Port 3478STUN / TURN

STUN and TURN commonly use port 3478 for NAT discovery and relaying; the IANA handle specifically denotes STUN behavior discovery over TCP.

inNetwork Services Voice and Chat

transport: tcp · udp
in transit: cleartext
assignment: official
risk: 4/10
lookups: 0

also known as stun-behavior, RFC 5780

2 other services are registered on port 3478. compare all 3 →

Technical Details

what runs on :3478

STUN and TURN commonly listen on UDP 3478 and may also accept TCP there; the IANA service description is specifically “STUN Behavior Discovery over TCP.” STUN messages have a 20-byte header with a magic cookie and transaction ID, and use message types and attributes for requests and responses. RFC 5780 behavior discovery uses attributes such as OTHER-ADDRESS and RESPONSE-ORIGIN to test NAT mapping and filtering behavior, and requires a suitably configured server with alternate addresses or ports. TURN uses STUN framing for allocation, permission, and channel operations, then relays client traffic. TLS is available but is not the default on 3478; deployments commonly use 5349 for STUN/TURN over TLS.

Security Information

exposure of :3478

risk score

4/ 10caution

worth attention. how exposed you are depends on configuration — don't leave it reachable from the internet without a reason.

network services averages 2.7 across 1,400 ports — this one sits 1.3 above.

in transit

cleartext

credentials and payloads are readable by anyone on path

assignment

official

registered with iana for this service — scanners fingerprint it by number

reachable over

tcp · udp

udp is connectionless — source addresses are trivially spoofed and it is a reflection favourite

security overview

A public STUN listener is normal when providing connectivity services, but it can reveal mapped public addresses and should be monitored and rate-limited. TURN should require authentication and relay restrictions: an unauthenticated or misconfigured open relay can be abused to carry unwanted traffic and consume bandwidth. Traffic on 3478 is not encrypted by default, so use TLS where transport confidentiality is needed.

Record

iana registry entry

port: :3478
service: STUN / TURN
transport: TCPUDP
encryption: cleartext
assignment: iana registered
risk: 4/10caution
category: Network Services Voice and Chat
usage: Port 3478 is widely used by STUN servers for NAT address discovery and by TURN servers to relay traffic when direct peer connections fail, including in WebRTC and VoIP systems. The IANA name `stun-behavior` refers specifically to STUN NAT behavior discovery, not the full range of common STUN/TURN use on this port.
lookups: 0rank 993
added: 2026-09-29
updated: 2026-09-29
references: IANA service name registry — port 3478
RFC 5780

Something wrong?

This record is maintained by the engineers who use port 3478. Every field on it is editable — change what's wrong, say how you know, and a reviewer publishes it, usually within a minute. Last touched 2026-09-29.

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all 1,400 in network services →

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:3128	Tatsoft Default HTTP Proxy	TCP	Web Services	caution	46.8k

risk mix of the 8 listed

caution100%

0 of 8 encrypted

Port :3478STUN / TURN

Technical Details

Security Information

Related Ports

Port 3478STUN / TURN