Network security challenges for remote access

Effective network security is most successful when it is built up using a layered approach. Here we review common technologies and challenges for secure remote access, and examine one commercial device-based approach.


Security considerations are always a major issue when deploying a remote access solution, and the difficulties are compounded when solutions must include support for embedded systems. Successful implementations must provide effective authentication and access control, and care must also be taken to ensure that data is secured during transport over the network.

Additional considerations arise when target devices are hosted as guests on remote networks administered by others. In such cases particular care must be taken to ensure that your systems do not open the hosting network to outside threats.

Effective network security is not based on any one technology or component; it is most successful when it is built up using a layered approach, following the OSI Seven Layer Networking Model, with multiple defenses contributing to the overall solution. Here we review some common technologies for developing secure remote access solutions, along with some of the real-world challenges faced. We will also examine one commercial offering that addresses these challenges in an innovative and cost-effect way.

Network-based access controls

Network-based access controls are used to ensure that only authorized hosts are allowed to establish connections to your networked devices. Such access control usually takes the form of Firewalls that may work at Layer 2 (also referred to as the data link layer in the OSI Seven Layer Networking Model) or Layer 3 (the network layer).

Layer 2 solutions are sometimes described as “stealth firewalls”– they do not appear as a router hop to the network layer. Instead they provide a filtering capability on top of a transparent bridging connection between two network end points.

A layer 2 firewall may have Access Control Lists that allow the operator to control connections to or from specific devices or to prevent traffic for specific network protocols. For example, you may configure such a system to block IP-based traffic to a specific host while permitting Novell Netware IPX-based traffic.

Layer 3 firewalls, also known as port-based firewalls, operate at the TCP layer. When setting up a layer 3 firewall, the administrator configures Access Control Lists that enable or block connections based upon specified source and destination IP addresses and ports. Some so-called “Layer 3/Layer 4” firewalls function by examining the contents of layer 3 packets for additional information to help make their decisions.

Significant Issues with network layer access controls

The success of firewall technology in addressing external network threats did not come without a price - universal deployment of firewalls has greatly aggravated the difficulty of providing remote access to network devices.

Although effective and usually offering good performance, firewalls are complex to set up and administer and require network administrative privileges on the protected network. When setting up a layer 3 firewall it is common practice to enable connections to a device only on those ports that you know will be used. This can often lead to problems when a new service is enabled and the required port is being blocked.

The networking industry’s initial response to the growing remote access challenge was the virtual private network (VPN). As its name implies, a VPN replaces dedicated leased lines, cellular links or other costly physical connections with a secure mechanism over which traffic from a remote device can be tunneled to the target network using an existing network connection.

As with firewalls, installing and operating your own VPN requires network administrator privileges. Both IPSec and SSL VPNs are “IT-oriented” solutions, used by network administrators to control access into their networks. Thus, installing such a device at each remote location is usually not an option for enabling remote access to devices on other people’s networks. Another issue for SSL VPN solutions is the challenge of maintaining large numbers of user-level security credentials for each support technician when accessing equipment at a large number of locations.

A final significant issue for VPNs when used to grant guest access is that once a VPN connection is established, the remote host essentially becomes another node on the remote network. This can be a problem when the goal is to grant limited access privileges to specific hosts.

One solution is to group guest devices onto their own local area network (LAN), but this is often not possible when your equipment is being hosted on networks outside your own administrative control.

Machine-to-machine remote management

One commercial offering that addresses these challenges is a machine-to-machine remote management device capable of providing easy yet secure remote Internet access to IP-enabled equipment– even when such equipment is located behind remote firewalls or a VPN. Readily adaptable to a wide range of management tasks, such devices are suited for accessing and managing embedded systems located on remote customer networks. They are also appropriate where support staff do not have administrator privileges on the remote network.

The ManageLinx management platform from Lantronix is one example. Its patent-pending ManageLinx VIP Access component provides transparent Layer 3 network access to any piece of remote equipment without specialized client software or network reconfiguration. Because it is able to work with any TCP/IP-enabled application running on any host or operating system, ManageLinx VIP Access is particularly useful for embedded systems deployments where dedicated VPN clients or specialized networking configuration changes are not an option.

ManageLinx works over conventional Internet connections with as little as one open port to the WAN and requires no reconfiguration of the target network’s firewall settings. Because it can use existing Internet connections, ManageLinx VIP Access eliminates the need for dedicated analog phone lines or cellular coverage.

Because the ManageLinx VIP Access operates at the Network layer and communication between VIP address and the endpoint device is fully automated, it is easy to integrate embedded devices into the system. No dedicated clients or specialized software is needed to access the system. Embedded systems programmers utilize traditional TCP/IP programming mechanisms:

With multiple defenses contributing to the overall solution, effective network security is attainable. Investigate the layered approach. With care, it is possible to provide effective, secure network access to remote access deployments, enabling new service models and increasing customer capabilities.

Errett Kroeter is director of corporate & channel marketing for Lantronix in Irvine, CA. . Additional information on the new ManageLinx VIP Access remote access solution, including a security white paper and a remote product services case study, are available at the Lantronix website .

Remote Control: Get Behind firewalls securely.

Renee Robbins , senior editor
Control Engineering News Desk
Register here and scroll down to select your choice of eNewsletters free .

The Top Plant program honors outstanding manufacturing facilities in North America. View the 2015 Top Plant.
The Product of the Year program recognizes products newly released in the manufacturing industries.
Each year, a panel of Control Engineering and Plant Engineering editors and industry expert judges select the System Integrator of the Year Award winners in three categories.
Pipe fabrication and IIoT; 2017 Product of the Year finalists
The future of electrical safety; Four keys to RPM success; Picking the right weld fume option
A new approach to the Skills Gap; Community colleges may hold the key for manufacturing; 2017 Engineering Leaders Under 40
Control room technology innovation; Practical approaches to corrosion protection; Pipeline regulator revises quality programs
The cloud, mobility, and remote operations; SCADA and contextual mobility; Custom UPS empowering a secure pipeline
Infrastructure for natural gas expansion; Artificial lift methods; Disruptive technology and fugitive gas emissions
Power system design for high-performance buildings; mitigating arc flash hazards
VFDs improving motion control applications; Powering automation and IIoT wirelessly; Connecting the dots
Natural gas engines; New applications for fuel cells; Large engines become more efficient; Extending boiler life

Annual Salary Survey

Before the calendar turned, 2016 already had the makings of a pivotal year for manufacturing, and for the world.

There were the big events for the year, including the United States as Partner Country at Hannover Messe in April and the 2016 International Manufacturing Technology Show in Chicago in September. There's also the matter of the U.S. presidential elections in November, which promise to shape policy in manufacturing for years to come.

But the year started with global economic turmoil, as a slowdown in Chinese manufacturing triggered a worldwide stock hiccup that sent values plummeting. The continued plunge in world oil prices has resulted in a slowdown in exploration and, by extension, the manufacture of exploration equipment.

Read more: 2015 Salary Survey

Maintenance and reliability tips and best practices from the maintenance and reliability coaches at Allied Reliability Group.
The One Voice for Manufacturing blog reports on federal public policy issues impacting the manufacturing sector. One Voice is a joint effort by the National Tooling and Machining...
The Society for Maintenance and Reliability Professionals an organization devoted...
Join this ongoing discussion of machine guarding topics, including solutions assessments, regulatory compliance, gap analysis...
IMS Research, recently acquired by IHS Inc., is a leading independent supplier of market research and consultancy to the global electronics industry.
Maintenance is not optional in manufacturing. It’s a profit center, driving productivity and uptime while reducing overall repair costs.
The Lachance on CMMS blog is about current maintenance topics. Blogger Paul Lachance is president and chief technology officer for Smartware Group.
The maintenance journey has been a long, slow trek for most manufacturers and has gone from preventive maintenance to predictive maintenance.
This digital report explains how plant engineers and subject matter experts (SME) need support for time series data and its many challenges.
This digital report will explore several aspects of how IIoT will transform manufacturing in the coming years.
Maintenance Manager; California Oils Corp.
Associate, Electrical Engineering; Wood Harbinger
Control Systems Engineer; Robert Bosch Corp.
This course focuses on climate analysis, appropriateness of cooling system selection, and combining cooling systems.
This course will help identify and reveal electrical hazards and identify the solutions to implementing and maintaining a safe work environment.
This course explains how maintaining power and communication systems through emergency power-generation systems is critical.
click me