Port 4756 (RDCenter)

IANA assigns port 4756 to RDCenter: Reticle Decision Center.

Registered (user) port, 1024-49151 TCP

IANA assignment

Service nameProtoDescriptionAssigneeReference

RDCenter TCP Reticle Decision Center KLA Tencor -

Registry dates for this port: registered 2016-10-17.

Linux: is anything listening on TCP 4756?

sudo ss -tlnp 'sport = :4756'

Linux / macOS: which process owns the port

sudo lsof -nP -i :4756

Older Linux / BSD (net-tools)

sudo netstat -tlnp | grep ':4756 '

Windows (Command Prompt)

netstat -ano | findstr :4756

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 4756 -State Listen | Select LocalAddress,OwningProcess

From another machine

nc -vz -w 5 HOST 4756

From Windows

Test-NetConnection HOST -Port 4756

ufw

sudo ufw deny 4756/tcp

iptables

sudo iptables -A INPUT -p tcp --dport 4756 -j DROP

nftables

sudo nft add rule inet filter input tcp dport 4756 drop

Windows Firewall

New-NetFirewallRule -DisplayName 'Block TCP 4756' -Direction Inbound -Protocol TCP -LocalPort 4756 -Action Block

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