Port 20999At Hand MMP

TCP and UDP port 20999 is assigned to At Hand MMP, a service registered to Stepan Riha.

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

Technical Details

what runs on :20999

At Hand MMP is registered on port :20999 over tcp and udp to Stepan Riha. 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 never observed open, so if it's open on your network it's more likely a custom or misconfigured service than the registered one.

find what's listening on :20999

this machine

# linux
sudo ss -tulpn 'sport = :20999'

# macos / bsd
sudo lsof -nP -i :20999

# windows (then: tasklist /FI "PID eq <pid>")
netstat -ano | findstr :20999

another host

nmap -sV -p T:20999 <host>
sudo nmap -sU -sV -p U:20999 <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 :20999

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 :20999 yet

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

Record

iana registry entry

port: :20999
service: At Hand MMP
transport: TCPUDP
encryption: cleartext
assignment: iana registered
risk: 1/10safe
category: uncategorised
usage: The IANA registry identifies TCP and UDP port 20999 as At Hand MMP and lists Stepan Riha as the registrant. No commonly deployed implementation or characteristic network behavior is established; the port has not appeared open in nmap's scan data.
lookups: 0rank 993
added: 2026-10-18
updated: 2026-10-18
references: IANA service name registry — port 20999

Something wrong?

This record is maintained by the engineers who use port 20999. 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 2026-10-18.

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 :20999, by lookups.

port	service	proto	category	risk	views
:21022	AMLFilter HTTPS	TCPtls	Web Services	caution	22.0k
:21012	AMLFilter HTTPS	TCPtls	Web Services	caution	21.7k
:21021	AMLFilter HTTP	TCP	Web Services	caution	20.6k
:21011	AMLFilter HTTP	TCP	Web Services	caution	20.2k
:21001	AMLFilter Admin	TCP	Security	caution	19.2k
:21000	IRTrans Control	TCPUDP	IoT	risk	0
:21010	Notezilla LAN Server	TCP	Network Services	safe	0

risk mix of the 7 listed

safe14%
caution71%
risk14%

2 of 7 encrypted

Port :20999At Hand MMP

Technical Details

Security Information

Related Ports

Port 20999At Hand MMP