Port 428OCS-CMU

Historic OCS-CMU service assignment on TCP/UDP 428; no current protocol or registered owner is documented.

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

Technical Details

what runs on :428

OCS-CMU is registered on port :428 over tcp and 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 found open rarely. What's listening is often not the registered service, so check before you assume.

find what's listening on :428

this machine

# linux
sudo ss -tulpn 'sport = :428'

# macos / bsd
sudo lsof -nP -i :428

# windows (then: tasklist /FI "PID eq <pid>")
netstat -ano | findstr :428

another host

nmap -sV -p T:428 <host>
sudo nmap -sU -sV -p U:428 <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 :428

risk score

1/ 10safe

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

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

tcp · udp

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

security overview

no security notes recorded for :428 yet

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

Record

iana registry entry

port: :428
service: OCS-CMU
transport: TCPUDP
encryption: cleartext
assignment: iana registered
risk: 1/10safe
category: uncategorised
usage: TCP and UDP port 428 is assigned to the historic OCS_CMU service, which is an alias for "ocs-cmu". IANA records no registered owner, and the assignment is not usable with many common service-discovery mechanisms.
lookups: 0rank 993
added: 2026-09-07
updated: 2026-09-07
references: IANA service name registry — port 428

Something wrong?

This record is maintained by the engineers who use port 428. 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 2026-09-07.

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

browse categories →

ports registered around :428, by lookups.

port	service	proto	category	risk	views
:443	HTTPS	TCPtls	Web Services	caution	65.9k
:445	Microsoft-DS / SMB	TCP	File Transfer	caution	22.3k
:475	tcpnethaspsrv	TCP	Security	caution	20.7k
:427	Service Location Protocol	TCPUDP	Network Services	caution	14.6k
:384	Remote Server System	TCPUDP	Remote Access	caution	11.5k
:383	HP Data Alarm Manager	TCPUDP	Network Services	caution	11.1k
:369	RPC2 Port Mapper	TCPUDP	Network Services	caution	11.1k
:464	Kerberos Password Change	TCPUDP	Security	safe	10.6k

risk mix of the 8 listed

safe13%
caution88%

1 of 8 encrypted

Port :428OCS-CMU

Technical Details

Security Information

Related Ports

Port 428OCS-CMU