the Connection header?
What does Connection: keep-alive do?

GET /announce?info_hash=0Z%22...&azver=3&azas=12576 HTTP/1.1
User-Agent: Azureus 4.7.0.2;Windows 7;Java 1.6.0_31
Connection: close
Accept-Encoding: gzip
Host: tracker.update.vuze.com:6969
Accept: text/html, image/gif, image/jpeg, *; q=.2, */*; q=.2
Connection: keep-alive
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1 Answer

  1. Editorial Team

    From RFC2616 section 4.2:

    Multiple message-header fields with the same field-name MAY be present
    in a message if and only if the entire field-value for that header
    field is defined as a comma-separated list [i.e., #(values)]. It MUST
    be possible to combine the multiple header fields into one
    “field-name: field-value” pair, without changing the semantics of the
    message, by appending each subsequent field-value to the first, each
    separated by a comma. The order in which header fields with the same
    field-name are received is therefore significant to the interpretation
    of the combined field value, and thus a proxy MUST NOT change the
    order of these field values when a message is forwarded.

    Edit:

    According to section 14.10, Connection is such a field-name, so having multiple Connection headers is technically correct.

    From 14.10 the grammar production for the Connection header is Connection = "Connection" ":" 1#(connection-token), so one or more comma separated tokens are valid.

    In practise however, it may be that the second Connection header will be ignored, and thus the web server will expect to close the underlying TCP connection once the response has been sent.

    For HTTP 1.1 the default mode is for the server to keep the underlying TCP connection open for subsequent requests, although many servers will limit the total number of requests made before closing the connection anyway.

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