Among the different possibilities to establish a hybrid connectivity with the Azure cloud exist VPN Point-to-Site (P2S). Through the VPN P2S you can enable connectivity from one location to the Azure environment, easily and securely. It is a useful solution to allow communication from remote locations to the Virtual Network of Azure, mostly used for test and development purposes. Can be activated alternatively to Site-to-Site VPN if you must provide connectivity to Azure for a very limited number of systems. This article describes the features of this connectivity and displays the latest news about.
To establish hybrid connectivity with Azure we can use different methodologies, each of which has different characteristics and may be eligible for specific scenarios, providing different levels of performance and reliability.
Figure 1 – Options to enable hybrid connectivity with Azure
The Point-to-Site VPN definitely provide a more limited set of features compared to other hybrid connectivity options and are appropriate in specific cases, where only a limited number of places should be connected to the Azure environment. The P2S connection is established by starting directly from the remote system and in the solution are not expected native systems to activate it in an automatic way.
Figure 2 – Comparison of hybrid connectivity options
Protocols used by the P2S VPN
The Point-to-site VPNs can be configured to use the following protocols:
- OpenVPN®: is a protocol recently added in Azure, but already widely used by different solutions, that enriches this type of connectivity. This is an SSL/TLS based VPN Protocol, that due to its characteristics more easily traverses firewalls. Furthermore, it is compatible with different platforms: Android, IOS (version 11.0 and above), Windows, Linux and Mac devices (OSX version 10.13 and later).
- Secure Socket Tunneling Protocol (SSTP): This is a Microsoft proprietary VPN protocol based on SSL and it can easily cross firewalls, but has the limitation that can only be used by Windows systems. In particular, Azure supports all versions of Windows that include SSTP (Windows 7 and newer).
- IKEv2: This is an IPsec VPN solution that can be used by different client platforms, but in order to function it requires that in the firewall are permitted specific communications. IKEv2 is supported on Windows 10 and Windows Server 2016, but in order to use it you need to install specific updates and set certain registry keys. Previous versions of the OS are not supported and can only use SSTP, orOpenVPN®.
Figure 3 – OpenVPN Protocols® and IKEv2 compared
The Point-to-Site VPN require the presence of a VPN gateway on the active virtual network of Azure and depending on the SKU vary the maximum number of possible connections. It should also be taken into account that the VPN Gateway Basic does not support IKEv2 and OpenVPN protocols.
Figure 4 – Gateway SKU in comparison for VPNs P2S
Coexistence between the P2S VPN and S2S VPN for the same virtual network is possible only in the presence of VPN gateway RouteBased.
Supported client authentications
Point-to-site VPN access provides the ability to use the following authentication methods:
- Azure native authentication using certificates. With this mode, the authentication takes place via a client certificate present on the device that needs to connect. Client certificates are generated by a trusted root certificate and must be installed on each system to connect. The root certificate can be issued by an Enterprise solution, or you can generate a self-signed certificate. The client certificate validation process is performed by the VPN gateway while attempting to connect the P2S VPN. The root certificate must be loaded into the Azure environment and is required for the validation process.
- Authentication using Active Directory (AD) Domain Server. Thanks to this type of authentication users can authenticate using domain credentials. This methodology requires a RADIUS server integrated with AD. RADIUS system can be deployed on-premises or in the VNet of Azure. Using this mechanism, during the authentication process, the Azure VPN Gateway communicates with the RADIUS system, therefore it is essential to provide this communication flow. If the RADIUS server is deployed on-premises, must therefore be a connectivity through S2S VPN with on-premises systems. The RADIUS server can use certificates issued by an internal Certification Authority as an alternative to certificates issued by Azure, with the advantage that it is not necessary to manage Azure upload root certificates and certificate revocation. Another important aspect is that the RADIUS server can be integrated with third-party authentication mechanisms, thus opening the possibility of also use multifactor authentication for P2S VPN access. At the moment the OpenVPN® Protocol is not supported with RADIUS authentication.
Conclusions
Point-to-Site VPNs (P2S) can be very useful to provide connectivity to the Azure Virtual Networks in very specific scenarios. Thanks to the introduction of the support to OpenVPN® protocol it is possible to activate more easily and from different devices (Windows, Mac and Linux), without neglecting safety aspects.
