Skip to main content

SFS Relay Server


SFS Relay Server (STUN / TURN)​

Q1. What is an SFS Relay Server?​

SFS Relay Server (Safe and Fast Streaming Relay Server) is a relay server built into the SHIELD Edge Link Outbound server, which safely delivers browser screen and data streaming between internal users and external web services in a remote browser (RBI) environment.


Q2. Why are STUN / TURN protocols necessary?​

RBI (Remote Browser Isolation) uses WebRTC technology to stream the remote browser screen. In this process, STUN/TURN is used for P2P connections/relays between the user PC, Edge server, and external services.

  • STUN (Session Traversal Utilities for NAT)

    • A protocol that helps clients check their public IP and port.

    • Finds the direct connection path in a NAT (Private Network ↔ Public Network) environment.

  • TURN (Traversal Using Relays around NAT)

    • If direct P2P connection is not possible, relay through a Relay server.

    • Ensure that screen data is reliably delivered to users in the RBI environment.

--> In other words, STUN attempts a direct connection, while TURN acts as a relay in case of failure.


  • Request for internal users to access external websites

  • Edge Link Outbound → Running SFS Relay Server

  • Attempt direct connection if possible through the STUN server.

  • If it is not possible, the TURN server relays the remote browser screen to the user.


Q4. What are the benefits of using the SFS Relay Server?​

  • Stability Guarantee: Seamless access even in firewall, NAT, and proxy environments

  • Enhanced Security: All screens are delivered isolated through the RBI server, blocking the influx of malware.

  • Providing Flexibility: Offering the Same Access Experience Regardless of User Environment