location / {
            proxy_set_header Host $http_host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;

            proxy_connect_timeout 300;
            # Default is HTTP/1, keepalive is only enabled in HTTP/1.1
            proxy_http_version 1.1;

import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/**
 * Tester to ensure forwarding wrapper works by delegating calls to the corresponding method with
 * the same parameters forwarded and return value forwarded back or exception propagated as is.
 *
 * <p>For example:
 *
 * {@snippet :
 * new ForwardingWrapperTester().testForwarding(Foo.class, new Function<Foo, Foo>() {
 *   public Foo apply(Foo foo) {

            @Override
            public Tuple3<String, String, String>[] getVirtualHosts() {
                return new Tuple3[] { new Tuple3<>("Host", "example.com", "site1"), new Tuple3<>("X-Forwarded-Host", "test.com", "site2") };
            }
        });

        MockletHttpServletRequest request = getMockRequest();
        HtmlNext page = new HtmlNext("/search");

        // No matching host header

				Host: "127.0.0.1:9000",
				Header: map[string][]string{
					"X-Forwarded-Scheme": {httpScheme},
				},
			},
			bucket:           "testbucket1",
			object:           "test/1.txt",
			expectedLocation: "http://127.0.0.1:9000/testbucket1/test/1.txt",
		},
		{
			request: &http.Request{
				Host: "127.0.0.1:9000",
				Header: map[string][]string{
					"X-Forwarded-Scheme": {httpsScheme},
				},
			},

        // 127.0.0.1 is configured as a trusted proxy by default
        final MockletHttpServletRequest request = getMockRequest();
        request.setRemoteAddr("127.0.0.1");
        request.addHeader("X-Forwarded-For", "203.0.113.50, 70.41.3.18, 150.172.238.178");
        assertEquals("203.0.113.50", rateLimitHelper.getClientIp(request));
    }

    @Test
    public void test_getClientIp_xRealIp_trustedProxy() {

* [X-Forwarded-Host](https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/X-Forwarded-Host)

///

然而，因為**應用伺服器**並不知道自己在受信任的**代理**之後，預設情況下它不會信任這些標頭。

但你可以設定**應用伺服器**去信任由**代理**送來的「轉發」標頭。若你使用 FastAPI CLI，可以用 *CLI 參數* `--forwarded-allow-ips` 指定應信任哪些 IP 來的「轉發」標頭。

例如，如果**應用伺服器**只會接收來自受信任**代理**的連線，你可以設定 `--forwarded-allow-ips="*"`，也就是信任所有來源 IP，因為實際上它只會收到**代理**那個 IP 送來的請求。

* [X-Forwarded-Proto](https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/X-Forwarded-Proto)
* [X-Forwarded-Host](https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/X-Forwarded-Host)

///

それでも、**アプリケーションサーバー**は信頼できる**プロキシ**の背後にあることを知らないため、デフォルトではそれらのヘッダーを信頼しません。

         proxy_buffering off;

        location / {
            proxy_set_header Host $http_host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;

            proxy_connect_timeout 300;
            # Default is HTTP/1, keepalive is only enabled in HTTP/1.1
            proxy_http_version 1.1;

 * interface-specific subclass of {@code ForwardingObject}, such as {@link ForwardingList}, to
 * preserve equality behavior, or override {@code equals} directly.
 *
 * <p>The {@code toString} method is forwarded to the delegate. Although this class does not
 * implement {@link Serializable}, a serializable subclass may be created since this class has a
 * parameter-less constructor.
 *
 * @author Mike Bostock
 * @since 2.0
 */

        if (isTrustedProxy(remoteAddr)) {
            final String xForwardedFor = request.getHeader("X-Forwarded-For");
            if (StringUtil.isNotBlank(xForwardedFor)) {
                final String clientIp = xForwardedFor.split(",")[0].trim();
                if (logger.isDebugEnabled()) {
                    logger.debug("Client IP from X-Forwarded-For: clientIp={}, remoteAddr={}", clientIp, remoteAddr);
                }