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Port 571 (meter)

IANA assigns port 571 to meter: udemon.

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

IANA assignment

Service nameProtoDescriptionAssigneeReference
meter TCP udemon - -
meter UDP udemon - -

Check what is listening on port 571

Linux: is anything listening on TCP 571?
sudo ss -tlnp 'sport = :571'
Linux: UDP 571
sudo ss -ulnp 'sport = :571'
Linux / macOS: which process owns the port
sudo lsof -nP -i :571
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':571 '
Windows (Command Prompt)
netstat -ano | findstr :571
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 571 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 571
From Windows
Test-NetConnection HOST -Port 571
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 571

Block port 571 in the firewall

ufw
sudo ufw deny 571/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 571 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 571 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 571' -Direction Inbound -Protocol TCP -LocalPort 571 -Action Block
ufw
sudo ufw deny 571/udp
iptables
sudo iptables -A INPUT -p udp --dport 571 -j DROP
nftables
sudo nft add rule inet filter input udp dport 571 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 571' -Direction Inbound -Protocol UDP -LocalPort 571 -Action Block

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