So how did a University of Arizona professor receive a lifetime ban from such a proudly permissive conference?

Christopher Hadnagy insists he still doesn’t know.

In February, DEF CON organizers announced they had received “multiple” reports about Hadnagy for violations of the convention’s code of conduct against harassment.

“After conversations with the reporting parties and Chris, we are confident the severity of the transgressions merits a ban from DEF CON,” organizers said in a statement on the convention’s website.

But Hadnagy says he was never told what he was accused of, and he denies doing anything wrong.

Now the adjunct professor in the UA’s College of Applied Science and Technology is suing the convention and its founding hacker, Jeff Moss, aka the Dark Tangent.

The defamation lawsuit filed Aug. 3 in a Pennsylvania federal court accuses Moss and DEF CON of ruining Hadnagy’s reputation and damaging his security consulting business with “vague yet scathing statements” that “falsely accuse him of what could only be despicable conduct.”

Hadnagy is seeking at least $375,000, plus punitive damages and legal fees.

Moss could not be reached. His attorney did not respond to a request for comment.

When contacted by email, Hadnagy professed his innocence and made several references to his lawsuit.

“My company and I consistently deny and continue to deny any and all allegations of misconduct,” he said in an email.

He referred all further questions to his lawyers, who declined to discuss the ongoing litigation.

Jeff Moss was just 18 when he organized the first DEF CON in 1993 as an excuse to party in Las Vegas with a few dozen of his hacker friends.

The event has grown…