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Port 4915 (frcs)

IANA assigns port 4915 to frcs: Fibics Remote Control Service.

Registered (user) port, 1024-49151 TCP

IANA assignment

Service nameProtoDescriptionAssigneeReference
frcs TCP Fibics Remote Control Service Ken Lagarec -

Registry dates for this port: registered 2009-04-17.

Check what is listening on port 4915

Linux: is anything listening on TCP 4915?
sudo ss -tlnp 'sport = :4915'
Linux / macOS: which process owns the port
sudo lsof -nP -i :4915
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':4915 '
Windows (Command Prompt)
netstat -ano | findstr :4915
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 4915 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 4915
From Windows
Test-NetConnection HOST -Port 4915

Block port 4915 in the firewall

ufw
sudo ufw deny 4915/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 4915 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 4915 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 4915' -Direction Inbound -Protocol TCP -LocalPort 4915 -Action Block

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Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.