Port 750 (kerberos-iv)

IANA assigns port 750 to kerberos-iv: kerberos version iv.

Well-known (system) port, 0-1023 UDP

Port 750 is normally used over UDP; the checker tests TCP only, so a "filtered" result does not mean the UDP service is down.

IANA assignment

Service nameProtoDescriptionAssigneeReference

kerberos-iv UDP kerberos version iv Martin Hamilton -

Linux: UDP 750

sudo ss -ulnp 'sport = :750'

Linux / macOS: which process owns the port

sudo lsof -nP -i :750

Windows (Command Prompt)

netstat -ano | findstr :750

Windows (PowerShell)

Get-NetUDPEndpoint -LocalPort 750

UDP probe (no reply does not prove it is closed)

nc -vzu -w 5 HOST 750

ufw

sudo ufw deny 750/udp

iptables

sudo iptables -A INPUT -p udp --dport 750 -j DROP

nftables

sudo nft add rule inet filter input udp dport 750 drop

Windows Firewall

New-NetFirewallRule -DisplayName 'Block UDP 750' -Direction Inbound -Protocol UDP -LocalPort 750 -Action Block

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