Port 55

isi-gl · TCP/UDP

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

Frequently asked questions

What is port 55 used for?

Port 55 is registered with the IANA for isi-gl (TCP/UDP). Description: ISI Graphics Language.

Is port 55 a well-known port?

Yes. Port 55 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 55 is open?

Locally on Linux with ss -tulpn | grep ':55\b', on Windows with netstat -ano | findstr :55. To test a remote host use Test-NetConnection <host> -Port 55 in PowerShell or nc -zv <host> 55 on Linux/macOS.

How do I open port 55 in the firewall?

Ubuntu/Debian (ufw): sudo ufw allow 55/tcp. Fedora/RHEL (firewalld): sudo firewall-cmd --add-port=55/tcp --permanent, then firewall-cmd --reload. Windows (PowerShell as administrator): New-NetFirewallRule -DisplayName "Port 55" -Direction Inbound -Protocol TCP -LocalPort 55 -Action Allow.

IANA registry entries

ProtocolServiceDescription (IANA)
TCPisi-glISI Graphics Language
UDPisi-glISI Graphics Language

Nearby entries