Implementing secure remote access to machines: key considerations

Madison Technologies

Tuesday, 12 March, 2019

Implementing secure remote access to machines: key considerations

Machine builders need a safe and effective way to gain visibility into their machines and to be able to remotely connect to and manage their machines.

The IIoT has revolutionised the way business owners view their production environment by providing the capability to acquire real-time data from machines and devices in the field so that business owners can efficiently monitor and control production processes. OEE and zero equipment downtime are no longer just buzzwords because they are the key to a successful business. In order to increase production efficiency and cut operation costs, business operators are adopting new technologies and tools to help them gain more insight into their processes and systems. This new trend is compelling machine builders to provide tools and services that support the goals of zero downtime and high OEE for business owners’ machines and equipment. Remote access technology is key to helping machine builders achieve these goals.

Data collected from experienced support engineers indicate that an estimated 60–70% of operational problems in machines simply require a software upgrade or some parameter changes to fix the problem, and tellingly, many of these can be done remotely! By adopting remote access solutions, machine builders can avoid time-consuming and expensive on-site work for troubleshooting such problems in the field.

Furthermore, with remote access technology, machine builders can acquire real-time data from machines installed at field sites. And, based on the actual condition of the equipment, machine builders can predict machine failures before they occur. This ability gives business owners the opportunity to schedule machine maintenance services in advance, thus enabling them to improve the availability of their machines, in addition to improving production quality and speed. Such predictive maintenance services provided by machine builders can dramatically improve the overall equipment effectiveness of plant machines and equipment.

Some machine builders have adopted traditional remote access methods, such as virtual private networking (VPN) and remote desktop connections (RDC), to improve their service levels and to provide quick response times for their customers. However, these traditional remote access solutions have various limitations and constraints that prevent machine builders from achieving their maximum service potential.

Challenges for OEMs in using VPN and RDC solutions

VPNs and RDC — the latter of which uses virtual network computing (VNC) — are two common methods used to remotely access machines and equipment at field sites.

Figure 1: Traditional remote management tools – VPN and RDC.

Figure 1: Traditional remote management tools — VPN and RDC. For a larger image, click here.

VPN and RDC solutions can facilitate secure connections to remote machines. However, many of these solutions lack the flexibility or the intelligence to meet the specific needs of industrial machine builders. There are five key elements that such machine builders have to consider when they use VPN and RDC solutions.

Time-consuming set-up process requiring extensive IT knowledge

Multiple parameters, including IP address, domain name, key ID, authentication mode, a suitable encryption algorithm and an efficient hash function, all need to be configured to properly establish connectivity with remote machines and to be able to exchange the necessary authentication keys and data. This process is complex and time-consuming, and requires extensive IT knowledge, which a majority of automation engineers may not be familiar with.

Compromises in corporate security policies are required

VPN applications require the VPN server to have a static public IP address, and some specific network ports need to be configured to permit inbound and outbound traffic. In the inbound firewall rules, users have to create NAT rules and enable port forwarding to allow inbound VPN connections. In the outbound firewall, UDP port 500 or UDP port 4500 or some other designated port has to be configured to allow outbound VPN connections. Most IT departments are unwilling to implement these changes in their organisation’s network because the changes may create network vulnerabilities and compromise network security. Creating firewall rules that are secure and flexible at the same time has proven to be a major challenge for most IT departments, especially those that manage industrial networks.

Complexity and high cost of ensuring security

VPN connections between machine builders and machine operators are usually site-to-site connections, which typically provide machine builders with remote access to all local devices in a plant’s network. Plant operators want to restrict the network access of machine builders so that only a selected set of machines are accessible. For example, plant operators need ways to restrict access by plant equipment and specify the applications that can be accessed remotely to prevent unauthorised access to production information and unauthorised or accidental operation of plant equipment. The only way to mitigate this risk is for IT departments to create separate end-to-end connections using VPN technology, which, as previously noted, is complex and expensive, thereby drastically increasing set-up and maintenance costs.

VPN security is difficult to manage

One way to achieve a higher level of security is to have different pre-shared keys or X.509 certificates for each VPN tunnel. When the number of VPN tunnels required are few, it is easy to manage the keys or certificates for these connections. However, as the number of VPN tunnels grows, it becomes more difficult to manage these keys and certificates. When VPN servers or client systems are changed, certificates have to be regenerated. When a certificate expires, a new certificate has to be assigned and reloaded to the system, which further complicates maintenance.

Scalability and flexibility are costly

VPN servers typically have a limitation on the number of VPN tunnels they can support. When a business grows, more and more machines and devices are connected to the network with an increasing number of engineers supporting business operations. This leads to an increase in the number of VPN connections required. Once this number exceeds the VPN server’s capabilities, machine builders will need to install a new VPN server and go through an additional time-consuming configuration process.

VPN servers are typically located in the machine builder’s service centre. A large number of VPN clients in remote sites are connected to these VPN servers in the centralised service centre. Support engineers typically do not have access to the server from outside the service centre, so in order to have access to the VPN servers from outside — for example, by using OpenVPN or L2TP over IPsec — VPN servers have to be installed at remote sites, and each VPN server needs to have a public IP address. This results in high installation and maintenance costs. In addition, a remote connection requires different network subnets on the server side as well as on the client side. If engineers want to simultaneously diagnose remote equipment on different sites, they have to be aware of the IP subnet configurations at the remote IP sites in order to avoid IP address conflicts and other problems.

Similarly, a remote desktop connection to a PLC or other controller is neither straightforward nor convenient. It requires, at a minimum, a dedicated PC that is connected to the machine and has all of the relevant software tools installed. As a business grows, the number of dedicated PCs and the number of software tool licences will increase, leading to a steep rise in IT costs. In addition, one needs to consider the effort to maintain the PCs and the software tools installed on them. Machine builders tend to prefer identical versions of the software tools to be installed on both the client and host machines since this simplifies the troubleshooting process. To do so, the IT engineers assigned for maintenance need to coordinate all updates to software tools between the server and client sides.

Because of these limitations and restrictions in VPN and RDC-based remote access solutions, machine builders and equipment manufacturers are looking for easy-to-use, secure, flexible and scalable solutions that can be used to remotely manage their machines and equipment.

Cloud-based secure remote access

Cloud-based remote access is a new type of remote access solution that enables flexible remote access to field machines. The network topology of a cloud-based remote access solution is composed of three components: a remote gateway, a cloud server and client software. Remote gateways are connected to field equipment in order to remotely access and control them, while client software is installed on the engineer’s PC or desktop. The cloud server can be installed on a cloud-based platform such as Amazon Web Services or Microsoft Azure.

The remote gateway and client software will both initiate outbound secure connection requests to the cloud server. The cloud server maps the two connection requests and, after successful authentication on both sides, a connection is established.

Figure 2: Cloud-based secure remote access.

Figure 2: Cloud-based secure remote access. For a larger image, click here.

Cloud-based secure remote access solutions implement a network topology that enables the creation of outbound connections in the form of remote access tunnels, thereby effectively overcoming the challenges that the traditional VPN and remote desktop control technologies present. In addition, cloud-based remote access brings a number of additional benefits for machine builders.

Ease of use

In a cloud-based remote access solution, security parameters are configured automatically, permitting plug-and-play access without the need for technical configuration. Machine builders do not need to configure these parameters; they just need to click on a button to establish a remote connection.

Virtual IP addresses make also multipoint remote access effortless. Irrespective of the initial IP addresses set up by machine builders, cloud-based solutions assign a unique virtual IP address to machines. Machine builders can use these virtual IP addresses to establish multiple simultaneous remote connections. In addition, machine builders can use identical IP schemes for different field sites without worrying about IP address conflicts.

Management is also easier because in cloud-based remote access solutions, the cloud server is the central point for establishing and managing remote connections. Administrators can monitor the traffic status and volume of each connection by connecting to the cloud server. Furthermore, administrators can easily manage client accounts, remote gateways and certificates without the need for frequent reconfiguration. All these management tasks can be done via an easy-to-set-up cloud-based server portal.

Enhanced security

Cloud-based remote access solutions provide end-to-end data encryption between an item of remote equipment and an engineer’s PC. The cloud server only routes the traffic and does not decrypt or store the data that is passing through, preventing data leaks.

The ability to provide on-demand remote access control simply is also an advantage. Machine builders use remote access solutions to perform troubleshooting, monitoring, maintenance and diagnostics. Remote access to machines and equipment is typically not required on a continuous basis and hence can be used on an as-needed basis to minimise security issues and reduce costs, especially in cases where remote connectivity is based on a volume-dependent pricing option, such as with cellular technology. Furthermore, machine operators want to be able to take measures to prevent machine builders from remotely accessing all applications on their local network by limiting the scope of remote access to only applications that machine builders need to access, thereby eliminating the risk of interference with plant operations. Cloud-based remote access provides machine operators with the ability to initiate or accept remote connections, and machine operators can create rules as to which services and applications — such as HTTPS or Telnet — that machine builders are authorised to use remotely. They can also control who has the authority to use them, for example, by restricting access to a specific set of service engineers.

Existing IT security policies can also be maintained, because cloud-based remote access solutions build outbound connections using the outbound service port 443 to access remote equipment, which does not present any issues for IT departments managing plant networks. Cloud-based remote access solutions can work in harmony with the IT security policies of machine operators.

Flexibility and scalability

Since client software isn’t limited to specific hardware, as long as they have an active client account, users can download the client software to any laptop or PC and have remote access from anywhere and at any time.

Cloud-based remote access solutions also create a transparent tunnel that connects the client with the remote equipment as if they were on the same network. So regardless of the remote equipment being accessed, and independent of the protocol used to pull data or for programming, machine builders can remotely acquire data or program remote equipment using their own software tools as if the machine builder was sitting next to the remote equipment.

Network expansion is also much easier. Network administrators can easily add and remove equipment and manage client accounts and certificates as they expand their remote networks.


OEMs and machine builders require a secure, easy-to-use and scalable remote access solution to enable on-demand remote access to their machines deployed in the field. Traditional VPN and RDC solutions are cumbersome and require IT and networking knowledge as well as changes in security and firewall policies. A remote access solution that is backed by a cloud-based management infrastructure can provide the ease of use, flexibility and scalability required by OEMs, without compromising on security.

Top image: ©

Related Articles

Making integration and continuous improvement easier

Enhancing existing controls infrastructure investment with IO-Link technologies.

Architecting the edge for performance and reliability

For most OT professionals long responsible for edge-based computing systems in their...

  • All content Copyright © 2020 Westwick-Farrow Pty Ltd