esp_eth_phy_802_3_reset_hw(phy_802_3);

// Before: Configuration via Kconfig
// CONFIG_ETH_RMII_CLK_INPUT=y

// After: Explicit configuration in code
eth_esp32_emac_config_t emac_config = ETH_ESP32_EMAC_DEFAULT_CONFIG();
emac_config.clock_config.rmii.clock_mode = EMAC_CLK_OUT;  // or EMAC_CLK_EXT_IN
emac_config.clock_config.rmii.clock_gpio = 0;  // GPIO0 for ESP32

Before:

.. code-block:: c

    esp_netif_t *it = NULL;
    while ((it = esp_netif_next(it)) != NULL) {
        // use "it"
    }

After (iterate unsafely in a controlled context):

.. code-block:: c

    esp_netif_t *it = NULL;
    while ((it = esp_netif_next_unsafe(it)) != NULL) {
        // use "it"
    }

Recommended (iterate within TCP/IP context):

.. code-block:: c

    static esp_err_t iterate_netifs(void *ctx)
    {
        esp_netif_t *it = NULL;
        while ((it = esp_netif_next_unsafe(it)) != NULL) {
            // use "it"
        }
        return ESP_OK;
    }

    // Execute iteration safely in TCP/IP context
    ESP_ERROR_CHECK(esp_netif_tcpip_exec(iterate_netifs, NULL));

Alternative (find with predicate):

.. code-block:: c

    static bool match_by_key(void *ctx, esp_netif_t *netif)
    {
        const char *wanted = (const char *)ctx;
        const char *key = esp_netif_get_ifkey(netif);
        return key && strcmp(key, wanted) == 0;
    }

    esp_netif_t *target = esp_netif_find_if(match_by_key, (void *)"WIFI_STA_DEF");
    if (target) {
        // use "target"
    }


DHCP Server DNS Option Behavior
-------------------------------

The ``LWIP_DHCPS_ADD_DNS`` macro has been removed.

Previously, when running a DHCP server on SoftAP, if no DNS offer option was set, the server IP address was automatically advertised as the DNS server.

**Current behavior:**

From this release onward, the DHCP server includes DNS information in its offers only when explicitly configured using :cpp:func:`esp_netif_dhcps_option` with the ``ESP_NETIF_DOMAIN_NAME_SERVER`` option. In that case, the currently configured main and/or backup DNS addresses for the SoftAP interface are sent to clients.

If the option is not enabled, the DHCP server's own IP address is sent as the DNS server, which preserves the previous default behavior.

**Migration:**

If applications rely on custom DNS settings, developers should:

1. Enable the DHCP server to include DNS information in its offers using :cpp:func:`esp_netif_dhcps_option` with the ``ESP_NETIF_DOMAIN_NAME_SERVER`` option.
2. Configure one or more DNS server addresses for the SoftAP interface using :cpp:func:`esp_netif_set_dns_info`.
3. If no DNS information should be sent at all, configure :cpp:func:`esp_netif_dhcps_option` but set the DNS server address to ``0.0.0.0`` using :cpp:func:`esp_netif_set_dns_info`.

This allows developers to:

- replicate the old behavior (advertising the SoftAP IP),
- provide custom DNS servers (for example, public resolvers), or
- suppress DNS information entirely by setting the DNS server to ``0.0.0.0``.


LWIP
****

The lwIP TCP/IP thread name has changed from "tiT" to "tcpip".


SNTP Header File Removal
------------------------

The deprecated ``sntp.h`` header file has been removed in IDF v6.0. Applications should now include ``esp_sntp.h`` instead of ``sntp.h`` for SNTP functionality.

Ping API Removal
----------------

The deprecated ping APIs and headers have been removed in IDF v6.0:

- ``esp_ping.h`` header file has been removed
- ``ping.h`` header file has been removed
- Functions ``ping_init()``, ``ping_deinit()``, ``esp_ping_set_target()``, ``esp_ping_get_target()``, and ``esp_ping_result()`` have been removed

Applications should now use the socket-based ping API from ``ping/ping_sock.h``:

.. code-block:: c

    #include "ping/ping_sock.h"
    // Create ping session
    esp_ping_config_t config = ESP_PING_DEFAULT_CONFIG();
    config.target_addr = target_ip;
    esp_ping_callbacks_t cbs = {
        .on_ping_success = on_ping_success,
        .on_ping_timeout = on_ping_timeout,
        .on_ping_end = on_ping_end,
    };
    esp_ping_handle_t ping;
    esp_ping_new_session(&config, &cbs, &ping);
    esp_ping_start(ping);

For a complete example, see :example:`protocols/icmp_echo`.