Port 6634MPLS Performance Measurement (out-of-band response)

UDP port 6634 is assigned for out-of-band responses to MPLS performance measurements.

transport: udp
in transit: cleartext
assignment: official
risk: 1/10
lookups: 0

also known as mpls-pm

Technical Details

what runs on :6634

MPLS Performance Measurement (out-of-band response) is registered on port :6634 over udp to Cisco Systems 2, assigned February 2014. We don't have a technical write-up for it beyond the IANA registry entry.

In nmap's internet-wide scan data this port is never observed open, so if it's open on your network it's more likely a custom or misconfigured service than the registered one.

find what's listening on :6634

this machine

# linux
sudo ss -ulpn 'sport = :6634'

# macos / bsd
sudo lsof -nP -i :6634

# windows (then: tasklist /FI "PID eq <pid>")
netstat -ano | findstr :6634

another host

sudo nmap -sU -sV -p U:6634 <host>

run it? the handshake, the implementations you meet in the wild and the flags that matter come from the engineers who do.

add technical details

Security Information

exposure of :6634

risk score

1/ 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 1,734 ports — this one sits 1.6 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

no security notes recorded for :6634 yet

known exploits, hardening advice, what a compromise looks like — suggest an edit if you know its exposure.

Record

iana registry entry

port: :6634
service: MPLS Performance Measurement (out-of-band response)
transport: UDP
encryption: cleartext
assignment: iana registered
risk: 1/10safe
category: Network Services
usage: IANA assigns UDP 6634 to out-of-band responses for MPLS Performance Measurement. The assignment is registered to Cisco Systems; broader deployment or product details are not established here.
lookups: 0rank 993
added: 2026-10-11
updated: 2026-10-11
references: IANA service name registry — port 6634

Something wrong?

This record is maintained by the engineers who use port 6634. 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 2026-10-11.

01edit any field on a page of its own
02a model checks it for accuracy and spam
03clean and confident goes live immediately

edit this record →back to the registry

Related Ports

all 1,734 in network services →

the 8 most looked-up other ports in network services — 1,734 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 :6634MPLS Performance Measurement (out-of-band response)

Technical Details

Security Information

Related Ports

Port 6634MPLS Performance Measurement (out-of-band response)