Port 9903Multicast Ping Protocol

UDP port 9903 is assigned to the Multicast Ping Protocol, but no common public-facing listener is established.

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

Technical Details

what runs on :9903

Multicast Ping Protocol is registered on port :9903 over udp. 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 :9903

this machine

# linux
sudo ss -ulpn 'sport = :9903'

# macos / bsd
sudo lsof -nP -i :9903

# windows (then: tasklist /FI "PID eq <pid>")
netstat -ano | findstr :9903

another host

sudo nmap -sU -sV -p U:9903 <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 :9903

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 1,862 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 :9903 yet

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

Record

iana registry entry

port: :9903
service: Multicast Ping Protocol
transport: UDP
encryption: cleartext
assignment: iana registered
risk: 1/10safe
category: Network Services
usage: IANA assigns UDP/9903 to the Multicast Ping Protocol, but no registrant is recorded. It has not been observed open in nmap's internet-wide scan data.
lookups: 0rank 993
added: 2026-10-16
updated: 2026-10-16
references: IANA service name registry — port 9903
RFC 6450

Something wrong?

This record is maintained by the engineers who use port 9903. 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 2026-10-16.

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 1,862 in network services →

the 8 most looked-up other ports in network services — 1,862 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 :9903Multicast Ping Protocol

Technical Details

Security Information

Related Ports

Port 9903Multicast Ping Protocol