Port 5351Port Control Protocol

PCP lets devices request and manage port mappings on NAT gateways and firewalls, typically from a trusted local network.

inNetwork Services

transport: udp
in transit: cleartext
assignment: official
risk: 7/10
lookups: 0

also known as pcp

1 other service is registered on port 5351. compare all 2 →

Technical Details

what runs on :5351

PCP uses UDP port 5351. In version 2, clients send requests such as MAP to create or renew a mapping, PEER to manage a mapping for a peer, or ANNOUNCE to discover server capabilities; the server returns a UDP response with a result code and, for mapping requests, the assigned external address and port. Requests include a lifetime and nonce, and can describe IPv4 or IPv6 addresses. PCP is a control protocol for a NAT or firewall, not an application data protocol; it is commonly used on the client-facing side of a gateway.

Security Information

exposure of :5351

risk score

7/ 10risk

treat as sensitive. widely scanned and regularly exploited when reachable — restrict it to known sources.

network services averages 2.6 across 1,637 ports — this one sits 4.4 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

udp

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

security overview

PCP is not encrypted and does not provide authentication by default. A PCP server should restrict requests to trusted interfaces and apply authorization and source-address checks; if reachable from an untrusted network, accepted requests could create or alter inbound mappings and expose internal services. It is generally intended for a trusted local network, not direct exposure to the internet.

Record

iana registry entry

port: :5351
service: Port Control Protocol
transport: UDP
encryption: cleartext
assignment: iana registered
risk: 7/10risk
category: Network Services
usage: Port Control Protocol (PCP) is used by clients on a private network to ask a NAT gateway or firewall to create or renew mappings for inbound traffic. Engineers are most likely to encounter it on a home or enterprise gateway listening on the LAN side, rather than as a service intended for the public internet.
lookups: 0rank 993
added: 2026-10-07
updated: 2026-10-07
references: IANA service name registry — port 5351
RFC 6887

Something wrong?

This record is maintained by the engineers who use port 5351. 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 2026-10-07.

01edit any field on a page of its own
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edit this record →back to the registry

Related Ports

all 1,637 in network services →

the 8 most looked-up other ports in network services — 1,637 ports carry that label.

port	service	proto	category	risk	views
: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 :5351Port Control Protocol

Technical Details

Security Information

Related Ports

Port 5351Port Control Protocol