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Port 41111 (fs-qos)

IANA assigns port 41111 to fs-qos: Foursticks QoS Protocol.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
fs-qos TCP Foursticks QoS Protocol Chee Kent Lam -
fs-qos UDP Foursticks QoS Protocol Chee Kent Lam -

Registry dates for this port: registered 2002-04.

Check what is listening on port 41111

Linux: is anything listening on TCP 41111?
sudo ss -tlnp 'sport = :41111'
Linux: UDP 41111
sudo ss -ulnp 'sport = :41111'
Linux / macOS: which process owns the port
sudo lsof -nP -i :41111
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':41111 '
Windows (Command Prompt)
netstat -ano | findstr :41111
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 41111 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 41111
From Windows
Test-NetConnection HOST -Port 41111
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 41111

Block port 41111 in the firewall

ufw
sudo ufw deny 41111/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 41111 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 41111 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 41111' -Direction Inbound -Protocol TCP -LocalPort 41111 -Action Block
ufw
sudo ufw deny 41111/udp
iptables
sudo iptables -A INPUT -p udp --dport 41111 -j DROP
nftables
sudo nft add rule inet filter input udp dport 41111 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 41111' -Direction Inbound -Protocol UDP -LocalPort 41111 -Action Block

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