使用 mitmprox 抓取 codex 数据包
标题里写的是
mitmprox，实际使用的工具名是mitmproxy。
这篇文章只做一件事：在 macOS 上用 mitmproxy 抓一次 Codex 发送 hello 的请求，并把请求体导出成文本文件。
Step 1. 安装 mitmproxy
brew install mitmproxy
确认安装成功：
mitmdump --version
Step 2. 启动抓包代理
打开第一个终端，执行：
mitmdump --listen-host 127.0.0.1 --listen-port 8080 -w codex-hello.mitm
这一步会：
- 在本机启动代理
127.0.0.1:8080 - 把抓到的流量保存到
codex-hello.mitm
这个终端先不要关。
Step 3. 安装 mitmproxy 根证书
第一次启动 mitmproxy 后，会在本机生成证书：
open ~/.mitmproxy
在 macOS 中操作：
- 双击
mitmproxy-ca-cert.pem - 导入到“登录”钥匙串
- 打开“钥匙串访问”
- 找到
mitmproxy证书 - 双击证书，展开“信任”
- 把“使用此证书时”改成“始终信任”
- 关闭窗口并输入密码保存
Step 4. 让 Codex 走本地代理
打开第二个终端，执行：
export HTTP_PROXY="http://127.0.0.1:8080"
export HTTPS_PROXY="http://127.0.0.1:8080"
export ALL_PROXY="http://127.0.0.1:8080"
export SSL_CERT_FILE="$HOME/.mitmproxy/mitmproxy-ca-cert.pem"
export NODE_EXTRA_CA_CERTS="$HOME/.mitmproxy/mitmproxy-ca-cert.pem"
Step 5. 启动 Codex 并发送 hello
还是在第二个终端里执行：
codex
进入交互界面后，输入：
hello
发送后，回到第一个终端，你应该能看到 mitmdump 打印出新的请求记录。
Step 6. 停止抓包并确认文件
在第一个终端按 Ctrl+C 停止抓包。
然后检查文件是否存在：
ls -lh codex-hello.mitm
如果文件存在，说明抓包成功。
Step 7. 回放抓包文件
mitmproxy -nr codex-hello.mitm
你可以在这里看到请求和响应。
Step 8. 把请求体导出成文本文件
新建一个脚本 save_request_body.py：
from pathlib import Path
from mitmproxy import http
saved = False
def request(flow: http.HTTPFlow) -> None:
global saved
if saved:
return
body = flow.request.get_text(strict=False)
Path("codex-hello-request.json").write_text(body, encoding="utf-8")
saved = True
然后执行：
mitmdump -nr codex-hello.mitm -s save_request_body.py
执行完成后，当前目录会多出一个文件：
codex-hello-request.json
这个文件就是抓到的请求体文本。
Step 9. 请求体完整长什么样
Codex 发送的请求体通常不是单独一个 hello，而是一整个 JSON 包，里面会带上模型、系统提示词、工具定义、推理配置和当前输入。
下面这个例子保留了完整请求体结构，但把长文本、路径、缓存键和其他敏感值做了脱敏。这样既能看清楚请求体完整长什么样，也适合公开展示。
{
"type": "response.create",
"model": "gpt-5.4",
"instructions": "<full system instructions redacted>",
"previous_response_id": null,
"input": [
{
"type": "message",
"role": "developer",
"content": [
{
"type": "input_text",
"text": "<permissions instructions redacted>"
}
]
},
{
"type": "message",
"role": "user",
"content": [
{
"type": "input_text",
"text": "# AGENTS.md instructions for <workspace path redacted>\n\n<INSTRUCTIONS>...redacted...</INSTRUCTIONS>"
},
{
"type": "input_text",
"text": "<environment_context>\n <cwd><workspace path redacted></cwd>\n <shell>zsh</shell>\n <current_date>2026-03-09</current_date>\n <timezone>Asia/Shanghai</timezone>\n</environment_context>"
}
]
},
{
"type": "message",
"role": "developer",
"content": [
{
"type": "input_text",
"text": "<collaboration_mode># Collaboration Mode: Default ... redacted ...</collaboration_mode>"
}
]
},
{
"type": "message",
"role": "user",
"content": [
{
"type": "input_text",
"text": "hello"
}
]
}
],
"tools": [
{
"type": "function",
"name": "exec_command",
"description": "Runs a command in a PTY, returning output or a session ID for ongoing interaction.",
"strict": false,
"parameters": {
"type": "object",
"properties": {
"cmd": {
"type": "string",
"description": "Shell command to execute."
},
"justification": {
"type": "string",
"description": "<redacted>"
},
"login": {
"type": "boolean",
"description": "Whether to run the shell with -l/-i semantics. Defaults to true."
},
"max_output_tokens": {
"type": "number",
"description": "Maximum number of tokens to return. Excess output will be truncated."
},
"prefix_rule": {
"type": "array",
"items": {
"type": "string"
},
"description": "<redacted>"
},
"sandbox_permissions": {
"type": "string",
"description": "Sandbox permissions for the command. Set to \"require_escalated\" to request running without sandbox restrictions; defaults to \"use_default\"."
},
"shell": {
"type": "string",
"description": "Shell binary to launch. Defaults to the user's default shell."
},
"tty": {
"type": "boolean",
"description": "Whether to allocate a TTY for the command."
},
"workdir": {
"type": "string",
"description": "Optional working directory to run the command in."
},
"yield_time_ms": {
"type": "number",
"description": "How long to wait (in milliseconds) for output before yielding."
}
},
"required": ["cmd"],
"additionalProperties": false
}
},
{
"type": "function",
"name": "write_stdin",
"description": "Writes characters to an existing unified exec session and returns recent output.",
"strict": false,
"parameters": {
"type": "object",
"properties": {
"chars": {
"type": "string",
"description": "Bytes to write to stdin (may be empty to poll)."
},
"max_output_tokens": {
"type": "number",
"description": "Maximum number of tokens to return. Excess output will be truncated."
},
"session_id": {
"type": "number",
"description": "Identifier of the running unified exec session."
},
"yield_time_ms": {
"type": "number",
"description": "How long to wait (in milliseconds) for output before yielding."
}
},
"required": ["session_id"],
"additionalProperties": false
}
},
{
"type": "function",
"name": "update_plan",
"description": "Updates the task plan.",
"strict": false,
"parameters": {
"type": "object",
"properties": {
"explanation": {
"type": "string"
},
"plan": {
"type": "array",
"items": {
"type": "object",
"properties": {
"status": {
"type": "string",
"description": "One of: pending, in_progress, completed"
},
"step": {
"type": "string"
}
},
"required": ["step", "status"],
"additionalProperties": false
}
}
},
"required": ["plan"],
"additionalProperties": false
}
},
{
"type": "function",
"name": "request_user_input",
"description": "Request user input for one to three short questions and wait for the response.",
"strict": false,
"parameters": {
"type": "object",
"properties": {
"questions": {
"type": "array",
"items": {
"type": "object",
"properties": {
"header": {
"type": "string"
},
"id": {
"type": "string"
},
"options": {
"type": "array",
"items": {
"type": "object",
"properties": {
"description": {
"type": "string"
},
"label": {
"type": "string"
}
},
"required": ["label", "description"],
"additionalProperties": false
}
},
"question": {
"type": "string"
}
},
"required": ["id", "header", "question", "options"],
"additionalProperties": false
}
}
},
"required": ["questions"],
"additionalProperties": false
}
},
{
"type": "custom",
"name": "apply_patch",
"description": "Use the `apply_patch` tool to edit files.",
"format": {
"type": "grammar",
"syntax": "lark",
"definition": "<lark grammar redacted>"
}
},
{
"type": "web_search",
"external_web_access": true,
"search_content_types": ["text", "image"]
},
{
"type": "function",
"name": "view_image",
"description": "View a local image from the filesystem.",
"strict": false,
"parameters": {
"type": "object",
"properties": {
"path": {
"type": "string",
"description": "Local filesystem path to an image file"
}
},
"required": ["path"],
"additionalProperties": false
}
}
],
"tool_choice": "auto",
"parallel_tool_calls": true,
"reasoning": {
"effort": "high"
},
"store": false,
"stream": true,
"include": ["reasoning.encrypted_content"],
"prompt_cache_key": "<redacted>",
"text": {
"verbosity": "low"
},
"generate": false,
"client_metadata": {
"x-codex-turn-metadata": "{\"turn_id\":\"<redacted>\",\"sandbox\":\"seatbelt\"}"
}
}
从这个例子可以看出来，hello 只是 input 里的最后一条用户消息，而不是整个请求体本身。真正发出去的是一个完整的代理请求包。
注意
不要把真实抓包里的 token、缓存键、本地路径、完整系统提示词或者完整会话内容直接发到博客、工单或公开仓库。要展示完整结构时，建议像上面这样保留字段、脱敏字段值。