cURL / Mailing Lists / curl-library / Single Mail


Re: problem from out of the blue: can't connect via libcurl

From: Daniel Stenberg <>
Date: Wed, 9 Dec 2009 13:41:13 +0100 (CET)

On Wed, 9 Dec 2009, Pete Wilson wrote:

> curl 7.15.5 (x86_64-redhat-linux-gnu) libcurl/7.15.5 OpenSSL/0.9.8b
> zlib/1.2.3 libidn/0.6.5
> The curl program runs perfectly.

Have you verified that they (curl and your tool) use the same libcurl? I mean
with ldd etc to see that they actually refer to the same file.

> My ISP support assures me that nothing on the server has changed.

You have reasons to question their words here. The bug could either be due to
a date-depdendent problem in libcurl which no other person in the world has
suffered from, seen or fixed. Or it could be something in your ISP's
environment that changed. I know what I'd put my money on...

> The problem: On my ISP, when my app asks libcurl to connect to a remote
> host, libcurl immediately complains
> * Unsupported protocol: https

That means your application uses a libcurl that was built without support for

> Same thing happens with http.

That means your application uses a libcurl that was built without support for
HTTP. That is somewhat more peculiar since that's a rather rare setup and
certainly not something that just happens by accident. When HTTPS is missing,
it could be an oversight by someone who just didn't pay attention if curl's
configure failed to find a proper SSL library. Not so when HTTP is

> * Do you have any idea what's happening at my ISP?

My advice: build your own libcurl and put it in your own homedir on the ISP
site and use that lib instead.

> * If not, how in the world am I going to approach debugging this issue on my
> ISP? I'm completely stymied.

Use strace to figure what is loaded. Use ldd to check what's linked/used. Use
gdb to see what happens in your code.

Good luck!

List admin:
Received on 2009-12-09