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Port 537 (nmsp)

IANA assigns port 537 to nmsp: Networked Media Streaming Protocol.

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

IANA assignment

Service nameProtoDescriptionAssigneeReference
nmsp TCP Networked Media Streaming Protocol Paul Santinelli Jr -
nmsp UDP Networked Media Streaming Protocol Paul Santinelli Jr -

Check what is listening on port 537

Linux: is anything listening on TCP 537?
sudo ss -tlnp 'sport = :537'
Linux: UDP 537
sudo ss -ulnp 'sport = :537'
Linux / macOS: which process owns the port
sudo lsof -nP -i :537
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':537 '
Windows (Command Prompt)
netstat -ano | findstr :537
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 537 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 537
From Windows
Test-NetConnection HOST -Port 537
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 537

Block port 537 in the firewall

ufw
sudo ufw deny 537/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 537 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 537 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 537' -Direction Inbound -Protocol TCP -LocalPort 537 -Action Block
ufw
sudo ufw deny 537/udp
iptables
sudo iptables -A INPUT -p udp --dport 537 -j DROP
nftables
sudo nft add rule inet filter input udp dport 537 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 537' -Direction Inbound -Protocol UDP -LocalPort 537 -Action Block

Related ports

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