Why should the server be blacklisted ?

By curl or another program ?

How server can get blacklisted ?

Is it server or program dependant ?

Is this the IP address that get blacklisted, or the name of the server in the http answer ?

PS : I don't know if it is relevant, but i'm running on Linux / Ubuntu.

Here is the full output (testing tornado in localhost)

> * Rebuilt URL to: localhost:8888/
* Hostname was NOT found in DNS cache
*   Trying
* Connected to localhost ( port 8888 (#0)
> GET / HTTP/1.1
> User-Agent: curl/7.35.0
> Host: localhost:8888
> Accept: */*
< HTTP/1.1 200 OK
< Date: Fri, 16 May 2014 16:35:40 GMT
< Content-Length: 12
< Etag: "e02aa1b106d5c7c6a98def2b13005d5b84fd8dc8"
< Content-Type: text/html; charset=UTF-8
* Server TornadoServer/3.2 is not blacklisted
< Server: TornadoServer/3.2
* Connection #0 to host localhost left intact
Hello, world

1 Answer 1


It is an internal message from curl.

See: https://github.com/bagder/curl/blob/master/lib/pipeline.c

Seems to be part of a curl feature related to pipelining.

bool Curl_pipeline_server_blacklisted(struct SessionHandle *handle,
                                      char *server_name)
    infof(handle, "Server %s is not blacklisted\n", server_name);
  • It start with a star, which means, according to the doc, that's it's a curl message. May 16, 2014 at 16:54
  • 4
    The notes in daniel.haxx.se/blog/2013/03/26/… describe blacklisting, and how libcurl uses this option to disable HTTP pipelining for certain sites. Not sure if there's a way to control this behaviour from the front-end curl application; this might only be tunable by calling the libcurl API directly.
    – Alex Varju
    Jun 13, 2014 at 22:40
  • 1
    So the blacklist is about HTTP pipelining only. No big deal then. Aug 6, 2014 at 14:37
  • 4
    think this answer should be expanded. only by reading the comments do one understand that it is somehow a curl-internal message relating to some http thing. and I, as a casual reader, is left just as blank when it comes to what the message really is about.
    – oligofren
    Jul 16, 2015 at 8:21
  • 1
    @oligofren, I agree, so I added "It is an internal message from curl." as an introduction.
    – wodow
    Jun 30, 2016 at 14:56

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