Port 16789 (cadsisvr)

IANA assigns port 16789 to cadsisvr: This server provides callable services to mainframe External Security Managers from any TCP/IP platform.

Registered (user) port, 1024-49151 TCP

IANA assignment

Service nameProtoDescriptionAssigneeReference

cadsisvr TCP This server provides callable services to mainframe External Security Managers from any TCP/IP platform Broadcom -

Registry dates for this port: registered 2015-06-02, last modified 2023-03-29.

Linux: is anything listening on TCP 16789?

sudo ss -tlnp 'sport = :16789'

Linux / macOS: which process owns the port

sudo lsof -nP -i :16789

Older Linux / BSD (net-tools)

sudo netstat -tlnp | grep ':16789 '

Windows (Command Prompt)

netstat -ano | findstr :16789

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 16789 -State Listen | Select LocalAddress,OwningProcess

From another machine

nc -vz -w 5 HOST 16789

From Windows

Test-NetConnection HOST -Port 16789

ufw

sudo ufw deny 16789/tcp

iptables

sudo iptables -A INPUT -p tcp --dport 16789 -j DROP

nftables

sudo nft add rule inet filter input tcp dport 16789 drop

Windows Firewall

New-NetFirewallRule -DisplayName 'Block TCP 16789' -Direction Inbound -Protocol TCP -LocalPort 16789 -Action Block

All port numbers · Open port checker
Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.