Port 6511DCCP-UDP Encapsulation

UDP port 6511 carries encapsulated DCCP traffic to help DCCP connections traverse NATs.

transport: udp
in transit: cleartext
assignment: official
risk: 2/10
lookups: 0

also known as DCCP over UDP, RFC 6773

Technical Details

what runs on :6511

UDP port 6511 is the assigned destination port for DCCP-UDP encapsulation, specified in RFC 6773. The endpoint carries DCCP packets inside UDP datagrams, so the DCCP connection setup and transport behavior remain inside the encapsulated traffic while NATs can handle the outer UDP flow. DCCP provides connection-oriented transport with congestion control but does not provide reliable delivery of application data. This is not ordinary application data sent directly over UDP, and the encapsulation itself does not add encryption.

Security Information

exposure of :6511

risk score

2/ 10safe

routine exposure. this port is rarely the way in on its own — keep it patched and logged and move on.

network services averages 2.6 across 1,723 ports — this one sits 0.6 below.

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

udp

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

security overview

The encapsulation is not an authentication or encryption layer; applications needing confidentiality or peer authentication must provide those separately. Since the protocol is uncommon, an internet-facing listener should be exposed only when deliberately deployed, with its DCCP implementation kept current and access restricted where possible. Unexpected traffic may warrant investigation, but the port is not commonly observed open in internet-wide scans.

Record

iana registry entry

port: :6511
service: DCCP-UDP Encapsulation
transport: UDP
encryption: cleartext
assignment: iana registered
risk: 2/10safe
category: Network Services
usage: This is the IETF-defined UDP encapsulation for Datagram Congestion Control Protocol (DCCP), intended to let DCCP traffic cross NATs and UDP-oriented firewalls. It is a specialized protocol and is rarely encountered on ordinary networks; an open port usually means a DCCP application or endpoint has explicitly enabled the encapsulation.
lookups: 0rank 993
added: 2026-10-10
updated: 2026-10-10
references: IANA service name registry — port 6511
RFC 6773

Something wrong?

This record is maintained by the engineers who use port 6511. 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 2026-10-10.

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Related Ports

all 1,723 in network services →

the 8 most looked-up other ports in network services — 1,723 ports carry that label.

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:9080	Groove RPC	TCPUDP	Web Services	caution	70.8k
:6543	Jetnet	UDP	Network Services	caution	65.3k
:5938	TeamViewer	TCPUDP	Remote Access	caution	65.0k
:8291	Winbox MikroTik Admin	TCP	Security	caution	62.9k
:3233	WhiskerControl Protocol	TCPUDP	Network Services	caution	61.9k
:3268	Microsoft Global Catalog (GC)	TCPUDP	Security	caution	54.6k
:135	Microsoft EPMAP	TCPUDP	Security	caution	51.9k
:3128	Tatsoft Default HTTP Proxy	TCP	Web Services	caution	46.8k

risk mix of the 8 listed

caution100%

0 of 8 encrypted

Port :6511DCCP-UDP Encapsulation

Technical Details

Security Information

Related Ports

Port 6511DCCP-UDP Encapsulation