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// Network services

Port 8953: unbound dns nameserver control

Port 8953 is assigned by IANA to ub-dns-control (unbound dns nameserver control).

8953

How ub-dns-control works

Network services
client:8953ub-dns-controlresponse client:8953ub-dns-controlresponse

The client sends a request to port 8953 and the ub-dns-control 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
Registered (1024-49151)
Category
Network services
01 Security

Is port 8953 dangerous?

We have no specific security note for port 8953. Its risk depends on the program actually listening on it. General advice for network services services:

  • Answer only the networks that need the service (no open resolvers, relays or reflectors).
  • UDP services can be abused for DDoS amplification: rate-limit or block them at the edge.
  • Disable legacy test services that have no use in production.
02 Registry

IANA registry entries for port 8953

ServicePortTransportDescriptionReferenceUpdated
ub-dns-control 8953 TCP unbound dns nameserver control - 2011-07-11
-8953-Reserved--

// source: IANA service name and port number registry

03 Check it

Which program uses port 8953, and is it reachable?

Linux

sudo ss -ltnup 'sport = :8953'      # process listening on 8953
sudo lsof -nP -i :8953

macOS

sudo lsof -nP -i :8953

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 8953 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 8953
netstat -ano | findstr :8953

From another machine

nmap -p 8953 -sV <host>
nc -zv <host> 8953

Block it in the firewall

sudo ufw deny 8953/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 8953" -Direction Inbound -LocalPort 8953 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 8953 used for?

Port 8953 is assigned by IANA to ub-dns-control (unbound dns nameserver control).

Is port 8953 TCP or UDP?

Port 8953 is registered for TCP.

Is it safe to open port 8953?

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. Answer only the networks that need the service (no open resolvers, relays or reflectors).

How do I check if port 8953 is open?

On Linux run "ss -ltnup 'sport = :8953'", on macOS "lsof -nP -i :8953", and on Windows "netstat -ano | findstr :8953" to see the local process. From another machine, "nmap -p 8953 <host>" shows whether it is reachable.

05 Related
:53 DNS tcp · udp · moderate risk :135 MS RPC tcp · udp · high risk :123 NTP udp · tcp · moderate risk :67 DHCP server udp · tcp · moderate risk :111 rpcbind tcp · udp · high risk :9100 Raw printing (JetDirect) tcp · udp · high risk :631 IPP / CUPS tcp · udp · high risk :5353 mDNS udp · tcp · moderate risk

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