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sneak 8d9bea7c43 README: blocks misbehaving scrapers, not normal ones (closes #387)
check / check (push) Failing after 1m41s
The opening now says a scraper within the default limits is left alone
whatever its user agent, and lists what bans a client: the rate and byte
limits, a probe for a secret path, and the refusal limit.

Model: opus-5-5
2026-11-14 16:40:41 +00:00
8 changed files with 61 additions and 133 deletions

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-14
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@@ -161,20 +161,6 @@ RUN git checkout --quiet --detach b4b2c785308b1ce785b6155c7fe5f16879080193 \
# ubuntu 26.04, 2026-09-27 # ubuntu 26.04, 2026-09-27
FROM ubuntu@sha256:f144425ff09be612d6d9ad965196e9cdc23dae1f42110a8a11a3e9a8198759f7 FROM ubuntu@sha256:f144425ff09be612d6d9ad965196e9cdc23dae1f42110a8a11a3e9a8198759f7
# The image's own labels, in place of the ones it would inherit from
# Ubuntu's. script/docker and script/cibuild pass the build arguments;
# a build that passes none labels the image unknown rather than leave
# Ubuntu's values.
ARG VERSION=unknown
ARG CREATED=unknown
ARG REVISION=unknown
LABEL org.opencontainers.image.title="smallwebwaf" \
org.opencontainers.image.description="A web application firewall for self-hosted web apps: sww rproxy in front of an app, and sww waf, which decides." \
org.opencontainers.image.version="${VERSION}" \
org.opencontainers.image.created="${CREATED}" \
org.opencontainers.image.revision="${REVISION}" \
org.opencontainers.image.source="https://git.eeqj.de/sneak/smallwebwaf"
# runit's install creates its _runit-log user with minsysusers, which # runit's install creates its _runit-log user with minsysusers, which
# reads this file in place of runit's /usr/lib/sysusers.d/runit.conf. # reads this file in place of runit's /usr/lib/sysusers.d/runit.conf.
# runit's line leaves out the shell, and minsysusers prints a Perl # runit's line leaves out the shell, and minsysusers prints a Perl
+28 -65
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@@ -5,17 +5,20 @@
requests of misbehaving scrapers, scanners and other abusers before they reach requests of misbehaving scrapers, scanners and other abusers before they reach
an app. an app.
With the default settings, a client is banned when it does any of these: It does not block scrapers as such. A scraper that stays within the limits below
is left alone, whatever its user agent. With the default settings, a client is
banned when it does any of these:
- makes more than 120 requests in a minute, 1500 in an hour or 6000 in a day; - makes more than 120 requests in a minute, 1500 in an hour or 6000 in a day;
- moves more than `50G` of request and response bodies in an hour, or `100G` in - moves more than `50G` of request and response bodies in an hour, or `100G` in
a day; a day;
- asks for a secret or backup file, such as `/.env` or `/.git/config`; - asks for a path no real visitor asks for, such as `/.env` or `/.git/config`;
- sends a user agent that names a security scanner, such as `sqlmap` or `nikto`;
- has more than 30 requests in a minute refused as probes or attacks. - has more than 30 requests in a minute refused as probes or attacks.
A scraper that does none of these is left alone. A scraper that waits 15 seconds A scraper that waits 15 seconds between requests stays under every one of these
between requests stays under the rate limits. limits. The user agent alone gets a client refused only when it names a security
scanner, such as `sqlmap` or `nikto`. Settings you add, such as a refused
country or a blocklist, can refuse any client.
## What it does ## What it does
@@ -23,10 +26,10 @@ A web application firewall reads each request on its way to a web app and
refuses the ones that look like abuse. `smallwebwaf` is one program, `sww`, refuses the ones that look like abuse. `smallwebwaf` is one program, `sww`,
shipped in one image, with two commands that do this together: shipped in one image, with two commands that do this together:
- `sww rproxy` is a small reverse proxy in front of one app. It sits behind a - `sww rproxy` is a small reverse proxy in front of one app. traefik routes to
TLS-terminating proxy, such as traefik, nginx or Caddy. It asks `waf` about it. It asks `waf` about each request, passes the allowed ones to the app, and
each request, passes the allowed ones to the app, and passes the app's answers passes the app's answers back. It keeps nothing between requests and writes
back. It keeps nothing between requests and writes nothing to disk. nothing to disk.
- `sww waf` decides. It runs the checks and keeps the bans, the counters and - `sww waf` decides. It runs the checks and keeps the bans, the counters and
each client's history. One `waf` serves many sites: a client banned through each client's history. One `waf` serves many sites: a client banned through
one site is refused on all of them, and its requests on all of them count one site is refused on all of them, and its requests on all of them count
@@ -70,7 +73,8 @@ For the operator, it:
Not built, and not planned: Not built, and not planned:
- TLS and routing by host name. Both stay with the TLS-terminating proxy. - TLS and routing by host name. Both stay with traefik, the reverse proxy in
front of `rproxy`.
- Browser challenges such as captchas. - Browser challenges such as captchas.
- A web console, or a configuration file. - A web console, or a configuration file.
- Defence against floods large enough to fill the host's network link. - Defence against floods large enough to fill the host's network link.
@@ -102,61 +106,20 @@ accepts connections, whether or not `waf` answers; in `waf`'s container, once
The usual setup is three containers on one private network: The usual setup is three containers on one private network:
- the app; - the app;
- `rproxy`, in front of the app, which the TLS-terminating proxy forwards to: - `rproxy`, in front of the app, which traefik routes to:
`SWW_RPROXY_WAF_BACKEND` names `waf` and `SWW_RPROXY_UPSTREAM_URL` names the `SWW_RPROXY_WAF_BACKEND` names `waf` and `SWW_RPROXY_UPSTREAM_URL` names the
app; app;
- `waf`, with `SWW_COMMAND=waf` and a volume at `/var/lib/sww` for its state - `waf`, with `SWW_COMMAND=waf` and a volume at `/var/lib/sww` for its state
files. files.
Publish no port of the app or of `waf`. Anything on that network can reach the Point traefik's labels at port 8080 of `rproxy`
app around `rproxy`, and can ask `waf` questions, so the network holds only what (`traefik.http.services.<name>.loadbalancer.server.port=8080`). Publish no port
you trust. Each further app adds its own container and its own `rproxy`, whose of the app or of `waf`. Anything on that network can reach the app around
`rproxy`, and can ask `waf` questions, so the network holds only what you trust.
Each further app adds its own container and its own `rproxy`, whose
`SWW_RPROXY_WAF_BACKEND` names the same `waf`. The "Smallest setup" example `SWW_RPROXY_WAF_BACKEND` names the same `waf`. The "Smallest setup" example
below shows this shape. below shows this shape.
### The TLS-terminating proxy
`rproxy` serves plain HTTP. It runs behind any TLS-terminating proxy, such as
traefik, nginx or Caddy. The TLS-terminating proxy must:
- forward each request to port 8080 of `rproxy` over plain HTTP;
- keep the visitor's `Host` header;
- add the visitor's address to `X-Forwarded-For`;
- set `X-Forwarded-Proto` to the scheme the visitor used;
- close an unused connection to `rproxy` in under 120 seconds;
- connect to `rproxy` from an address in `SWW_RPROXY_TRUSTED_PROXIES`, by
default `10.0.0.0/8`, `172.16.0.0/12` or `192.168.0.0/16`.
From any other address, `rproxy` ignores the forwarded headers and takes the
TLS-terminating proxy for the visitor. Every visitor then shares one address,
and one ban.
traefik and Caddy keep the `Host` header and set both forwarded headers by
default. traefik's Docker label
`traefik.http.services.<name>.loadbalancer.server.port=8080` names the port.
Caddy keeps an unused connection for 120 seconds by default, so its site
shortens that to 90 seconds:
```caddyfile
reverse_proxy rproxy:8080 {
transport http {
keepalive 90s
}
}
```
By default nginx sends the host in `proxy_pass` as `Host` and sets neither
forwarded header, so its site sets all three:
```nginx
location / {
proxy_pass http://rproxy:8080;
proxy_set_header Host $host;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto $scheme;
}
```
### `rproxy` in the app's container ### `rproxy` in the app's container
An app's image can instead be built on the `smallwebwaf` image, so that `rproxy` An app's image can instead be built on the `smallwebwaf` image, so that `rproxy`
@@ -207,13 +170,13 @@ entrypoint starts `rproxy` and the app side by side, each as its own user. Run
the app's image with `SWW_RPROXY_WAF_BACKEND` set. `deploy/example-app` is such the app's image with `SWW_RPROXY_WAF_BACKEND` set. `deploy/example-app` is such
an app, and the "`rproxy` beside the app" example below runs one. an app, and the "`rproxy` beside the app" example below runs one.
The app's TCP peer is `rproxy`. The app sees the headers the TLS-terminating The app sees the headers traefik sent, with traefik's address added to
proxy sent, with that proxy's address added to `X-Forwarded-For`. So the app `X-Forwarded-For`, from a TCP peer that is `rproxy`. So the app must trust
must trust `rproxy`'s address for forwarded headers. In a container of its own, `rproxy`'s address for forwarded headers. In a container of its own, `rproxy` is
`rproxy` is on the private network, which the usual default of a trusted-proxy on the private network, which the usual default of a trusted-proxy setting
setting covers. Beside the app, its address is `127.0.0.1` or `::1`, which the covers. Beside the app, its address is `127.0.0.1` or `::1`, which the private
private ranges leave out, so the app's own setting must name them too, as ranges leave out, so the app's own setting must name them too, as `app.run`
`app.run` does. does.
### Checking that it works ### Checking that it works
@@ -221,7 +184,7 @@ private ranges leave out, so the app's own setting must name them too, as
`healthy` for each container of `smallwebwaf`. `healthy` for each container of `smallwebwaf`.
- A log line with `"msg":"starting"` gives the version, the address and every - A log line with `"msg":"starting"` gives the version, the address and every
setting in effect, with secrets masked. setting in effect, with secrets masked.
- A request to the site through the TLS-terminating proxy gets the app's answer. - A request to the site through traefik gets the app's answer.
`https://<site>/_sww/healthz` answers `ok`. `waf`'s log lines about the `https://<site>/_sww/healthz` answers `ok`. `waf`'s log lines about the
request have `"action":"forward"`. request have `"action":"forward"`.
- To see a refusal without banning yourself, run `waf` with - To see a refusal without banning yourself, run `waf` with
+29 -35
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@@ -3,7 +3,7 @@
`smallwebwaf` is a web application firewall for self-hosted apps. It is one `smallwebwaf` is a web application firewall for self-hosted apps. It is one
binary, `sww`, and two of its commands do the work: binary, `sww`, and two of its commands do the work:
- `sww rproxy` is a reverse proxy between a TLS-terminating proxy and one app. - `sww rproxy` is a reverse proxy between traefik and one app.
- `sww waf` decides what happens to each request, for many sites. - `sww waf` decides what happens to each request, for many sites.
This document says what it must do and why, each requirement once. Everything in This document says what it must do and why, each requirement once. Everything in
@@ -45,8 +45,7 @@ never as a time.
## Non-goals ## Non-goals
- TLS, certificates and routing by host name. Those are the job of the - TLS, certificates and routing by host name. Those are traefik's job.
TLS-terminating proxy, such as traefik, nginx or Caddy.
- More than one app behind one `rproxy`. Each app has its own. - More than one app behind one `rproxy`. Each app has its own.
- Browser challenges such as captchas or proof of work. If wanted, chain Anubis - Browser challenges such as captchas or proof of work. If wanted, chain Anubis
between `rproxy` and the app. between `rproxy` and the app.
@@ -1944,10 +1943,10 @@ leave out a cookie only when its name matches exactly, case included.
### Ban lengths, response and scope ### Ban lengths, response and scope
`SWW_WAF_BAN_RESPONSE` is `403` by default, which makes a ban easy to recognise `SWW_WAF_BAN_RESPONSE` is `403` by default, which makes a ban easy to recognise
when debugging; `429` and `close` are the alternatives. `close` does not leave when debugging; `429` and `close` are the alternatives. Behind traefik, `close`
the client unanswered: the TLS-terminating proxy answers `502`, as it does does not leave the client unanswered: traefik answers `502`, as it does whenever
whenever its backend drops a connection. `SWW_WAF_BAN_SCOPE_V4_PREFIX` widens an its backend drops a connection. `SWW_WAF_BAN_SCOPE_V4_PREFIX` widens an IPv4 ban
IPv4 ban to the surrounding netblock. The four ban lengths are under "Bans". to the surrounding netblock. The four ban lengths are under "Bans".
### Reputation ### Reputation
@@ -2772,9 +2771,9 @@ its whole body. The visitor gets that answer at once, and the connection closes
after it. after it.
The largest request line and headers is 32 KiB. A kept-open connection is closed The largest request line and headers is 32 KiB. A kept-open connection is closed
after 120 seconds idle. Neither has a setting. The TLS-terminating proxy should after 120 seconds idle. Neither has a setting. traefik, by default, closes an
close an unused connection sooner, so that it never sends a request on a unused connection after 90 seconds. So traefik closes first, and never sends a
connection `rproxy` is closing. traefik closes one after 90 seconds by default. request on a connection `rproxy` is closing.
What the visitor gets when a limit is passed: What the visitor gets when a limit is passed:
@@ -2825,16 +2824,14 @@ chooses: `waf` runs `waf`, and with it unset the image runs `rproxy`.
The usual setup is three containers on one private network: The usual setup is three containers on one private network:
- the app; - the app;
- `rproxy`, which the TLS-terminating proxy forwards to, with - `rproxy`, which traefik routes to, with `SWW_RPROXY_UPSTREAM_URL` naming the
`SWW_RPROXY_UPSTREAM_URL` naming the app and `SWW_RPROXY_WAF_BACKEND` naming app and `SWW_RPROXY_WAF_BACKEND` naming `waf`;
`waf`;
- `waf`, with `SWW_COMMAND=waf` and a volume for its state files. - `waf`, with `SWW_COMMAND=waf` and a volume for its state files.
Each further app adds its own container and its own `rproxy`, whose Each further app adds its own container and its own `rproxy`, whose
`SWW_RPROXY_WAF_BACKEND` names the same `waf` (see "Sites"). Anything on that `SWW_RPROXY_WAF_BACKEND` names the same `waf` (see "Sites"). Anything on that
network can reach an app around `rproxy`, and can ask `waf` questions or send it network can reach an app around `rproxy`, and can ask `waf` questions or send it
reports. So the network holds only what you trust. `README.md` lists what the reports. So the network holds only what you trust.
TLS-terminating proxy must do.
### `rproxy` in the app's container ### `rproxy` in the app's container
@@ -2906,10 +2903,10 @@ process that stops at start is started again every second, not in a tight loop.
container's output, which `docker logs` shows. container's output, which `docker logs` shows.
- When a service exits, runit runs its `run` script again, and the container - When a service exits, runit runs its `run` script again, and the container
does not stop. Beside an app, the other process keeps running. does not stop. Beside an app, the other process keeps running.
- While `rproxy` is down, the TLS-terminating proxy answers `502`. While the app - While `rproxy` is down, traefik answers `502`. While the app is down, `rproxy`
is down, `rproxy` answers `502`, which is not a client offence. While `waf` is answers `502`, which is not a client offence. While `waf` is down,
down, `SWW_RPROXY_WAF_BACKEND_NO_ANSWER_DISPOSITION` decides (see "Without an `SWW_RPROXY_WAF_BACKEND_NO_ANSWER_DISPOSITION` decides (see "Without an answer
answer from `waf`"). from `waf`").
- Only faults found at start stop `waf`: - Only faults found at start stop `waf`:
- invalid configuration; - invalid configuration;
- a lookup database that is missing or unreadable; - a lookup database that is missing or unreadable;
@@ -2942,26 +2939,23 @@ checks:
- With `SWW_COMMAND` unset, empty or `rproxy`, it passes while `rproxy` answers - With `SWW_COMMAND` unset, empty or `rproxy`, it passes while `rproxy` answers
that request on `127.0.0.1`, at the port in `SWW_RPROXY_LISTEN_ADDR`, and the that request on `127.0.0.1`, at the port in `SWW_RPROXY_LISTEN_ADDR`, and the
app accepts connections at `SWW_RPROXY_UPSTREAM_URL`. It does not ask `waf`, app accepts connections at `SWW_RPROXY_UPSTREAM_URL`. It does not ask `waf`,
so that the site stays in the TLS-terminating proxy's routes while `waf` is so that the site stays in traefik's routes while `waf` is down.
down.
- With any other value, it fails with a message naming `SWW_COMMAND` and its - With any other value, it fails with a message naming `SWW_COMMAND` and its
value. value.
A TLS-terminating proxy that reads Docker's health status, as traefik does, traefik sends a container no requests until it shows as healthy. So the check
sends a container no requests until it shows as healthy. So the check runs every runs every second from the container's start until it first passes, for up to a
second from the container's start until it first passes, for up to a minute, and minute, and every 30 seconds after that. An app with a health check of its own
every 30 seconds after that. An app with a health check of its own can replace can replace the image's `HEALTHCHECK` with one that checks both.
the image's `HEALTHCHECK` with one that checks both.
### Ports ### Ports
`rproxy` listens on no port but the one in `SWW_RPROXY_LISTEN_ADDR`, 8080 by `rproxy` listens on no port but the one in `SWW_RPROXY_LISTEN_ADDR`, 8080 by
default, which the TLS-terminating proxy forwards to. It passes requests to the default, which traefik routes to. It passes requests to the app at
app at `SWW_RPROXY_UPSTREAM_URL`, `http://127.0.0.1:8081` by default. Another `SWW_RPROXY_UPSTREAM_URL`, `http://127.0.0.1:8081` by default. Another port may
port may be set: the health check follows the setting, and the TLS-terminating be set: the health check follows the setting, and traefik's port label
proxy must name it, as traefik's port label (`traefik.http.services.<name>.loadbalancer.server.port`) must name it. An app
(`traefik.http.services.<name>.loadbalancer.server.port`) does. An app beside beside `rproxy` must leave that port free.
`rproxy` must leave that port free.
`waf` listens on no port but the one in `SWW_WAF_LISTEN_ADDR`, 8080 by default. `waf` listens on no port but the one in `SWW_WAF_LISTEN_ADDR`, 8080 by default.
The questions, the reports and its own endpoints all come there. The questions, the reports and its own endpoints all come there.
@@ -3002,9 +2996,9 @@ in `docs/settings.md` shows the commands.
### Forwarded headers ### Forwarded headers
The app's TCP peer is `rproxy`, and the `X-Forwarded-For` the app receives ends The app's TCP peer is `rproxy`, and the `X-Forwarded-For` the app receives ends
with the TLS-terminating proxy's address, which `rproxy` adds after the with traefik's address, which `rproxy` adds after the visitor's. So the app must
visitor's. So the app must trust `rproxy`'s address for forwarded headers, trust `rproxy`'s address for forwarded headers, besides the private address
besides the private address ranges the TLS-terminating proxy is on. ranges traefik is on.
- In a container of its own, `rproxy`'s address is on the private network. The - In a container of its own, `rproxy`'s address is on the private network. The
usual default for a trusted-proxy setting, the private ranges, covers it. usual default for a trusted-proxy setting, the private ranges, covers it.
-4
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@@ -9,10 +9,6 @@
ARG SWW_IMAGE=smallwebwaf ARG SWW_IMAGE=smallwebwaf
FROM ${SWW_IMAGE} FROM ${SWW_IMAGE}
# Its own title and description, in place of the smallwebwaf image's.
LABEL org.opencontainers.image.title="smallwebwaf-example-app" \
org.opencontainers.image.description="An example app built on the smallwebwaf image."
# Packages the app needs, from the nixpkgs in the image. # Packages the app needs, from the nixpkgs in the image.
RUN nix-env -iA nixpkgs.busybox RUN nix-env -iA nixpkgs.busybox
+1 -2
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@@ -68,8 +68,7 @@ Every one of these lines has:
### Request detail ### Request detail
- `request_id`: the id `rproxy` made for the request when it arrived. - `request_id`: the id `rproxy` made for the request when it arrived.
- `peer_ip`: the address of `rproxy`'s TCP peer, normally the TLS-terminating - `peer_ip`: the address of `rproxy`'s TCP peer, normally traefik.
proxy.
- `forwarded_for`: the `X-Forwarded-For` header the visitor's request came with. - `forwarded_for`: the `X-Forwarded-For` header the visitor's request came with.
- `client_group`: the client as rate limiting counts it, an IPv4 address as a - `client_group`: the client as rate limiting counts it, an IPv4 address as a
/32 or an IPv6 group. /32 or an IPv6 group.
+3 -3
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@@ -478,9 +478,9 @@ start, and an invalid value stops the start. Any can be given as a file, as a
`10.0.0.0/8,172.16.0.0/12,192.168.0.0/16`): the netblocks whose `10.0.0.0/8,172.16.0.0/12,192.168.0.0/16`): the netblocks whose
`X-Forwarded-For` is believed. Set but empty, it trusts nothing. A client `X-Forwarded-For` is believed. Set but empty, it trusts nothing. A client
outside these netblocks cannot claim another address. Where other containers outside these netblocks cannot claim another address. Where other containers
reach `rproxy` directly, or visitors on a private network reach the reach `rproxy` directly, or visitors on a private network reach traefik, they
TLS-terminating proxy, they can name another address in the header. Narrowing can name another address in the header. Narrowing the setting to traefik's own
the setting to the TLS-terminating proxy's own network closes that gap. network closes that gap.
## The image's command ## The image's command
-5
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@@ -20,13 +20,8 @@ main() {
# the version a build stage derives from the .git in the context. # the version a build stage derives from the .git in the context.
version="$(git describe --tags --always --dirty 2>/dev/null || true)" version="$(git describe --tags --always --dirty 2>/dev/null || true)"
[ -n "$version" ] || version="unknown" [ -n "$version" ] || version="unknown"
revision="$(git rev-parse HEAD 2>/dev/null || true)"
[ -n "$revision" ] || revision="unknown"
created="$(date -u +%Y-%m-%dT%H:%M:%SZ)"
docker build --no-cache \ docker build --no-cache \
--build-arg VERSION="$version" \ --build-arg VERSION="$version" \
--build-arg REVISION="$revision" \
--build-arg CREATED="$created" \
-t "$("$SCRIPT_DIR/projectname")" . -t "$("$SCRIPT_DIR/projectname")" .
} }
-5
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@@ -16,13 +16,8 @@ main() {
# the version a build stage derives from the .git in the context. # the version a build stage derives from the .git in the context.
version="$(git describe --tags --always --dirty 2>/dev/null || true)" version="$(git describe --tags --always --dirty 2>/dev/null || true)"
[ -n "$version" ] || version="unknown" [ -n "$version" ] || version="unknown"
revision="$(git rev-parse HEAD 2>/dev/null || true)"
[ -n "$revision" ] || revision="unknown"
created="$(date -u +%Y-%m-%dT%H:%M:%SZ)"
docker build --no-cache \ docker build --no-cache \
--build-arg VERSION="$version" \ --build-arg VERSION="$version" \
--build-arg REVISION="$revision" \
--build-arg CREATED="$created" \
-t "$("$SCRIPT_DIR/projectname")" . -t "$("$SCRIPT_DIR/projectname")" .
} }