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// Other services

Port 473: hybrid-pop

Port 473 is assigned by IANA to hybrid-pop (hybrid-pop).

473

How hybrid-pop works

Other services
client:473hybrid-popresponse client:473hybrid-popresponse

The client sends a request to port 473 and the hybrid-pop 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 473 dangerous?

We have no specific security note for port 473. 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 473

ServicePortTransportDescriptionReferenceUpdated
hybrid-pop 473 TCP, UDP hybrid-pop - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 473, and is it reachable?

Linux

sudo ss -ltnup 'sport = :473'      # process listening on 473
sudo lsof -nP -i :473

macOS

sudo lsof -nP -i :473

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 473 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 473
netstat -ano | findstr :473

From another machine

nmap -p 473 -sV <host>
sudo nmap -sU -p 473 <host>
nc -zv <host> 473

Block it in the firewall

sudo ufw deny 473/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 473" -Direction Inbound -LocalPort 473 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 473 used for?

Port 473 is assigned by IANA to hybrid-pop (hybrid-pop).

Is port 473 TCP or UDP?

Port 473 is registered for TCP and UDP.

Is it safe to open port 473?

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 473 is open?

On Linux run "ss -ltnup 'sport = :473'", on macOS "lsof -nP -i :473", and on Windows "netstat -ano | findstr :473" to see the local process. From another machine, "nmap -p 473 <host>" shows whether it is reachable.

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