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// Other services

Port 953: BIND9 remote name daemon controller

Port 953 is assigned by IANA to rndc (BIND9 remote name daemon controller).

953

How rndc works

Other services
client:953rndcresponse client:953rndcresponse

The client sends a request to port 953 and the rndc service answers.

Transport
TCP
Exposure risk
not rated depends on the program listening
Encryption
Unknownnot stated by the registry
IANA status
Assigned1 registered service
Range
Well-known (0-1023)
Category
Other services
01 Security

Is port 953 dangerous?

We have no specific security note for port 953. Its risk depends on the program actually listening on it. General advice for other services services:

  • Close the port if nothing on the host needs it.
  • Identify the process that listens on it (commands below) before opening it in a firewall.
  • Expose a service only to the networks that use it.
02 Registry

IANA registry entries for port 953

ServicePortTransportDescriptionReferenceUpdated
rndc 953 TCP BIND9 remote name daemon controller - 2017-06-08
-953-Reserved--

// source: IANA service name and port number registry

03 Check it

Which program uses port 953, and is it reachable?

Linux

sudo ss -ltnup 'sport = :953'      # process listening on 953
sudo lsof -nP -i :953

macOS

sudo lsof -nP -i :953

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 953 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 953
netstat -ano | findstr :953

From another machine

nmap -p 953 -sV <host>
nc -zv <host> 953

Block it in the firewall

sudo ufw deny 953/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 953" -Direction Inbound -LocalPort 953 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 953 used for?

Port 953 is assigned by IANA to rndc (BIND9 remote name daemon controller).

Is port 953 TCP or UDP?

Port 953 is registered for TCP.

Is it safe to open port 953?

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. Close the port if nothing on the host needs it.

How do I check if port 953 is open?

On Linux run "ss -ltnup 'sport = :953'", on macOS "lsof -nP -i :953", and on Windows "netstat -ano | findstr :953" to see the local process. From another machine, "nmap -p 953 <host>" shows whether it is reachable.

05 Related
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