DROP connectivity checker

This host runs DROP (Diagnostic Reachability & Obstacle Probe), a diagnostic service for peer-to-peer file sharing clients. A client contacts it to find out its own public IP address and whether it can accept incoming connections.

Did this host connect to me?

Then software on your network asked it to, moments earlier, over an authenticated HTTPS connection from your own address. DROP only ever connects back to the address that contacted it — there is no way to ask it to probe anyone else, and it will not connect to an address that has not just requested a test.

The connection carries a single line beginning DROP/1 CHALLENGE and closes immediately. It transfers nothing, reads nothing, and attempts no login. If nobody on your network runs a Direct Connect client, the most likely explanation is that your address was recently reassigned from someone who does.

Is this a port scanner?

No. It tests only ports that the requesting client nominated for itself, and reports a port as reachable only when the client answers a one-time secret sent over that connection. Requests are rate limited per address and per network.

Contact

Questions, complaints, or a request to be excluded: abuse@quickdc.org, operated by quickdc.org.

For client authors

Machine-readable capabilities: /v1/server. Your public address: /v1/whoami.