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Port 189 (qft)

IANA assigns port 189 to qft: Queued File Transport.

Well-known (system) port, 0-1023 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
qft TCP Queued File Transport Wayne Schroeder -
qft UDP Queued File Transport Wayne Schroeder -

Check what is listening on port 189

Linux: is anything listening on TCP 189?
sudo ss -tlnp 'sport = :189'
Linux: UDP 189
sudo ss -ulnp 'sport = :189'
Linux / macOS: which process owns the port
sudo lsof -nP -i :189
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':189 '
Windows (Command Prompt)
netstat -ano | findstr :189
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 189 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 189
From Windows
Test-NetConnection HOST -Port 189
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 189

Block port 189 in the firewall

ufw
sudo ufw deny 189/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 189 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 189 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 189' -Direction Inbound -Protocol TCP -LocalPort 189 -Action Block
ufw
sudo ufw deny 189/udp
iptables
sudo iptables -A INPUT -p udp --dport 189 -j DROP
nftables
sudo nft add rule inet filter input udp dport 189 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 189' -Direction Inbound -Protocol UDP -LocalPort 189 -Action Block

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