Port 2021Service Exec (servexec)

IANA registers 2021 for servexec, a legacy remote service execution service; widespread modern use is not established.

transport: tcp · udp
in transit: cleartext
assignment: official
risk: 7/10
lookups: 0

Technical Details

what runs on :2021

Service Exec (servexec) uses port :2021 over tcp and udp. We don't have a technical write-up for it yet.

find what's listening on :2021

this machine

# linux
sudo ss -tulpn 'sport = :2021'

# macos / bsd
sudo lsof -nP -i :2021

# windows (then: tasklist /FI "PID eq <pid>")
netstat -ano | findstr :2021

another host

nmap -sV -p T:2021 <host>
sudo nmap -sU -sV -p U:2021 <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 :2021

risk score

7/ 10risk

treat as sensitive. widely scanned and regularly exploited when reachable — restrict it to known sources.

remote access averages 4.0 across 246 ports — this one sits 3.0 above.

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

If a listener is providing remote service execution, exposing it could allow remote command execution and should be treated as high risk. The IANA assignment does not specify authentication or encryption, so do not assume the service is protected; avoid exposing an unidentified listener to the internet.

Record

iana registry entry

port: :2021
service: Service Exec (servexec)
transport: TCPUDP
encryption: cleartext
assignment: iana registered
risk: 7/10risk
category: Remote Access System
usage: The IANA registry assigns this port to servexec, described as remote service execution. I don't know of a widely deployed modern service that uses it, so a listener on 2021 should not be identified by port number alone.
lookups: 0rank 993
added: 2026-10-27
updated: 2026-10-27
references: IANA Service Name and Transport Protocol Port Number Registry

Something wrong?

This record is maintained by the engineers who use port 2021. 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 2026-10-27.

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

all 246 in remote access →

the 8 most looked-up other ports in remote access — 246 ports carry that label.

port	service	proto	category	risk	views
:8000	Intel Remote Desktop / Alternate HTTP Port	TCP	Web Services	safe	84.3k
:8888	D2GS Admin Console	TCP	Remote Access	caution	83.7k
:8881	Atlasz Secure Server	TCP	Web Services	caution	67.6k
:5938	TeamViewer	TCPUDP	Remote Access	caution	65.0k
:8291	Winbox MikroTik Admin	TCP	Security	caution	62.9k
:8008	IBM HTTP Server Admin	TCP	Web Services	caution	58.3k
:135	Microsoft EPMAP	TCPUDP	Security	caution	51.9k
:23	Telnet	TCP	Remote Access	caution	34.8k

risk mix of the 8 listed

safe13%
caution88%

0 of 8 encrypted

Port :2021Service Exec (servexec)

Technical Details

Security Information

Related Ports

Port 2021Service Exec (servexec)