Port 69 (TFTP)

Trivial File Transfer Protocol: PXE network boot images, VoIP phone provisioning and router/switch config backups.

Well-known (system) port, 0-1023 UDP File transfer and storage Do not expose to the internet

Port 69 is normally used over UDP; the checker tests TCP only, so a "filtered" result does not mean the UDP service is down.

What port 69 is used for

Trivial File Transfer Protocol: PXE network boot images, VoIP phone provisioning and router/switch config backups.

Security: should port 69 be open?

Do not expose to the internet. TFTP has no authentication at all; an exposed server lets anyone download (and sometimes upload) files, often device configs with passwords. LAN only.

IANA assignment

Service nameProtoDescriptionAssigneeReference

tftp TCP Trivial File Transfer David Clark -

tftp UDP Trivial File Transfer David Clark -

Check what is listening on port 69

Linux: UDP 69

sudo ss -ulnp 'sport = :69'

Linux / macOS: which process owns the port

sudo lsof -nP -i :69

Windows (Command Prompt)

netstat -ano | findstr :69

Windows (PowerShell)

Get-NetUDPEndpoint -LocalPort 69

Test it from outside

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

nc -vzu -w 5 HOST 69

Block port 69 in the firewall

ufw

sudo ufw deny 69/udp

iptables

sudo iptables -A INPUT -p udp --dport 69 -j DROP

nftables

sudo nft add rule inet filter input udp dport 69 drop

Windows Firewall

New-NetFirewallRule -DisplayName 'Block UDP 69' -Direction Inbound -Protocol UDP -LocalPort 69 -Action Block

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