Port 69: TFTP

What is port 69 used for?

Booting devices over the network and pushing firmware or configs.

Is it safe to expose port 69 to the internet?

No authentication or encryption. Keep it on a management network and never expose it.

If port 69 seems closed or unreachable

1. Check that the TFTP service is running and listening on port 69, not only on 127.0.0.1.
2. Check the firewall on the host itself (Windows Defender Firewall, iptables, nftables, ufw) for a rule that allows UDP 69.
3. If the host is behind a router, confirm the forwarding rule points to the correct internal address and that your internet provider does not use carrier-grade NAT.
4. Test from outside your own network. A port can be open locally and blocked at the edge, or the other way round.

Using port 69 safely

Treat port 69 as an internal-only service. Reach it through a VPN or an SSH tunnel, restrict it by source address, and keep the software that listens on it patched.