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// Remote access

Port 43000: Receiver Remote Control

Port 43000 is assigned by IANA to recvr-rc (Receiver Remote Control), recvr-rc-disc (Receiver Remote Control Discovery).

43000

How recvr-rc works

Remote access
terminal:43000recvr-rc terminal:43000recvr-rc

The client opens a session to port 43000: 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
Assigned2 registered services
Range
Registered (1024-49151)
Category
Remote access
01 Security

Is port 43000 dangerous?

We have no specific security note for port 43000. 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 43000

ServicePortTransportDescriptionReferenceUpdated
recvr-rc 43000 TCP Receiver Remote Control - 2012-12-20
recvr-rc-disc 43000 UDP Receiver Remote Control Discovery - 2012-12-20

// source: IANA service name and port number registry

03 Check it

Which program uses port 43000, and is it reachable?

Linux

sudo ss -ltnup 'sport = :43000'      # process listening on 43000
sudo lsof -nP -i :43000

macOS

sudo lsof -nP -i :43000

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 43000 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 43000
netstat -ano | findstr :43000

From another machine

nmap -p 43000 -sV <host>
sudo nmap -sU -p 43000 <host>
nc -zv <host> 43000

Block it in the firewall

sudo ufw deny 43000/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 43000" -Direction Inbound -LocalPort 43000 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 43000 used for?

Port 43000 is assigned by IANA to recvr-rc (Receiver Remote Control), recvr-rc-disc (Receiver Remote Control Discovery).

Is port 43000 TCP or UDP?

Port 43000 is registered for TCP and UDP.

Is it safe to open port 43000?

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 43000 is open?

On Linux run "ss -ltnup 'sport = :43000'", on macOS "lsof -nP -i :43000", and on Windows "netstat -ano | findstr :43000" to see the local process. From another machine, "nmap -p 43000 <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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