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fix(termux-connect): Cloudflare Host header 421 #16

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Merged
FineComputer14451 merged 1 commit into from
Sep 7, 2026
Merged

fix(termux-connect): Cloudflare Host header 421 #16

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28 changes: 28 additions & 0 deletions plugins/grokhunter-termux-connect/skills/termux-connect/scripts/server.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -140,6 +140,33 @@ def main() -> None:
)
sys.exit(1)

# FastMCP defaults DNS-rebinding Host allowlist to 127.0.0.1/localhost only.
# Cloudflare quick tunnels send Host: *.trycloudflare.com → 421 Invalid Host.
# Bind stays loopback; Bearer auth remains the access gate.
from mcp.server.transport_security import TransportSecuritySettings

transport_security = TransportSecuritySettings(
enable_dns_rebinding_protection=False,
)
extra_hosts = [
h.strip()
for h in os.environ.get("TERMUX_CONNECT_ALLOWED_HOSTS", "").split(",")
if h.strip()
]
if extra_hosts:
transport_security = TransportSecuritySettings(
enable_dns_rebinding_protection=True,
allowed_hosts=[
f"{HOST}:{PORT}",
HOST,
"localhost",
f"localhost:{PORT}",
"127.0.0.1:*",
"localhost:*",
*extra_hosts,
],
)

mcp = FastMCP(
"grokhunter-termux-connect",
instructions=(
Expand All @@ -150,6 +177,7 @@ def main() -> None:
port=PORT,
streamable_http_path="/mcp",
stateless_http=True,
transport_security=transport_security,
)

@mcp.tool()
Expand Down
28 changes: 28 additions & 0 deletions skills/termux-connect/scripts/server.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -140,6 +140,33 @@ def main() -> None:
)
sys.exit(1)

# FastMCP defaults DNS-rebinding Host allowlist to 127.0.0.1/localhost only.
# Cloudflare quick tunnels send Host: *.trycloudflare.com → 421 Invalid Host.
# Bind stays loopback; Bearer auth remains the access gate.
from mcp.server.transport_security import TransportSecuritySettings

transport_security = TransportSecuritySettings(
enable_dns_rebinding_protection=False,
)
extra_hosts = [
h.strip()
for h in os.environ.get("TERMUX_CONNECT_ALLOWED_HOSTS", "").split(",")
if h.strip()
]
if extra_hosts:
transport_security = TransportSecuritySettings(
enable_dns_rebinding_protection=True,
allowed_hosts=[
f"{HOST}:{PORT}",
HOST,
"localhost",
f"localhost:{PORT}",
"127.0.0.1:*",
"localhost:*",
*extra_hosts,
],
)

mcp = FastMCP(
"grokhunter-termux-connect",
instructions=(
Expand All @@ -150,6 +177,7 @@ def main() -> None:
port=PORT,
streamable_http_path="/mcp",
stateless_http=True,
transport_security=transport_security,
)

@mcp.tool()
Expand Down
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