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Port 4987 (smar-se-port1)

IANA assigns port 4987 to smar-se-port1: SMAR Ethernet Port 1.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
smar-se-port1 TCP SMAR Ethernet Port 1 - -
smar-se-port1 UDP SMAR Ethernet Port 1 - -

Check what is listening on port 4987

Linux: is anything listening on TCP 4987?
sudo ss -tlnp 'sport = :4987'
Linux: UDP 4987
sudo ss -ulnp 'sport = :4987'
Linux / macOS: which process owns the port
sudo lsof -nP -i :4987
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':4987 '
Windows (Command Prompt)
netstat -ano | findstr :4987
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 4987 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 4987
From Windows
Test-NetConnection HOST -Port 4987
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 4987

Block port 4987 in the firewall

ufw
sudo ufw deny 4987/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 4987 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 4987 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 4987' -Direction Inbound -Protocol TCP -LocalPort 4987 -Action Block
ufw
sudo ufw deny 4987/udp
iptables
sudo iptables -A INPUT -p udp --dport 4987 -j DROP
nftables
sudo nft add rule inet filter input udp dport 4987 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 4987' -Direction Inbound -Protocol UDP -LocalPort 4987 -Action Block

Related ports

4985gerhcs4986mrip4988smar-se-port24989parallel

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