What is SSL VPN?

Last updated: November 30, 2020

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When you cannot go to your workplace due to the COVID-19 crisis and want to access your official resources securely as a remote worker, you should rely on an SSL VPN service.

If you need to access web-based applications, client-server apps, and other internal network resources without using specialized client software, an SSL VPN service comes to your rescue again.

Read this post in detail to discover what is an SSL VPN and why it is a better option than IPsec VPN.

What is an SSL VPN?

An SSL VPN uses SSL (Secure Sockets Layer) protocol to create a secure and encrypted connection over a less-secure connection like the internet. At present, the SSL VPN depends on the Transport Layer Security (TLS) protocol, the successor of SSL protocol in modern web browsers, to provide a secure VPN connection.

Besides, it uses end-to-end encryption (E2EE) that protects the data transmitted between the client’s device and the SSL VPN server.

How does it work?

An SSL VPN helps users experience secure remote access from anywhere. Furthermore, it allows them to create secure connections to internal HTTP (Hypertext Transfer Protocol) and HTTPS (Hypertext Transfer Protocol Secure) services through standard web browsers or apps responsible for providing direct access to networks.

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When you connect to an SSL VPN service, you will realize that an ‘s’ alphabet has been added to your “HTTP’ address. As a result, the address becomes ‘HTTPS,’ i.e., HTTP-Secure.

Similarly, you can see a padlock at the bottom of a web page that indicates you are visiting a website protected by an SSL VPN.

As soon as you send a request to the server to fetch a secure page, the browser is bound to send a digital certificate and a public key in return. Consequently, your browser uses that public key to encrypt the data.

Furthermore, the data will be transmitted through the secure protocol. For instance, if two computers are using an SSL VPN, the data transfer will occur once the encryption process is completed.

Types of SSL VPN

There are two main types of SSL VPNs. The first one is the SSL Tunnel VPN, and the second one is the SSL Portal VPN.

SSL Tunnel VPN

As far as SSL Tunnel VPN goes, it allows users to access various network services through standard web browsers and protocols alongside other apps that are not web-based securely. In this scenario, the role of the VPN tunnel comes in handy.

In reality, it acts just like a pathway created between the remote user and the VPN server. However, the server can connect to different private services, websites, or other resources simultaneously on users’ behalf.

SSL Portal VPN

SSL Portal VPN is another type of SSL VPN that establishes one SSL VPN connection to remote websites at a time. That said, users have to complete the authentication process by which they can access the gateway using their web browsers.

Once users authenticate themselves, they can use a portal, a single web page that lets them access other internal network services.  

Advantages and disadvantages of SSL VPN

There are different advantages you can obtain by using SSL VPN services. Firstly, organizations can help their remote users access organizational resources from anywhere. Apart from this, SSL VPNs provide a reliable connection to their users as they are incredibly compatible with client platforms.

Through an SSL VPN service, you can prevent unauthorized people from keeping an eye on network communications and official data to a certain degree.

Despite offering multiple benefits to users, SSL VPNs do have some disadvantages as well. They can spread malware to the enterprise’s network if any device runs with outdated antivirus software.

Unfortunately, hackers and other cyber goons can use the split tunneling feature of SSL VPNs to fulfill their objectives. They can target the users’ sensitive traffic if it passes through an insecure tunnel.

Difference between IPsec VPN and SSL VPN

As far as IPsec VPN goes, you have to install IPsec client software on clients’ systems first. For that reason, you will need to purchase and install the additional software. This way, you can use IPsec VPN connections accordingly.

Compared to IPsec VPNs, SSL VPNs are easily configurable, and you do not need to install additional software on your devices. Interestingly, you can set up SSL VPNs through your existing web browsers, stress-free.

Surprisingly, a remote user can access the whole internal network while using an IPsec VPN service. But in the case of SSL VPNs, organizations can provide limited access to their remote workers, and that is a good thing from a security point of view.

It means that enterprises may give different access rights to different users, depending on their requirements using SSL VPN. 

How can I set up an SSL VPN? 

If you want to configure SSL VPN on your device, follow these steps as mentioned below:

First Step – Deactivate Port 443 for site-to-site and client-to-site VPN

In order to disable port 443, go to Configuration>Configuration Tree>Box>Virtual Servers>your virtual server>Assigned Servers>VPN>VPN Settings.

At this point, click Lock, then click the “Click here for sever settings” link. The server settings window will appear on your screen. Now, set the “Port 443 VPN Listener” option to no, then click OK>Send Changes>Activate.

Second Step – Configure SSL VPN General Service Settings

You will need to activate the SSL VPN service and add the listening IP addresses. Now, go to Configuration>Configuration Tree>Box>Virtual Servers> your virtual server>Assigned Services>VPN-Service>SSL-VPN, then click “Lock”.

You should set the “Enable SSL VPN” option to Yes, then click + to add a listening IP address. Furthermore, you should also activate “Restrict to Strong Ciphers Only”. At this point, choose the identification type:

Generated-Certificate – The firewall creates the certificate and private key automatically.

Self-Signed-Certificate – You should click New that creates a self-signed private key. Now, you should edit it to create the Self-Signed Certificate.

External-Certificate – You should click Ex/Import to import the CA-signed External Certificate and the External-Signed Private Key.

Similarly, you should also import the certificate chain that consists of intermediaries and the CA’s root certificate when importing an external trusted certificate. Once you have performed this step, click Send Changes and Activate.

Third Step – Configure Login

In this step, you should go to Configuration>Configuration Tree>Box>Virtual Servers>your virtual server>Assigned Services>VPN-Service>SSL-VPN. Now, you have to click “Login” using the left menu.

You should now click “Lock” using the Login section and set the Identity Scheme to your desired authentication method, i.e., MS-Active Directory.

In case a client certificate is needed, set the “Use Client Certificate” option to yes. At this point, you need to click + to add the Root Certificates used to verify peer certificates. Likewise, you should click + to add your access control policy to the list of Access Control Policies.

You may configure the following settings if required:

Use Max Concurrent Users – You can activate this setting if you want to limit the number of multi-logins using the SSL VPN service.

Max Concurrent Users – You can enter the maximum number of users connected to the SSL VPN service.

Session Timeout (m) – Mention the session timeout in minutes.

Deny Remember Me – Choose the Yes option to remove the Remember me check box given on the login page. Now, you should click Send Changes and Activate.

Fourth Step – Use Custom Cipher String

In this step, you will have to configure a custom cipher string used by the SSL VPN service. At this point, go to Configuration>Configuration Tree>Box>Virtual Servers>your virtual server>Assigned Services>VPN-Service>SSL-VPN.

Now click “Basic Setup” using the left menu, then click “Lock”. You should expand Configuration Mode given in the left menu and click “Switch to Advanced view”. Similarly, you will have to deactivate the Allow SSLv3 option and activate “Restrict to Strong Ciphers Only”.

You have to enter your custom SSL Cipher Spec String and set Strict SSL Security to yes. At this point, click Send Changes and Activate. This way, you can set up an SSL VPN on your devices accordingly.

FAQs

Are SSL and TLS the same?

 In simple words, you can consider TLS (Transport Layer Security) protocol as an improved version of the SSL ( Secure Sockets Layer) protocol. The former works in the same manner as the latter. Moreover, it uses symmetric-key encryption that ensures the secure transfer of data and information.

Is SSL VPN safe?

 SSL VPN is safe to use since it offers secure communication for all sorts of devices across the public and private networks. The whole traffic between a web browser and an SSL VPN device is encrypted through TLS (Transport Layer Protocol).

Wrapping Up

SSL VPNs do play their crucial role when it comes to improving information security next level. There is no denying that various threats can influence business data or information adversely.

Therefore, organizations should benefit from using SSL VPN services since they are easy to use and compatible with the latest operating systems and web browsers.

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