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// Network services

Port 5352: DNS Long-Lived Queries

Port 5352 is assigned by IANA to dns-llq (DNS Long-Lived Queries).

5352

How dns-llq works

Network services
client:5352dns-llqresponse client:5352dns-llqresponse

The client sends a request to port 5352 and the dns-llq service answers.

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
Network services
01 Security

Is port 5352 dangerous?

We have no specific security note for port 5352. 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 5352

ServicePortTransportDescriptionReferenceUpdated
dns-llq 5352 TCP, UDP DNS Long-Lived Queries RFC 8764 2019-08-26

// source: IANA service name and port number registry

03 Check it

Which program uses port 5352, and is it reachable?

Linux

sudo ss -ltnup 'sport = :5352'      # process listening on 5352
sudo lsof -nP -i :5352

macOS

sudo lsof -nP -i :5352

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 5352 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 5352
netstat -ano | findstr :5352

From another machine

nmap -p 5352 -sV <host>
sudo nmap -sU -p 5352 <host>
nc -zv <host> 5352

Block it in the firewall

sudo ufw deny 5352/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 5352" -Direction Inbound -LocalPort 5352 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 5352 used for?

Port 5352 is assigned by IANA to dns-llq (DNS Long-Lived Queries).

Is port 5352 TCP or UDP?

Port 5352 is registered for TCP and UDP.

Is it safe to open port 5352?

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 5352 is open?

On Linux run "ss -ltnup 'sport = :5352'", on macOS "lsof -nP -i :5352", and on Windows "netstat -ano | findstr :5352" to see the local process. From another machine, "nmap -p 5352 <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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