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Port 18888 (apc-necmp)

IANA assigns port 18888 to apc-necmp: APCNECMP.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
apc-necmp TCP APCNECMP Michael Yip -
apc-necmp UDP APCNECMP Michael Yip -

Check what is listening on port 18888

Linux: is anything listening on TCP 18888?
sudo ss -tlnp 'sport = :18888'
Linux: UDP 18888
sudo ss -ulnp 'sport = :18888'
Linux / macOS: which process owns the port
sudo lsof -nP -i :18888
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':18888 '
Windows (Command Prompt)
netstat -ano | findstr :18888
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 18888 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 18888
From Windows
Test-NetConnection HOST -Port 18888
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 18888

Block port 18888 in the firewall

ufw
sudo ufw deny 18888/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 18888 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 18888 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 18888' -Direction Inbound -Protocol TCP -LocalPort 18888 -Action Block
ufw
sudo ufw deny 18888/udp
iptables
sudo iptables -A INPUT -p udp --dport 18888 -j DROP
nftables
sudo nft add rule inet filter input udp dport 18888 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 18888' -Direction Inbound -Protocol UDP -LocalPort 18888 -Action Block

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