OmniRoute/docs/STEALTH_GUIDE.md

Stealth Guide

Source of truth: open-sse/utils/tlsClient.ts, open-sse/services/{chatgptTlsClient,claudeCodeCCH,claudeCodeFingerprint,claudeCodeObfuscation,claudeCodeCompatible,antigravityObfuscation}.ts, open-sse/config/cliFingerprints.ts, src/mitm/ Last updated: 2026-05-13 — v3.8.0 Audience: Engineers maintaining provider-specific stealth integrations.

OmniRoute integrates with providers whose edges actively fingerprint non-official clients (TLS JA3/JA4, header ordering, JSON body shape, integrity tokens). This page documents the stealth surfaces OmniRoute exposes and where they are implemented.

Legal and Ethical Notice

Stealth features exist so OmniRoute can act as a compatibility layer between user-owned official accounts (Claude Code CLI, ChatGPT Desktop/Web, Antigravity, Cursor, etc.) and OmniRoute's unified API. They are not for evading fraud detection, sharing credentials, or violating provider Terms of Service. The maintainers expect operators to comply with the upstream ToS they signed when creating accounts.

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TLS Fingerprinting Layer

open-sse/utils/tlsClient.ts — wreq-js (Chrome 124)

Lazy-loaded wreq-js session that impersonates Chrome 124 on macOS. Used as a generic JA3/JA4 wrapper for upstreams behind Cloudflare. Falls back to native fetch when wreq-js is not installed (available = false).

• Singleton session: browser: "chrome_124", os: "macos"
• Proxy resolution (priority): HTTPS_PROXY → HTTP_PROXY → ALL_PROXY (also lower-case)
• Timeout: TLS_CLIENT_TIMEOUT_MS (inherits from FETCH_TIMEOUT_MS, default 600000)
• wreq-js Response is fetch-compatible (headers, text(), json(), clone(), body).

open-sse/services/chatgptTlsClient.ts — tls-client-node (Firefox 148)

Dedicated TLS impersonator for chatgpt.com. ChatGPT's Cloudflare config pins cf_clearance to JA3/JA4 + HTTP/2 SETTINGS frame ordering — undici's handshake gets cf-mitigated: challenge even with valid cookies.

• Profile: firefox_148 (must match the Firefox 148 User-Agent sent)
• Mode: runtimeMode: "native" (koffi-loaded shared library; avoids managed sidecar HTTP)
• withRandomTLSExtensionOrder: true
• tlsFetchChatGpt(url, options) supports streaming (writes body to temp file, tailed as ReadableStream)
• Hang detection: raceWithTimeout + TlsClientHangError triggers resetClientCache() so the next call respawns the binding
• Proxy resolution (priority): per-call proxyUrl → OMNIROUTE_TLS_PROXY_URL → HTTPS_PROXY/HTTP_PROXY/ALL_PROXY (the native binding does not read these envs itself; it must be threaded through)
• Errors: TlsClientUnavailableError (binary missing), TlsClientHangError (binding deadlocked)

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Claude Code Stealth Bundle

When cliCompatMode is on, OmniRoute reshapes outgoing Claude requests so they are indistinguishable from claude-cli traffic. Three modules collaborate:

claudeCodeFingerprint.ts

Computes the 3-char cc_version fingerprint embedded in the billing header:

SHA256(SALT + msg[4] + msg[7] + msg[20] + version)[:3]

• FINGERPRINT_SALT = "59cf53e54c78" (hardcoded; matches official client)
• Inputs: chars at index 4, 7, 20 of the first user message text + version string
• Output: 3-char hex prefix

claudeCodeCCH.ts (Client Content Hash)

Server-side integrity check the official Claude Code CLI computes via Bun/Zig. OmniRoute reimplements with xxhash-wasm:

1. Serialize body with cch=00000; placeholder
2. xxhash64(bytes, seed) & 0xFFFFF
3. Zero-padded 5-char lowercase hex
4. Replace cch=00000; with the computed token

Constants:

• Seed: 0x6e52736ac806831e
• Pattern: /\bcch=([0-9a-f]{5});/

claudeCodeObfuscation.ts

Inserts a Unicode zero-width joiner (U+200D) after the first character of "sensitive" client names so upstream filters cannot grep them. Default word list:

opencode, open-code, cline, roo-cline, roo_cline, cursor, windsurf,
aider, continue.dev, copilot, avante, codecompanion

Applied to: system blocks, all messages[].content, and tools[].description / tools[].function.description. Operator-overridable via setSensitiveWords().

claudeCodeCompatible.ts — anthropic-compatible-cc-* providers

For third-party Anthropic relays that only accept "real Claude Code" traffic:

• CLAUDE_CODE_COMPATIBLE_USER_AGENT = "claude-cli/2.1.137 (external, sdk-cli)"
• CLAUDE_CODE_COMPATIBLE_STAINLESS_PACKAGE_VERSION = "0.81.0"
• CLAUDE_CODE_COMPATIBLE_STAINLESS_RUNTIME_VERSION = "v24.3.0"
• anthropic-beta = "claude-code-20250219,interleaved-thinking-2025-05-14,effort-2025-11-24"
• CONTEXT_1M_BETA_HEADER = "context-1m-2025-08-07" (Opus/Sonnet 4.x family)
• Default path: /v1/messages?beta=true

Sister modules in the same bundle:

• claudeCodeConstraints.ts — temperature + cache-control rules
• claudeCodeToolRemapper.ts — tool-name remapping
• claudeCodeExtraRemap.ts — extra payload normalization

---

Antigravity Stealth

antigravityObfuscation.ts

Same zero-width-joiner trick as Claude Code, but with an expanded word list that also masks: claude code, claude-code, kilo code, kilocode, omniroute. Mirrors ZeroGravity's ZEROGRAVITY_SENSITIVE_WORDS and CLIProxyAPI's cloak system.

antigravityHeaderScrub.ts

Strips Stainless SDK markers (x-stainless-lang, x-stainless-package-version, x-stainless-os, x-stainless-arch, x-stainless-runtime, x-stainless-runtime-version, x-stainless-timeout, x-stainless-retry-count, x-stainless-helper-method) before forwarding.

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CLI Fingerprint Registry — open-sse/config/cliFingerprints.ts

Per-provider table that pins exact header ordering and JSON body field ordering captured from mitmproxy traces of the official CLIs. Currently registered: codex, claude, plus runtime-derived profiles in providerHeaderProfiles.ts for antigravity, qwen, github.

interface CliFingerprint {
  headerOrder: string[]; // case-sensitive
  bodyFieldOrder: string[]; // top-level JSON keys
  userAgent?: string | (() => string);
  extraHeaders?: Record<string, string>;
}

Toggle per provider via env (see below). When disabled, headers/body keys appear in whatever order Node/JSON gave them — easy to fingerprint.

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MITM Proxy (Antigravity, Linux/macOS/Windows)

For CLIs whose binaries cannot be redirected via OPENAI_BASE_URL, OmniRoute runs a local TLS-terminating proxy. Endpoints live under src/app/api/cli-tools/antigravity-mitm/.

Method	Endpoint	Purpose
GET	/api/cli-tools/antigravity-mitm	Status — running, pid, dnsConfigured, certExists
POST	/api/cli-tools/antigravity-mitm	Start MITM (requires apiKey + sudoPassword)
DELETE	/api/cli-tools/antigravity-mitm	Stop MITM
GET	/api/cli-tools/antigravity-mitm/alias	List model aliases
PUT	/api/cli-tools/antigravity-mitm/alias	Save model aliases for a tool

Target intercepted host: daily-cloudcode-pa.googleapis.com (Antigravity's upstream).

Start sequence (src/mitm/manager.ts::startMitm)

1. Generate self-signed cert via selfsigned (RSA-2048, SHA-256, 1y) — cert/generate.ts
2. Install cert to system trust store — cert/install.ts
3. Add hosts entry 127.0.0.1 daily-cloudcode-pa.googleapis.com — dns/dnsConfig.ts
4. Spawn src/mitm/server.cjs with ROUTER_API_KEY + MITM_LOCAL_PORT (default 443)
5. Persist PID to <DATA_DIR>/mitm/.mitm.pid

Linux dynamic trust-store detection — cert/install.ts

getLinuxCertConfig() walks a priority list and picks the first existing directory:

Distro family	Directory	Update command
Debian / Ubuntu	/usr/local/share/ca-certificates	update-ca-certificates
Arch / CachyOS / Manjaro	/etc/ca-certificates/trust-source/anchors	update-ca-trust
Fedora / RHEL / CentOS	/etc/pki/ca-trust/source/anchors	update-ca-trust
openSUSE	/etc/pki/trust/anchors	update-ca-certificates

Cert filename: omniroute-mitm.crt. Fingerprint match via getCertFingerprint() (SHA-1 of DER).

Additionally, updateNssDatabases() installs into per-user NSS DBs when certutil is available: ~/.pki/nssdb, ~/snap/chromium/.../nssdb, all Firefox profiles (including snap), under the nickname OmniRoute MITM Root CA.

macOS / Windows

• macOS: security add-trusted-cert -d -r trustRoot -k /Library/Keychains/System.keychain
• Windows: elevated PowerShell → certutil -addstore Root

Auth

All MITM endpoints require management auth (requireCliToolsAuth). The sudo password is cached in module scope (never globalThis) and cleared on stopMitm().

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User-Agent Overrides — env vars (.env.example section 12)

Variable	Default
CLAUDE_USER_AGENT	claude-cli/2.1.137 (external, cli)
CODEX_USER_AGENT	codex-cli/0.130.0 (Windows 10.0.26200; x64)
GITHUB_USER_AGENT	GitHubCopilotChat/0.45.1
ANTIGRAVITY_USER_AGENT	antigravity/1.23.2 darwin/arm64
KIRO_USER_AGENT	AWS-SDK-JS/3.0.0 kiro-ide/1.0.0
QODER_USER_AGENT	Qoder-Cli
QWEN_USER_AGENT	QwenCode/0.15.9 (linux; x64)
CURSOR_USER_AGENT	Cursor/3.3
GEMINI_CLI_USER_AGENT	google-api-nodejs-client/10.3.0

Consumed by open-sse/executors/base.ts::buildHeaders() via dynamic lookup. Bump these when providers release new CLI versions — stale UA strings start getting rejected as outdated clients.

CLI Compatibility Mode Toggles (.env.example section 13)

Variable	Effect
CLI_COMPAT_CODEX=1	Codex fingerprint
CLI_COMPAT_CLAUDE=1	claude-cli fingerprint
CLI_COMPAT_GITHUB=1	GitHub Copilot Chat fingerprint
CLI_COMPAT_ANTIGRAVITY=1	Antigravity fingerprint
CLI_COMPAT_KIRO=1	Kiro
CLI_COMPAT_CURSOR=1	Cursor
CLI_COMPAT_KIMI_CODING=1	Kimi Coding
CLI_COMPAT_KILOCODE=1	KiloCode
CLI_COMPAT_CLINE=1	Cline
CLI_COMPAT_QWEN=1	Qwen Code
CLI_COMPAT_ALL=1	Enable all of the above

The provider IP is always preserved — the toggle only reshapes the request wire image, it does not switch IP egress.

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Inbound Header Sanitization

OmniRoute scrubs inbound client headers before forwarding so a request that arrives from Cursor doesn't leak User-Agent: Cursor/X.Y.Z to a Claude upstream. See src/shared/constants/upstreamHeaders.ts for the denylist, kept in lockstep with the Zod schemas and unit tests.

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Updating Fingerprints When a Provider Rotates

1. Capture official CLI traffic with mitmproxy (TLS interception + dump)
2. Extract JA3/JA4 and the literal header order
3. Update the relevant CLI_FINGERPRINTS[...] entry
4. Bump matching *_USER_AGENT default in .env.example
5. If TLS handshake itself changed: update chatgptTlsClient.ts::CHATGPT_PROFILE or wreq-js browser: option
6. Run chatgptTlsClient.test.ts and a manual canary against the live provider
7. Ship in a patch release; document in CHANGELOG.md

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Tests

• open-sse/services/__tests__/chatgptTlsClient.test.ts — proxy resolution priority, abort handling, hang recovery
• tests/unit/anthropic-cache-fingerprint.test.ts — fingerprint determinism
• tests/unit/chatgpt-web.test.ts — end-to-end stealth path for ChatGPT

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See Also

• RESILIENCE_GUIDE.md — what happens when a stealth path gets a 403
• TROUBLESHOOTING.md
• ENVIRONMENT.md — full env reference
• CLI-TOOLS.md — operator view of the MITM workflow