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// Other services

Port 546: DHCPv6 Client

Port 546 is assigned by IANA to dhcpv6-client (DHCPv6 Client).

546

How dhcpv6-client works

Other services
client:546dhcpv6-clientresponse client:546dhcpv6-clientresponse

The client sends a request to port 546 and the dhcpv6-client 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
Well-known (0-1023)
Category
Other services
01 Security

Is port 546 dangerous?

We have no specific security note for port 546. 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 546

ServicePortTransportDescriptionReferenceUpdated
dhcpv6-client 546 TCP, UDP DHCPv6 Client - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 546, and is it reachable?

Linux

sudo ss -ltnup 'sport = :546'      # process listening on 546
sudo lsof -nP -i :546

macOS

sudo lsof -nP -i :546

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 546 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 546
netstat -ano | findstr :546

From another machine

nmap -p 546 -sV <host>
sudo nmap -sU -p 546 <host>
nc -zv <host> 546

Block it in the firewall

sudo ufw deny 546/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 546" -Direction Inbound -LocalPort 546 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 546 used for?

Port 546 is assigned by IANA to dhcpv6-client (DHCPv6 Client).

Is port 546 TCP or UDP?

Port 546 is registered for TCP and UDP.

Is it safe to open port 546?

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 546 is open?

On Linux run "ss -ltnup 'sport = :546'", on macOS "lsof -nP -i :546", and on Windows "netstat -ano | findstr :546" to see the local process. From another machine, "nmap -p 546 <host>" shows whether it is reachable.

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