Port 5191America Online 1

America Online 1 traffic assigned to TCP and UDP port 5191.

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

also known as aol-1

Technical Details

what runs on :5191

no technical write-up for :5191 yet

the handshake, the implementations you meet in the wild, the flags that matter. we have the registry entry — the detail comes from the engineers who run it.

add technical details

Security Information

exposure of :5191

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 :5191 yet

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

Record

iana registry entry

port: :5191
service: America Online 1
transport: TCPUDP
encryption: cleartext
assignment: iana registered
risk: 1/10safe
category: uncategorised
usage: Port 5191 is assigned to the AmericaOnline1 service. The registration is held by Bruce Mackey; publicly documented usage and deployment details are not available.
lookups: 0rank 994
added: 2026-08-26
updated: 2026-08-26
references: IANA service name registry — port 5191

Something wrong?

This record is maintained by the engineers who use port 5191. 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 2026-08-26.

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 :5191, by lookups.

port	service	proto	category	risk	views
:5247	CAPWAP Data	UDP	Network Services	caution	17.9k
:5223	XMPP over SSL	TCPtls	Security	caution	16.3k
:5246	CAPWAP Control	UDP	Network Services	caution	13.2k
:5222	XMPP Client Connection	TCP	Network Services	caution	11.7k
:5190	ICQ & AIM	TCP	Voice and Chat	caution	8.5k
:5151	ESRI SDE Remote Start	UDP	Databases	caution	6.1k
:5176	ConsoleWorks UI	TCP	Security	caution	6.0k
:5151	ESRI SDE	TCP	Databases	caution	5.8k

risk mix of the 8 listed

caution100%

1 of 8 encrypted

Port :5191America Online 1

Technical Details

Security Information

Related Ports

Port 5191America Online 1