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nginx: trust X-Forwarded-For only from TRUSTED_PROXIES (closes #64)
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nginx trusted X-Forwarded-For from every RFC1918 address, so a client
reaching it from one could write a new address on each request and
get a fresh rate-limit allowance. The container's TRUSTED_PROXIES now
names the reverse proxies nginx trusts, none by default.
bin/entrypoint.sh makes each entry a CIDR, checks it with the new
"netwatch-server check-cidr", which runs the server's own
TRUSTED_PROXIES parsing, and writes one set_real_ip_from line per
entry into /etc/nginx/trusted-proxies.conf, which nginx.conf includes.
The backend is started with TRUSTED_PROXIES=127.0.0.1/32, since nginx
is its only client. The viewport test mounts an empty file there.

Model: opus-5-5
This commit is contained in:
clawbot
2026-09-29 06:22:56 +00:00
parent 6022cc8b02
commit a911353023
11 changed files with 129 additions and 34 deletions
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backend/README.md
+17 -5
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@@ -87,9 +87,10 @@ Internal packages in `internal/` follow standard Go project layout:
| `CORS_ALLOWED_ORIGINS` | empty | Comma-separated origins whose pages may call the API; see [CORS](#cors) |
`TRUSTED_PROXIES` defaults to `127.0.0.1/32,::1/128,10.0.0.0/8,172.16.0.0/12,192.168.0.0/16`.
The loopback entries cover the reverse proxy that shares the container; the
RFC1918 ranges match `nginx.conf`. A request whose direct peer is outside this
set has its forwarded headers ignored, and the direct peer is logged instead.
The loopback entries cover a reverse proxy on the same host. A request whose
direct peer is outside this set has its forwarded headers ignored, and the
direct peer is logged and rate-limited instead. The container image does not use
this default; see [Container image](#container-image).
A variable set to a value the server cannot use, such as `PORT=abc`,
`DEBUG=maybe` or a `BIND_ADDRESS` that is not an IP address, stops it from
@@ -101,8 +102,19 @@ The root `Dockerfile` builds one image in which nginx listens on the public port
8080, serves the frontend, and proxies `/api/` and `/.well-known/healthcheck` to
this server. The image's entrypoint, `bin/entrypoint.sh`, starts the server as
user `netwatch` (uid 1000) with `BIND_ADDRESS=127.0.0.1` and `PORT=8081`, so
only nginx reaches it. `DATA_DIR` is `/data/reports`, on the `/data` volume,
which `netwatch` owns.
only nginx reaches it, and with `TRUSTED_PROXIES=127.0.0.1/32`, so it takes the
client address nginx passes on and no other. `DATA_DIR` is `/data/reports`, on
the `/data` volume, which `netwatch` owns.
The container's own `TRUSTED_PROXIES` goes to nginx instead: IP addresses or
CIDRs, separated by commas, of the reverse proxies in front of the container.
nginx takes the client address from `X-Forwarded-For` only on a request from one
of them. Unset or empty, nginx trusts no proxy, and the client address is the
one each request comes from, so every client behind a proxy shares one rate
limit. An entry that is not an IP address or CIDR, such as a hostname or
`1.2.3`, stops the container at start with an error naming `TRUSTED_PROXIES`:
the entrypoint checks each entry with `netwatch-server check-cidr`, which parses
it as this server parses its own `TRUSTED_PROXIES`.
### Report storage