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// Remote access

Port 4334: NETCONF Call Home (SSH)

Port 4334 is assigned by IANA to netconf-ch-ssh (NETCONF Call Home (SSH)).

4334

How netconf-ch-ssh works

Remote access
terminal:4334netconf-ch-ssh terminal:4334netconf-ch-ssh

The client opens a session to port 4334: each command typed is sent to the server, which runs it and returns the output.

Transport
TCP
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 4334 dangerous?

We have no specific security note for port 4334. 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 4334

ServicePortTransportDescriptionReferenceUpdated
netconf-ch-ssh 4334 TCP NETCONF Call Home (SSH) RFC 8071 2016-01-12
-4334-Reserved--

// source: IANA service name and port number registry

03 Check it

Which program uses port 4334, and is it reachable?

Linux

sudo ss -ltnup 'sport = :4334'      # process listening on 4334
sudo lsof -nP -i :4334

macOS

sudo lsof -nP -i :4334

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 4334 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 4334
netstat -ano | findstr :4334

From another machine

nmap -p 4334 -sV <host>
nc -zv <host> 4334

Block it in the firewall

sudo ufw deny 4334/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 4334" -Direction Inbound -LocalPort 4334 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 4334 used for?

Port 4334 is assigned by IANA to netconf-ch-ssh (NETCONF Call Home (SSH)).

Is port 4334 TCP or UDP?

Port 4334 is registered for TCP.

Is it safe to open port 4334?

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 4334 is open?

On Linux run "ss -ltnup 'sport = :4334'", on macOS "lsof -nP -i :4334", and on Windows "netstat -ano | findstr :4334" to see the local process. From another machine, "nmap -p 4334 <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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