Question: I'm trying to setup *github-pages* on my Ubuntu laptop, and following the guide provided by Github I have to install the *bundler* package; giving the command

```
~$ gem install bundler

```

returns me this error.

`ERROR: While executing gem ... (Gem::Exception)
 Unable to require openssl, install OpenSSL and rebuild ruby (preferred) or use non-HTTPS sources`

Then I have installed OpenSSL, launched the command to update software and stuff and tried again to install *bundler*, but the error kept showing.

How can I fix this? Is there any specific command to rebuild ruby making it aware about the fact that openSSL is now installed?

Answer: 
I've found the answer to my own question, and I think it would be more clear to post as an answer, rather than editing the question.

**1st try. Let's go through the path of non-safe source link.**

As pointed out [here](https://stackoverflow.com/a/25186429), a possible choice to bypass the openSSL check is to remove the safe *https* link and add the non-safe one:

```
gem source -r https://rubygems.org/
gem source -a http://rubygems.org/

```

This way, the installation seems to go fine, but somewhere around the process openSSL is required again (for *nokogiri* gem, if I remember it well).

**2nd try. Rebuild Ruby (it was so easy).**

By the time I asked this question, my brain was probably not working properly. After installing openSSL by the usual way:

```
sudo apt-get install openssl

```

I got to my ruby directory and typed the following lines:

```
pushd ext/openssl
ruby extconf.rb
make
make install
popd

```

This way, I had all dependencies issues and stuff solved (I guess). Then, running

```
./configure
make
make install

```

I've rebuilt Ruby and finally the installation went fine.
Rebuilding ruby after `sudo apt-get install libssl-dev libreadline-dev libgdbm-dev` can solve this issue.

The solution is found here: <http://www.larshaendler.com/2015/05/20/unable-to-require-openssl-install-openssl-and-rebuild-ruby-on-ubuntu-14-lts/>