lsof

type OpenFile struct {
	Command    string `json:"command"`
	PID        int32  `json:"pid"`
	User       string `json:"user"`
	FD         string `json:"fd"`
	Type       string `json:"type"`
	Device     string `json:"device,omitempty"`
	Size       int64  `json:"size,omitempty"`
	Node       string `json:"node,omitempty"`
	Name       string `json:"name"`
	State      string `json:"state,omitempty"`
	Protocol   string `json:"protocol,omitempty"`
	LocalIP    string `json:"local_ip,omitempty"`
	LocalPort  uint32 `json:"local_port,omitempty"`
	RemoteIP   string `json:"remote_ip,omitempty"`
	RemotePort uint32 `json:"remote_port,omitempty"`
}

type Options struct {
	PID         int    // -p: show files for specific PID
	User        string // -u: show files for specific user
	Port        int    // -i: show files using specific port
	Protocol    string // -i: filter by protocol (tcp, udp)
	Network     bool   // -i: show network files only
	Files       bool   // show file descriptors (default behavior)
	Command     string // -c: filter by command name prefix
	NoHeaders   bool   // -n: don't print headers
	JSON        bool   // -j: output as JSON
	IPv4        bool   // -4: show only IPv4
	IPv6        bool   // -6: show only IPv6
	Listen      bool   // show only listening sockets
	Established bool   // show only established connections
}