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// Remote access

Port 2122: CauPC Remote Control

Port 2122 is assigned by IANA to caupc-remote (CauPC Remote Control).

2122

How caupc-remote works

Remote access
terminal:2122caupc-remote terminal:2122caupc-remote

The client opens a session to port 2122: each command typed is sent to the server, which runs it and returns the output.

Transport
TCP · UDP
Exposure risk
not rated depends on the program listening
Encryption
Unknownnot stated by the registry
IANA status
Assigned1 registered service
Range
Registered (1024-49151)
Category
Remote access
01 Security

Is port 2122 dangerous?

We have no specific security note for port 2122. Its risk depends on the program actually listening on it. General advice for remote access services:

  • Do not expose remote administration directly: use a VPN or a zero-trust access proxy.
  • Require MFA or key-based authentication and lock out brute-force attempts.
  • Log every login and alert on new source addresses.
02 Registry

IANA registry entries for port 2122

ServicePortTransportDescriptionReferenceUpdated
caupc-remote 2122 TCP, UDP CauPC Remote Control - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 2122, and is it reachable?

Linux

sudo ss -ltnup 'sport = :2122'      # process listening on 2122
sudo lsof -nP -i :2122

macOS

sudo lsof -nP -i :2122

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 2122 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 2122
netstat -ano | findstr :2122

From another machine

nmap -p 2122 -sV <host>
sudo nmap -sU -p 2122 <host>
nc -zv <host> 2122

Block it in the firewall

sudo ufw deny 2122/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 2122" -Direction Inbound -LocalPort 2122 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 2122 used for?

Port 2122 is assigned by IANA to caupc-remote (CauPC Remote Control).

Is port 2122 TCP or UDP?

Port 2122 is registered for TCP and UDP.

Is it safe to open port 2122?

It depends on the program that listens on it. Open it only for a service you know and only to the networks that need it. Do not expose remote administration directly: use a VPN or a zero-trust access proxy.

How do I check if port 2122 is open?

On Linux run "ss -ltnup 'sport = :2122'", on macOS "lsof -nP -i :2122", and on Windows "netstat -ano | findstr :2122" to see the local process. From another machine, "nmap -p 2122 <host>" shows whether it is reachable.

05 Related
:22 SSH tcp · udp · sctp · moderate risk :3389 RDP tcp · udp · critical risk :23 Telnet tcp · udp · critical risk :5900 VNC tcp · udp · critical risk :5985 WinRM (HTTP) tcp · udp · high risk :5986 WinRM (HTTPS) tcp · udp · high risk :10000 Webmin tcp · udp · high risk :89 SU/MIT Telnet Gateway tcp · udp

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