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Port 4900 (hfcs)

IANA assigns port 4900 to hfcs: HFSQL Client/Server Database Engine.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
hfcs TCP HFSQL Client/Server Database Engine PC SOFT -
hfcs UDP HFSQL Client/Server Database Engine PC SOFT -

Registry dates for this port: registered 2006-03-02, last modified 2014-02-02.

Check what is listening on port 4900

Linux: is anything listening on TCP 4900?
sudo ss -tlnp 'sport = :4900'
Linux: UDP 4900
sudo ss -ulnp 'sport = :4900'
Linux / macOS: which process owns the port
sudo lsof -nP -i :4900
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':4900 '
Windows (Command Prompt)
netstat -ano | findstr :4900
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 4900 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 4900
From Windows
Test-NetConnection HOST -Port 4900
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 4900

Block port 4900 in the firewall

ufw
sudo ufw deny 4900/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 4900 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 4900 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 4900' -Direction Inbound -Protocol TCP -LocalPort 4900 -Action Block
ufw
sudo ufw deny 4900/udp
iptables
sudo iptables -A INPUT -p udp --dport 4900 -j DROP
nftables
sudo nft add rule inet filter input udp dport 4900 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 4900' -Direction Inbound -Protocol UDP -LocalPort 4900 -Action Block

Related ports

4894lyskom4899radmin-port4901flr-agent, flr_agent4902magiccontrol

All port numbers · Open port checker
Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.