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Port 3987 (centerline)

IANA assigns port 3987 to centerline: Centerline.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
centerline TCP Centerline Mark Simpson -
centerline UDP Centerline Mark Simpson -

Check what is listening on port 3987

Linux: is anything listening on TCP 3987?
sudo ss -tlnp 'sport = :3987'
Linux: UDP 3987
sudo ss -ulnp 'sport = :3987'
Linux / macOS: which process owns the port
sudo lsof -nP -i :3987
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':3987 '
Windows (Command Prompt)
netstat -ano | findstr :3987
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 3987 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 3987
From Windows
Test-NetConnection HOST -Port 3987
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 3987

Block port 3987 in the firewall

ufw
sudo ufw deny 3987/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 3987 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 3987 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 3987' -Direction Inbound -Protocol TCP -LocalPort 3987 -Action Block
ufw
sudo ufw deny 3987/udp
iptables
sudo iptables -A INPUT -p udp --dport 3987 -j DROP
nftables
sudo nft add rule inet filter input udp dport 3987 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 3987' -Direction Inbound -Protocol UDP -LocalPort 3987 -Action Block

Related ports

3985mapper-mapethd3986mapper-ws-ethd, mapper-ws_ethd3988dcs-config3989bv-queryengine

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