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// Network services

Port 5354: Multicast DNS Responder IPC

Port 5354 is assigned by IANA to mdnsresponder (Multicast DNS Responder IPC).

5354

How mdnsresponder works

Network services
client:5354mdnsresponderresponse client:5354mdnsresponderresponse

The client sends a request to port 5354 and the mdnsresponder 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 5354 dangerous?

We have no specific security note for port 5354. 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 5354

ServicePortTransportDescriptionReferenceUpdated
mdnsresponder 5354 TCP, UDP Multicast DNS Responder IPC - 2004-06

// source: IANA service name and port number registry

03 Check it

Which program uses port 5354, and is it reachable?

Linux

sudo ss -ltnup 'sport = :5354'      # process listening on 5354
sudo lsof -nP -i :5354

macOS

sudo lsof -nP -i :5354

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 5354 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 5354
netstat -ano | findstr :5354

From another machine

nmap -p 5354 -sV <host>
sudo nmap -sU -p 5354 <host>
nc -zv <host> 5354

Block it in the firewall

sudo ufw deny 5354/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 5354" -Direction Inbound -LocalPort 5354 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 5354 used for?

Port 5354 is assigned by IANA to mdnsresponder (Multicast DNS Responder IPC).

Is port 5354 TCP or UDP?

Port 5354 is registered for TCP and UDP.

Is it safe to open port 5354?

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 5354 is open?

On Linux run "ss -ltnup 'sport = :5354'", on macOS "lsof -nP -i :5354", and on Windows "netstat -ano | findstr :5354" to see the local process. From another machine, "nmap -p 5354 <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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