Port 3303

opsession-clnt · TCP/UDP

RangeRegistered port (1024–49151)
ProtocolTCP/UDP
Serviceopsession-clnt

Frequently asked questions

What is port 3303 used for?

Port 3303 is registered with the IANA for opsession-clnt (TCP/UDP). Description: OP Session Client.

Is port 3303 a well-known port?

No. Port 3303 is in the range 1024–49151 (registered or user ports). Ordinary programs may open it without root privileges.

How do I check whether port 3303 is open?

Locally on Linux with ss -tulpn | grep ':3303\b', on Windows with netstat -ano | findstr :3303. To test a remote host use Test-NetConnection <host> -Port 3303 in PowerShell or nc -zv <host> 3303 on Linux/macOS.

How do I open port 3303 in the firewall?

Ubuntu/Debian (ufw): sudo ufw allow 3303/tcp. Fedora/RHEL (firewalld): sudo firewall-cmd --add-port=3303/tcp --permanent, then firewall-cmd --reload. Windows (PowerShell as administrator): New-NetFirewallRule -DisplayName "Port 3303" -Direction Inbound -Protocol TCP -LocalPort 3303 -Action Allow.

IANA registry entries

ProtocolServiceDescription (IANA)
TCPopsession-clntOP Session Client
UDPopsession-clntOP Session Client

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