STUN, TURN & ICE for NAT Traversal


A setback to VoIP and Video telephony adoption has been the restriction NATs and firewalls pose to reliable call completion. NATs and firewalls play a very important role in securing and enhancing the usability of internal networks, however impose significant problems in setting up VoIP calls between end users.  IETF standards STUN, TURN and ICE were developed to address the NAT traversal problem.


STUN helps VoIP end-points to:

  1. discover whether they are behind a NAT/firewall, and if so,

  2. to determine the public IP address and type of the firewall. STUN then uses this information to assist in establishing peer-to-peer VoIP or video telephony calls.

While STUN is effective in addressing the NAT issue with most consumer NAT devices (routers), it doesn’t work effectively for many corporate networks. TURN, which stands for Traversal Using Relay NAT, addresses this by providing a fallback NAT traversal technique using a media relay server to facilitate media transport between end-points.

ICE is a framework that leverages both STUN and TURN to provide reliable VoIP or video call set-up and media transport, through a SIP offer/answer model for end-points to exchange multiple candidate IP addresses and ports (such as private addresses and TURN server addresses).

Eyeball Networks patented AnyFirewall Technology is at the core of several Eyeball Networks products that utilize the STUN, TURN and ICE standards, and our AnyFirewall Engine and AnyFirewall Server are the reference software for PacketCable 2.0 certification.

There are several important standards related to NAT traversal, and STUN, TURN, ICE implementations. Eyeball Networks technology supports and is compliant with the following standards:

RFC 5245 – ICE

RFC 5389 – STUN

RFC 5766 – TURN

RFC 5768 – ICE – SIP

RFC 6336 – ICE – IANA Registry

RFC 6544 – ICE – TCP

RFC 5928 – TURN Resolution Mechanism

RFC 6062 – TURN Extensions for TCP Allocations

RFC 6156 – Extension for IPv6

MS-STUN – Microsoft STUN extensions

MS-TURN – Microsoft TURN extensions

MS-ICE – Microsoft ICE extensions

MS-ICE2 – Microsoft ICE2 extensions

Other benefits to Eyeball Networks implementation of the STUN, TURN and ICE standards are:

  • Guaranteed 100% call completion

  • Peer-to-peer for services scalable to 50M + subscribers

  • No compromise in NAT/firewall security

  • Easy integration with existing VoIP products and services

  • Standards based for maximum interoperability

  • Massive scalability for carrier-class implementations

  • Media delivery in UDP networks

Eyeball Networks has several products that exploit the advantages of STUN, TURN, ICE to deliver reliable VoIP and video telephony services, including:

AnyFirewall EngineSTUN TURN ICE Library for
Guaranteed VoIP Connectivity

AFS_full_web90pxSTUN TURN Server Software for
Guaranteed VoIP Connectivity

AnyConnect-gatewaylEnterprise Border Session Controller (E-SBC)
for Network Inter-Connectivity