Port 243Survey Measurement

TCP and UDP port 243 is assigned to Survey Measurement, a service registered to Dave Clark.

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

also known as sur-meas

Technical Details

what runs on :243

Survey Measurement is registered on port :243 over tcp and udp to Dave Clark. 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 :243

this machine

# linux
sudo ss -tulpn 'sport = :243'

# macos / bsd
sudo lsof -nP -i :243

# windows (then: tasklist /FI "PID eq <pid>")
netstat -ano | findstr :243

another host

nmap -sV -p T:243 <host>
sudo nmap -sU -sV -p U:243 <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 :243

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 :243 yet

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

Record

iana registry entry

port: :243
service: Survey Measurement
transport: TCPUDP
encryption: cleartext
assignment: iana registered
risk: 1/10safe
category: uncategorised
usage: IANA assigns this port under the service name "sur-meas" for Survey Measurement and records Dave Clark as the registrant. No widely documented implementation or deployment pattern is established by the registry entry.
lookups: 0rank 993
added: 2026-08-28
updated: 2026-08-28
references: IANA service name registry — port 243

Something wrong?

This record is maintained by the engineers who use port 243. 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 2026-08-28.

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 :243, by lookups.

port	service	proto	category	risk	views
:201	AppleTalk Routing	TCPUDP	Network Services	caution	19.7k
:194	Internet Relay Chat	TCPUDP	Voice and Chat	caution	17.5k
:213	IPX	TCPUDP	Network Services	caution	13.9k
:264	Border Gateway Multicast Protocol	TCPUDP	Network Services	caution	12.2k
:179	Border Gateway Protocol	TCP	Network Services	caution	11.1k
:210	ANSI Z39.50	TCPUDP	Databases	caution	9.0k
:199	SMUX (SNMP Multiplexer)	TCPUDP	Network Services	caution	9.0k
:220	IMAP v3	TCPUDP	Email	caution	8.6k

risk mix of the 8 listed

caution100%

0 of 8 encrypted

Port :243Survey Measurement

Technical Details

Security Information

Related Ports

Port 243Survey Measurement