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Port 3300 (ceph)

IANA assigns port 3300 to ceph: Ceph monitor.

Registered (user) port, 1024-49151 TCP

IANA assignment

Service nameProtoDescriptionAssigneeReference
ceph TCP Ceph monitor Sage Weil -

Registry dates for this port: registered 2015-06-29.

Check what is listening on port 3300

Linux: is anything listening on TCP 3300?
sudo ss -tlnp 'sport = :3300'
Linux / macOS: which process owns the port
sudo lsof -nP -i :3300
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':3300 '
Windows (Command Prompt)
netstat -ano | findstr :3300
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 3300 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 3300
From Windows
Test-NetConnection HOST -Port 3300

Block port 3300 in the firewall

ufw
sudo ufw deny 3300/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 3300 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 3300 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 3300' -Direction Inbound -Protocol TCP -LocalPort 3300 -Action Block

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