network-interface-list

network.el

(defun test-internet ()
  (remove-if (lambda (el)
                     (string-match-p "lo.*" (car el)))
             (network-interface-list)))

(test-internet)

(defun tzz-has-network ()
  (remove-if (lambda (i)
                     (or (string-match-p "\\(vboxnet\\|docker\\).*" i)
                         (member 'loopback (nth 4 (network-interface-info i)))))
             (mapcar 'car (network-interface-list))))

(tzz-has-network)

(network-interface-info "eth0")
(network-interface-list)