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// Databases & caches

Port 4900: HFSQL Client/Server Database Engine

Port 4900 is assigned by IANA to hfcs (HFSQL Client/Server Database Engine).

4900

How hfcs works

Databases & caches
app:4900hfcs app:4900hfcs

The application sends a SQL query to the hfcs server on port 4900, which returns rows from its tables.

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
Databases & caches
01 Security

Is port 4900 dangerous?

We have no specific security note for port 4900. Its risk depends on the program actually listening on it. General advice for databases & caches services:

  • Bind the service to localhost or a private network, never to a public address.
  • Enable authentication, use per-application accounts and require TLS.
  • Watch for exposed Docker ports: publish them on 127.0.0.1 only.
02 Registry

IANA registry entries for port 4900

ServicePortTransportDescriptionReferenceUpdated
hfcs 4900 TCP, UDP HFSQL Client/Server Database Engine - 2014-02-02

// source: IANA service name and port number registry

03 Check it

Which program uses port 4900, and is it reachable?

Linux

sudo ss -ltnup 'sport = :4900'      # process listening on 4900
sudo lsof -nP -i :4900

macOS

sudo lsof -nP -i :4900

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 4900 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 4900
netstat -ano | findstr :4900

From another machine

nmap -p 4900 -sV <host>
sudo nmap -sU -p 4900 <host>
nc -zv <host> 4900

Block it in the firewall

sudo ufw deny 4900/tcp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 4900" -Direction Inbound -LocalPort 4900 -Protocol TCP -Action Block  # Windows
04 FAQ
What is port 4900 used for?

Port 4900 is assigned by IANA to hfcs (HFSQL Client/Server Database Engine).

Is port 4900 TCP or UDP?

Port 4900 is registered for TCP and UDP.

Is it safe to open port 4900?

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. Bind the service to localhost or a private network, never to a public address.

How do I check if port 4900 is open?

On Linux run "ss -ltnup 'sport = :4900'", on macOS "lsof -nP -i :4900", and on Windows "netstat -ano | findstr :4900" to see the local process. From another machine, "nmap -p 4900 <host>" shows whether it is reachable.

05 Related
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