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Is it safe to use ":" as proxy user/pwd when none required ?

From: Nicolás Ojeda Bär <>
Date: Tue, 29 May 2018 18:36:26 +0200

Dear all,

First of all, thanks for this great library.

I am deploying libcurl under Windows in a corporate environment where
proxies are used. One of my users had success passing ":" as proxy
user/password in order to authenticate.

If I understand correctly, this tells libcurl to use, under some
circumstances and protocol combinations, the Windows credentials to

My question is: is it safe to always pass ":" as proxy user/password, even
in the case where no username/password is required? Do you see any issues
with doing this? Unfortunately, I am not able to test this in the actual
environment, which is why I am asking here.


Best wishes,

Received on 2018-05-29