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Port 581 (bdp)

IANA assigns port 581 to bdp: Bundle Discovery Protocol.

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

IANA assignment

Service nameProtoDescriptionAssigneeReference
bdp TCP Bundle Discovery Protocol Gary Malkin -
bdp UDP Bundle Discovery Protocol Gary Malkin -

Check what is listening on port 581

Linux: is anything listening on TCP 581?
sudo ss -tlnp 'sport = :581'
Linux: UDP 581
sudo ss -ulnp 'sport = :581'
Linux / macOS: which process owns the port
sudo lsof -nP -i :581
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':581 '
Windows (Command Prompt)
netstat -ano | findstr :581
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 581 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 581
From Windows
Test-NetConnection HOST -Port 581
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 581

Block port 581 in the firewall

ufw
sudo ufw deny 581/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 581 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 581 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 581' -Direction Inbound -Protocol TCP -LocalPort 581 -Action Block
ufw
sudo ufw deny 581/udp
iptables
sudo iptables -A INPUT -p udp --dport 581 -j DROP
nftables
sudo nft add rule inet filter input udp dport 581 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 581' -Direction Inbound -Protocol UDP -LocalPort 581 -Action Block

Related ports

579decbsrv580sntp-heartbeat582scc-security583philips-vc

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