For two decades the corporate VPN was the default way to reach internal systems. It worked when apps lived in a data centre and most staff worked from an office.
Hybrid work and cloud apps broke that model. Users connect from anywhere, apps span many clouds, and the network perimeter no longer marks the boundary of trust. That shift drives Zero Trust, delivered through SASE and SSE.
Why the VPN model struggles
A VPN drops a device onto the corporate network and grants broad access once connected. That implicit trust is the problem: a compromised device or credential often inherits wide lateral movement.
VPNs also backhaul traffic through central concentrators, adding latency for users just trying to reach a cloud app.
Zero Trust in one sentence: never trust, always verify — every request judged on identity, device posture, and context, with least privilege.
SASE and SSE: the delivery model
Secure Access Service Edge converges networking and security into one cloud-delivered service, applying policy close to the user. Security Service Edge is its security-focused subset — the same controls without the wide-area networking.
For teams tackling secure access first, SSE is the practical start, with three core services doing the heavy lifting.
- ZTNA — brokers access to individual private apps by identity and device posture, never the underlying network.
- SWG — inspects and filters outbound web traffic, blocking malicious sites and command-and-control.
- CASB — gives visibility and control over sanctioned and unsanctioned SaaS, catching risky sharing and shadow IT.
How the pieces work together
They work best as one policy plane, not three products. A request is evaluated once against identity and device signals, then the right control applies — ZTNA, SWG, or CASB.
Because policy sits at a cloud edge near the user, traffic no longer backhauls through a VPN concentrator, usually improving performance while tightening security.
Migrating without disruption
This is a phased journey, not a flag-day cutover. A common sequence: publish a few private apps through ZTNA for a pilot group, run it alongside the VPN, then migrate more apps and users.
Layer in SWG and CASB as confidence grows. Strong identity — MFA and device posture — is the prerequisite the whole model rests on.
Takeaway: you do not have to rip out the VPN overnight. Start with ZTNA for your most sensitive apps, insist on solid identity, and expand in stages toward a converged SSE.