Cybersecurity firms and snake-oil salesmen promising protection from online threats are ubiquitous these days, and it's hard to stand out in such a crowded field—unless you're the former leader of the world's best hacking outfit. In that case, the promises you sell carry more weight—and a higher price tag.

Which may well explain why Gen. Keith Alexander, the former head of the NSA and U.S. Cyber Command, has launched the consulting firm IronNet Cybersecurity. It also may explain why a congressman has reminded the former spy that selling top secret info is a crime.

To capitalize on his recent departure from military intelligence—Alexander retired in March following months of revelations by NSA whistleblower Edward Snowden—the general is offering his security expertise to the banking industry for the fire sale price of $600,000 per month after first asking for $1 million. There are threats everywhere, Alexander warns, and “It would be devastating if one of our major banks was hit, because they’re so interconnected.”

That may be, but Rep. Alan Grayson (D-Florida) is suspicious that Alexander has anything useful to offer at that price—unless, that is, he's peddling national security secrets.

In letters sent Wednesday (.pdf) to the Securities Industry and Financial Markets Association, the Consumer Bankers Association, the Financial Services Roundtable and the Clearing House—all of which Alexander reportedly has approached about his services—Grayson made it clear to Alexander and those who might retain him that selling classified information is illegal.

"I am writing with concerns about the potential disclosure of classified information by former National Security Agency Director Keith Alexander," Grayson wrote. "Disclosing or misusing classified information for profit is, as Mr. Alexander well knows, a felony.

"I question how Mr. Alexander can provide any of the services he is offering unless he discloses or misuses classified information, including extremely sensitive sources and methods," Grayson continued. "Without the classified information he acquired in his former position, he literally would have nothing to offer to you."

Grayson's staff says the congressman has not yet received a response from Alexander or any of the organizations that received the letter.

"The Congressman is very interested in what they have to say," said Matt Stoller, Grayson's senior policy advisor, in an email to WIRED.

Alexander could not be reached for comment.