IP addresses are metadata - and don't require search warrants, meaning they are fair game for dragnet surveillance. Tapping into a backbone, a la Room 641A, can be used to cross-reference timestamped public posts on an anonymous message board to other data sources (e.g. subpoena Netflix for payer based of Netflix's access logs from VPN exit IPs)
IP addresses are metadata - and don't require search warrants, meaning they are fair game for dragnet surveillance. Tapping into a backbone, a la Room 641A, can be used to cross-reference timestamped public posts on an anonymous message board to other data sources (e.g. subpoena Netflix for payer based of Netflix's access logs from VPN exit IPs)