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Port 4737 (ipdr-sp)

IANA assigns port 4737 to ipdr-sp: IPDR/SP.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
ipdr-sp TCP IPDR/SP Ken Sarno -
ipdr-sp UDP IPDR/SP Ken Sarno -

Registry dates for this port: registered 2005-08.

Check what is listening on port 4737

Linux: is anything listening on TCP 4737?
sudo ss -tlnp 'sport = :4737'
Linux: UDP 4737
sudo ss -ulnp 'sport = :4737'
Linux / macOS: which process owns the port
sudo lsof -nP -i :4737
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':4737 '
Windows (Command Prompt)
netstat -ano | findstr :4737
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 4737 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 4737
From Windows
Test-NetConnection HOST -Port 4737
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 4737

Block port 4737 in the firewall

ufw
sudo ufw deny 4737/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 4737 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 4737 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 4737' -Direction Inbound -Protocol TCP -LocalPort 4737 -Action Block
ufw
sudo ufw deny 4737/udp
iptables
sudo iptables -A INPUT -p udp --dport 4737 -j DROP
nftables
sudo nft add rule inet filter input udp dport 4737 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 4737' -Direction Inbound -Protocol UDP -LocalPort 4737 -Action Block

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