"They don't give me reasons, but they generally seem to be investigating a specific attacker who they think may have visited the Nmap page at a certain time....In some cases, they asked too late and data had already been purged through our data retention policy. In other cases, they failed to serve the subpoena properly. Sometimes they try asking without a subpoena and give up when I demand one....Protecting your privacy is important to me, but Nmap users should be savvy enough to know that all of your network activity leave traces....Remember this security mantra: defense in depth."