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// Other services

Port 4827: HTCP

Port 4827 is assigned by IANA to htcp (HTCP).

4827

How htcp works

Other services
client:4827htcpresponse client:4827htcpresponse

The client sends a request to port 4827 and the htcp 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
Other services
01 Security

Is port 4827 dangerous?

We have no specific security note for port 4827. 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 4827

ServicePortTransportDescriptionReferenceUpdated
htcp 4827 TCP, UDP HTCP - -

// source: IANA service name and port number registry

03 Check it

Which program uses port 4827, and is it reachable?

Linux

sudo ss -ltnup 'sport = :4827'      # process listening on 4827
sudo lsof -nP -i :4827

macOS

sudo lsof -nP -i :4827

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 4827 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 4827
netstat -ano | findstr :4827

From another machine

nmap -p 4827 -sV <host>
sudo nmap -sU -p 4827 <host>
nc -zv <host> 4827

Block it in the firewall

sudo ufw deny 4827/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 4827" -Direction Inbound -LocalPort 4827 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 4827 used for?

Port 4827 is assigned by IANA to htcp (HTCP).

Is port 4827 TCP or UDP?

Port 4827 is registered for TCP and UDP.

Is it safe to open port 4827?

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 4827 is open?

On Linux run "ss -ltnup 'sport = :4827'", on macOS "lsof -nP -i :4827", and on Windows "netstat -ano | findstr :4827" to see the local process. From another machine, "nmap -p 4827 <host>" shows whether it is reachable.

05 Related
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