Your company suspects a potential security breach and has hired you as a Certified Ethical Hacker to investigate. You discover evidence of footprinting through search engines and advanced Google hacking techniques. The attacker utilized Google search operators to extract sensitive information. You further notice queries that indicate the use of the Google Hacking Database (CHDB) with an emphasis on VPN footprinting. Which of the following Google advanced search operators would be the LEAST useful in providing the attacker with sensitive VPN-related information?