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Port 12865 (netperf)

IANA assigns port 12865 to netperf: control port for the netperf benchmark.

Registered (user) port, 1024-49151 TCP

IANA assignment

Service nameProtoDescriptionAssigneeReference
netperf TCP control port for the netperf benchmark netperf.org -

Registry dates for this port: registered 2013-04-05.

Check what is listening on port 12865

Linux: is anything listening on TCP 12865?
sudo ss -tlnp 'sport = :12865'
Linux / macOS: which process owns the port
sudo lsof -nP -i :12865
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':12865 '
Windows (Command Prompt)
netstat -ano | findstr :12865
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 12865 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 12865
From Windows
Test-NetConnection HOST -Port 12865

Block port 12865 in the firewall

ufw
sudo ufw deny 12865/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 12865 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 12865 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 12865' -Direction Inbound -Protocol TCP -LocalPort 12865 -Action Block

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