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Port 6209 (qmtps)

IANA assigns port 6209 to qmtps: QMTP over TLS.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
qmtps TCP QMTP over TLS FEHCom -
qmtps UDP QMTP over TLS FEHCom -

Registry dates for this port: registered 2015-01-09.

Check what is listening on port 6209

Linux: is anything listening on TCP 6209?
sudo ss -tlnp 'sport = :6209'
Linux: UDP 6209
sudo ss -ulnp 'sport = :6209'
Linux / macOS: which process owns the port
sudo lsof -nP -i :6209
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':6209 '
Windows (Command Prompt)
netstat -ano | findstr :6209
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 6209 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 6209
From Windows
Test-NetConnection HOST -Port 6209
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 6209

Block port 6209 in the firewall

ufw
sudo ufw deny 6209/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 6209 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 6209 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 6209' -Direction Inbound -Protocol TCP -LocalPort 6209 -Action Block
ufw
sudo ufw deny 6209/udp
iptables
sudo iptables -A INPUT -p udp --dport 6209 -j DROP
nftables
sudo nft add rule inet filter input udp dport 6209 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 6209' -Direction Inbound -Protocol UDP -LocalPort 6209 -Action Block

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