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SPEC: the one place for behaviour and reasons; docs/ as lookup lists only
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docs/core-rule-set.md, docs/lookup.md, docs/reputation.md and docs/bans.md
restated the spec and are folded back into it and removed. The remaining
docs files hold only lists: settings with their defaults and value forms,
the request log's fields, the metrics, the endpoints, the state files and
their contents, the rule file format and default file, the alert events
and messages, the image's contents and pins, and the gitea notes. Every
behaviour each of them held moves to the spec, said once. The settings
groups have the same names in both files. Stale comments in
internal/state and script/example-app point at the right places.

Model: fable-5-1
This commit is contained in:
sneak
2026-10-22 21:51:39 +00:00
parent d712bb1496
commit 4ea0a975c8
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SPEC.md
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docs/admin-endpoints.md
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# Admin endpoints
`smallwebwaf` answers these requests itself, on the app's own address and
through traefik like any other request. Apart from the health check, each needs
a token, sent as `Authorization: Bearer <token>`, and goes through every check
any other request goes through. It is answered where another request would be
passed to the app: a banned client stays refused, and each request counts toward
rate limiting. A missing or wrong token is answered `401`, in `observe` mode
too. Such a refusal counts toward the error burst, so a client guessing tokens
is soon banned. While a token is unset, its endpoints answer `404`.
The endpoints under `/_smallwebwaf/`, what each takes and what each answers.
"Admin endpoints" in [`SPEC.md`](../SPEC.md) says which checks they go through
and how their tokens work.
- `GET /_smallwebwaf/healthz`: `200` and `ok`, to anyone, before any check and
without asking the app.
- `GET /_smallwebwaf/healthz`: `200` and `ok`, to anyone.
- `GET /_smallwebwaf/metrics`: the metrics, for `SWWAF_METRICS_TOKEN` (see
[`metrics.md`](metrics.md)).
- `GET /_smallwebwaf/bans`: every ban held, under `bans`, each as `bans.json`
lists it. Needs `SWWAF_ADMIN_TOKEN`, as do the three below.
- `POST /_smallwebwaf/bans`: bans a netblock. The body is a JSON object of
`netblock`, `duration` and, if you like, `reason`. `netblock` is a netblock
such as `203.0.113.0/24`, or a client's address. A client's address bans its
IPv4 netblock (`SWWAF_BAN_SCOPE_V4_PREFIX`) or its IPv6 group. `duration` is a
duration such as `1h` or `7d`, or `permanent`. The ban starts at once, with
the cause `admin`. A bad body is answered `400`, saying what is wrong:
such as `203.0.113.0/24`, or a client's address, which bans its IPv4 netblock
(`SWWAF_BAN_SCOPE_V4_PREFIX`) or its IPv6 group. `duration` is a duration such
as `1h` or `7d`, or `permanent`. A bad body is answered `400`, saying what is
wrong:
- one that is not such an object, or has another field;
- one longer than 4 KiB;
- one that names an IPv4-mapped netblock, or an address with a zone.
@@ -28,8 +22,27 @@ is soon banned. While a token is unset, its endpoints answer `404`.
address `<client>`. It answers `404` when none is active.
- `GET /_smallwebwaf/clients/<ip>`: what `smallwebwaf` knows of the client.
Under `client`, its counters and history as `clients.json` holds them, or
`null` when it has never been seen. Under `bans`, every ban covering the
address, with its notes.
`null` when `clients.json` does not hold it. Under `bans`, every ban covering
the address, with its notes.
An admin whose own address is banned lifts that ban by editing `bans.json` (see
[`bans.md`](bans.md)).
## Examples
With `SWWAF_ADMIN_TOKEN` set, and the token in `$TOKEN`:
```sh
# Every ban.
curl -H "Authorization: Bearer $TOKEN" https://app.example/_smallwebwaf/bans
# Ban 203.0.113.0/24 for seven days.
curl -H "Authorization: Bearer $TOKEN" \
--json '{"netblock": "203.0.113.0/24", "duration": "7d", "reason": "probes for logins"}' \
https://app.example/_smallwebwaf/bans
# Lift the bans on 203.0.113.9.
curl -H "Authorization: Bearer $TOKEN" -X DELETE \
https://app.example/_smallwebwaf/bans/203.0.113.9
# What smallwebwaf knows of 203.0.113.9.
curl -H "Authorization: Bearer $TOKEN" \
https://app.example/_smallwebwaf/clients/203.0.113.9
```
docs/alerts.md
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# Alerts
Each alert goes to each destination you name. `SWWAF_ALERT_WEBHOOK_URL` gets it
as one JSON object. `SWWAF_ALERT_SLACK_WEBHOOK_URL` and `SWWAF_ALERT_NTFY_URL`
get a message made from it. The settings are under "Alert destinations" in
[`settings.md`](settings.md). An alert is one of these events, and is sent when
its event is in `SWWAF_ALERT_EVENTS`:
The alert events, the JSON object the webhook gets, and the messages Slack and
ntfy get. "Alerting" in [`SPEC.md`](../SPEC.md) says when an alert is sent, held
back or dropped.
## Events
- `ban`: a ban `smallwebwaf` made.
- `permanent_ban`: a permanent ban it made, or an existing ban made permanent by
a request.
- `waf_block`: the Core Rule Set scored a request at or over the threshold. In
`block` mode the request was refused. In `detect` mode it was not, and the
alert's `detail` gives `mode`.
- `waf_block`: the Core Rule Set scored a request at or over the threshold. The
request was refused unless the alert's `detail` gives `mode`: `detect` or
`observe`.
- `anomaly`: a count over an anomaly threshold.
- `reputation_hit`: a request from a client on a blocklist, the CrowdSec
decision list or a DNS blocklist, or with an AbuseIPDB score that is a hit.
@@ -25,12 +25,7 @@ its event is in `SWWAF_ALERT_EVENTS`:
- a rule file or state file edit with an error;
- a state file that cannot be written;
- a replacement lookup database that cannot be read.
- `summary`: the hourly summary described under "Repeats and the hourly cap"
below.
The bans you make raise no alert. In `observe` mode, a request that would have
made a ban still raises the ban's alert, with `mode` set to `observe` in its
`detail`.
- `summary`: the hourly summary of alerts held back.
## The JSON object
@@ -81,24 +76,26 @@ on one line:
}
```
- `instance` is `SWWAF_INSTANCE_NAME`. `time` is when the alert was raised.
`event` is one of the events above.
- `client` is the address whose request raised the alert. `netblock` is the
ban's netblock, the netblock an anomaly counted, or the client's group. Both
are empty for `source_failure` and `file_error`. `asn`, `as_name` and
`country` are the client's as known when the alert was raised. They are empty
when GeoJS had not answered yet.
- `reason` is a short sentence, such as
- `instance`: `SWWAF_INSTANCE_NAME`. `time`: when the alert was raised. `event`:
one of the events above.
- `client`: the address whose request raised the alert. `netblock`: the ban's
netblock, the netblock an anomaly counted, or, for the other events, the
client as rate limiting counts it: an IPv4 address as a /32, or an IPv6 group.
Both are empty for `source_failure` and `file_error`.
- `asn`, `as_name` and `country`: the client's as known when the alert was
raised. They are empty when GeoJS had not answered yet.
- `reason`: a short sentence, such as
`requests per minute over the limit of 1000` or `listed by a blocklist`.
- `detail` is what is particular to the event:
- for a ban, its `cause`, `ban_expires` and `notes` (see
[`bans.md`](bans.md) for the notes);
- `detail`: what is particular to the event:
- for a ban, its `cause`, `ban_expires` and `notes` (the notes are listed
under `bans.json` in [`state-files.md`](state-files.md));
- for an anomaly, the `scope`, `window`, `kind`, `count` and `threshold`;
- for a reputation hit, the `source` and, for AbuseIPDB, the `score`;
- for a Core Rule Set match, the `rule_ids`, `score`, `method` and `path`;
- for a source failure, the `source` and `error`;
- for a file error, the `file` and `error`.
- `suppressed_repeats` is how many repeats the cooldown held back before this
- for a file error, the `file` and `error`;
- `mode`, when the request was not refused: `detect` or `observe`.
- `suppressed_repeats`: how many repeats the cooldown held back before this
alert.
## Slack and ntfy
@@ -128,22 +125,3 @@ The priority and tag by event:
- `reputation_hit`: priority `low`, tag `label`.
- `source_failure` and `file_error`: priority `high`, tag `warning`.
- `summary`: priority `default`, tag `bar_chart`.
## Repeats and the hourly cap
A repeat is an alert for the same event on the same netblock, source, file or
thing counted, less than `SWWAF_ALERT_COOLDOWN` after the last. It is held back
and counted, and the next alert sent gives the count. Past
`SWWAF_ALERT_MAX_PER_HOUR` alerts in an hour, the rest are held back and counted
by event. Once the hour ends, one alert with the event `summary` gives those
counts. It also counts the repeats that a cooldown held back and that no later
alert reported.
## Sending
Each destination has a queue of at most 1000 alerts, sent one at a time, so a
slow destination holds up nothing. A `2xx` answer takes an alert. A `4xx` other
than `408` and `429` refuses it, and it is dropped. Anything else is a failure:
the alert is sent again a second later, and twice as long after each further
failure, up to a minute. `alerts.json` keeps the queues and cooldowns across a
restart (see [`state-files.md`](state-files.md)).
docs/bans.md
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# Bans
How bans are made, what they cover and how long they last is under "Bans" in
[`SPEC.md`](../SPEC.md); the settings are under "How long bans last and what
they cover" in [`settings.md`](settings.md). This file says what a ban's notes
hold, and how to make, keep or lift a ban.
## The notes
Each ban carries notes for deciding whether to lift it, drawn from what
`smallwebwaf` already knows. Nothing is looked up to fill them:
- the AS number, AS name and country, added when the lookup answers (empty when
lookups are off);
- what was broken: the rule id and target that matched, or the trap path, or the
limit, its window and the count reached;
- the client's percentage of the limit, with the setting that gave it;
- the reputation sources the client is on;
- the request that caused the ban: time, method, host, path with its query
string, status and user agent, each text cut to 256 bytes;
- the netblock's requests since it was first seen, and how many this ban has
refused so far, kept up to date while the ban lasts;
- how many earlier bans the netblock had, by cause.
## Managing bans by editing `bans.json`
`bans.json` in the state directory holds every ban, indented to be read. A
permanent ban's `expires` is `null`. `smallwebwaf` watches the file and takes in
an edit as soon as it is saved (see [`state-files.md`](state-files.md)).
To ban a netblock, add an entry with its `netblock`, `start` and `expires`.
`expires` is `null` for a ban that never ends. `reason`, `notes` and `cause` may
be left out; the cause is then `admin`:
```json
{
"version": 1,
"bans": [
{
"netblock": "203.0.113.0/24",
"start": "2026-10-06T12:00:00Z",
"expires": null,
"reason": "probes for logins"
}
]
}
```
To keep a ban `smallwebwaf` made, so that it is never dropped, set its `cause`
to `admin`. To lift a ban, add `"lifted"` with the time you lift it, such as
`"lifted": "2026-10-06T13:00:00Z"`. The ban then refuses nothing and does not
make the netblock's next ban longer. It is kept with its notes. To forget a ban,
delete its entry. A ban whose cause is `attack` becomes permanent at the first
request it refuses. One whose cause is `admin` or `crowdsec` does not.
An edit that cannot be read does not stop the running `smallwebwaf`. It keeps
what it holds. At the file's next write it renames your file to `bans.json.bad`,
writes the file again from memory, and logs and alerts the error. Mend the
`.bad` file and move it back.
## Managing bans through the admin endpoints
With `SWWAF_ADMIN_TOKEN` set, and the token in `$TOKEN`:
```sh
# Every ban.
curl -H "Authorization: Bearer $TOKEN" https://app.example/_smallwebwaf/bans
# Ban 203.0.113.0/24 for seven days.
curl -H "Authorization: Bearer $TOKEN" \
--json '{"netblock": "203.0.113.0/24", "duration": "7d", "reason": "probes for logins"}' \
https://app.example/_smallwebwaf/bans
# Lift the bans on 203.0.113.9.
curl -H "Authorization: Bearer $TOKEN" -X DELETE \
https://app.example/_smallwebwaf/bans/203.0.113.9
# What smallwebwaf knows of 203.0.113.9.
curl -H "Authorization: Bearer $TOKEN" \
https://app.example/_smallwebwaf/clients/203.0.113.9
```
See [`admin-endpoints.md`](admin-endpoints.md) for what each answers. An admin
whose own address is banned lifts that ban by editing `bans.json`.
docs/core-rule-set.md
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# The Core Rule Set
The OWASP Core Rule Set 4.25.0 runs on each request after the rule files, unless
`SWWAF_WAF_MODE` is `off`. It reads the method, the URL with its query, and the
headers. Once `SWWAF_WAF_BODY_LIMIT` is set, it also reads a body that is form
data, multipart, JSON or XML. No answer is inspected. The settings are under
"Attack detection" in [`settings.md`](settings.md). The same section of
[`SPEC.md`](../SPEC.md) says why bodies are not read by default, and gives the
six changes `smallwebwaf` makes to the Core Rule Set, with the reason for each.
Each rule that matches adds to the request's score. A score at or over
`SWWAF_WAF_ANOMALY_THRESHOLD` is a match. A match is refused with `403` while
`SWWAF_WAF_MODE` is `block`, and let through while it is `detect`. Either way
the log line gives the rule ids and the score, and a `waf_block` alert is sent.
A request with more than 1000 query parameters or body fields adds 5 to its
score, since Coraza reads only the first 1000. The Core Rule Set inspects only a
request that every earlier check let through. It skips a path under
`SWWAF_WAF_EXEMPT_PATHS` and a client in `SWWAF_ALLOW_NETS`. An engine error on
a request forwards the request, and is logged and counted.
Body inspection suits apps whose forms carry no code. In front of a code forge
it refuses issue and comment text, wiki pages and files saved in the web editor
that hold shell commands or code. The log line names the rule ids, which
`SWWAF_WAF_DISABLED_RULES` can switch off. A body the Core Rule Set cannot parse
adds 5 to the score. So does a multipart body cut by the limit in the middle of
a part's header. The client has until `SWWAF_CLIENT_REQUEST_TIMEOUT` runs out to
send the part that is read. Any other body, such as a git push, reaches the app
uninspected.
[`gitea.md`](gitea.md) records what the Core Rule Set still refuses in front of
gitea, with and without body inspection.
docs/gitea.md
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@@ -13,16 +13,19 @@ checked again when gitea or the Core Rule Set changes version.
by it.
- A clone is a response. It fits the defaults of 30 minutes and 5 GiB for all
but the largest repositories and slowest links.
- A push is a request, and so is every other upload: a git push, an LFS object,
a container image layer, a package file or a release attachment. At the
defaults, an upload larger than 100 MiB or taking more than 60 seconds is cut
off. The client is answered `413` for a body that is too large, before
anything reaches gitea when the request announces its size. It is answered
`408` for a body it sends too slowly, or `504` if gitea is too slow to take
it. The upload fails, and no one is banned for it. A gitea that takes large
uploads needs `SWWAF_REQUEST_MAX_BYTES`, `SWWAF_CLIENT_REQUEST_TIMEOUT` and
`SWWAF_UPSTREAM_REQUEST_TIMEOUT` raised to fit. The Core Rule Set does not
read an upload's body, which streams through without being held in memory.
- A push is a request, and so is every other upload:
- a git push;
- an LFS object;
- a container image layer;
- a package file;
- a release attachment.
At the defaults, an upload larger than 100 MiB or taking more than 60
seconds is cut off, and no one is banned for it. "Size and time limits" in
`SPEC.md` gives the answers the client gets. A gitea that takes large
uploads needs `SWWAF_REQUEST_MAX_BYTES`, `SWWAF_CLIENT_REQUEST_TIMEOUT` and
`SWWAF_UPSTREAM_REQUEST_TIMEOUT` raised to fit.
- Archive download and blame or history pages are what scrapers hammer. The
request limits do most of the work there.
- An Actions runner that reaches gitea through `smallwebwaf` sends requests all
@@ -32,8 +35,7 @@ checked again when gitea or the Core Rule Set changes version.
jobs. It is then banned, the job it is running fails, and each repeat within a
day makes the ban longer. Newer runners ask less often, but a busy one, or
several on one address, can still pass it. Put the runners' addresses in
`SWWAF_RATE_LIMIT_EXEMPT_NETS`. That takes them out of the request and byte
limits, while the error burst, attack detection and bans still apply.
`SWWAF_RATE_LIMIT_EXEMPT_NETS`.
## What the Core Rule Set lets through
@@ -55,10 +57,9 @@ the refusals in the next section:
## What the Core Rule Set still refuses
Each refusal answers only that request, with `403`, and bans no one by itself.
It counts toward the error burst, which a person does not reach this way. The
request log names the rule in `waf_rule_ids`, which `SWWAF_WAF_DISABLED_RULES`
can switch off.
Each refusal answers only that request ("Bans" in `SPEC.md` says what it counts
toward). The request log names the rule in `waf_rule_ids`, which
`SWWAF_WAF_DISABLED_RULES` can switch off.
### A query string that reads as an attack
@@ -151,9 +152,9 @@ carries it.
A push can reuse a layer of an image docker has pushed to that gitea before.
docker then asks gitea to take the layer from that image, naming it in the query
parameter `from`, which 932260 checks. The request is refused when the image's
owner, or its name after the owner, starts with an entry on the list of
commands. Examples are `owner/python3-app`, `owner/docker-base`, and any image
of an owner named `ansible` or `docker-team`.
owner starts with an entry on the list of commands. So is one whose name after
the owner does. Examples are `owner/python3-app`, `owner/docker-base`, and any
image of an owner named `ansible` or `docker-team`.
What happens next depends on docker's image store. A docker that keeps its
images in containerd's image store fails the push, and fails each new try the
docs/image.md
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# What the image holds
The `smallwebwaf` image is the base of each app's own image. The requirements
are under "Deployment" in [`SPEC.md`](../SPEC.md); this file lists what the
image holds, how each part is pinned, and why.
The contents of the `smallwebwaf` image, and how each part is pinned.
"Deployment" in [`SPEC.md`](../SPEC.md) says why each part is there and why it
is pinned that way.
## Contents
- Ubuntu 26.04 LTS, the newest long-term support release of Ubuntu, pinned by
digest. The image moves to the next LTS release when that ships.
- `ca-certificates`, `nix-bin` and `runit` from Ubuntu, installed from a dated
snapshot of its archive and checked by hash. The Ubuntu image has no CA
certificates; without them Nix cannot download packages and `smallwebwaf`
cannot reach GeoJS.
- Nix and nixpkgs, fixed at one release. Root uses Nix directly; no Nix daemon
runs. `nix-bin` creates no build users, so `build-users-group =` in
`/etc/nix/nix.conf` lets root build without them.
- runit, and `runsvinit` as the entrypoint, as the owner's code style guide asks
for service containers. No package carries `runsvinit`, so the image builds it
from its archived source (`github.com/peterbourgon/runsvinit`, unchanged
since 2015) at a fixed commit hash, with a `go.mod` the build writes.
`runsvinit` starts runit's `runsvdir`, which runs the `run` script of each
directory under `/etc/service` and runs it again whenever it exits. Ubuntu's
`sv` looks for services there too.
- The `smallwebwaf` binary, and a user of its own, `smallwebwaf` (uid and gid
65532).
- The service directory `/etc/service/smallwebwaf`. Its `run` script waits one
second (`sleep 1`), makes `SWWAF_STATE_DIR` and every file in it belong to the
`smallwebwaf` user, and starts `smallwebwaf` as that user with runit's
`chpst`.
- The directory `/var/lib/smallwebwaf` for the state files, and
`/etc/smallwebwaf/rules.d` with the default rule file.
- Port 8080 declared (`EXPOSE 8080`), and the health check (`HEALTHCHECK`) that
"The health check" in `SPEC.md` describes.
- Ubuntu 26.04 LTS, pinned by digest.
- `ca-certificates`, `nix-bin` and `runit` from Ubuntu, from the snapshot of its
archive at `20261001T000000Z`.
- Nix, with nixpkgs `nixos-26.05.11045.774debe7a0d1` set up for root as
`nixpkgs`. No Nix daemon; `build-users-group =` in `/etc/nix/nix.conf`. Root's
Nix profile, `/nix/var/nix/profiles/default/bin`, last on the `PATH`.
Unpacked, nixpkgs takes about 500 MiB.
- `runsvinit` as the entrypoint, built from `github.com/peterbourgon/runsvinit`
at a fixed commit hash.
- The `smallwebwaf` binary, and the user `smallwebwaf` (uid and gid 65532).
- The service directory `/etc/service/smallwebwaf`, with the `run` script
`share/smallwebwaf.run`.
- `/var/lib/smallwebwaf` for the state files, and `/etc/smallwebwaf/rules.d`
with the default rule file `share/rules.d/00-default.rules`.
- `EXPOSE 8080`, and the `HEALTHCHECK` that runs `smallwebwaf healthcheck`.
## Pinning
## Pins
- Ubuntu's packages come from Ubuntu's snapshot service, the archive as it was
at the moment the Dockerfile names (`--snapshot 20261001T000000Z`), never
earlier than the pinned Ubuntu image's date. The Dockerfile names the SHA-256
hash of each of the snapshot's `InRelease` files, which cover every package
list and so every package, and the build checks them before installing. The
hashes are the amd64 archive's, so the image is built for amd64 only. The
snapshot is fetched over HTTPS with the CA certificates of the Go image that
builds `smallwebwaf`, itself pinned by digest, since the Ubuntu image has
none.
- nixpkgs comes from a release file on `releases.nixos.org` (`nixexprs.tar.xz`
of `nixos-26.05.11045.774debe7a0d1`), named with its SHA-256 hash, not from a
GitHub archive, whose bytes can change. It is set up for root as `nixpkgs`.
Root's Nix profile, `/nix/var/nix/profiles/default/bin`, is last on the
`PATH`, so that no package hides the image's own commands; busybox's `sv`, for
one, looks for services elsewhere. Unpacked, nixpkgs takes about 500 MiB.
- An app built on the image gets the same packages each time it is built.
Security fixes from Ubuntu and nixpkgs come with a newer `smallwebwaf` image,
which an app takes by changing the digest in its `FROM` line. The image moves
to each new nixpkgs release, every six months.
- Ubuntu's packages: the snapshot service, `--snapshot 20261001T000000Z` on both
`apt-get update` and `apt-get install`. The SHA-256 hash of each of the
snapshot's `InRelease` files is named in the `Dockerfile` and checked after
`apt-get update`. The hashes are the amd64 archive's.
- nixpkgs: the release file `nixexprs.tar.xz` of
`nixos-26.05.11045.774debe7a0d1` on `releases.nixos.org`, named with its
SHA-256 hash.
- `runsvinit`: the archived repository, unchanged since 2015, at tag `v2.0.0`,
by commit hash, with a `go.mod` the build writes.
- The Go image that builds `smallwebwaf`: by digest.
docs/lookup.md
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# GeoJS and the lookup database
`smallwebwaf` looks up each client's AS number and country, through GeoJS by
default or in a database file on your own host. The settings are under "Looking
up the AS number and country" in [`settings.md`](settings.md); the reasons for
the defaults are under "Lookup of AS number and country" in
[`SPEC.md`](../SPEC.md).
## GeoJS
By default `smallwebwaf` asks GeoJS, a free web service that needs no account,
about every new visitor's address. It asks whether or not a setting uses the
answer, since the log line, the history, the ban notes and the metrics carry the
AS number and country. These addresses are never sent:
- one in `SWWAF_ALLOW_NETS` or `SWWAF_DENY_NETS`;
- one under a ban;
- a private, loopback or link-local address, which no source can place.
For an IPv6 visitor, GeoJS is asked about the first address of its group.
Addresses are asked about together, up to 200 in one request
(`https://get.geojs.io/v1/ip/geo.json?ip=a,b,c`), one request at a time. Each
answer's `country_code`, `asn` and `organization_name` are read. An answer
without a `country_code`, or with the `asn` `64512`, counts as unknown. Each
answer is kept for seven days, in memory and in `lookups.json`, separately from
the table of clients. Up to 100,000 answers are kept; past that, the answer used
longest ago goes first.
A request waits for its client's first answer only when a setting needs the
answer before the request goes on. It waits up to `SWWAF_LOOKUP_TIMEOUT`. The
settings that make it wait:
- a country list;
- `SWWAF_ADD_LOOKUP_HEADERS`;
- any setting under "Lower limits by AS number and country" in
[`settings.md`](settings.md).
Otherwise the request goes on at once, logged without the answer. The answer
reaches the client's history and ban notes when it comes. A client whose answer
has not come in time counts as from an unknown country until it comes, and its
later requests do not wait. While GeoJS fails, new visitors count as from an
unknown country, which `SWWAF_EXCLUSIVELY_ALLOWED_COUNTRIES` refuses. GeoJS is
then left alone for a second, and twice as long after each further failure, up
to five minutes, and one `source_failure` alert is sent per cooldown.
## The database file
To keep your visitors' addresses on your own host, set
`SWWAF_LOOKUP_SOURCE=off`, or set it to `file`. `file` looks every client up in
the free IPinfo Lite database (`ipinfo_lite.mmdb`) at `SWWAF_LOOKUP_DB_PATH`,
reading its `asn`, `as_name` and `country_code` fields. You download the
database with an IPinfo account and mount it into the container; `smallwebwaf`
never fetches it and holds no account or token for it. It answers at once, with
nothing sent off the host. A client whose address it does not hold counts as
from an unknown country.
`smallwebwaf` reads the whole file at start. It reads the file again once it has
gone 2 seconds without a change after you replace it. A replacement it cannot
read is logged and alerted, and the file read before stays in use. Mount the
directory that holds the file, not the file itself. Many editors and download
tools save a file by replacing it, and a container keeps seeing the old file
when only the file is mounted.
IPinfo updates the database daily, and releases it under the Creative Commons
Attribution-ShareAlike 4.0 licence. It asks for a link to IPinfo on the site
that uses it, such as "IP address data is powered by IPinfo".
## A client without a country
A client the lookup cannot place has an unknown country and AS number. That is
one of:
- a client on a private address;
- one GeoJS or the database does not know;
- one whose GeoJS answer has not come in time.
`SWWAF_EXCLUSIVELY_ALLOWED_COUNTRIES` refuses such a client, and the lower
limits give it `SWWAF_UNKNOWN_LIMIT_PERCENT`. Nothing else treats it
differently.
docs/reputation.md
-113
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@@ -1,113 +0,0 @@
# Reputation sources
A reputation source judges a client by what others saw it do. None is on by
default. The settings are under "Reputation sources" in
[`settings.md`](settings.md); the reasons for the defaults are under
"Reputation" in [`SPEC.md`](../SPEC.md). The sources are checked in this order,
and a source the client is on refuses it, lowers its limits, or only notes it,
as `SWWAF_BLOCKLIST_ACTION` and `SWWAF_REPUTATION_ACTION` say.
## Blocklists
`SWWAF_BLOCKLIST_URLS` lists text files of addresses and netblocks, one to a
line, as the Spamhaus DROP list is written. Anything after a `;` or `#` is left
out. An IPv4-mapped address such as `::ffff:192.0.2.0/120` is read as the IPv4
netblock it stands for.
Each list is fetched again `SWWAF_BLOCKLIST_REFRESH` after its last try, one
list at a time. The file of `SWWAF_ASN_LIMIT_PERCENT_URL` is too.
`reputation.json` keeps when each was last tried, so a restart does not fetch a
list again before its time. A fetch fails when:
- the server answers other than `200`;
- the fetch does not finish within a minute;
- the list is longer than 16 MiB;
- a line is not an address or netblock, or, for the AS number file, not
`AS<number>:<percent>`.
The copy fetched before stays in use, comment lines included. The failure is
logged and raised as a `source_failure` alert. The log, the alerts, the ban
notes and the metrics name each list by its URL, so keep a secret out of it.
The Spamhaus DROP list is The Spamhaus Project's. Its terms, and what they mean
for `SWWAF_BLOCKLIST_REFRESH` and for several instances on one host, are under
"Reputation" in [`SPEC.md`](../SPEC.md). The copy in `reputation.json` keeps the
list's date and copyright lines.
## CrowdSec
While `SWWAF_CROWDSEC_LAPI_URL` is set to the local API of a CrowdSec engine you
run, `smallwebwaf` fetches its decision list every minute. It sends
`SWWAF_CROWDSEC_LAPI_KEY` in the `X-Api-Key` header. The list is kept as a
blocklist is kept. The decisions of the type `ban` on an address or a netblock
are used. Any other, such as a captcha or a country, is left out. A decision
lasts for the `duration` it had left when the engine answered.
A request is refused when a decision still in force names its client. The
client's netblock is banned until the decision ends, with the cause `crowdsec`.
Only a client that sends a request is banned, so a long list does not fill
`bans.json`. Such a ban is never made permanent, and does not lengthen the
netblock's next ban for a broken limit. If you lift a ban while the decision is
in force, the client's next request makes another. Delete the decision in
CrowdSec first, such as with `cscli decisions delete --ip 203.0.113.9`, and lift
the ban once the list has been fetched again. A fetch fails when:
- the engine answers other than `200`, a redirect included;
- the fetch does not finish within a minute;
- the answer is longer than 16 MiB;
- the answer is not a list of decisions.
## DNS blocklists
Each zone in `SWWAF_DNSBL_ZONES` is asked about a client's own address in the
background, the first time the client is seen. The request goes on at once, and
so does every request from the client until the zone has answered. The name
asked about is the one RFC 5782 gives: the numbers of an IPv4 address reversed,
or the 32 hex digits of an IPv6 address reversed. `192.0.2.99` is asked about as
`99.2.0.192.dnsbl.dronebl.org`. An answer in `127.0.0.0/8` lists the client, but
one in `127.255.255.0/24` is Spamhaus refusing the query. A name that does not
exist does not list the client. These are failures:
- an answer in `127.255.255.0/24`;
- an answer outside `127.0.0.0/8`;
- a resolver error;
- no answer within `SWWAF_REPUTATION_TIMEOUT`.
A failure is logged and alerted, and the zone is not asked again for a minute.
Each verdict is kept for `SWWAF_REPUTATION_CACHE_TTL`, in memory and in
`reputation.json`. Up to 100,000 verdicts are kept; past that, the one fetched
longest ago goes first. At most 1,000 queries are under way at once.
The key of a Spamhaus zone under `dq.spamhaus.net` is its first label.
`smallwebwaf` shows `********` in its place wherever it names the zone. Only
`reputation.json` keeps the zone with its key.
## AbuseIPDB
While `SWWAF_ABUSEIPDB_KEY` is set, `smallwebwaf` asks AbuseIPDB's check
endpoint for the abuse confidence score of a client, from 0 to 100. Only a
client that has committed an offence is checked. An offence is one of:
- a broken limit;
- a `ban` rule match or a trap path;
- a refusal by a `block` rule, the Core Rule Set or a token check.
The check runs in the background, at the client's first request after the
offence that no ban refuses, so no request waits. The score applies to the
client's later requests. For an IPv6 client, AbuseIPDB is asked about the
address of the request that set off the check, and the score is used for the
whole group. A score at or over `SWWAF_ABUSEIPDB_MIN_SCORE` is a hit, and
`SWWAF_REPUTATION_ACTION` says what is done. Each score is kept for
`SWWAF_REPUTATION_CACHE_TTL`, up to 100,000 scores.
At most `SWWAF_ABUSEIPDB_DAILY_BUDGET` checks are made in a day, counted in UTC
and kept in `reputation.json`. A restart does not make the budget whole again.
The check that spends the last of the budget is logged and alerted. No client is
checked until the day ends. A check fails when:
- AbuseIPDB answers other than `200`;
- the answer gives no score;
- no answer comes within `SWWAF_REPUTATION_TIMEOUT`.
A failure is logged and alerted, and no client is checked for a minute. The key
is sent in the `Key` header and nowhere else, and is never logged.
docs/request-log.md
+15 -35
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@@ -1,8 +1,8 @@
# The request log's fields
`smallwebwaf` writes one JSON object per line on stdout for every request. The
requirements are under "Request log" in [`SPEC.md`](../SPEC.md); this file lists
the fields. A field that does not apply to a request is left out.
The fields of the JSON object `smallwebwaf` writes for each request. "Request
log" in [`SPEC.md`](../SPEC.md) says when a line is written and how the log is
sent to a syslog server. A field that does not apply to a request is left out.
## Example
@@ -10,6 +10,12 @@ the fields. A field that does not apply to a request is left out.
{"type":"request","time":"2026-10-03T12:00:00.123Z","instance":"fsn1app1/gitea","client_ip":"203.0.113.9","method":"GET","scheme":"https","host":"app.example","path":"/","query":"","protocol":"HTTP/1.1","status":200,"request_bytes":0,"response_bytes":5120,"referer":"","user_agent":"curl/8.9.1","request_id":"7Q2NHZ4KJ3VXW5YB6R3MEFTD2A","peer_ip":"172.18.0.2","forwarded_for":"203.0.113.9","client_group":"203.0.113.9/32","asn":"AS64496","as_name":"Example Net","country":"DE","request_headers":{"accept":"*/*"},"response_content_type":"text/html; charset=utf-8","upstream_status":200,"action":"forward","counts":{"minute":1,"hour":12,"day":40,"minute_bytes":5120,"hour_bytes":61440,"day_bytes":204800},"duration_total":3.217,"duration_checks":0.041,"duration_upstream_connect":0.052,"duration_upstream_first_byte":2.874,"duration_upstream_total":3.104}
```
## Every line
Every line has `type` (`request`; the process's own messages have `process`),
the standard web log fields, `request_id`, `peer_ip`, `client_group`, `asn`,
`as_name`, `country`, `action` and `duration_total`.
## Standard web log fields
- `time`: when the request arrived, RFC 3339 with milliseconds, in UTC;
@@ -66,11 +72,12 @@ the fields. A field that does not apply to a request is left out.
- `limit_percent` and `limit_percent_setting`: the client's percentage of the
rate limits and the setting that lowered it, when one did. `bytes_percent` and
`bytes_percent_setting` do the same for the byte limits.
- `counts`: the client's requests in the minute, hour and day as rate limiting
counts them, this request included, as `minute`, `hour` and `day`; its bytes
as `minute_bytes`, `hour_bytes` and `day_bytes`. A count can have a fraction,
since each window is counted in two buckets with the earlier one weighted.
`counts` is left out when rate limiting did not count the request.
- `counts`: the client's totals as rate limiting counts them, this request
included. It is left out when rate limiting did not count the request. A count
can have a fraction, since each window is counted in two buckets with the
earlier one weighted:
- `minute`, `hour` and `day`: requests;
- `minute_bytes`, `hour_bytes` and `day_bytes`: bytes.
- `limit_hit`: the limit broken: `minute`, `hour` or `day` for a rate limit;
`minute_bytes`, `hour_bytes` or `day_bytes` for a byte limit; or
`error_burst`. A request whose bytes broke a limit was passed on whole, so its
@@ -99,30 +106,3 @@ All in milliseconds:
connection;
- `duration_upstream_first_byte`: until the first byte of the answer;
- `duration_upstream_total`: until the end of the answer.
## Every line
Every line has `type`, the standard web log fields, `request_id`, `peer_ip`,
`client_group`, `asn`, `as_name`, `country`, `action` and `duration_total`. The
process's own messages share the stream with `"type":"process"`; request lines
carry `"type":"request"`.
## Sending the log to a syslog server
While `SWWAF_LOG_REMOTE_URL` is set, every line on stdout is also sent to that
server, as the message of an RFC 5424 syslog record. Over UDP each record is one
datagram. Over TCP and TLS each record follows its length in bytes and a space.
stdout is unchanged. The record carries:
- the facility from `SWWAF_LOG_REMOTE_FACILITY`;
- the severity informational;
- the time;
- the host's name;
- the app name from `SWWAF_LOG_REMOTE_APP_NAME`.
Lines wait in a buffer of `SWWAF_LOG_REMOTE_BUFFER` lines, so a server that is
slow or down never holds up a request. When the buffer is full, the oldest line
is dropped. A failed connection is tried again a second later, and twice as long
after each further failure, up to a minute. A line too long for one UDP datagram
is dropped alone. As `smallwebwaf` stops, it spends at most two seconds sending
the lines still waiting, and drops the rest. stdout has carried them.
docs/rules.md
+12 -59
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@@ -1,10 +1,8 @@
# Rule files
`smallwebwaf` reads every `*.rules` file in `SWWAF_RULES_DIR`, in the order of
their names, and checks each request against their rules in that order, unless
the client is in `SWWAF_ALLOW_NETS`. The requirements the files meet are under
"Rule files" in [`SPEC.md`](../SPEC.md). A file whose name starts with `.`, such
as an editor's lock file, is not a rule file.
The format of a rule file, and the default file the image ships. "Rule files" in
[`SPEC.md`](../SPEC.md) says how the files are read, watched and mounted, and
what each action leads to.
## The format
@@ -18,7 +16,7 @@ env-file path ban (?i)^/\.env(\.[a-z]+)?$
scanner-agent user_agent ban (?i)\b(sqlmap|nikto|nuclei|wpscan)\b
```
- The id is letters, digits, `-` and `_`. No two rules share one. The log line,
- The id is letters, digits, `-` and `_`, unique across all files. The log line,
the metrics, the alerts and a ban's notes name the rule by it.
- The target is what the regex is matched against:
- `path`: the path without the query;
@@ -26,42 +24,10 @@ scanner-agent user_agent ban (?i)\b(sqlmap|nikto|nuclei|wpscan)\b
- `query`: the query as sent;
- `method`, `host`, `user_agent` and `referer`;
- `header:<Name>`: any one request header but `Host` and
`Transfer-Encoding`, which Go's HTTP server takes out of every request.
`path` and `uri` are matched both as sent and once percent-decoded, so that
an encoded probe does not slip past. A header sent more than once is matched
with its values joined by `, `. A header not sent is empty text. No body is
read; reading bodies is the Core Rule Set's job, once `SWWAF_WAF_BODY_LIMIT`
switches it on.
- The action is `log`, `block` or `ban`. `log` only notes the match in the log
line. `block` refuses the request with `403` and bans no one; the refusal
counts toward the error burst. `ban` refuses it and bans the client, as a
clear sign of attack. Matching stops at the first rule that refuses. Keep
`ban` for requests no real visitor sends. Anchor a path at the site root with
`^/`: a file of the same name deeper in a site can be ordinary content.
- The regex is in Go's syntax, RE2. It has no backreferences or lookaround, and
takes time linear in the text it reads, so no rule can be made to stall the
proxy. It matches anywhere in the target unless anchored with `^` and `$`.
`(?i)` at its front makes it ignore case.
## Errors
These stop the start, with a message naming the file and line:
- a line that is not a rule;
- a bad `header:` name, or a rule for `Host` or `Transfer-Encoding`;
- a regex that does not compile;
- an id used twice.
So does a `SWWAF_RULES_DIR` that does not exist. An empty directory is not an
error: the log says that no rules were loaded.
While it runs, `smallwebwaf` watches the directory. It reads the files again
once the directory has had no change for 2 seconds, so that a file still being
written is read whole. If the files then hold such an error, the rules stay as
they were. The log and a `file_error` alert name the file and line. Once the
file is fixed, it is read again.
`Transfer-Encoding`.
- The action is `log`, `block` or `ban`.
- The regex is in Go's syntax, RE2. It matches anywhere in the target unless
anchored with `^` and `$`. `(?i)` at its front makes it ignore case.
## The default file
@@ -86,13 +52,10 @@ path-traversal uri block (\.\./){2,}
empty-agent user_agent log ^$
```
It is kept short and limited to patterns that are wrong for every app, with its
path rules anchored at the site root. In front of gitea, `/.env` is a probe,
while `/<owner>/<repo>/src/branch/main/.env.example` is a file in a repository
that any visitor may open. Anything app-specific belongs in a file the app's
`Dockerfile` adds or the deployer mounts. A request for `/wp-login.php`, for
example, is a clear sign of attack in front of gitea and an ordinary login in
front of WordPress. Such a rule goes in a file named to sort after the default:
## A file of your own
An app's `Dockerfile` adds rules of its own in a file named to sort after the
default, such as `50-gitea.rules`:
```
# 50-gitea.rules: WordPress probes, which gitea never serves
@@ -102,13 +65,3 @@ wp-probe path ban (?i)^/(wp-login\.php|xmlrpc\.php|wp-admin/)
```dockerfile
COPY 50-gitea.rules /etc/smallwebwaf/rules.d/50-gitea.rules
```
## Mounting rule files
A directory mounted over `/etc/smallwebwaf/rules.d` replaces the default file;
single files mounted into it add to it. Many editors save a file by replacing
it, and a container keeps seeing the old one when the file alone is mounted. So
rules to be edited while `smallwebwaf` runs belong in a mounted directory, with
a copy of the default file if the defaults are to stay. The lookup database is
mounted the same way, for the same reason. To run without rules, mount an empty
directory or set `SWWAF_RULES_ENABLED=false`.
docs/settings.md
+221 -378
View File
@@ -1,27 +1,19 @@
# Settings
Every setting is an environment variable whose name starts with `SWWAF_`. Every
setting has a default, so none has to be set. Settings are read once, at start.
To change one, restart the container.
Every setting, its default and the values it takes, in the groups of "Settings"
in [`SPEC.md`](../SPEC.md). That section gives the conventions, the settings
that take `off`, the `_FILE` form, and what each group does and why. A setting
set to a value its entry does not allow stops the start.
A setting that is set to a value it cannot take stops the start. The process
writes one line, `"type":"process"` with `"msg":"invalid setting"`, naming the
variable and what is wrong with the value. It exits with status 1, and runit
starts it again every second until the value is fixed. The entries below say
which values each setting takes. Any other value stops the start. At start, the
settings in effect are logged on one line. Tokens, keys and the paths of
webhooks are shown as `********`.
The forms of values:
## Forms of values
- A duration is Go's syntax, with `d` for days: `90s`, `15m`, `24h`, `7d`. Zero
and negative durations are refused.
- A size is a number of bytes with an optional `K`, `M` or `G`, which are powers
of 1024: `1K` is 1024 bytes, `512K`, `100M`, `5G`.
of 1024, so `1K` is 1024 bytes. Examples: `512K`, `100M`, `5G`.
- A count is a whole number of requests, such as `1000`.
- `off` switches a setting off, where its entry below says it takes `off`.
- A list is comma separated, with spaces around items ignored. An empty item is
refused. A list set but empty is an empty list, and replaces the default.
refused.
- A netblock is an address and a prefix length, such as `10.0.0.0/8`. A bare
address stands for itself alone.
- A country is a two-letter code of ISO 3166-1, in either case: `de` and `DE`
@@ -31,337 +23,58 @@ The forms of values:
- A percentage is a whole number from 0 to 100.
- A path prefix starts with `/`, such as `/assets/`.
## Where it listens and what it protects
## Core
- `SWWAF_LISTEN_ADDR` (default `:8080`): where `smallwebwaf` listens, an
optional host and a port. Keep the host empty: `:9000`, never
`127.0.0.1:9000`. The app must not listen on that port. The health check
follows the setting, and traefik's label must name the port.
- `SWWAF_UPSTREAM_URL` (default `http://127.0.0.1:8081`): the app. An `http` or
`https` URL with a host and an optional port, and nothing more: no path, user
or query.
- `SWWAF_INSTANCE_NAME` (default: the container's host name, the first 12
characters of the container's id): the `instance` name in every log line,
alert and metric. Set it to a name that survives deploys and tells instances
apart, such as `fsn1app1/gitea`. It must be valid UTF-8. While
`SWWAF_ALERT_NTFY_URL` is set, it may hold no control character. While
`SWWAF_LOG_REMOTE_URL` is set and `SWWAF_LOG_REMOTE_APP_NAME` is not, it must
be 1 to 48 printable ASCII characters without a space.
- `SWWAF_MODE` (default `enforce`): `enforce`, or `observe` to ban no one and
log what `enforce` would have done. Observe mode still refuses a request over
a size or time limit, and one without the right token.
- `SWWAF_TRUSTED_PROXIES` (default `10.0.0.0/8,172.16.0.0/12,192.168.0.0/16`,
the private address ranges): the netblocks whose `X-Forwarded-For` is
believed, normally where traefik comes from. Set but empty, it trusts nothing:
every TCP peer is then the client.
- `SWWAF_IPV6_GROUP_PREFIX` (default `64`): the length of the netblock that is
one IPv6 client, from 32 to 128. After a change, each IPv6 client starts
afresh. Existing bans keep refusing their netblocks until they end.
- `SWWAF_MAX_TRACKED_CLIENTS` (default `20000`): the most clients kept in memory
and in `clients.json`, a whole number above zero. Past it, the least recently
seen client is dropped first.
## Time and size limits
Each request has limits on both sides: between the client and `smallwebwaf`, and
between `smallwebwaf` and the app. Bodies stream through in both directions,
except the part the Core Rule Set reads while `SWWAF_WAF_BODY_LIMIT` is set.
- `SWWAF_CLIENT_REQUEST_TIMEOUT` (default `60s`): how long a client may take to
send its request line and headers, and then, from the end of the headers, its
body. A duration or `off`.
- `SWWAF_CLIENT_REQUEST_HEADER_MAX_BYTES` (default `32K`): the largest request
line and headers. A size over `4K`. It cannot be `off`: Go's HTTP server
always has such a limit.
- `SWWAF_CLIENT_IDLE_TIMEOUT` (default `120s`): how long a kept-open connection
may wait for its next request before it is closed. A duration or `off`. The
default is longer than the 90 seconds after which traefik closes an unused
connection, so traefik closes first.
- `SWWAF_CLIENT_RESPONSE_TIMEOUT` (default `30m`): how long the answer may take
to reach the client, from the end of the request to the last byte. A duration
or `off`.
- `SWWAF_UPSTREAM_REQUEST_TIMEOUT` (default `60s`): how long connecting to the
app and sending it the whole request may take. A duration or `off`.
- `SWWAF_UPSTREAM_RESPONSE_TIMEOUT` (default `30m`): how long the app may take
to send its whole answer. A duration or `off`.
- `SWWAF_REQUEST_MAX_BYTES` (default `100M`): the largest request body. A size
or `off`. A request that announces a larger body is refused before anything
reaches the app.
- `SWWAF_RESPONSE_MAX_BYTES` (default `5G`): the largest response body. A size
or `off`.
In front of a code forge, a clone is a response and a push is a request. At the
defaults, an upload over 100 MiB or slower than 60 seconds is cut off. A forge
that takes large uploads needs `SWWAF_REQUEST_MAX_BYTES`,
`SWWAF_CLIENT_REQUEST_TIMEOUT` and `SWWAF_UPSTREAM_REQUEST_TIMEOUT` raised to
fit.
What the client gets when a limit is passed is under "Size and time limits" in
[`SPEC.md`](../SPEC.md).
## Netblock lists
- `SWWAF_ALLOW_NETS` (default empty): netblocks whose clients skip every check,
such as your monitoring or your own network. The size and time limits still
apply to them. They are not looked up. They still need a token for the admin
endpoints.
- `SWWAF_RATE_LIMIT_EXEMPT_NETS` (default empty): netblocks whose clients are
exempt from rate limiting and the byte limits, such as a machine that talks to
the app all day. Everything else still applies to them.
- `SWWAF_DENY_NETS` (default empty): netblocks whose clients are always refused.
A client in both lists is let through.
## Rate limiting and byte limits
- `SWWAF_RATE_LIMIT_PER_MINUTE` (default `1000`), `SWWAF_RATE_LIMIT_PER_HOUR`
(default `10000`) and `SWWAF_RATE_LIMIT_PER_DAY` (default `50000`): the most
requests a client may make in each window. A count or `off`. The defaults are
several times what one busy person produces. A browser loading a heavy page
makes a few hundred requests, and several people often share one address.
- `SWWAF_RATE_LIMIT_EXEMPT_PATHS` (default empty): path prefixes exempt from
rate limiting, such as `/assets/`. Their bytes are not counted either. The
path is matched exactly as sent, without the query, and is not
percent-decoded. `/assets/` matches `/assets/app.js`. It does not match
`/Assets/app.js`, `/%61ssets/app.js` or `/static/assets/app.js`. There are no
wildcards. A path holding `..`, a backslash or an encoded slash (`%2F`) is
never exempt, since the app may read it as a path outside the prefix.
- `SWWAF_BYTES_LIMIT_PER_MINUTE` (default `10G`), `SWWAF_BYTES_LIMIT_PER_HOUR`
(default `20G`) and `SWWAF_BYTES_LIMIT_PER_DAY` (default `50G`): the most
bytes a client may have counted in each window. A size or `off`. Bytes are
counted once the answer has ended, so a byte limit never cuts an answer short.
The client's next request is refused instead. Each default is above the
largest request and answer together, so at the defaults no single download
breaks a limit.
- `SWWAF_BYTES_COUNT` (default `both`): which body bytes the byte limits count:
`response`, `request` or `both`. For a WebSocket, what it carried each way
counts once it closes.
## Looking up the AS number and country
- `SWWAF_LOOKUP_SOURCE` (default `geojs`): `geojs`, `file` or `off`. `geojs`
asks the GeoJS web service, which is then told the address of every new
visitor. `file` looks clients up in the IPinfo Lite database file at
`SWWAF_LOOKUP_DB_PATH`, and sends nothing off the host. `off` looks up no
client. With `off`, a setting that needs lookups stops the start:
- a country list;
- `SWWAF_ADD_LOOKUP_HEADERS`;
- an entry in `SWWAF_ASN_LIMIT_PERCENT`, `SWWAF_COUNTRY_LIMIT_PERCENT`,
`SWWAF_ASN_BYTES_PERCENT` or `SWWAF_COUNTRY_BYTES_PERCENT`;
- `SWWAF_UNKNOWN_LIMIT_PERCENT` below 100;
- `SWWAF_ASN_LIMIT_PERCENT_URL`;
- an anomaly threshold per AS number.
- `SWWAF_LOOKUP_DB_PATH` (default empty): the IPinfo Lite database file, in its
`.mmdb` form, for `SWWAF_LOOKUP_SOURCE=file`. `file` without it stops the
start, and so does setting it with any other source. A file that is missing or
cannot be read stops the start too.
- `SWWAF_LOOKUP_TIMEOUT` (default `1s`): how long a request waits for its
client's first answer from GeoJS when a setting needs it, and how long a
request to GeoJS may take. A duration; it cannot be `off`.
- `SWWAF_ADD_LOOKUP_HEADERS` (default `false`): `true` passes the app the
client's AS number in `X-Client-ASN` and its country in `X-Client-Country`. A
header whose value is unknown is left out. Whatever this setting says, any
such header the client sent is removed.
See [`lookup.md`](lookup.md) for what each source sends where, and how long
answers are kept.
## Country lists
- `SWWAF_DENIED_COUNTRIES` (default empty): countries whose clients are refused,
such as `cn,ru,kp`.
- `SWWAF_EXCLUSIVELY_ALLOWED_COUNTRIES` (default empty): when set, the only
countries whose clients get through, such as `us,de`. A client whose country
cannot be found is refused too. Otherwise every new client would be let in
whenever GeoJS stops answering. A client on a private address has no country,
so it is refused unless it is in `SWWAF_ALLOW_NETS`.
A country on both lists stops the start. What a refused request gets, and why
the lists are empty by default, is under "Country lists" in
[`SPEC.md`](../SPEC.md).
## Lower limits by AS number and country
Clients of the AS numbers and countries listed here get a percentage of every
rate limit and byte limit. A lowered limit is rounded down. "Biased thresholds"
in [`SPEC.md`](../SPEC.md) says why the lists are empty by default and why no
budget is shared by a whole AS number or country.
- `SWWAF_ASN_LIMIT_PERCENT` (default empty): a list of AS numbers, each with `:`
and a percentage, such as `AS14061:50,AS16276:50,AS45102:25`. An AS number
listed twice is refused.
- `SWWAF_COUNTRY_LIMIT_PERCENT` (default empty): the same by country, such as
`cn:25,ru:50`.
- `SWWAF_ASN_BYTES_PERCENT` and `SWWAF_COUNTRY_BYTES_PERCENT` (default empty):
the same for the byte limits alone. For the AS numbers and countries they
list, they take the place of the two settings above.
- `SWWAF_UNKNOWN_LIMIT_PERCENT` (default `100`): the percentage of every limit
for a client without a country:
- one the lookup cannot place;
- one on a private address;
- one whose answer from GeoJS has not come in time.
- `SWWAF_ASN_LIMIT_PERCENT_URL` (default unset): the `http` or `https` URL of a
text file of such entries, one to a line, such as `AS14061:50`. One list can
then serve several instances. It is fetched and kept as a blocklist is. Where
it and `SWWAF_ASN_LIMIT_PERCENT` both give a percentage, the lower applies. A
URL that is also in `SWWAF_BLOCKLIST_URLS` stops the start.
A client to which several percentages apply gets the lowest. The log line of
each counted request, and the notes of each ban, say which setting lowered the
limit.
## Reputation sources
None is on by default. A reputation source judges a client by what others saw it
do. The defaults judge it by what it does to your service.
- `SWWAF_BLOCKLIST_URLS` (default empty): blocklists to fetch, such as
`https://www.spamhaus.org/drop/drop.txt`. Each is an `http` or `https` URL
without a user or a fragment. A URL listed twice is refused.
- `SWWAF_BLOCKLIST_REFRESH` (default `24h`): how long a list waits after its
last fetch, or failed try, before it is fetched again. A duration of `1h` or
more; it cannot be `off`. The Spamhaus lists may be fetched no more than once
an hour.
- `SWWAF_BLOCKLIST_ACTION` (default `deny`): what is done with a client on a
blocklist. `deny` refuses its requests. `limit:<percent>`, such as `limit:25`,
gives it that percentage of every limit. `log` only notes the list in the log
line and raises an alert.
- `SWWAF_DNSBL_ZONES` (default empty): the DNS blocklists to ask about each
client, such as `dnsbl.dronebl.org`. A DNS blocklist answers a DNS query for a
name made from an address, and so says whether the address is on it. A zone is
a DNS name of at most 189 characters. A Spamhaus zone carries its key, as in
`<key>.xbl.dq.spamhaus.net`, and is shown with the key masked. A zone listed
twice is refused, whatever its case or key. Do not name a zone meant for mail:
such a zone holds the residential addresses ordinary visitors come from.
- `SWWAF_DNSBL_RESOLVER` (default unset): the resolver to ask the zones through,
such as `192.0.2.53` or `[2001:db8::53]:5353`. An IP address with an optional
port, 53 when none is given. Unset, the host's resolver is used. Several zones
refuse queries that come through a public resolver.
- `SWWAF_ABUSEIPDB_KEY` (default unset): the key of your AbuseIPDB account.
While it is set, a client that has committed an offence is checked. A control
character in it is refused.
- `SWWAF_ABUSEIPDB_MIN_SCORE` (default `75`): the least abuse confidence score,
from 0 to 100, that is a hit.
- `SWWAF_ABUSEIPDB_DAILY_BUDGET` (default `900`): the most checks made in a day,
in UTC, a whole number above zero. AbuseIPDB's free accounts may make 1,000.
- `SWWAF_CROWDSEC_LAPI_URL` (default unset): the local API of a CrowdSec engine
you run, such as `http://172.17.0.1:8080`. An `http` or `https` URL without a
user or a fragment. Its decision list is at `v1/decisions` under that URL, and
is fetched every minute. Set without the key, it stops the start. So does a
decision list URL that is also in `SWWAF_BLOCKLIST_URLS`, or that is
`SWWAF_ASN_LIMIT_PERCENT_URL`.
- `SWWAF_CROWDSEC_LAPI_KEY` (default unset): the key the engine gave for
`smallwebwaf`, as `cscli bouncers add smallwebwaf` prints it. Set without the
URL, it stops the start.
- `SWWAF_REPUTATION_ACTION` (default `limit:25`): what is done with a client on
a DNS blocklist, or one whose AbuseIPDB score is a hit. `deny`,
`limit:<percent>` or `log`, as for `SWWAF_BLOCKLIST_ACTION`. Such a verdict is
less certain than the Spamhaus DROP list, so by default the client gets a
quarter of every limit.
- `SWWAF_REPUTATION_CACHE_TTL` (default `24h`): how long a zone's verdict or
AbuseIPDB's score is used. A duration; it cannot be `off`.
- `SWWAF_REPUTATION_TIMEOUT` (default `2s`): how long a query to a zone or a
check with AbuseIPDB may take. A duration; it cannot be `off`.
See [`reputation.md`](reputation.md) for how each source is asked and what it
does with the answer.
## Attack detection
- `SWWAF_RULES_DIR` (default `/etc/smallwebwaf/rules.d`): the directory of the
rule files (see [`rules.md`](rules.md)). A directory that cannot be read stops
the start. An empty one is no error.
- `SWWAF_RULES_ENABLED` (default `true`): `false` reads no rule file.
- `SWWAF_TRAP_PATHS` (default empty): paths the app never serves and only
scanners ask for, such as `/wp-login.php,/xmlrpc.php` in front of a code
forge. A request for one bans the client, as a `ban` rule does. Each starts
with `/` and holds no `?`. A trap path is matched whole, without the query,
against the path as sent and once percent-decoded. `/wp-login.php` matches
`/wp-login.php?x=1` and `/%77p-login.php`. It does not match `/wp-login.php/`
or `/blog/wp-login.php`.
- `SWWAF_WAF_MODE` (default `block`): what the Core Rule Set does with a request
it takes for an attack. `block` refuses it with `403`. `detect` lets it
through, logged and alerted. `off` inspects no request.
- `SWWAF_WAF_PARANOIA_LEVEL` (default `1`): the Core Rule Set's paranoia level,
from 1 to 4. Each level up runs more rules. Those find more attacks, and take
more ordinary requests for attacks.
- `SWWAF_WAF_ANOMALY_THRESHOLD` (default `5`): the score at which a request is a
match. Each rule that matches adds to the request's score, and a rule rated
critical adds 5. So by default one such rule is enough. A whole number above
zero, or `off`. With `off` no request is a match, and scores are still logged.
- `SWWAF_WAF_DISABLED_RULES` (default
`920340,920420,920440,920640,930130,930140`): the ids of Core Rule Set rules
to switch off. The log line names the rules a request matched, so a rule that
refuses your app's ordinary requests can be found there. "Attack detection" in
[`SPEC.md`](../SPEC.md) says what the six default ids refuse and why they are
off. A list you give replaces the default, so name these six ids in it to keep
them off. An id must be a whole number above zero. An id from 900000 to 900999
is refused: those are the rules that set the Core Rule Set up, and
`smallwebwaf`'s own.
- `SWWAF_WAF_EXEMPT_PATHS` (default empty): path prefixes the Core Rule Set does
not inspect, matched as `SWWAF_RATE_LIMIT_EXEMPT_PATHS` is.
- `SWWAF_WAF_BODY_LIMIT` (default `off`): `off` reads no request body. A size,
at most `1G`, switches body inspection on. The Core Rule Set then reads a form
data or multipart body up to that size, and the rest streams on to the app. It
reads a JSON or XML body no larger than that size, since those cannot be read
in part. Any other body, such as a git push, reaches the app uninspected. See
[`core-rule-set.md`](core-rule-set.md).
- `SWWAF_ERROR_BURST_THRESHOLD` (default `30`): the most refusals of one client
in a minute for a rule match, a trap path, a Core Rule Set match or a failed
token check. One more bans the client, as a broken rate limit does. A count or
`off`. The app's own `401` and `404` answers are not counted.
## How long bans last and what they cover
- `SWWAF_BAN_RESPONSE` (default `403`): how a refused client is answered: `403`,
`429`, or `close` to close the connection without an answer. A `block` rule
and the Core Rule Set always answer `403`.
- `SWWAF_LIMIT_BAN_DURATION` (default `1h`): the ban for a first broken rate
limit, byte limit or error burst. A duration; it cannot be `off`.
- `SWWAF_LIMIT_BAN_REPEAT_WINDOW` (default `24h`): a client that breaks a limit
again within this time after its ban ended is banned three times as long. A
duration; it cannot be `off`.
- `SWWAF_MAX_BAN_DURATION` (default `7d`): a ban for a broken limit that would
be longer is permanent instead. A duration; it cannot be `off`.
- `SWWAF_ATTACK_BAN_DURATION` (default `7d`): the ban for a first clear sign of
attack. A duration; it cannot be `off`.
`https` URL with a host and an optional port, and nothing more.
- `SWWAF_LISTEN_ADDR` (default `:8080`): where `smallwebwaf` listens, an
optional host and a port. The host stays empty.
- `SWWAF_INSTANCE_NAME` (default: the container's host name): the `instance`
name in every log line, alert and metric, such as `fsn1app1/gitea`. Valid
UTF-8. No control character while `SWWAF_ALERT_NTFY_URL` is set. 1 to 48
printable ASCII characters without a space while `SWWAF_LOG_REMOTE_URL` is set
and `SWWAF_LOG_REMOTE_APP_NAME` is not.
- `SWWAF_MODE` (default `enforce`): `enforce` or `observe`.
- `SWWAF_TRUSTED_PROXIES` (default `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.
- `SWWAF_IPV6_GROUP_PREFIX` (default `64`): the prefix length of an IPv6
client's group, from 32 to 128.
- `SWWAF_MAX_TRACKED_CLIENTS` (default `20000`): the most clients kept, a whole
number above zero.
- `SWWAF_MAX_BANS` (default `5000`): the most bans `smallwebwaf` made that are
kept, whether past, active or permanent. A whole number above zero. Bans whose
cause is `admin` are kept besides and never dropped (see
[`bans.md`](bans.md)).
- `SWWAF_BAN_SCOPE_V4_PREFIX` (default `32`): the length of the netblock around
an IPv4 client that a ban covers, from 0 to 32. `24` bans the surrounding /24.
An IPv6 ban covers the client's group.
kept, a whole number above zero.
## Where and how often the state files are written
## Tokens
- `SWWAF_ADMIN_TOKEN` (default unset): the token for the ban endpoints and
`/_smallwebwaf/clients/<ip>`. At least 32 characters.
- `SWWAF_METRICS_TOKEN` (default unset): the token for `/_smallwebwaf/metrics`.
At least 32 characters.
## State files
- `SWWAF_STATE_DIR` (default `/var/lib/smallwebwaf`): the directory of the state
files, an absolute path. A directory that does not exist or cannot be written
stops the start.
files, an absolute path that exists and can be written.
- `SWWAF_STATE_WRITE_DELAY` (default `10s`): how long `bans.json` waits to be
written after a ban is made, lifted or made permanent. Every change in between
goes into the same write. A duration; it cannot be `off`.
written after a ban is made, lifted or made permanent. A duration.
- `SWWAF_STATE_COUNTER_INTERVAL` (default `15m`): how often every state file is
written. A duration; it cannot be `off`.
written. A duration.
## Logging
- `SWWAF_LOG_LEVEL` (default `info`): the least severe of `smallwebwaf`'s own
messages that are written: `debug`, `info`, `warn` or `error`.
- `SWWAF_LOG_REQUEST_HEADERS` (default
`accept,accept-language,accept-encoding,content-type,origin,range`): the
request headers to record in the log line, in either case. `Authorization`,
`Cookie` and `Set-Cookie` are never logged, even if listed. `Host` and
`Transfer-Encoding` are refused: Go's HTTP server takes them out of the
request. The host is the field `host`.
- `SWWAF_LOG_LEVEL` (default `info`): the least severe of `smallwebwaf`'s own
messages that are written: `debug`, `info`, `warn` or `error`. No message is
at `debug`. It holds back no request log line. `warn` and `error` hold back
the line of settings at start.
- `SWWAF_LOG_REMOTE_URL` (default unset): a syslog server every line on stdout
is also sent to, such as `syslog+tls://logs.example:6514`. The forms are
`syslog+udp://`, `syslog+tcp://` and `syslog+tls://`, each with a host and a
port and nothing more.
request headers recorded in the log line, in either case. `Host` and
`Transfer-Encoding` are refused; the host is the field `host`.
- `SWWAF_LOG_REMOTE_URL` (default unset): a syslog server that also gets every
line written to stdout: `syslog+udp://`, `syslog+tcp://` or `syslog+tls://`,
each with a host and a port and nothing more.
- `SWWAF_LOG_REMOTE_TLS_CA_FILE` (default unset): a file of PEM certificates
that a `syslog+tls` server's certificate must chain to, instead of the host's
own. A file that cannot be read, or holds no certificate, stops the start.
own. A file that cannot be read, or holds no certificate, is refused.
- `SWWAF_LOG_REMOTE_BUFFER` (default `10000`): the most lines held while they
wait to be sent, a whole number above zero.
- `SWWAF_LOG_REMOTE_FACILITY` (default `local0`): the syslog facility: `kern`,
@@ -370,53 +83,193 @@ does with the answer.
- `SWWAF_LOG_REMOTE_APP_NAME` (default: `SWWAF_INSTANCE_NAME`): the app name in
each syslog record, 1 to 48 printable ASCII characters without a space.
## Tokens and metrics
## Metrics
- `SWWAF_ADMIN_TOKEN` (default unset): the token for the ban endpoints and
`/_smallwebwaf/clients/<ip>`. A long random value of at least 32 characters.
Unset, those endpoints are off. Give it as a file to keep it from the app (see
"Settings given as files" below).
- `SWWAF_METRICS_TOKEN` (default unset): the token a scraper sends for
`/_smallwebwaf/metrics`, at least 32 characters. Unset, the metrics are off.
It is separate from the admin token, so a scraper cannot manage bans.
- `SWWAF_METRICS_TOP_N` (default `50`): how many AS numbers and how many
countries get series of their own in the metrics. The rest count as `other`. A
whole number above zero.
countries get series of their own. A whole number above zero.
## Alert destinations
## Static lists
- `SWWAF_ALLOW_NETS` (default empty): netblocks whose clients are refused only
for a size or time limit or a missing or wrong token, such as your monitoring.
- `SWWAF_RATE_LIMIT_EXEMPT_NETS` (default empty): netblocks whose clients are
exempt from rate limiting and the byte limits.
- `SWWAF_DENY_NETS` (default empty): netblocks whose clients are always refused.
## Request rate limits, per client
- `SWWAF_RATE_LIMIT_PER_MINUTE` (default `1000`), `SWWAF_RATE_LIMIT_PER_HOUR`
(default `10000`) and `SWWAF_RATE_LIMIT_PER_DAY` (default `50000`): the most
requests a client may make in each window. A count or `off`.
- `SWWAF_RATE_LIMIT_EXEMPT_PATHS` (default empty): path prefixes exempt from
rate limiting and the byte limits, such as `/assets/`.
## Byte limits, per client
- `SWWAF_BYTES_LIMIT_PER_MINUTE` (default `10G`), `SWWAF_BYTES_LIMIT_PER_HOUR`
(default `20G`) and `SWWAF_BYTES_LIMIT_PER_DAY` (default `50G`): the most
bytes counted for a client in each window. A size or `off`.
- `SWWAF_BYTES_COUNT` (default `both`): which body bytes the byte limits count:
`response`, `request` or `both`.
## Size and time limits
- `SWWAF_CLIENT_REQUEST_TIMEOUT` (default `60s`): how long a client may take to
send its request line and headers, and then, from the end of the headers, its
body. A duration or `off`.
- `SWWAF_CLIENT_REQUEST_HEADER_MAX_BYTES` (default `32K`): the largest request
line and headers. A size over `4K`; never `off`.
- `SWWAF_CLIENT_IDLE_TIMEOUT` (default `120s`): how long a kept-open connection
may wait for its next request before it is closed. A duration or `off`.
- `SWWAF_CLIENT_RESPONSE_TIMEOUT` (default `30m`): how long the answer may take
to reach the client, from the end of the request to the last byte. A duration
or `off`.
- `SWWAF_UPSTREAM_REQUEST_TIMEOUT` (default `60s`): how long connecting to the
app and sending it the whole request may take. A duration or `off`.
- `SWWAF_UPSTREAM_RESPONSE_TIMEOUT` (default `30m`): how long the app may take
to send its whole answer. A duration or `off`.
- `SWWAF_REQUEST_MAX_BYTES` (default `100M`): the largest request body. A size
or `off`.
- `SWWAF_RESPONSE_MAX_BYTES` (default `5G`): the largest response body. A size
or `off`.
## Lookup of AS number and country
- `SWWAF_LOOKUP_SOURCE` (default `geojs`): `geojs`, `file` or `off`.
- `SWWAF_LOOKUP_DB_PATH` (default empty): the IPinfo Lite database file, in its
`.mmdb` form, for `SWWAF_LOOKUP_SOURCE=file`.
- `SWWAF_LOOKUP_TIMEOUT` (default `1s`): how long a request waits for its
client's first answer from GeoJS, and how long a request to GeoJS may take. A
duration; never `off`.
- `SWWAF_ADD_LOOKUP_HEADERS` (default `false`): `true` passes the app the
client's AS number in `X-Client-ASN` and its country in `X-Client-Country`.
## Country lists
- `SWWAF_DENIED_COUNTRIES` (default empty): countries whose clients are refused,
such as `cn,ru,kp`.
- `SWWAF_EXCLUSIVELY_ALLOWED_COUNTRIES` (default empty): when set, the only
countries whose clients get through, such as `us,de`. A country on both lists
is refused.
## Biased thresholds
- `SWWAF_ASN_LIMIT_PERCENT` (default empty): a list of AS numbers, each with `:`
and a percentage, such as `AS14061:50,AS16276:50,AS45102:25`. An AS number
listed twice is refused.
- `SWWAF_COUNTRY_LIMIT_PERCENT` (default empty): the same by country, such as
`cn:25,ru:50`.
- `SWWAF_ASN_BYTES_PERCENT` and `SWWAF_COUNTRY_BYTES_PERCENT` (default empty):
the same, for the byte limits alone.
- `SWWAF_UNKNOWN_LIMIT_PERCENT` (default `100`): the percentage for a client the
lookup cannot place.
- `SWWAF_ASN_LIMIT_PERCENT_URL` (default unset): the `http` or `https` URL of a
text file of `AS<number>:<percent>` lines, one to a line. A URL that is also
in `SWWAF_BLOCKLIST_URLS` is refused.
## Attack detection
- `SWWAF_RULES_DIR` (default `/etc/smallwebwaf/rules.d`): the directory of the
rule files.
- `SWWAF_RULES_ENABLED` (default `true`): `false` reads no rule file.
- `SWWAF_TRAP_PATHS` (default empty): paths only scanners ask for, such as
`/wp-login.php,/xmlrpc.php`. Each starts with `/` and holds no `?`.
- `SWWAF_WAF_MODE` (default `block`): `off`, `detect` or `block`.
- `SWWAF_WAF_PARANOIA_LEVEL` (default `1`): the Core Rule Set's paranoia level,
from 1 to 4.
- `SWWAF_WAF_ANOMALY_THRESHOLD` (default `5`): the score at which a request is a
match. A whole number above zero, or `off`.
- `SWWAF_WAF_DISABLED_RULES` (default
`920340,920420,920440,920640,930130,930140`): the ids of Core Rule Set rules
to switch off. Each a whole number above zero. An id from 900000 to 900999 is
refused: those are the rules that set the Core Rule Set up, and
`smallwebwaf`'s own.
- `SWWAF_WAF_EXEMPT_PATHS` (default empty): path prefixes the Core Rule Set does
not inspect.
- `SWWAF_WAF_BODY_LIMIT` (default `off`): `off`, or how much of a request body
the Core Rule Set reads, a size of at most `1G`.
- `SWWAF_ERROR_BURST_THRESHOLD` (default `30`): the most refusals of one client
in a minute for a rule match, a trap path, a Core Rule Set match or a failed
token check. A count or `off`.
## Ban lengths, response and scope
- `SWWAF_BAN_RESPONSE` (default `403`): `403`, `429` or `close`.
- `SWWAF_LIMIT_BAN_DURATION` (default `1h`): the ban for a first broken limit. A
duration.
- `SWWAF_LIMIT_BAN_REPEAT_WINDOW` (default `24h`): the time after a ban ends
within which breaking a limit again lengthens the next ban. A duration.
- `SWWAF_MAX_BAN_DURATION` (default `7d`): the longest ban for a broken limit;
one that would be longer is permanent. A duration.
- `SWWAF_ATTACK_BAN_DURATION` (default `7d`): the ban for a first clear sign of
attack. A duration.
- `SWWAF_BAN_SCOPE_V4_PREFIX` (default `32`): how much a ban on an IPv4 client
covers: the prefix length of its netblock, from 0 to 32.
## Reputation
- `SWWAF_BLOCKLIST_URLS` (default empty): blocklists to fetch, such as
`https://www.spamhaus.org/drop/drop.txt`. Each an `http` or `https` URL
without a user or a fragment. A URL listed twice is refused.
- `SWWAF_BLOCKLIST_REFRESH` (default `24h`): how long a list waits after its
last try before it is fetched again. A duration of `1h` or more.
- `SWWAF_BLOCKLIST_ACTION` (default `deny`): `deny`, `limit:<percent>` or `log`.
- `SWWAF_DNSBL_ZONES` (default empty): the DNS blocklists to ask, such as
`dnsbl.dronebl.org`. Each a DNS name of at most 189 characters. A Spamhaus
zone carries its key, as in `<key>.xbl.dq.spamhaus.net`. A zone listed twice
is refused, whatever its case or key.
- `SWWAF_DNSBL_RESOLVER` (default unset): the resolver to ask the zones through,
such as `192.0.2.53` or `[2001:db8::53]:5353`. An IP address with an optional
port, 53 when none is given. Unset, the host's resolver is used.
- `SWWAF_ABUSEIPDB_KEY` (default unset): the key of your AbuseIPDB account. A
control character in it is refused.
- `SWWAF_ABUSEIPDB_MIN_SCORE` (default `75`): the least abuse confidence score,
from 0 to 100, that is a hit.
- `SWWAF_ABUSEIPDB_DAILY_BUDGET` (default `900`): the most checks made in a day,
a whole number above zero. AbuseIPDB's free accounts may make 1,000.
- `SWWAF_CROWDSEC_LAPI_URL` (default unset): the local API of a CrowdSec engine
you run, such as `http://172.17.0.1:8080`. An `http` or `https` URL without a
user or a fragment; its decision list is at `v1/decisions` under it. Set
without the key, it is refused. So is a decision list URL that is also in
`SWWAF_BLOCKLIST_URLS`, or that is `SWWAF_ASN_LIMIT_PERCENT_URL`.
- `SWWAF_CROWDSEC_LAPI_KEY` (default unset): the key the engine gave for
`smallwebwaf`, as `cscli bouncers add smallwebwaf` prints it. Set without the
URL, it is refused.
- `SWWAF_REPUTATION_ACTION` (default `limit:25`): `deny`, `limit:<percent>` or
`log`, for DNS blocklist and AbuseIPDB hits.
- `SWWAF_REPUTATION_CACHE_TTL` (default `24h`): how long a zone's verdict or
AbuseIPDB's score is used. A duration.
- `SWWAF_REPUTATION_TIMEOUT` (default `2s`): how long a query to a zone or a
check with AbuseIPDB may take. A duration.
## Alerting
- `SWWAF_ALERT_WEBHOOK_URL` (default unset): the webhook that receives each
alert as a JSON object. An `http` or `https` URL without a user or a fragment.
The settings logged at start show its path and query as `********`, since many
webhooks carry their secret there.
- `SWWAF_ALERT_WEBHOOK_HEADERS` (default empty): headers sent with each post,
such as `Authorization:Bearer 0123456789abcdef`. A list of name, `:` and
value. A value cannot hold a comma.
- `SWWAF_ALERT_SLACK_WEBHOOK_URL` (default unset): the Slack incoming webhook
that receives each alert as a message. It is checked and masked as the webhook
URL is.
that receives each alert as a message, checked as the webhook URL is.
- `SWWAF_ALERT_NTFY_URL` (default unset): the ntfy topic that receives each
alert, as the topic's full URL, such as `https://ntfy.sh/my-alerts`. It is
checked and masked as the webhook URL is.
- `SWWAF_ALERT_NTFY_TOKEN` (default unset): an ntfy access token, sent as
`Authorization: Bearer <token>`. A control character in it is refused.
alert, as the topic's full URL, such as `https://ntfy.sh/my-alerts`, checked
as the webhook URL is.
- `SWWAF_ALERT_NTFY_TOKEN` (default unset): an ntfy access token. A control
character in it is refused.
- `SWWAF_ALERT_EVENTS` (default
`ban,permanent_ban,waf_block,anomaly,reputation_hit,source_failure,file_error`):
the events alerts are sent for. Any other name is refused.
the event types alerts are sent for, from those in [`alerts.md`](alerts.md)
but `summary`. Any other name is refused.
- `SWWAF_ALERT_COOLDOWN` (default `15m`): how long a repeat of an alert is held
back. A duration or `off`.
- `SWWAF_ALERT_MAX_PER_HOUR` (default `60`): the most alerts sent in an hour.
The rest are rolled into one summary. A whole number above zero, or `off`.
See [`alerts.md`](alerts.md) for the events and what each destination gets.
- `SWWAF_ALERT_MAX_PER_HOUR` (default `60`): the most alerts sent in an hour. A
whole number above zero, or `off`.
## Anomaly thresholds
These only alert. They refuse and ban nothing. Each scope has four thresholds:
the most requests and the most bytes counted in a minute and in an hour.
Requests are counts, bytes are sizes. Each is `off` by default. What is unusual
depends on each service's normal traffic, which the metrics show. The four
thresholds per client are:
Each scope has four thresholds: the most requests and the most bytes counted in
a minute and in an hour. Requests are counts, bytes are sizes. Each is `off` by
default. The four thresholds per client are:
- `SWWAF_ANOMALY_CLIENT_REQUESTS_PER_MINUTE`;
- `SWWAF_ANOMALY_CLIENT_REQUESTS_PER_HOUR`;
@@ -432,30 +285,19 @@ as `REQUESTS_PER_MINUTE`:
client;
- `SWWAF_ANOMALY_NET_V6_PREFIX` (default `48`, from 0 to 128) for an IPv6
client.
- `SWWAF_ANOMALY_ASN_...`: per AS number. Needs lookups on.
- `SWWAF_ANOMALY_ASN_...`: per AS number. Needs a lookup source.
- `SWWAF_ANOMALY_TOTAL_...`: the whole service.
- `SWWAF_WATCH_...`: each netblock in `SWWAF_WATCH_NETS`, as a whole.
`SWWAF_WATCH_NETS` (default empty) is a list of name, `=` and netblock, such
as `office=203.0.113.0/24,scraper-x=198.51.100.0/22`. An item without `=` or a
name, or with a bad netblock, is refused. So is a name used twice.
Every request but the health check is counted, whatever was done with it,
clients in `SWWAF_ALLOW_NETS` included. At most 20,000 counters are kept.
`alerts.json` keeps them across a restart.
## Settings given as files
Any setting may be given as a file holding its value. Add `_FILE` to the
setting's name: `SWWAF_METRICS_TOKEN_FILE` names the file that holds
`SWWAF_METRICS_TOKEN`. The file's contents are the value, less one newline at
the end. They are checked as the value itself would be. Setting both forms stops
the start, and so does naming a file that cannot be read.
`SWWAF_LOG_REMOTE_TLS_CA_FILE` already holds a file name, so it has no `_FILE`
form.
A token given as a file is out of the app's reach only while the `smallwebwaf`
user alone can read the file. Make it on the host, owned by uid 65532 with mode
`0400`:
Add `_FILE` to a setting's name to read its value from a file:
`SWWAF_METRICS_TOKEN_FILE` names the file that holds `SWWAF_METRICS_TOKEN`. To
keep a token from the app, make the file on the host, owned by uid 65532 with
mode `0400`:
```sh
mkdir -p /srv/app/tokens
@@ -477,7 +319,8 @@ docker run \
A few limits are fixed rather than settings:
- at most 100,000 GeoJS answers are kept, for 7 days each;
- at most 100,000 GeoJS answers are kept;
- at most 100,000 DNS blocklist verdicts and 100,000 AbuseIPDB scores are kept;
- at most 1,000 DNS blocklist queries are under way at once;
- the CrowdSec decision list is fetched again a minute after the last fetch.
- at most 20,000 anomaly counters are kept;
- each alert destination's queue holds at most 1,000 alerts.
docs/state-files.md
+90 -92
View File
@@ -1,102 +1,100 @@
# State files
`smallwebwaf` keeps its state in memory, and a copy of it in five JSON files in
`SWWAF_STATE_DIR`. The files are meant for people as well: you can read or edit
them at any time, and the running `smallwebwaf` takes the edit in. The
requirements they meet are under "Persistent state" in [`SPEC.md`](../SPEC.md).
## The files
The five JSON files in `SWWAF_STATE_DIR`, and what each holds. "Persistent
state" in [`SPEC.md`](../SPEC.md) says how they are written, read and edited.
Each has a top-level `version` of 1.
- `bans.json`: active and past bans, up to `SWWAF_MAX_BANS` that `smallwebwaf`
made and every ban you made, indented to be read. Per entry:
- the netblock, start and expiry (`null` for permanent);
- the cause: `attack`, `limit`, `admin` or `crowdsec`;
- a short reason;
- when it was lifted, if you lifted it;
- the notes (see [`bans.md`](bans.md)).
- `clients.json`: per client, its minute, hour and day counters and its history
since it was first seen, one client per line, so `grep` shows everything about
one. The history holds:
- the first and last time seen;
- the AS number, AS name and country last looked up, and when;
- total requests, and how many were forwarded and how many refused;
- bytes in each direction;
- responses by status class;
- offences by kind: `limit`, `attack`, `rule_blocked`, `waf_blocked` and
`token_refused`.
## `bans.json`
Clients that were never banned are kept too, so every client's history
survives a restart.
Active and past bans: every ban an admin made, and up to `SWWAF_MAX_BANS` of
those `smallwebwaf` made. Per entry:
- `lookups.json`: GeoJS answers, one per line: the AS number, AS name and
country, when GeoJS was asked and when the answer was last used.
- `reputation.json`:
- the last good copy of each list fetched from a URL, with when it was last
tried;
- each DNS blocklist verdict still in use;
- AbuseIPDB's scores, and the checks spent today.
- `alerts.json`:
- the anomaly counters;
- the alert cooldowns: for each event and netblock, source, file or thing
counted, when it was last sent and the count of repeats held back since;
- the alerts sent and held back in the current hour;
- the alerts waiting for each destination.
- `netblock`, `start` and `expires` (`null` for a permanent ban);
- `cause`: `attack`, `limit`, `admin` or `crowdsec`;
- `reason`: a short reason;
- `lifted`: when an admin lifted it, if one did;
- `notes`: the notes below.
Times are RFC 3339 UTC. Durations and sizes are plain numbers, with the unit in
the field name. `bans.json`, `reputation.json` and `alerts.json` are indented;
`clients.json` and `lookups.json` put each entry on one line.
To ban a netblock, add an entry with its `netblock`, `start` and `expires`.
`reason`, `notes` and `cause` may be left out; the cause is then `admin`:
```json
{
"version": 1,
"bans": [
{
"netblock": "203.0.113.0/24",
"start": "2026-10-06T12:00:00Z",
"expires": null,
"reason": "probes for logins"
}
]
}
```
To lift a ban, add `"lifted"` with the time you lift it, such as
`"lifted": "2026-10-06T13:00:00Z"`. To keep a ban `smallwebwaf` made, set its
`cause` to `admin`. To forget a ban, delete its entry.
The notes:
- `asn`, `as_name` and `country`: the client's, added when the lookup answers
(empty when lookups are off);
- what was broken: the rule id and target that matched, or the trap path, or the
limit, its window and the count reached;
- the client's percentage of the limit, with the setting that gave it;
- the reputation sources the client is on;
- `request`: the request that caused the ban: time, method, host, path with its
query string, status and user agent, each text cut to 256 bytes;
- `requests` and `refused`: the netblock's requests since it was first seen, and
how many this ban has refused so far, kept up to date while the ban lasts;
- `earlier_bans`: how many earlier bans the netblock had, by cause.
## `clients.json`
Per client, one per line: its minute, hour and day counters, and its history
since it was first seen:
- the first and last time seen;
- the AS number, AS name and country last looked up, and when;
- total requests, and how many were forwarded and how many refused;
- bytes in each direction;
- responses by status class;
- offences by kind: `limit`, `attack`, `rule_blocked`, `waf_blocked` and
`token_refused`.
## `lookups.json`
GeoJS answers, one per line:
- `client`;
- `asn`, `as_name` and `country`;
- `answered`: when GeoJS answered;
- `used`: when the answer was last used.
## `reputation.json`
- the last good copy of each list fetched from a URL, with when it was last
tried;
- each DNS blocklist verdict still in use;
- AbuseIPDB's scores, and the checks spent today.
## `alerts.json`
- the anomaly counters;
- the alert cooldowns: for each event and netblock, source, file or anomaly
scope, when it was last sent and the count of repeats held back since;
- the alerts sent and held back in the current hour;
- the alerts waiting for each destination.
## Sizes
`clients.json` takes about 1 KiB per client, about 20 MiB at the default
`SWWAF_MAX_TRACKED_CLIENTS`. Written every 15 minutes, that is under 2 GiB of
disk writes a day. `bans.json` takes about 1.2 KiB per ban, at most about 2.5
KiB, so about 6 MiB at the default `SWWAF_MAX_BANS`. With a full file, a hundred
new bans a day come to about 600 MiB of writes. `lookups.json` takes about 150
bytes per answer, under 1.5 GiB of writes a day when full. The other two files
are usually a few MiB or less.
## Writing
`bans.json` is written `SWWAF_STATE_WRITE_DELAY` after a ban is made, lifted or
made permanent. Every file is written every `SWWAF_STATE_COUNTER_INTERVAL`, and
when `smallwebwaf` stops. Each write goes to a temporary file that then replaces
the file, so a crash leaves the old file or the new one, whole. Before writing a
file, `smallwebwaf` takes in any edit you made to it, so your edit is not
overwritten. A write that fails is logged, raised as a `file_error` alert, and
tried again at the next write. A hard kill loses what changed since the last
write:
- ban changes from the last `SWWAF_STATE_WRITE_DELAY` (10 seconds);
- everything else from the last `SWWAF_STATE_COUNTER_INTERVAL` (15 minutes):
- counts and history, and the counts in ban notes;
- GeoJS answers;
- reputation verdicts and the AbuseIPDB count;
- anomaly counters and alert cooldowns.
## Reading at start
The files are read back. Each client keeps its counts, so a restart gives no one
a fresh allowance. Each ban keeps refusing until it ends. Counter buckets and
cache entries whose time has passed are discarded. A missing file is empty
state. These stop the start, with a message naming the file and the place:
- a file that does not parse, or has another `version`;
- an entry without a field it needs;
- a ban whose `cause` is not `limit`, `attack`, `admin` or `crowdsec`;
- a ban whose `expires` is not after its `start`.
## Editing while it runs
`smallwebwaf` watches the directory and takes in your edit of a file as soon as
you save it. What the file then holds replaces what `smallwebwaf` held for it.
It tells its own writes from yours by comparing the file with what it last read
or wrote. A change it made after you opened the file, such as a new ban, is lost
when you save over it; most editors warn when a file changed on disk while it
was open. An edit with an error that would stop the start does not stop the
running `smallwebwaf`. It keeps what it holds. At the file's next write it
renames your file to `<name>.bad`, writes the file again from memory, and logs
and alerts the file and the place of the error. Mend the `.bad` file and move it
back. A file you remove is written again at its next write.
- `clients.json`: about 1 KiB per client, about 20 MiB at the default
`SWWAF_MAX_TRACKED_CLIENTS`. Written every 15 minutes, that is under 2 GiB of
disk writes a day.
- `bans.json`: about 1.2 KiB per ban, at most about 2.5 KiB, so about 6 MiB at
the default `SWWAF_MAX_BANS`. With a full file, a hundred new bans a day come
to about 600 MiB of writes.
- `lookups.json`: about 150 bytes per answer, under 1.5 GiB of writes a day when
full.
- `reputation.json` and `alerts.json`: usually a few MiB or less.
internal/remotelog/remotelog.go
+3 -4
View File
@@ -1,9 +1,8 @@
// Package remotelog sends the lines smallwebwaf writes on stdout to the
// remote log endpoint, SWWAF_LOG_REMOTE_URL, as the "Request log" section
// of SPEC.md requires and "Sending the log to a syslog server" in
// docs/request-log.md describes: each line as the message of an RFC 5424
// syslog record, over UDP, TCP or TLS. Lines wait in a bounded buffer, so
// a slow or unreachable endpoint never holds up a request or stdout.
// of SPEC.md describes: each line as the message of an RFC 5424 syslog
// record, over UDP, TCP or TLS. Lines wait in a bounded buffer, so a slow
// or unreachable endpoint never holds up a request or stdout.
package remotelog
import (
internal/state/state.go
+2 -1
View File
@@ -1,5 +1,6 @@
// Package state keeps smallwebwaf's state in JSON files in
// SWWAF_STATE_DIR, as the "Persistent state" section of SPEC.md describes:
// SWWAF_STATE_DIR, as the "Persistent state" section of SPEC.md requires
// and docs/state-files.md lists them:
// bans.json holds the bans, clients.json each client's counters and
// history, lookups.json GeoJS's answers, reputation.json the last try and
// last good copy of each list fetched from a URL, the DNSBL zones'
internal/state/state_test.go
+2 -2
View File
@@ -1019,8 +1019,8 @@ func TestEditJustBeforeAScheduledWriteSurvivesIt(t *testing.T) {
edit(t, dir, bansJSON, permanentBansJSON)
// The write takes the edit in first, and writes it back. The second
// ban, made after the admin opened the file, is lost, as "Edits
// while running" in SPEC.md says.
// ban, made after the admin opened the file, is lost, as the
// "Persistent state" section of SPEC.md says.
time.Sleep(time.Nanosecond)
synctest.Wait()
script/example-app
+1 -1
View File
@@ -87,7 +87,7 @@ start_container() {
# start_moved_container: run the app's container with the state files on
# a new volume at /srv/state, which SWWAF_STATE_DIR_FILE names in a file
# only the smallwebwaf user can read, as under "Settings given as files"
# in README.md, and wait until it is healthy. smallwebwaf can write the
# in docs/settings.md, and wait until it is healthy. smallwebwaf can write the
# new volume only once the run script has given it to that user.
start_moved_container() {
docker volume create "$MOVED_VOLUME" >/dev/null