Port 261
nsiiops · TCP/UDP
| Range | System/well-known port (0–1023) |
|---|---|
| Protocol | TCP/UDP |
| Service | nsiiops |
Frequently asked questions
What is port 261 used for?
Port 261 is registered with the IANA for nsiiops (TCP/UDP). Description: IIOP Name Service over TLS/SSL.
Is port 261 a well-known port?
Yes. Port 261 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 261 is open?
Locally on Linux with ss -tulpn | grep ':261\b', on Windows with netstat -ano | findstr :261. To test a remote host use Test-NetConnection <host> -Port 261 in PowerShell or nc -zv <host> 261 on Linux/macOS.
How do I open port 261 in the firewall?
Ubuntu/Debian (ufw): sudo ufw allow 261/tcp. Fedora/RHEL (firewalld): sudo firewall-cmd --add-port=261/tcp --permanent, then firewall-cmd --reload. Windows (PowerShell as administrator): New-NetFirewallRule -DisplayName "Port 261" -Direction Inbound -Protocol TCP -LocalPort 261 -Action Allow.
IANA registry entries
| Protocol | Service | Description (IANA) |
|---|---|---|
| TCP | nsiiops | IIOP Name Service over TLS/SSL |
| UDP | nsiiops | IIOP Name Service over TLS/SSL |