[BUG] Unable to connect to MCP Server when using HTTP PROXY.

[Steve0x2a]

Environment

• Platform (select one):
  • Anthropic API
  • AWS Bedrock
  • Google Vertex AI
  • Other:
• Claude CLI version: 1.0.56
• Operating System: MacOS 15.5
• Terminal: iTerm2

Bug Description

When I use the HTTP_PROXY or HTTPS_PROXY environment variables, I am unable to connect to the local STDIO MCP.

Steps to Reproduce

1. set HTTP_PROXY or HTTPS_PROXY in ~/.claude/settings.json
2. run claude
3. run /mcp command

Expected Behavior

Successfully connected to MCP

Actual Behavior

Unable to connect to MCP until timeout.

Additional Context

[DEBUG] MCP server "thinking": Connection failed: Error: Connection to MCP server "thinking" timed out after 30000ms
[DEBUG] MCP server "thinking": Error message: Connection to MCP server "thinking" timed out after 30000ms
[DEBUG] MCP server "thinking": Error stack: Error: Connection to MCP server "thinking" timed out after 30000ms
at Timeout._onTimeout (file:///Users/xxx/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:1317:2421)
at listOnTimeout (node:internal/timers:608:17)
at process.processTimers (node:internal/timers:543:7)

[DEBUG] MCP server "thinking": Connection attempt completed in 30025ms - status: failed
[DEBUG] MCP server "thinking": Connection attempt completed in 29504ms - status: failed
[DEBUG] MCP server "thinking": Connection attempt completed in 29245ms - status: failed

My MCP Config:

{
    "thinking": {
      "type": "stdio",
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-sequential-thinking"
      ],
      "env": {}
    }
  }

[bitk0der]

same here, did you found a solution?

[Steve0x2a]

same here, did you found a solution?

no😩

[terenceYu1997]

Using Python to implement a layer of forwarding can achieve NO_PROXY

1. bypass-proxy.py (to forward locally to port 8889)

import socket
import socketserver
import threading
import select
import time

PROXY_HOST = "127.0.0.1"
PROXY_PORT = 8889  # 本地转发代理端口
CLASH_PROXY = ("127.0.0.1", 7890)  # Clash 代理

# 本地绕过列表
LOCAL_BYPASS = {
    "127.0.0.1", 
    "localhost", 
    "0.0.0.0",
    "::1"  # IPv6 localhost
}

class ProxyHandler(socketserver.StreamRequestHandler):
    def handle(self):
        try:
            data = self.connection.recv(8192)
            if not data:
                return

            # 解析目标主机
            first_line = data.split(b"\r\n", 1)[0].decode(errors="ignore")
            
            if first_line.startswith("CONNECT"):
                host = first_line.split()[1].split(":")[0]
                port = int(first_line.split()[1].split(":")[1])
            else:
                host_line = [line for line in data.split(b"\r\n") if line.lower().startswith(b"host:")]
                host = host_line[0].decode(errors="ignore").split(":")[1].strip() if host_line else ""
                port = 80

            # 判断是否直连
            if host in LOCAL_BYPASS or any(bypass in host for bypass in LOCAL_BYPASS):
                self.direct_connect(data, host, port if 'port' in locals() else 80)
            else:
                self.proxy_connect(data)
        except Exception as e:
            pass  # 静默处理错误

    def direct_connect(self, first_data, host, port=80):
        try:
            if first_data.startswith(b"CONNECT"):
                port = int(first_data.split(b" ")[1].split(b":")[1])
                self.connection.sendall(b"HTTP/1.1 200 Connection Established\r\n\r\n")
            else:
                try:
                    if ":" in host:
                        host, port = host.split(":")
                        port = int(port)
                except:
                    pass

            with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as remote:
                remote.settimeout(10)
                remote.connect((host, port))
                if not first_data.startswith(b"CONNECT"):
                    remote.sendall(first_data)
                self.forward_data(self.connection, remote)
        except Exception as e:
            pass

    def proxy_connect(self, first_data):
        try:
            with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as remote:
                remote.settimeout(10)
                remote.connect(CLASH_PROXY)
                remote.sendall(first_data)
                self.forward_data(self.connection, remote)
        except Exception as e:
            pass

    def forward_data(self, client, remote):
        try:
            sockets = [client, remote]
            while True:
                rlist, _, _ = select.select(sockets, [], [], 1.0)
                if not rlist:
                    continue
                    
                if client in rlist:
                    data = client.recv(8192)
                    if not data:
                        break
                    remote.sendall(data)
                if remote in rlist:
                    data = remote.recv(8192)
                    if not data:
                        break
                    client.sendall(data)
        except Exception as e:
            pass

def start_proxy():
    server = socketserver.ThreadingTCPServer((PROXY_HOST, PROXY_PORT), ProxyHandler)
    server.allow_reuse_address = True
    print(f"Bypass proxy running on {PROXY_HOST}:{PROXY_PORT}")
    server.serve_forever()

if __name__ == "__main__":
    try:
        threading.Thread(target=start_proxy).start()
        print("代理服务器已启动，按 Ctrl+C 停止")
        while True:
            time.sleep(1)
    except KeyboardInterrupt:
        print("\n正在停止代理服务器...")

2. modify ~/.claude/settings.json

{
  "env": {
"HTTP_PROXY": "http://127.0.0.1:8889",
    "HTTPS_PROXY": "http://127.0.0.1:8889"
  },
  "feedbackSurveyState": {
    "lastShownTime": 1754086996267
  },
  "$schema": "https://json.schemastore.org/claude-code-settings.json"
}

[bitk0der]

Using Python to implement a layer of forwarding can achieve NO_PROXY

1. bypass-proxy.py (to forward locally to port 8889)

Sorry, but not the solution, the only viable solution is natively support of NO_PROXY env

[terenceYu1997]

Using Python to implement a layer of forwarding can achieve NO_PROXY
1. bypass-proxy.py (to forward locally to port 8889)

Sorry, but not the solution, the only viable solution is natively support of NO_PROXY env

I have tested that it can be used

[rocky-terracotta]

You can try using privoxy to proxy the traffic. For example in /etc/privoxy/config:

forward-socks5 / 127.0.0.1:1080 .
forward 10.1.0.1:3000 .

This creates a http proxy that proxies all traffic except for MCP traffic (which in this example is hosted on 10.1.0.1 on port 3000)

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