Problem

When running OpenClaw with Clash (or any TUN-based proxy) in fake-ip mode, web_fetch is completely broken for all domains.

Root Cause

Clash's fake-ip mode returns placeholder IPs from the 198.18.0.0/15 range (IANA reserved for benchmarking) for all DNS queries. The actual routing happens at the TUN network layer — the fake IP is just a token that the virtual NIC intercepts and forwards to the real destination.

However, web_fetch performs an application-layer DNS pre-check before initiating any HTTP request:

web_fetch(url)
  → DNS resolve → gets 198.18.0.x (fake IP)
  → SSRF check  → blocked: special-use IP ❌
  → (never reaches the actual HTTP request)

The SSRF guard fires before any proxy (HTTP_PROXY / HTTPS_PROXY) can intervene, because the guard runs at the DNS resolution stage, not the connection stage.

Environment

• macOS (Apple Silicon) + Clash Verge (mihomo core), fake-ip mode
• Windows + Clash Verge, fake-ip mode (reproduced on both)
• HTTPS_PROXY=http://127.0.0.1:7897 set in LaunchAgent EnvironmentVariables — does not help because the SSRF pre-check happens before the proxy dispatcher is invoked

Verification

# All domains resolve to fake IPs under Clash TUN fake-ip mode
dig google.com +short   # → 198.18.0.21
dig github.com +short   # → 198.18.0.70
dig example.com +short  # → 198.18.0.22

Every web_fetch call fails with:

Blocked: resolves to private/internal/special-use IP address

Workaround

Switching Clash DNS mode from fake-ip to redir-host resolves the issue — DNS returns real IPs, SSRF check passes. However, this reduces DNS privacy (DNS queries are sent to upstream resolvers rather than being handled locally).

Proposed Fix

Consider one or more of the following:

1. Config option to skip DNS pre-check when a proxy is configured — if HTTPS_PROXY is set, the application won't do its own DNS resolution anyway, so the pre-check is redundant and should be skippable.

2. Configurable SSRF allowlist for IP ranges — allow users to whitelist specific IP ranges (e.g. 198.18.0.0/15) that are known to be local proxy tokens, not real destinations.

3. Detect fake-ip pattern — if the resolved IP falls in 198.18.0.0/15 AND a proxy is configured, trust the proxy to handle routing rather than blocking.

Impact

Clash TUN fake-ip is the default and recommended mode in Clash Verge and many other Clash-based clients. This makes web_fetch effectively unusable for a large portion of users running OpenClaw on macOS/Windows with a TUN proxy — which is an extremely common setup in regions where proxy usage is prevalent.

browser tool works fine (operates at network layer), web_search works fine (cloud-side), but web_fetch is the only tool broken by this architectural conflict.