Port 187

aci · TCP/UDP

RangeSystem/well-known port (0–1023)
ProtocolTCP/UDP
Serviceaci

Frequently asked questions

What is port 187 used for?

Port 187 is registered with the IANA for aci (TCP/UDP). Description: Application Communication Interface.

Is port 187 a well-known port?

Yes. Port 187 is in the range 0–1023 (system or well-known ports). On Linux and macOS only privileged processes may bind to these ports.

How do I check whether port 187 is open?

Locally on Linux with ss -tulpn | grep ':187\b', on Windows with netstat -ano | findstr :187. To test a remote host use Test-NetConnection <host> -Port 187 in PowerShell or nc -zv <host> 187 on Linux/macOS.

How do I open port 187 in the firewall?

Ubuntu/Debian (ufw): sudo ufw allow 187/tcp. Fedora/RHEL (firewalld): sudo firewall-cmd --add-port=187/tcp --permanent, then firewall-cmd --reload. Windows (PowerShell as administrator): New-NetFirewallRule -DisplayName "Port 187" -Direction Inbound -Protocol TCP -LocalPort 187 -Action Allow.

IANA registry entries

ProtocolServiceDescription (IANA)
TCPaciApplication Communication Interface
UDPaciApplication Communication Interface

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