Port 204AppleTalk Echo

Legacy AppleTalk diagnostic service that tests reachability by returning echo requests.

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

also known as at-echo, AEP, AppleTalk Echo Protocol

Technical Details

what runs on :204

AppleTalk Echo Protocol (AEP) uses a simple request/reply exchange in which the responder returns an echo request, generally preserving its payload. Classic AEP operates within AppleTalk's Datagram Delivery Protocol (DDP), commonly associated with the AppleTalk echo socket; implementations exposing it through IP may map the service to TCP or UDP port 204, with stream framing dependent on the implementation. The protocol provides no encryption or application-level authentication.

Security Information

exposure of :204

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 3.3 across 830 ports — this one sits 2.3 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

tcp · udp

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

security overview

This is an obsolete diagnostic service and should not normally be exposed to the public Internet. A UDP implementation can potentially be used for reflection or bandwidth abuse, while any responder may disclose reachability and returned diagnostic data; its rarity makes it a low-priority target compared with contemporary services.

Record

iana registry entry

port: :204
service: AppleTalk Echo
transport: TCPUDP
encryption: cleartext
assignment: iana registered
risk: 1/10safe
category: Network Services System
usage: AppleTalk Echo is a legacy reachability and diagnostic service found on older Apple systems, AppleTalk hosts, and gateways. It is rarely encountered on modern networks; IANA lists the assignment for both TCP and UDP port 204.
lookups: 0rank 994
added: 2026-08-29
updated: 2026-08-29
references: IANA service name registry — port 204

Something wrong?

This record is maintained by the engineers who use port 204. 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 2026-08-29.

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edit this record →back to the registry

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risk mix of the 8 listed

caution100%

0 of 8 encrypted

Port :204AppleTalk Echo

Technical Details

Security Information

Related Ports

Port 204AppleTalk Echo