Port 4646DDoS Open Threat Signaling (DOTS) Signal Channel

DOTS signal channel traffic lets a client communicate with a service to request or coordinate DDoS mitigation.

transport: tcp · udp
in transit: encrypted
assignment: official
risk: 3/10
lookups: 0

also known as dots-signal, DOTS, DOTS signal channel

Technical Details

what runs on :4646

Port 4646 is the IANA-assigned DOTS signal channel port on both UDP and TCP. The protocol uses CoAP: over UDP it runs over DTLS, while the TCP transport uses CoAP over TLS. A DOTS client initiates a secured channel to a DOTS server to exchange signaling, including mitigation requests; the UDP form uses CoAP datagrams and the TCP form uses CoAP's TCP framing. The port is also used in the SRV service names _dots-signal._udp and _dots-signal._tcp for server discovery.

Security Information

exposure of :4646

risk score

3/ 10caution

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

security averages 3.1 across 376 ports — this one sits 0.1 below.

in transit

encrypted

payloads are protected on the wire

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

The signal channel is designed to use DTLS or TLS, with authentication and authorization needed to control which clients can request mitigation. It should normally be reachable only by intended DOTS clients, not exposed as an unauthenticated general-purpose service: misuse could trigger or alter mitigation actions and affect availability. Keep the implementation patched and restrict access to trusted peers.

Record

iana registry entry

port: :4646
service: DDoS Open Threat Signaling (DOTS) Signal Channel
transport: TCPUDP
encryption: tls / encrypted
assignment: iana registered
risk: 3/10caution
category: Security Network Services
usage: DOTS clients use this port to contact a DOTS server, typically operated by a network or DDoS-mitigation provider, and coordinate mitigation actions. It is a standards-based service rather than a common general-purpose listener, so it is not often seen open in broad internet scans.
lookups: 0rank 993
added: 2026-10-05
updated: 2026-10-05
references: IANA service name registry — port 4646
RFC 8973
RFC 9132

Something wrong?

This record is maintained by the engineers who use port 4646. 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 2026-10-05.

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risk mix of the 8 listed

caution100%

2 of 8 encrypted

Port :4646DDoS Open Threat Signaling (DOTS) Signal Channel

Technical Details

Security Information

Related Ports

Port 4646DDoS Open Threat Signaling (DOTS) Signal Channel