What is a Software-Defined Perimeter (SDP)?

The software-defined perimeter (SDP) is a network infrastructure that protects cloud-based and on-premise data centers using remote capabilities. The purpose of an SDP strategy is to employ software rather than hardware as the foundation for the network perimeter. The SDP was created by the Cloud Security Alliance in 2013 as a solution for secure networks that minimized the danger of data breaches.

Secure access to network-based services, applications, and systems in public and private clouds, as well as on-premises, is provided by SDP as it cloaks systems within the perimeter so others can’t see them, the SDP technique is frequently referred to as creating a “black cloud.”

SDP software is designed to provide the perimeter security architecture required for zero-trust applications and workload-centric network connectivity to medium and large businesses. SDP’s virtual border surrounding the network layer not only reduces the attack surface but also eliminates vendor pandemonium by enabling installation on any host without network reconfiguration or appliance lock-in.

SDN Security Model

Need of SDP:

Most companies previously relied on a perimeter-oriented approach to security. This security paradigm assumes that all risks come from outside the company and that anyone with access to the internal network is trustworthy. This security method inspects all incoming and outgoing data traffic and aims to keep attackers outside and the company’s important data inside by placing security solutions on the network perimeter. While this strategy was never fully effective, the advent of cloud computing and a remote workforce made it much less. 

Today, significant resources and employees of a company are placed outside of the traditional boundaries. As a result, organizations often need to give other parties access to their internal networks to allow sensitive data to flow outside the perimeter. The problem now is to ensure that these data transfers are secure and that they are directed to the appropriate recipients. This problem can be addressed using a software-defined perimeter approach. It drastically reduces the company’s hazard surface and exposure to cyber risk by restricting access to the internal network based on user identification.

Features of SDP:

1. Better User Experience
2. Enhanced Security
3. Zero trust access
4. Reduced Third-party access risk
5. Better scale for remote cloud access

SDP Architecture:

There are two components to a software-defined perimeter architecture:

1. SDP Host
2. SDP Controller

SDP Host

An SDP Host is a server that controls the flow of data between devices and apps. SDP Hosts are divided into two categories :

1. An Initiating Host connects with an SDP controller, providing information about devices attempting to join the network, requesting a list of Accepting Hosts and establishing a TLS connection with those hosts.
2. An Accepting Host link authorized devices to apps that have been requested. Only an SDP controller and the Initiating Hosts are connected to this sort of host.

SDP Controller

An identification system is used by an SDP controller to identify devices (public key infrastructure, fingerprints, geolocation, OpenID, Kerberos, Active Directory, etc.). It also grants Accepting Hosts access and enforces access regulations.

SDP Controller

SDP hosts can communicate with each other as determined by an SDP controller. An SDP host can either initiate or accept a connection. To identify which hosts they can connect to, and initiate SDP host connects with an SDP controller. Only approved messages and connections from an SDP controller are accepted by an accepting SDP host. 

Gateways are used in some SDP topologies to function as the accepting host between the two connected devices/users. All communications and users/devices are kept safe through encrypted connections – commonly a virtual private network (VPN) tunnel – between controllers, hosts, and gateways.

SDP Framework:

SDP technology creates a secure perimeter by isolating services from vulnerable networks using rules. The SDP of the CSA accomplishes three goals :

1. It offers a network that is air-gapped, provisioned, and on-demand.
2. It divides network resources into network perimeters that are defined.
3. Before connecting to an isolated service, it authenticates devices and users before approving the device/user combination. Unauthorized devices and users are unable to connect to isolated services thanks to the SDP framework.

Trusted devices receive a one-time temporary connection to the network infrastructure after authentication. Organizations can use software-defined management to simplify application security and user authentication activities.

SDP Workflow:

1. An Initiating Host transmits a multifactor token together with user credentials to an SDP controller after receiving it. These credentials contain information such as the kind of device, geolocation, biometric data (for mobile devices), and more.
2. An identity provider receives the authentication token and credentials from the SDP controller. This service provider generates, maintains, and manages the data required for the user and device identification. The provider returns access permissions to the SDP controller if identification is successful.
3. The SDP controller searches for an Accepting Host that can grant the user access to the resource they’ve requested. The IP address of that host is then sent to the initiating host.
4. The Initiating Host connects to the Accepting Host over an encrypted VPN connection.

Use cases of SDP:

Used as an alternative to VPN: SDP allows users to access applications faster and verify their identities with a single sign-on, keeping them happy and productive. Users who are permitted to use the application are the only ones who can connect to it. Users are never put on the network, and their IP addresses are never revealed.

Multi-cloud access with secured connection: For both developers and end-users, the direct-to-cloud strategy delivers a seamless user experience. Regardless of the application type, device, or location. SDP is very agile and scalable since it is software-based, whereas appliances cannot grow beyond their restricted capacity. SDP provides secure remote access on a “need to know” basis by granting access based on detailed rules.

Risk Reduction: IT administrators can use SDP to restrict third-party access to just permission apps. This essentially prevents users from moving laterally within the network. VPN gateways no longer require third-party partners to log in.

Broad Network Access Prevention: Individual entities are unable to access large network subnets or segments due to SDPs. As a result, devices can only connect to specified hosts and services that are allowed by policy. This minimizes the network’s attack surface. It also stops malicious software and individuals from checking for vulnerabilities.

SDPs Can Connect Anything: Software-Defined Security enables staff employees to connect to IT resources they need. It also removes the need for expensive mounting hardware and time-consuming administration.

SDP vs VPN:

SDPs may also be less difficult to manage than VPNs, particularly if internal users require many levels of access. VPNs can be used by SDPs to provide secure network connections between user devices and the servers they need to visit. SDPs, on the other hand, isn’t the same thing as VPNs. SDPs are more secure in certain aspects than VPNs since they do not share network connections and allow all connected users to access the full network. SDPs may be easier to manage than VPNs, particularly if internal users require many levels of access. VPNs are used to manage several tiers of network access necessitates numerous VPN deployments.

The granularity of SDPs, on the other hand, is much greater. There is no VPN that everyone connects to using the same resources. Instead, each user has their own network connection. It’s almost like everyone has their own personal virtual private network (VPN). Furthermore, SDPs check both devices and users, making it significantly more difficult for an attacker to obtain access to the system using stolen credentials alone.

Advantages of SDP:

1. An SDP controller must identify any device or user before it can be trusted. Users and resources have a dynamic and encrypted relationship.
2. Users are only connected to a resource by an SDP controller if they have the appropriate access permissions. Access might be restricted for a certain position, a group of users, or a single user.
3. Any information, including DNS server addresses, maybe hidden from outsiders using an SDP. Users who have been identified can only connect to the resources to which they have been granted access; all other resources are concealed from them.
4. An SDP is made up of components that are based on industry standards, such as mutual TLS and VPNs. It allows for simple integration with other common security systems.
5. Data transfers are encrypted with TLS, SAML, or X.509.
6. An SDP obfuscates business resources and inhibits wide network access. Hackers find it difficult to attack something they don’t understand.

Disadvantages of SDP:

1. Despite compatibility for a wide range of current devices, connecting outdated routers or vendor-specific devices to SDP software may be difficult.
2. An SDP obfuscates business resources and inhibits wide network access. Hackers find it difficult to attack something they don’t understand.
3. Controllers play a critical function in an SDP design because they connect devices to protected resources. It’s difficult to connect to resources if controllers aren’t available.
4. SDPs are not the same as typical network security measures. Because you’ll need to modify all devices and apps, implementing an SDP solution might create network and infrastructure interruptions in large companies.