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Port 3622 (ff-lr-port)

IANA assigns port 3622 to ff-lr-port: FF LAN Redundancy Port.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
ff-lr-port TCP FF LAN Redundancy Port Fieldbus Foundation -
ff-lr-port UDP FF LAN Redundancy Port Fieldbus Foundation -

Registry dates for this port: registered 2002-10.

Check what is listening on port 3622

Linux: is anything listening on TCP 3622?
sudo ss -tlnp 'sport = :3622'
Linux: UDP 3622
sudo ss -ulnp 'sport = :3622'
Linux / macOS: which process owns the port
sudo lsof -nP -i :3622
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':3622 '
Windows (Command Prompt)
netstat -ano | findstr :3622
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 3622 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 3622
From Windows
Test-NetConnection HOST -Port 3622
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 3622

Block port 3622 in the firewall

ufw
sudo ufw deny 3622/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 3622 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 3622 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 3622' -Direction Inbound -Protocol TCP -LocalPort 3622 -Action Block
ufw
sudo ufw deny 3622/udp
iptables
sudo iptables -A INPUT -p udp --dport 3622 -j DROP
nftables
sudo nft add rule inet filter input udp dport 3622 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 3622' -Direction Inbound -Protocol UDP -LocalPort 3622 -Action Block

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