What is Software Defined Perimeter (SDP)?

What is Software Defined Perimeter (SDP)?
What is Software Defined Perimeter (SDP)?

The Software Defined Perimeter (SDP) is a security framework that builds a wall around your company's cloud network and limits user access to the resources hosted on the cloud based on their identity.

It establishes a security perimeter using software to hide your company's network infrastructure from outsiders and malicious users and enable authenticated and authorized user access to the network and its resources.

SDP is also referred to as the 'black cloud'—obscuring the network's systems by hiding them within the perimeter that is invisible to outsiders. Unlike other access-based control systems, an SDP creates a virtual boundary around the company systems at the network layer and not the application layer.

The benefits of SDP include enhanced security, better user experience, seamless scalability for remote cloud access, protection from third-party access, and robust Zero Trust Access.

Network Security Before Software Defined Perimeter (SDP)

Before SDPs, enterprises used firewalls to protect their network from outsiders, allowing those inside the network to go out of it and preventing outsiders from entering the network.

They did an adequate job of limiting hackers' visibility and preventing external threats from entering and exploiting the network.

However, these security solutions came with many vulnerabilities, such as

  • Devices users manage on their own, which leads to network vulnerability. While an IT administrator can employ security measures to protect the network and the device, an individual user may not effectively do that, leaving the entire network vulnerable.
  • High risks of phishing attacks. Before SDP, security solutions only required users to enter their credentials, username and password to log in to the network. Phishing attackers tricked users into entering these credentials on a fake website and collecting their information to enter your company network.

SDP eliminated all these risks by allowing IT admins to deploy network perimeter and authenticate the user's identity and device before granting access to the network.

Weaknesses of the Traditional Setup

Traditional security solutions, like VPNs, don't provide the control, visibility, and threat inspection required to secure your network. Some of the weaknesses that traditional setups brought with them include:

  • The lack of user access control and network segmentation is important to limit the user's access to the network.
  • The lack of network traffic visibility and unwanted traffic entering the network.
  • The lack of seamless scalability, increasing maintenance complexity and operational costs.
  • The lack of on-premise user security allows bad actors to move laterally within the network and exploit its resources.

Unlike SDP, traditional security solutions don't implement strict user authentication and authorisation, allowing every user to penetrate the network and increasing the risks of data breaches and malicious attacks.

What is the Purpose of SDP?

SDP serves a greater purpose in establishing secure network connections in today's remote working environment.

No longer do organisations operate fully from on-premise locations. Instead, the remote and hybrid working models are the new norm and will stay for a longer time—making the internet the new enterprise network. Hence, when employees try to connect to the company's network from remote locations with their personal devices via public internet—it leaves the network vulnerable and makes it easier for unauthorised and malicious users to access the network.

Thus, a hardware-defined perimeter for corporates doesn't ensure network security.

An SDP secures the connection between the two endpoints—remote employees and the company network through strict user and device authentication. It also distributes the network resources evenly, which are defined on an individual user basis, ensuring a simplified and centralised access control mechanism.

Moreover, SDP also lets you grant users access to the network through a least privilege basis, making it more difficult for hackers to move laterally within the network and exploit its resources. Thus, an SDP ensures that only authenticated and authorised users can access your network, ensuring greater security from malicious online breaches.

How Does SDP Work?

SDP work by allowing users to access the network only after:

  • Verifying their identity.
  • Assessing the device's state.

Thus, it focuses on securing the network applications, the user, and the connection between the two. Once it authenticates the user and device, it creates a secure individual network connection between the user's device and the network it tries to access. Instead of logging the authorised user to the entire network, the user is given access to a private network that no one else can enter or access, consisting of resources and services the user is approved to access.

Thus, an SDP works on these four key principles:

  • Doesn't grant excessive implicit trust to the users, and only after authentication and authorisation can users access the network resources they're permitted to use.
  • SDP cloaks the application and network infrastructure, not receiving or accepting inbound connection requests, eliminating cybersecurity attack risks.
  • It provides application segmentation instead of network segmentation, allowing you to control application access on a need-to-know and one-on-one basis. Native application segmentation gives more granular control access and makes managing network access a breeze.
  • SDP focuses on protecting user-to-application connections on the internet instead of only securing users' access to your company's network.

Thus, SDP eliminates network security risks and keeps hackers and online breaches away from your network.

Principle of SDP

The SDP work on the following principles:

  • They don't grant users access to the network before authentication and authorisation.
  • They authenticate both the user and the device, adding a security layer and preventing malicious hacking attempts.
  • They implement the least privilege access, allowing you to control the user's access to the network applications on a need-to-know basis.

Thus, an SDP gives your company network a much stronger security posture, preventing intruders from accessing the network and giving you more control over who can access what.

History of Software Defined Perimeter (SDP)

Software Defined Perimeter (SDP) was developed by Cloud Security Alliance (CSA), a non-profit that works on cloud-based security research and education. It is because of the motivating principle of controlling access to the network based on the user's identity. It was developed to keep malicious users and hackers away from the network and its sensitive resources and applications. SDP is a framework CSA evolved based on the work conducted at the Defense Information Systems Agency (DISA) under Global Information Grid (GIG) in 2007.

Over the years, many organisations and leading global network solutions started adopting SDP services, whose market size is anticipated to reach upto $13.8 billion by 2024 with a Compound Annual Growth Rate (CAGR) of 36.5%.

Software Defined Perimeter (SDP) Architecture

The two primary components of an SDP architecture are hosts and Controllers to authenticate users and devices before granting access to the network.

SDP Controllers decide how the hosts communicate within the network. An SDP host can either accept or initiate the communication. If it initiates the communication, it gets connected to the SDP Controller.

In an SDP architecture, devices that users use to access the network or its resources are referred to as clients.

Here's how all these components within an SDP architecture work together to secure your network:

  • The client initiates a communication request to the SDP Controller.
  • The Controller follows up to respond to the client's request with a list of the areas of services the client can access. Set predesigned policies to govern these resources clients can access.
  • The Controller determines if the client uses an appropriate gateway and then forwards all the required information about the access policy to the gateway.
  • The gateway then reaches out to the client running on endpoints, like laptops, computers, or desktops.
  • The client receives this information, processes it, and recognises the policies it must run along with the gateways it's required to connect.
  • The client then initiates an authentication process once it knows the gateways it requires to access the resources. This process is unique to every client and is based on the device information, such as the IP address, configuration, and geolocation information.
  • Once the Controller receives the information, it verifies if the client satisfies the authentication requirements and the client's security state. If this security state doesn't match the predetermined state of safety, the client is denied access to the network.
  • However, the client can securely connect to the gateway after successful authentication, allowing clients to access the resources they need directly.

How to Set up a Software Defined Perimeter (SDP)

Here are the steps to set up SDP for your organisation:

  1. You first must verify the user's identity to set up SDP using methods like Single Sign-on (SSA), MFA, and Security Assertion Markup Language (SAML).
  2. The next step is verifying the device's security before granting access and after the session expires. You can use various device endpoints for this verification, including its location, registry information, malware status, firewall status, antivirus settings, and hard drive encryption.

This verification is done based on predefined states and policies. If the device matches these policies, the device is granted access to the network.

  1. The last step is ensuring data protection, where SDP vendors play an important role. The SDP vendors take the additional step of setting up secure communication tunnels between devices and applications it accesses.

If it encrypts the data for the entire session, the user enjoys a private, encrypted, and secure connection without compromising sensitive details and information.

This verification and data encryption establishes the most secure connection between user devices and the network.

How Do SDPs Relate To Zero Trust Security?

SDP is an advanced way to implement Zero Trust Security, which believes in and follows the principle of trusting nothing and verifying everything. Hence, SDP aligns with the Zero Trust concepts and principles because of the verification processes.

An SDP assesses the device's state and only grants users access to the network after device and user authentication and authorisation.

Thus, you can consider SDP a more advanced form of the Zero Trust Security model. Like Zero Trust, SDP also considers anyone trying to access the network, whether user or device, as a threat and prevents unauthorised and malicious network access.

SDP and Zero Trust Network Access (ZTNA)

Zero Trust Network Access (ZTNA) is a common and popular network security framework based on the same principles as Software Defined Perimeter (SDP).

Both ZTNA and SDP have no internal network, and users can only access the network and its resources after user, identity and device verification.

Much like SDP, ZTNA minimises the risk of attacks by reducing the network's attack surface and lets you leverage features and services, like passwordless authentication, granular access policies and complete network visibility.

Thus, ZTNA very much works on the similar lines and principles of an SDP.

SDP vs VPN: What are the differences?

While VPNs and SDP require their users to connect to the network after identity verification, SDPs are much more secure and robust than VPNs. Here's how these two differ from one another.




Network access

VPN allows users to access the entire network and its resources as they follow a 'moat and castle' approach regarding network security. 

SDP doesn't allow users to access the entire network. Instead, it gives users their private connections to access specifically approved resources. 


VPNs don't effectively balance scalability and simplicity. Trying to scale the VPN network or add more users increases the management complexity and makes the network more vulnerable. 

SDPs are scalable, and you cna set them up wherever you want with a variety of infrastructure because they're software-based and not hardware-based. 

User access

With VPN, each user accesses the network through a single portal or tunnel. 

An SDP meets the requests and needs of an individual user, allowing them to access the network through a private, secure connection. 

Remote working 

VPNs don't efficiently meet the security needs of the modern remote working environment. 

If a user joins the network using public internet remotely, it opens the door for intruders to get into the network and exploit the resources. 

With BYOD policies and user and device authentication and verification in SDP, remote users can easily and securely access the network and its applications without hassle. 

SDP easily integrates with multi-cloud and hybrid environments, allowing for connection from any location, making it ideal for managing remote working teams. 

Granular access

In VPN, you cannot control which user can access which resources, as the network is open to everyone and all the resources are visible. 

SDP provides granular-level access control, making it easier to set access policies and restrict sensitive resources from users. 

How Does a User Gain Access Over an SDP?

Here are the steps through which the user gains access to an SDP:

  • User identity verification through a third-party identity provider or SSO and MFA solutions.
  • Device verification to check the device's safety and ensure it runs optimally and is up-to-date. It also checks the device's malware infections and other security inspections.
  • SDP Controller approval to connect the right devices and servers. After device and user authentication, it passes the user and device approval to the SDP Gateway.
  • Establishing a secure network connection between the user device and the network resources it needs to access by the SDP Gateway.
  • User access allows users to access the requested resources within an encrypted and secure network connection.

The Benefits of SDP for Organisations

Here are the most important benefits of SDP for an organisation's network security:

  • Multi-layer network: SDP enable encrypted traffic tunnels to create secure one-to-one connections between the device and the resources they want to access. These tunnels are enforced with solutions like SSO, MFA, 2FA, ad other security tools to minimise the network's attack surface.
  • No hardware limitations: perimeter-based network security solutions fight against basic attacks but fail to ensure maximum data security and advanced cybersecurity protection.
  • Supports remote working: SDP seamlessly deploys in any location as they're software-based, making them beneficial for remote working environments. SDP deployment enables simple, secure, and low-latency connections, allowing remote global employees to access network resources with ease and high security.

InstaSafe and SDP/ZTNA

AT InstaSafe, we provide Zero trust Network Access (ZTNA) and Zero Trust Application Access (ZTAA) that work on the principle of SDP and Zero Trust Security.

Here's how our Zero Trust products can help your organisation:

  • Minimises the network attack surface and application access to unauthorised users
  • Eliminates the risks of data breaches by cloaking the network and applications from outsiders, preventing lateral movement, and enforcing the least privilege access concept.
  • Supports hybrid and remote working by ensuring seamless scalability and allowing employees and users to access applications and resources securely from remote locations.
  • Ensures data security by making the data flow through secure ad encrypted end-to-end channels.
  • Enables complete risk assessment for each user request access for continuous risk and trust assessment, making it easier to detect malicious threats.
  • Reduces operational and management complexity by eliminating the VPN-based security stacks and ensuring rapid deployment and scalability with no complexities.

Check out InstaSafe ZTNA and ZTAA solutions to learn more. You can even book a free demo today!

SDP Use Cases

Here are the common SDP use cases amongst organisations and enterprises:

  • An excellent VPN alternative to overcome VPN drawbacks, including poor security, management complexity, poor scalability, and hampered user experience. SDP solves these VPN issues and provides secure and scalable remote network access to your company with an enhanced user experience.
  • Reduce third-party risks by removing the excessive implicit trust and restricting authorised users' access to the network's resources and applications.
  • Secure multi-cloud access, which organisations can use for cloud storage, development, and more. As SDP secures network connections based on predetermined policies, it can be used to secure muti-cloud access for users from remote locations.
  • Seamless M&A integration. Traditional mergers and acquisitions lead to organisations converging networks that result in overlapping IP addresses. SDP simplifies this process, ensuring a successful lM&A integration in less time and providing quick and high value to businesses.

Frequently Asked Questions (FAQs) on SDP

  1. What is an SDP?

Software Defined Perimeter (SDP) is a framework to cloak the network infrastructure from external users or the internet, preventing unauthorised users and outsiders. It authenticates and verifies both the user identity and their devices to grant access to specific network resources they require.

2.  What are the three core pillars of a software-defined perimeter?

The three most important and core SDP pillars are

  • Zero Trust: It applies Zero Trust's microsegmentation to apply for the least privilege access and reduce the network's attack surface.
  • Identity-centric: It verifies the user's identity and not the IP address to grant access to the network.
  • Cloud-based: It's designed to operate efficiently in cloud networks and environments to deliver a secure and scalable remote access solution.

3. What is the difference between software-defined perimeter and zero trust?

SDP is a solution that restricts network access and provides secure, customised, and manageable access to networked systems.

On the other hand, Zero Trust is a network security concept based on the belief that enterprises and organisations shouldn't trust anyone inside or outside the network perimeter. It eliminates unauthorised access and only grants granular access to authorised and verified users and devices.

4. What are the capabilities of software perimeter solutions?

Some critical SDP capabilities include:

  • Reducing the network's attack surface with the robust user and device authentication.
  • Enabling granular access control with easy and centralised management.
  • They're software and cloud-agnostic, ensuring easy and scalable deployment and enabling remote employees to access on-premise resources.
  • Providing microsegmentation to prevent the network from exposing by malicious means.
  • Addressing internal and external network security challenges that come with BYOD capabilities.

These capabilities allow SDP to ensure greater network security and secure remote access.

5. What is SDP in architecture?

SDP architecture includes

  • SDP Host that either initiates or accepts the communication request.
  • SDP Controller determines which hosts can communicate with each other and if the client uses the right gateway.

An SDP architecture simplifies your network's inbound stack by significantly reducing the reliance on DDoS protection, VPNs, firewall appliances, and global load balancing.

6. Is SDP a zero trust?

SDP isn't exactly Zero Trust, but it's an advanced form of Zero Trust that aligns with Zero Trust fundamental principles and verification concepts. It considers every user and device outside the network as a threat, only accepting authorised and authenticated users to access set and specific resources.

7. Who qualifies for SDP?

Every organisation and enterprise looking for a VPN alternative and secure remote access solution for employees and third-party users qualify to adopt SDP solutions and ensure network security.

8. What are the benefits of SDP for my organisation?

SDP offers excellent benefits to organisations, including

  • Enabling multi-layer network security.
  • Removing hardware limitations as it is a software and cloud-agnostic solution.
  • Supporting remote working environments.
  • Protecting the network from online breaches and malicious cybersecurity attacks.

9. Why is SDP relevant for modern enterprises?

Today's modern enterprises and organisations require a scalable and secure solution to meet remote access needs and growing demand.

SDP is easily deployable, enabling remote employees to access on-premise network resources and applications from any remote location and addressing the challenges of weak traditional security services, like VPNs.

10. What are some common use cases of SDP?

Some current and excellent use cases of SDP include

  • VPN alternatives.
  • Mergers and acquisition integration.
  • Securing multi-cloud access.
  • Reducing third-party risks.

Read more about SDP and Zero trust:

Secure your network perimeter and applications with our Zero Trust Security solutions. Check out our products and solutions to strengthen your organisation's security posture today.