I've noticed that when I plug a USB Ethernet adapter into my iPad, an “Ethernet” option appears in the Settings menu. How does the system detect that the adapter has been connected? Hope to receive your reply again.

Thank you for your reply. I tried blow method to get interface type. extern uint32_t functionalTypeForInterfaceNamed(const char * name) { int fd = socket(AF_INET, SOCK_DGRAM, 0); if (fd < 0) { return IFRTYPE_FUNCTIONAL_UNKNOWN; } struct ifreq ifr = {}; strlcpy(ifr.ifr_name, name, sizeof(ifr.ifr_name)); bool success = ioctl(fd, SIOCGIFFUNCTIONALTYPE, &ifr) >= 0; int junk = close(fd); assert(junk == 0); if (!success) { return IFRTYPE_FUNCTIONAL_UNKNOWN; } return ifr.ifr_ifru.ifru_functional_type; } There are three default enX interfaces, the en0 is IFRTYPE_FUNCTIONAL_WIFI_INFRA, the en1,en2 are IFRTYPE_FUNCTIONAL_WIRED, but I haven't inserted any ethernet adapter on my iPad yet. When I insert an ethernet adapter, an additional network interface which is also IFRTYPE_FUNCTIONAL_WIRED appear. It definitely affect my judgement. How to distinguish between those default enX which are IFRTYPE_FUNCTIONAL_WIRED type and the real ethernet adapter which insert on my iPad?