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Port 6581 (parsec-peer)

IANA assigns port 6581 to parsec-peer: Parsec Peer-to-Peer.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
parsec-peer TCP Parsec Peer-to-Peer Andreas Varga -
parsec-peer UDP Parsec Peer-to-Peer Andreas Varga -

Check what is listening on port 6581

Linux: is anything listening on TCP 6581?
sudo ss -tlnp 'sport = :6581'
Linux: UDP 6581
sudo ss -ulnp 'sport = :6581'
Linux / macOS: which process owns the port
sudo lsof -nP -i :6581
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':6581 '
Windows (Command Prompt)
netstat -ano | findstr :6581
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 6581 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 6581
From Windows
Test-NetConnection HOST -Port 6581
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 6581

Block port 6581 in the firewall

ufw
sudo ufw deny 6581/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 6581 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 6581 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 6581' -Direction Inbound -Protocol TCP -LocalPort 6581 -Action Block
ufw
sudo ufw deny 6581/udp
iptables
sudo iptables -A INPUT -p udp --dport 6581 -j DROP
nftables
sudo nft add rule inet filter input udp dport 6581 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 6581' -Direction Inbound -Protocol UDP -LocalPort 6581 -Action Block

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All port numbers · Open port checker
Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.