STUN NAT Traversal Stack

Softil NAT Traversal Toolkit is a STUN (Simple Traversal Underneath NAT) developer solution for STUN Clients and Servers that complies with IETF Standard RFC 5389. The Toolkit enables support for both existing STUN servers, as well as those under development, and serves as a foundation for ICE (Interactive Connectivity Establishment), which is based on the updated STUN standard.

Key highlights

  • Compliancy to RFC 5389

    Enables development of STUN clients and servers compliant with current STUN servers and ready for future generations of STUN, which are mandatory for ICE.

  • Part of the Softil protocol stack family

    For seamless integration with all Softil’s protocol stacks, including SIP, MEGACO, DIAMETER, RTSP, and RTP.

The ICE NAT Traversal Toolkit is used to develop:

  • NAT-aware VoIP clients
  • STUN servers
  • ICE-ready network elements
  • Terminals
  • Gateways

The NAT Traversal Challenges

With the growing awareness of the advantages of voice and video telephony over the Internet, the need for viable standard-based solutions to traverse NAT are felt by enterprise and home users alike. NAT traversal solutions are necessary to allow transparent communication with anyone, anywhere in the world, while maintaining security and privacy.

The STUN protocol was developed to solve certain NAT shortcomings. While providing many benefits, NATs can break many existing IP applications, making it difficult to deploy new ones.


The user application is built on top of one or more Signaling Toolkits, and is plugged on top of the STUN NAT Traversal stack. The STUN NAT Traversal stack enables STUN negotiation and uses signaling and RTP stacks for the actual call/dialogue.


The NAT Traversal stack is part of Softil’s SIP Developer Suite, which includes SIP-related toolkits, add-ons, and products that provide all the capabilities a SIP network-element developer needs. The Softil NAT Traversal stack works either in conjunction with other Softil stacks or as a standalone implementation.

The ICE NAT Traversal Toolkit comes with

  • Full source code
  • Complete source code sample applications
  • Full documentation, programmer’s guide and reference guide
  • Porting guide (for unsupported operating systems)
  • Training
  • Version upgrades
  • Professional customer support
  • Professional customer support
  • Turnkey solutions (upon request)
  • Porting services (upon request)


STUN NAT Traversal Toolkit Interoperability

All Softil products and solutions take into account interoperability issues between disparate networks, protocols and devices. The STUN NAT Traversal stack has been thoroughly tested for full interoperability.

As a significant contributor in the IETF related working groups (BEHAVE, MMUSIC), Softil contributes and follows closely STUN standardization. This is very important in ensuring interoperability with other STUN implementations and the ability to integrate NAT traversal solutions with different protocols, such as SIP, RTSP, MEGACO and others in different network topologies.

The STUN NAT Traversal stack is based on Softil’s Common Core, an operating system abstraction layer specifically optimized for communication protocols and embedded platforms. This ensures easy portability of developed products between platforms and operating systems, including those not directly supported by Softil.

Softil STUN NAT Traversal Toolkit Data Sheet
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