Port 205AppleTalk Unused

An unused AppleTalk-assigned port with no recorded registrant or expected application traffic.

also known as at-5

Technical Details

what runs on :205

AppleTalk Unused is registered on port :205 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 :205

this machine

# linux
sudo ss -tulpn 'sport = :205'

# macos / bsd
sudo lsof -nP -i :205

# windows (then: tasklist /FI "PID eq <pid>")
netstat -ano | findstr :205

another host

nmap -sV -p T:205 <host>
sudo nmap -sU -sV -p U:205 <host>

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

exposure of :205

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 :205 yet

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

ports registered around :205, by lookups.

port	service	proto	category	risk	views
:143	IMAP	TCPUDP	Email	caution	20.7k
: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
:156	SQL Service	TCPUDP	Databases	caution	11.2k
:179	Border Gateway Protocol	TCP	Network Services	caution	11.1k
:161	SNMP	UDP	Security	caution	10.8k

risk mix of the 8 listed

0 of 8 encrypted