Add upstream SOCKS5 proxy support for inspector proxy

client/bin/start.js

@@ -13,7 +13,13 @@ function delay(ms) {
   return new Promise((resolve) => setTimeout(resolve, ms, true));
 }
 
-function getClientUrl(port, authDisabled, sessionToken, serverPort) {
+function getClientUrl(
+  port,
+  authDisabled,
+  sessionToken,
+  serverPort,
+  upstreamSocks5Proxy,
+) {
   const host = process.env.HOST || "localhost";
   const baseUrl = `http://${host}:${port}`;
 
@@ -24,6 +30,9 @@ function getClientUrl(port, authDisabled, sessionToken, serverPort) {
   if (!authDisabled) {
     params.set("MCP_PROXY_AUTH_TOKEN", sessionToken);
   }
+  if (upstreamSocks5Proxy) {
+    params.set("MCP_UPSTREAM_SOCKS5_PROXY", upstreamSocks5Proxy);
+  }
   return params.size > 0 ? `${baseUrl}/?${params.toString()}` : baseUrl;
 }
 
@@ -36,6 +45,7 @@ async function startDevServer(serverOptions) {
     abort,
     transport,
     serverUrl,
+    upstreamSocks5Proxy,
   } = serverOptions;
   const serverCommand = "npx";
   const serverArgs = ["tsx", "watch", "--clear-screen=false", "src/index.ts"];
@@ -51,6 +61,9 @@ async function startDevServer(serverOptions) {
       MCP_ENV_VARS: JSON.stringify(envVars),
       ...(transport ? { MCP_TRANSPORT: transport } : {}),
       ...(serverUrl ? { MCP_SERVER_URL: serverUrl } : {}),
+      ...(upstreamSocks5Proxy
+        ? { MCP_UPSTREAM_SOCKS5_PROXY: upstreamSocks5Proxy }
+        : {}),
     },
     signal: abort.signal,
     echoOutput: true,
@@ -91,6 +104,7 @@ async function startProdServer(serverOptions) {
     mcpServerArgs,
     transport,
     serverUrl,
+    upstreamSocks5Proxy,
   } = serverOptions;
   const inspectorServerPath = resolve(
     __dirname,
@@ -110,6 +124,7 @@ async function startProdServer(serverOptions) {
         : []),
       ...(transport ? [`--transport=${transport}`] : []),
       ...(serverUrl ? [`--server-url=${serverUrl}`] : []),
+      ...(upstreamSocks5Proxy ? [`--socks5=${upstreamSocks5Proxy}`] : []),
     ],
     {
       env: {
@@ -138,6 +153,7 @@ async function startDevClient(clientOptions) {
     sessionToken,
     abort,
     cancelled,
+    upstreamSocks5Proxy,
   } = clientOptions;
   const clientCommand = "npx";
   const host = process.env.HOST || "localhost";
@@ -163,6 +179,7 @@ async function startDevClient(clientOptions) {
     authDisabled,
     sessionToken,
     SERVER_PORT,
+    upstreamSocks5Proxy,
   );
 
   // Give vite time to start before opening or logging the URL
@@ -196,6 +213,7 @@ async function startProdClient(clientOptions) {
     sessionToken,
     abort,
     cancelled,
+    upstreamSocks5Proxy,
   } = clientOptions;
   const inspectorClientPath = resolve(
     __dirname,
@@ -210,6 +228,7 @@ async function startProdClient(clientOptions) {
     authDisabled,
     sessionToken,
     SERVER_PORT,
+    upstreamSocks5Proxy,
   );
 
   await spawnPromise("node", [inspectorClientPath], {
@@ -233,6 +252,7 @@ async function main() {
   let isDev = false;
   let transport = null;
   let serverUrl = null;
+  let upstreamSocks5Proxy = process.env.MCP_UPSTREAM_SOCKS5_PROXY || null;
 
   for (let i = 0; i < args.length; i++) {
     const arg = args[i];
@@ -257,6 +277,11 @@ async function main() {
       continue;
     }
 
+    if (parsingFlags && arg === "--socks5" && i + 1 < args.length) {
+      upstreamSocks5Proxy = args[++i];
+      continue;
+    }
+
     if (parsingFlags && arg === "-e" && i + 1 < args.length) {
       const envVar = args[++i];
       const equalsIndex = envVar.indexOf("=");
@@ -310,6 +335,7 @@ async function main() {
       mcpServerArgs,
       transport,
       serverUrl,
+      upstreamSocks5Proxy,
     };
 
     const result = isDev
@@ -329,6 +355,7 @@ async function main() {
         sessionToken,
         abort,
         cancelled,
+        upstreamSocks5Proxy,
       };
 
       await (isDev

client/src/App.tsx

@@ -724,6 +724,21 @@ const App = () => {
         if (data.defaultServerUrl) {
           setSseUrl(data.defaultServerUrl);
         }
+        if (data.defaultUpstreamSocks5Proxy) {
+          setConfig((prev) => {
+            if (prev.MCP_UPSTREAM_SOCKS5_PROXY.value) {
+              return prev;
+            }
+
+            return {
+              ...prev,
+              MCP_UPSTREAM_SOCKS5_PROXY: {
+                ...prev.MCP_UPSTREAM_SOCKS5_PROXY,
+                value: data.defaultUpstreamSocks5Proxy,
+              },
+            };
+          });
+        }
       })
       .catch((error) =>
         console.error("Error fetching default environment:", error),

client/src/lib/configurationTypes.ts

@@ -41,6 +41,11 @@ export type InspectorConfig = {
    */
   MCP_PROXY_AUTH_TOKEN: ConfigItem;
 
+  /**
+   * Optional SOCKS5 proxy URL used by the Inspector proxy server when connecting to upstream SSE or Streamable HTTP MCP servers.
+   */
+  MCP_UPSTREAM_SOCKS5_PROXY: ConfigItem;
+
   /**
    * Default Time-to-Live (TTL) in milliseconds for newly created tasks.
    */

client/src/lib/constants.ts

@@ -85,6 +85,13 @@ export const DEFAULT_INSPECTOR_CONFIG: InspectorConfig = {
     value: "",
     is_session_item: true,
   },
+  MCP_UPSTREAM_SOCKS5_PROXY: {
+    label: "Upstream SOCKS5 Proxy",
+    description:
+      "Optional SOCKS5 proxy for the Inspector proxy server when it connects to upstream SSE or Streamable HTTP MCP servers. Example: socks5://127.0.0.1:1080",
+    value: "",
+    is_session_item: false,
+  },
   MCP_TASK_TTL: {
     label: "Task TTL",
     description:

client/src/lib/hooks/useConnection.ts

@@ -643,6 +643,8 @@ export function useConnection({
         }
 
         let mcpProxyServerUrl;
+        const upstreamSocks5Proxy = config.MCP_UPSTREAM_SOCKS5_PROXY
+          .value as string;
         switch (transportType) {
           case "stdio": {
             mcpProxyServerUrl = new URL(`${getMCPProxyAddress(config)}/stdio`);
@@ -680,6 +682,12 @@ export function useConnection({
           case "sse": {
             mcpProxyServerUrl = new URL(`${getMCPProxyAddress(config)}/sse`);
             mcpProxyServerUrl.searchParams.append("url", sseUrl);
+            if (upstreamSocks5Proxy) {
+              mcpProxyServerUrl.searchParams.append(
+                "socks5",
+                upstreamSocks5Proxy,
+              );
+            }
 
             const proxyFullAddressSSE = config.MCP_PROXY_FULL_ADDRESS
               .value as string;
@@ -711,6 +719,12 @@ export function useConnection({
           case "streamable-http":
             mcpProxyServerUrl = new URL(`${getMCPProxyAddress(config)}/mcp`);
             mcpProxyServerUrl.searchParams.append("url", sseUrl);
+            if (upstreamSocks5Proxy) {
+              mcpProxyServerUrl.searchParams.append(
+                "socks5",
+                upstreamSocks5Proxy,
+              );
+            }
             transportOptions = {
               authProvider: serverAuthProvider,
               eventSourceInit: {

package.json

@@ -60,7 +60,9 @@
     "node-fetch": "^3.3.2",
     "open": "^10.2.0",
     "shell-quote": "^1.8.3",
+    "socks-proxy-agent": "^10.0.0",
     "spawn-rx": "^5.1.2",
+    "tailwind-merge": "^3.6.0",
     "ts-node": "^10.9.2",
     "zod": "^3.25.76"
   },

server/package.json

@@ -38,6 +38,7 @@
     "@modelcontextprotocol/sdk": "^1.25.2",
     "cors": "^2.8.5",
     "express": "^5.1.0",
+    "socks-proxy-agent": "^10.0.0",
     "shell-quote": "^1.8.3",
     "shx": "^0.3.4",
     "spawn-rx": "^5.1.2",