The SSL certificate

Some of you might wonder in which situations an SSL certificate should be used. This tutorial will help you to find an answer whether or not you should upgrade your website or anything else by adding encryption.

The most important parts of a certificate are the public key and the private key.
The following image shows you what is happening when a client tries to establish an encrypted connection to some webserver.



First the client contacts the server and offers available encryption types, the server and the client come to an agreement on which type to use.
The web server sends the public key to the client so the client will be able to encrypt its requests. The webserver got his private key to decrypt all encrypted client requests. With the private key you are able to decrypt all client requests which were encrypted with the public key, that is why you should never hand out your private key to any third party.

To show you the advantage of using encryption, we created an HTML page containing a simple form which can be found on many websites. In the textfields we entered a username and password.

The username we chose: test@contabo.de

The password we entered: "unencryptedpassword"

To show the difference between encrypted messages and not encrypted messages, we captured some packets using a networking-tool.

Without any encryption we could easily extract the username and password used, we could also see which sites we visit.


With encryption enabled we could not find neither username nor password.
It just shows a packet containing some encrypted data, without the private key we cannot determine which data was actually sent.

If you are running a website, an email server or just an FTP server, it is always up to you to offer encryption or not. Offering encryption to your customers is the best way to act professionally.

There are many types of encryption, this post just handles certificates. Usually encryption algorithms have not changed for years, if you are going to optimize your server you will of course have to think about encryption types, etc.


The real meaning of those connection warnings:

If you are running a web interface (cPanel, Plesk, Webmin etc.) you probably encountered a warning as follows:


"The connection is not private", usually you should rethink if you really want to proceed. There is the possibility that some server got hijacked and you are redirected to the wrong website. In this case the warning pops up because the certificate is not valid for the domain we entered. On a web interface you will get a similar warning when using a so called "self signed certificate". Your browser got a list of authorities which it will trust, signed certificates by one of those authorities will not show any warning.

It can be really unwanted if that warning is showing to all of your customers, sometimes this warning is misinterpreted and the website will be left.

There is only one way to remove this warning, you need to get a certificate signed by some official authority.

Some official authorities, such as "Lets Encrypt", will sign your certificate for free, this is a nice option but not really recommended on a production environment. Usually the domain validated certificate or wildcard  certificate is being used for production environment, those certificates usually are valid for 365 days (1 year).

There are some differences between single domain, multi domain and wildcard certificates. Usually you would want a certificate for "yourdomain.tld" or "www.yourdomain.tld". A single domain certificate will be valid only for one of those domains, a multi domain certificate alias UCC (Unified Communications Certificate) is valid for all domains included within that certificate. In case you want "www.yourdomain.tld", "yourdomain.tld" and "subdomain.yourdomain.tld" within a single certificate, a UCC should fit your needs.

There is also some extended validation available, some bigger companies take advantage of this (e.g. PayPal pp_ev). At this point I want to mention that the private key and certificate will always remain the same, there is no encryption change, the certificate will just get signed.

Right after you got your certificate signed by some official authority, everyone will be able to access your encrypted website without any warning.


Encryption is important, all services (email server, FTP server, web server, etc.) running on your server should offer a way to establish an encrypted connection. There is no need of installing a signed certificate on each service, for most services self-signed certificates are fine.


Posted by: Gianni-Donato | Tagged as: , , , , 4 Comments

Webspace: Free SSL certificates available now!

We have some great news for our webspace customers and those of you who are considering to buy their webspace at Contabo! We have improved our packages with another upgrade: From now on you get a free SSL certificate for every domain you use with your webspace. This of course also applies for new domains, which you might want to add in the future.

The technical implementation is realized through the popular Let's Encrypt project. The process of the creation and the renewal of the SSL certificate is automated, which means that you do not have to perform any manual steps yourself. Of course, these certificates are considered trustworthy by all common Internet browsers.

Using the Let's Encrypt certificate offers you many advantages: It is for free, already integrated in cPanel, the creation and renewal runs automatically and you can encrypt the connection to your own website via HTTPS in no time at all!
It is important to mention that you should change static URLs (e.g. for pictures) from http to https or make use of relative URLs - otherwise the files are considered as unsafe elements by your browser when accessing them via https.

This new feature is also available for our existing customers. Hence it makes our webspace plans even more attractive – likewise for beginners and professionals! In addition we offer you more than 300 different PHP-scripts, which you can install with just one single click. You may create your own blog, a survey, a web portal, e-commerce solutions or content management systems - guaranteed hassle-free: Our auto-installer ensures that you can take care of the things that really matter and annoying installation processes are a thing of the past. Now you get all these features via HTTPS for free.

Benefit from our low-cost webspace offers, starting at just 2.99 €/month!
You can find an overview of our offers here.

Posted by: Markus | Tagged as: , , , No Comments