feat: add trust_forwarded_proto option for SSL redirect handling in reverse proxy scenarios

When Nginx is behind another proxy server (like CloudFlare or AWS ALB), the force-SSL
feature can cause redirect loops because Nginx sees the connection as plain HTTP
while SSL is already handled upstream. This adds a new boolean option to trust
the X-Forwarded-Proto header from upstream proxies.

Changes:
- Add `trust_forwarded_proto` column to proxy_host table (migration)
- Update model and API schema to support the new boolean field
- Modify force-ssl Nginx template to check X-Forwarded-Proto/X-Forwarded-Scheme
- Add map directives in nginx.conf to validate and sanitize forwarded headers
- Add advanced option toggle in frontend UI with i18n support (EN/ZH)
- Set proxy headers from validated map variables instead of $scheme

This allows administrators to control SSL redirect behavior when Nginx is deployed
behind a TLS-terminating proxy.

backend/migrations/20260131163528_trust_forwarded_proto.js

@@ -0,0 +1,31 @@
+import { migrate as logger } from "../logger.js";
+
+const migrateName = "redirect_auto_scheme";
+
+/**
+ * Migrate
+ *
+ * @see http://knexjs.org/#Schema
+ *
+ * @param   {Object} knex
+ * @returns {Promise}
+ */
+const up = function (knex) {
+    return knex.schema.alterTable('proxy_host', (table) => {
+        table.tinyint('trust_forwarded_proto').notNullable().defaultTo(0);
+    });
+};
+
+/**
+ * Undo Migrate
+ *
+ * @param   {Object} knex
+ * @returns {Promise}
+ */
+const down = function (knex) {
+    return knex.schema.alterTable('proxy_host', (table) => {
+        table.dropColumn('trust_forwarded_proto');
+    });
+};
+
+export { up, down };

backend/models/proxy_host.js

@@ -21,6 +21,7 @@ const boolFields = [
 	"enabled",
 	"hsts_enabled",
 	"hsts_subdomains",
+	"trust_forwarded_proto",
 ];
 
 class ProxyHost extends Model {

backend/schema/components/proxy-host-object.json

@@ -22,7 +22,8 @@
 		"enabled",
 		"locations",
 		"hsts_enabled",
-		"hsts_subdomains"
+		"hsts_subdomains",
+		"trust_forwarded_proto"
 	],
 	"properties": {
 		"id": {
@@ -141,6 +142,10 @@
 		"hsts_subdomains": {
 			"$ref": "../common.json#/properties/hsts_subdomains"
 		},
+		"trust_forwarded_proto":{
+			"type": "boolean",
+			"example": false
+		},
 		"certificate": {
 			"oneOf": [
 				{

backend/schema/paths/nginx/proxy-hosts/hostID/put.json

@@ -56,6 +56,9 @@
 						"hsts_subdomains": {
 							"$ref": "../../../../components/proxy-host-object.json#/properties/hsts_subdomains"
 						},
+						"trust_forwarded_proto": {
+    						"$ref": "../../../../components/proxy-host-object.json#/properties/trust_forwarded_proto"
+						},
 						"http2_support": {
 							"$ref": "../../../../components/proxy-host-object.json#/properties/http2_support"
 						},

backend/schema/paths/nginx/proxy-hosts/post.json

@@ -48,6 +48,9 @@
 						"hsts_subdomains": {
 							"$ref": "../../../components/proxy-host-object.json#/properties/hsts_subdomains"
 						},
+						"trust_forwarded_proto": {
+    						"$ref": "../../../components/proxy-host-object.json#/properties/trust_forwarded_proto"
+						},
 						"http2_support": {
 							"$ref": "../../../components/proxy-host-object.json#/properties/http2_support"
 						},

backend/templates/_forced_ssl.conf

@@ -1,6 +1,11 @@
 {% if certificate and certificate_id > 0 -%}
 {% if ssl_forced == 1 or ssl_forced == true %}
     # Force SSL
+    {% if trust_forwarded_proto == true %}
+    set $trust_forwarded_proto "T";
+    {% else %}
+    set $trust_forwarded_proto "F";
+    {% endif %}
     include conf.d/include/force-ssl.conf;
 {% endif %}
 {% endif %}

docker/rootfs/etc/nginx/conf.d/include/force-ssl.conf

@@ -5,9 +5,25 @@ if ($scheme = "http") {
 if ($request_uri = /.well-known/acme-challenge/test-challenge) {
 	set $test "${test}T";
 }
+
+# Check if the ssl staff has been handled
+set $test_proto "";
+if ($trust_forwarded_proto = T){
+	set $test_proto "${test_proto}T";
+}
 if ($http_x_forwarded_proto = "https") {
+	set $test_proto "${test_proto}S";
+}
+if ($http_x_forwarded_scheme = "https") {
+	set $test_proto "${test_proto}S";
+}
+if ($test_proto = "TSS") {
+	set $test_proto "TS";
+}
+if ($test_proto = "TS") {
 	set $test "${test}S";
 }
+
 if ($test = H) {
 	return 301 https://$host$request_uri;
 }

docker/rootfs/etc/nginx/conf.d/include/proxy.conf

@@ -1,7 +1,7 @@
 add_header       X-Served-By $host;
 proxy_set_header Host $host;
-proxy_set_header X-Forwarded-Scheme $scheme;
+proxy_set_header X-Forwarded-Scheme $x_forwarded_scheme;
-proxy_set_header X-Forwarded-Proto  $scheme;
+proxy_set_header X-Forwarded-Proto  $x_forwarded_proto;
 proxy_set_header X-Forwarded-For    $proxy_add_x_forwarded_for;
 proxy_set_header X-Real-IP          $remote_addr;
 proxy_pass       $forward_scheme://$server:$port$request_uri;

docker/rootfs/etc/nginx/nginx.conf

@@ -57,6 +57,18 @@ http {
 		default http;
 	}
 
+	# Handle upstream X-Forwarded-Proto and X-Forwarded-Scheme header
+	map $http_x_forwarded_proto $x_forwarded_proto {
+		"http" "http";
+		"https" "https";
+		default $scheme;
+	}
+	map $http_x_forwarded_scheme $x_forwarded_scheme {
+		"http" "http";
+		"https" "https";
+		default $scheme;
+	} 
+
 	# Real IP Determination
 
 	# Local subnets:

frontend/src/api/backend/models.ts

@@ -127,6 +127,7 @@ export interface ProxyHost {
 	locations?: ProxyLocation[];
 	hstsEnabled: boolean;
 	hstsSubdomains: boolean;
+	trustForwardedProto: boolean;
 	// Expansions:
 	owner?: User;
 	accessList?: AccessList;

frontend/src/components/Form/SSLOptionsFields.tsx

@@ -15,7 +15,7 @@ export function SSLOptionsFields({ forHttp = true, forceDNSForNew, requireDomain
 
 	const newCertificate = v?.certificateId === "new";
 	const hasCertificate = newCertificate || (v?.certificateId && v?.certificateId > 0);
-	const { sslForced, http2Support, hstsEnabled, hstsSubdomains, meta } = v;
+	const { sslForced, http2Support, hstsEnabled, hstsSubdomains, trustForwardedProto, meta } = v;
 	const { dnsChallenge } = meta || {};
 
 	if (forceDNSForNew && newCertificate && !dnsChallenge) {
@@ -140,6 +140,31 @@ export function SSLOptionsFields({ forHttp = true, forceDNSForNew, requireDomain
 					{dnsChallenge ? <DNSProviderFields showBoundaryBox /> : null}
 				</>
 			) : null}
+			{<div>
+				<details>
+					<summary className="mb-1"><T id="domains.advanced" /></summary>
+					<div className="row">
+						<div className="col-12">
+							<Field name="trustForwardedProto">
+								{({ field }: any) => (
+									<label className="form-check form-switch mt-1">
+										<input
+											className={trustForwardedProto ? toggleEnabled : toggleClasses}
+											type="checkbox"
+											checked={!!trustForwardedProto}
+											onChange={(e) => handleToggleChange(e, field.name)}
+											disabled={!hasCertificate || !sslForced}
+										/>
+										<span className="form-check-label">
+											<T id="domains.trust-forwarded-proto" />
+										</span>
+									</label>
+								)}
+							</Field>
+						</div>
+					</div>
+				</details>
+			</div>}
 		</div>
 	);
 }

frontend/src/hooks/useProxyHost.ts

@@ -24,6 +24,7 @@ const fetchProxyHost = (id: number | "new") => {
 			enabled: true,
 			hstsEnabled: false,
 			hstsSubdomains: false,
+			trustForwardedProto: false,
 		} as ProxyHost);
 	}
 	return getProxyHost(id, ["owner"]);

frontend/src/locale/src/en.json

@@ -347,6 +347,9 @@
 	"domain-names.wildcards-not-supported": {
 		"defaultMessage": "Wildcards not supported for this CA"
 	},
+	"domains.advanced": {
+		"defaultMessage": "Advanced"
+	},
 	"domains.force-ssl": {
 		"defaultMessage": "Force SSL"
 	},
@@ -359,6 +362,9 @@
 	"domains.http2-support": {
 		"defaultMessage": "HTTP/2 Support"
 	},
+	"domains.trust-forwarded-proto": {
+		"defaultMessage": "Trust Upstream Forwarded Proto Headers"
+	},
 	"domains.use-dns": {
 		"defaultMessage": "Use DNS Challenge"
 	},

frontend/src/locale/src/zh.json

@@ -275,6 +275,9 @@
 	"domain-names.wildcards-not-supported": {
 		"defaultMessage": "此 CA 不支持通配符"
 	},
+	"domains.advanced": {
+		"defaultMessage": "高级选项"
+	},
 	"domains.force-ssl": {
 		"defaultMessage": "强制 SSL"
 	},
@@ -287,6 +290,9 @@
 	"domains.http2-support": {
 		"defaultMessage": "HTTP/2 支持"
 	},
+	"domains.trust-forwarded-proto": {
+		"defaultMessage": "信任上游代理传递的协议类型头"
+	},
 	"domains.use-dns": {
 		"defaultMessage": "使用DNS验证"
 	},

frontend/src/modals/ProxyHostModal.tsx

@@ -88,6 +88,7 @@ const ProxyHostModal = EasyModal.create(({ id, visible, remove }: Props) => {
 							http2Support: data?.http2Support || false,
 							hstsEnabled: data?.hstsEnabled || false,
 							hstsSubdomains: data?.hstsSubdomains || false,
+							trustForwardedProto: data?.trustForwardedProto || false,
 							// Advanced tab
 							advancedConfig: data?.advancedConfig || "",
 							meta: data?.meta || {},