Qt – Installing Qt 5.5.1 on Ubuntu 14.04 Throws qt.network.ssl Error


I am planning to install qt 5.5.1 on my ubuntu 14.04 running on virtual machine. I have downloaded the installer from qt-io and when I try to install the setup, I notice the below warning on my terminal, and then the installer pop up.

qt.network.ssl: QSslSocket: cannot resolve SSLv2_client_method
qt.network.ssl: QSslSocket: cannot resolve SSLv2_server_method

Do I need to worry much about this warning ? I dont see any error of this kind when I installed qt 5.3.1 on same machine.

Is there a way to resolve this warning ? Any help is appreciated. Thanks.

This is the current version of openSSL on my machine.

openssl version -v
OpenSSL 1.0.1f 6 Jan 2014

Best Answer

Now OpenSSL in Ubuntu is compiled without sslv2 because it’s insecure, but Qt 5.5.x still requires it. In order to enable sslv2 the package needs to be re-configued without the no-sslv2 flag.

Install the prerequisite packages

sudo apt-get update
sudo apt-get install libssl-dev devscripts dpkg-dev cdbs debhelper dh-autoreconf libev-dev libpcre3-dev pkg-config

And then, grab the source

cd ~/Downloads
sudo apt-get update
apt-get source openssl

Now we need to edit the file in openssl-1.0.1f/debian/rules. Find the line 44 (maybe the line number will be different in various version) and remove no-ssl2 so that it will be like below:

cd openssl-1.0.1f
nano debian/rules
CONFARGS  = --prefix=/usr --openssldir=/usr/lib/ssl --libdir=lib/$(DEB_HOST_MULTIARCH) no-idea no-mdc2 no-rc5 no-zlib  enable-tlsext no-ssl3 enable-unit-test $(ARCH_CONFARGS)

Next we will add a comment and commit the change. Then re-build the package, this is going to take some time so skip down to the nmap part and download the source. You might get some error says copyright was unable to be verified, ignore it. Moreover, the compiling might take a while so be patient.

dch –n 'Allow SSLv2'
dpkg-source --commit
debuild -uc -us

Now back to ~/Downloads you will see all the deb packages built. Install them:

cd ..
sudo dpkg -i *ssl*.deb

Now redo your Qt 5.5.1 installation to see if the warnings persist.