Last pass: the sixth README review and the fifth SPEC review

The spec names every fault that stops the start, runs step 15 for every
request but the health check, and states each of the fourteen repeated
requirements once. docs/alerts.md says which alerts have an empty client
and netblock and what a summary's detail holds; docs/settings.md lists
the settings that need a lookup and points at step 3 for the two static
lists. The README and the spec now travel in one branch, so the README
never names a spec section that does not exist yet.

Model: fable-5-1

docs/admin-endpoints.md

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+# Admin endpoints
+
+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.
+- `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, 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.
+- `DELETE /_smallwebwaf/bans/<client>`: lifts every active ban covering the
+  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 `clients.json` does not hold it. Under `bans`, every ban covering
+  the address, with its notes.
+
+## 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
+
+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. 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.
+  One alert per source.
+- `source_failure`: one of:
+    - GeoJS failing;
+    - a list that cannot be fetched;
+    - a DNS blocklist or AbuseIPDB failing or refusing a query;
+    - the day's AbuseIPDB checks used up.
+- `file_error`: one of:
+    - 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 of alerts held back.
+
+## The JSON object
+
+This is the alert for a ban for a broken rate limit, shown indented; it is sent
+on one line:
+
+```json
+{
+    "instance": "fsn1app1/gitea",
+    "time": "2026-10-06T12:00:00.123461Z",
+    "event": "ban",
+    "client": "203.0.113.9",
+    "netblock": "203.0.113.9/32",
+    "asn": "",
+    "as_name": "",
+    "country": "",
+    "reason": "requests per minute over the limit of 1000",
+    "detail": {
+        "ban_expires": "2026-10-06T13:00:00.123Z",
+        "cause": "limit",
+        "notes": {
+            "asn": "",
+            "as_name": "",
+            "country": "",
+            "kind": "requests",
+            "limit": 1000,
+            "window": "minute",
+            "count": 1001,
+            "request": {
+                "time": "2026-10-06T12:00:00.123456789Z",
+                "method": "GET",
+                "host": "app.example",
+                "path": "/owner/repo/commits/branch/main?page=812",
+                "status": 403,
+                "user_agent": "scraper/1.0"
+            },
+            "requests": 5210,
+            "refused": 0,
+            "earlier_bans": {
+                "limit": 0,
+                "attack": 0,
+                "admin": 0,
+                "crowdsec": 0
+            }
+        }
+    },
+    "suppressed_repeats": 0
+}
+```
+
+- `instance`: `SWWAF_INSTANCE_NAME`. `time`: when the alert was raised. `event`:
+  one of the events above.
+- `client`: the address whose request raised the alert. Empty for
+  `source_failure`, `file_error` and `summary`.
+- `netblock`: empty for `source_failure`, `file_error` and `summary`; otherwise
+  one of:
+    - the ban's netblock;
+    - the netblock an anomaly counted, empty in the `asn` and `total` scopes;
+    - for the other events, the client as rate limiting counts it: an IPv4
+      address as a /32, or an IPv6 group.
+- `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`: 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`;
+    - for a summary, the `hour` it covers, the `count` of alerts held back, and
+      that count by event in `events`;
+    - `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
+
+Slack and ntfy get a message with a title and a text. The title is the instance
+and the event, such as `fsn1app1/gitea: ban`. The text is the `reason`, then one
+line for each of these that the alert has:
+
+- the client, the netblock and the country;
+- the file, the source, the error and the mode from `detail`;
+- the suppressed repeats, if any.
+
+Slack gets the title in bold and the text below it, with `&`, `<` and `>`
+escaped. ntfy gets the text as the message, with these headers:
+
+- `Title`: the title;
+- `Authorization`: the token, as `Bearer <token>`, while
+  `SWWAF_ALERT_NTFY_TOKEN` is set;
+- `Priority` and `Tags`: by event, as listed below.
+
+The priority and tag by event:
+
+- `ban`: priority `default`, tag `no_entry`.
+- `permanent_ban`: priority `high`, tag `no_entry`.
+- `waf_block`: priority `default`, tag `shield`.
+- `anomaly`: priority `high`, tag `chart_with_upwards_trend`.
+- `reputation_hit`: priority `low`, tag `label`.
+- `source_failure` and `file_error`: priority `high`, tag `warning`.
+- `summary`: priority `default`, tag `bar_chart`.

docs/gitea.md

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+# smallwebwaf in front of gitea
+
+These notes record what `smallwebwaf` does in front of gitea at the default
+settings. They are observations, not requirements; the requirements are in
+[`SPEC.md`](../SPEC.md). `script/gitea-requests` runs gitea behind the image and
+sends through it a sample of gitea's ordinary use and the requests named below.
+It reports each request the Core Rule Set refuses, so that these notes can be
+checked again when gitea or the Core Rule Set changes version.
+
+## What the defaults cover
+
+- SSH access to gitea does not pass through `smallwebwaf` and is not protected
+  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;
+    - a release attachment.
+
+    At the defaults, an upload larger than 100 MiB or taking more than 60
+    seconds is cut off ("Size and time limits" in `SPEC.md`). 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
+  day. One older than version 0.4 (April 2026) asks for work every 2 seconds,
+  43,200 requests a day, and reports a running job's log and state every second.
+  So it passes the day limit of 50,000 after about an hour and a quarter of
+  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`.
+
+## What the Core Rule Set lets through
+
+At the defaults, the Core Rule Set lets gitea's ordinary use through, apart from
+the refusals in the next section:
+
+- browsing and views of files in a repository, with their history, blame and the
+  file tree;
+- diffs, including their hidden lines and large files, and pull request review;
+- git's clone, fetch and push over HTTP;
+- signing in, including the return to the page a visitor came from, and sign-in
+  with Git Credential Manager, git-credential-oauth or tea;
+- the API's calls for a file and its commits;
+- pushing and pulling container images and packages;
+- Actions runners, and artifacts uploaded with `actions/upload-artifact@v4`;
+- posting issues, pull requests, comments, wiki pages and files saved in the web
+  editor, code included, since no body is read;
+- the page gitea shows after a change, with its message naming what was done.
+
+## What the Core Rule Set still refuses
+
+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
+
+Most often this is a search. A search term is a query parameter, which the Core
+Rule Set checks against its lists of system files and commands (see the fourth
+change under "Attack detection" in `SPEC.md`). A release attachment uploaded
+through the API as `docker-compose.yml` is refused the same way. Examples:
+
+- a name on those lists, such as `package.json`, `.gitignore` or
+  `docker-compose.yml`;
+- text that starts with a command name, such as `python3` or `ssh key`, or has
+  one right after a `/` in its first word, such as `feat/docker-support`;
+- a shell command with its options or a system path (`ls -la`, `sed -i`,
+  `/bin/sh`), or a command in backticks;
+- script code (`fetch(`, `${VAR}`, `process.env`), HTML (`<img src=`) or an SQL
+  statement (`SELECT * FROM users WHERE`);
+- a URL naming an IP address or `localhost`.
+
+### A branch, tag or file name that starts with a command name
+
+The Core Rule Set's list of commands (932260) holds names such as `docker-`,
+`python3`, `ansible`, `base64` and `whoami`. A query parameter holding a branch,
+tag or file name that starts with one is refused. So is one that has such a name
+right after a `/`, such as `feat/docker-support`, `fix/docker-build` or
+`renovate/docker-build-push-action-6.x`. gitea's own pages send the name in a
+query parameter that 930120, 932160 and 932260 still check:
+
+- `refSubUrl`, the branch or tag of a directory listing. A listing sends it when
+  it asks for its entries' last commits in a second request. It does so whenever
+  gitea takes more than a second to work them out;
+- `name`, when a branch is deleted or restored on the branches page;
+- `tag`, when a release is started from a tag;
+- `template`, the file of an issue template, when an issue is opened from it;
+- `rule_name`, when a branch protection rule is opened for editing in the
+  repository's settings or has just been saved.
+
+What a visitor sees, for a branch named `docker-build`:
+
+- A directory listing that makes that second request leaves those last commits
+  out and shows an error.
+- The branches page shows an error instead of deleting or restoring the branch.
+- A release started from such a tag gets the `403` answer of `smallwebwaf` in
+  place of its form. So does an issue opened from such a template, and such a
+  rule opened for editing.
+- Saving such a rule stores it. gitea then returns to the branch settings page,
+  which gets the `403` answer, so the save looks as if it failed.
+
+### A file name in a query parameter that trips the code rules
+
+The Core Rule Set's rules for Java, script, PowerShell and SQL find what they
+look for in some file names. This holds too in the ten query parameters that
+930120, 932160 and 932260 do not check (see the fourth change under "Attack
+detection" in `SPEC.md`). Examples:
+
+- `runtime` in OpenJDK's `src/java.base/share/classes/java/lang/Runtime.java`
+  (944110);
+- a Java class, as in `java.lang.String.md` (944130);
+- `document.write.js` (941180);
+- `process.env.d.ts` (934100);
+- `__proto__` (934130);
+- the PowerShell command `Install-Script`, as in `install-script.sh` (932120);
+- a database's name, as in PostgreSQL's `information_schema.sql` (942140).
+
+For such a file, these requests are refused:
+
+- the API's list of its commits (`path`);
+- the API's call for the contents of files that names it in its query (`body`);
+- the commit graph of that file alone (`file`);
+- the hidden lines of its diff (`path`), which stay hidden;
+- the sign-in page, for a visitor who opens a page of the file that needs
+  signing in, such as its edit page (`redirect_to`). The visitor can still sign
+  in by opening the sign-in page itself.
+
+### A path
+
+- A file name ending in `~`, or an `.xhtml` file whose path holds a space.
+- A path that holds what the Core Rule Set takes for a Java class (944130), as
+  `java.lang.String.md` and
+  `META-INF/services/org.apache.commons.logging.LogFactory` do.
+- A path that holds what it takes for Node.js code (934100), as
+  `process.env.d.ts` does.
+- A path with a directory named `...` (930100, 930110), such as `.../notes.txt`.
+
+For such a file, these are refused:
+
+- the page of the file;
+- its raw file;
+- its history and its blame;
+- its edit page.
+
+The directory that holds it lists it, and a clone carries it.
+
+### A container image push that reuses a layer
+
+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 starts with an entry on the list of commands. It is refused too when the
+image's name after the owner starts with one. 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
+same way. A new install of Docker Engine 29 does this. A docker that keeps them
+in its own older image store uploads the layer instead. The push then succeeds
+after one refusal for each layer it reuses, and each of those refusals counts
+toward the error burst ("Attack detection" in `SPEC.md`).
+
+### Artifact uploads from `actions/upload-artifact@v3`
+
+This action sends the header `Content-Range`, which the Core Rule Set refuses
+(920450). The action sends two files at a time, does not retry a `403`, and
+sends no further file once one is refused. So an upload is refused once or
+twice, however many files it holds, and the step fails. One upload does not ban
+the runner. The error burst ("Attack detection" in `SPEC.md`) bans it after more
+than 30 such refusals from its address in a minute, as when many jobs upload at
+once. `actions/upload-artifact@v4` does not send the header.
+
+## What body inspection refuses
+
+With `SWWAF_WAF_BODY_LIMIT` set, the Core Rule Set reads request bodies too. In
+front of gitea it then refuses these, until their rule ids, named in the request
+log, are added to `SWWAF_WAF_DISABLED_RULES`:
+
+- issue and comment text, wiki pages and files saved in the web editor that hold
+  shell commands or code (932125, 932235, 932250 and others);
+- package descriptions that show code;
+- PyPI uploads (922130);
+- attachments named like `debug.log` or `config.yml` (932180).
+
+## What `script/gitea-requests` sends
+
+Of the requests above, the script sends:
+
+- for each file named under "A file name in a query parameter that trips the
+  code rules", the API's list of its commits;
+- for `Runtime.java` alone, the commit graph of that file, the hidden lines of
+  its diff, and the API's call for the contents of files that names it;
+- the sign-in page for a visitor who opens the edit page of `document.write.js`;
+- the pages of `java.lang.String.md`,
+  `META-INF/services/org.apache.commons.logging.LogFactory`, `process.env.d.ts`
+  and `.../notes.txt`;
+- one container image push that reuses a layer, which it does not try again.
+
+It does not send the raw file, history, blame or edit page of those four files,
+or the pages of the directories `META-INF/services` and `...`. It also sends a
+short sample of gitea's ordinary use:
+
+- signing in;
+- pages of files and commits, and a diff;
+- the API;
+- a push, and clone and fetch over HTTP;
+- two container image pushes.

docs/image.md

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+# What the image holds
+
+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, 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`.
+
+## Pins
+
+- 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 its last commit
+  (`b4b2c78`, eight commits after `v2.0.0`), by commit hash, with a `go.mod` the
+  build writes.
+- The Go image that builds `smallwebwaf`: by digest.

docs/metrics.md

@@ -0,0 +1,81 @@
+# The metrics
+
+What `GET /_smallwebwaf/metrics` answers with. "Metrics endpoint" in
+[`SPEC.md`](../SPEC.md) describes the endpoint. Prometheus keeps the `instance`
+label as `exported_instance` unless the scrape sets `honor_labels: true`.
+
+## Traffic
+
+- `smallwebwaf_requests_total`, `smallwebwaf_request_bytes_total` and
+  `smallwebwaf_response_bytes_total`, by `status_class` such as `2xx` and by
+  `action`;
+- `smallwebwaf_request_duration_seconds` and
+  `smallwebwaf_upstream_duration_seconds`, as histograms;
+- `smallwebwaf_requests_in_flight`.
+
+## Limits and bans
+
+- `smallwebwaf_rate_limit_hits_total`, by `window` and by `kind` (`requests`,
+  `bytes` or `refusals`);
+- `smallwebwaf_size_and_time_limit_hits_total`, by `limit`, the setting passed;
+- `smallwebwaf_offences_total`, by `kind`;
+- `smallwebwaf_bans_made_total`, by `cause`;
+- `smallwebwaf_active_bans` and `smallwebwaf_permanent_bans`.
+
+## Attack detection
+
+- `smallwebwaf_rule_matches_total`, by `rule_id` and `action`, and
+  `smallwebwaf_rules_loaded`;
+- `smallwebwaf_waf_matches_total`, by `mode` and `rule_id`, for the rules that
+  fired.
+
+## Countries and AS numbers
+
+For the `SWWAF_METRICS_TOP_N` busiest of each, the rest as `other`:
+
+- `smallwebwaf_country_requests_total`,
+  `smallwebwaf_country_request_bytes_total`,
+  `smallwebwaf_country_response_bytes_total` and
+  `smallwebwaf_country_list_refusals_total`, by `country`;
+- `smallwebwaf_asn_requests_total`, `smallwebwaf_asn_request_bytes_total` and
+  `smallwebwaf_asn_response_bytes_total`, by `asn`.
+
+## Lookups
+
+- `smallwebwaf_geojs_requests_total` and `smallwebwaf_geojs_failures_total`;
+- `smallwebwaf_geojs_unanswered_total`: the requests that needed an answer and
+  went on without it;
+- with the file source,
+  `smallwebwaf_lookup_database_last_read_timestamp_seconds` and
+  `smallwebwaf_lookup_database_read_failures_total`.
+
+## Reputation sources
+
+By `source`: each list's URL, each zone, and `abuseipdb`:
+
+- `smallwebwaf_reputation_hits_total`, `smallwebwaf_reputation_queries_total`
+  and `smallwebwaf_reputation_failures_total`;
+- `smallwebwaf_reputation_last_fetch_timestamp_seconds`, for a list;
+- `smallwebwaf_reputation_daily_budget_remaining`, for AbuseIPDB.
+
+## State files
+
+By `file`:
+
+- `smallwebwaf_state_file_writes_total`,
+  `smallwebwaf_state_file_write_failures_total`,
+  `smallwebwaf_state_file_last_write_timestamp_seconds` and
+  `smallwebwaf_state_file_size_bytes`;
+- `smallwebwaf_state_file_edits_taken_in_total` and
+  `smallwebwaf_state_file_edits_set_aside_total`;
+- `smallwebwaf_tracked_clients`: the clients in the table.
+
+## Remote log, alerts and the process
+
+- while a syslog server is set, `smallwebwaf_remote_log_lines_sent_total`,
+  `smallwebwaf_remote_log_lines_dropped_total` and
+  `smallwebwaf_remote_log_buffer_depth`;
+- by `destination`, `smallwebwaf_alerts_sent_total`,
+  `smallwebwaf_alerts_failed_total`, `smallwebwaf_alerts_suppressed_total` and
+  `smallwebwaf_alerts_dropped_total`;
+- Go's own `go_` metrics and the process's `process_` metrics.

docs/request-log.md

@@ -0,0 +1,119 @@
+# The request log's fields
+
+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
+
+```
+{"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` and `client_group`;
+- `asn`, `as_name` and `country`;
+- `action` and `duration_total`.
+
+## Standard web log fields
+
+- `time`: when the request arrived, RFC 3339 with milliseconds, in UTC;
+- `instance`: `SWWAF_INSTANCE_NAME`;
+- `client_ip`, `method`, `scheme`, `host`, `path`, `query`, `protocol`;
+- `status`: what the client was sent, `0` if nothing;
+- `request_bytes` and `response_bytes`: body bytes each way;
+- `referer` and `user_agent`.
+
+## Request detail
+
+- `request_id`: the `X-Request-ID` a trusted proxy sent, or a new random one of
+  26 letters and digits.
+- `peer_ip`: the TCP peer, normally traefik.
+- `forwarded_for`: the `X-Forwarded-For` header as received.
+- `client_group`: the client as rate limiting counts it, an IPv4 address as a
+  /32 or an IPv6 group.
+- `asn`, `as_name` and `country`: the client's, as looked up. Each is empty
+  when:
+    - lookups are off;
+    - the client is not looked up;
+    - the source cannot place the client;
+    - GeoJS had not answered by the time the request went on.
+- `content_type` and `content_length`: the request's own.
+- `request_headers`: the headers listed in `SWWAF_LOG_REQUEST_HEADERS`, by name
+  in lower case.
+- `has_authorization` and `has_cookie`: true when the request had those headers.
+  Their values are never logged.
+- `websocket`: true when the app switched the connection to another protocol.
+
+## Response detail
+
+- `upstream_status`: what the app answered. It differs from `status` when
+  `smallwebwaf` answered itself.
+- `response_content_type`, `cache_control` and `location`: the answer's headers.
+- `aborted`: true when the client went away early.
+
+## Decision
+
+- `action`: what was done:
+    - `forward`: passed to the app;
+    - `denied`: refused for `SWWAF_DENY_NETS`, or for a reputation source with
+      the action `deny`;
+    - `banned`: refused under a ban, or for a `ban` rule, a trap path or a
+      CrowdSec decision, each of which bans the client;
+    - `country_denied`, `rate_limited`, `rule_blocked` and `waf_blocked`:
+      refused by that check;
+    - `too_large` and `timed_out`: a size or time limit was passed;
+    - `upstream_error`: the app could not be reached, or its answer broke off;
+    - `admin`: answered at one of `smallwebwaf`'s own endpoints.
+- `would_action`: in `observe` mode, what `enforce` mode would have done with a
+  request it would have refused. `action` then names what was done, normally
+  `forward`.
+- `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 totals as rate limiting counts them, this request
+  included. It is left out when rate limiting did not count the request. It
+  holds:
+    - `minute`, `hour` and `day`: requests;
+    - `minute_bytes`, `hour_bytes` and `day_bytes`: bytes.
+
+    A count can have a fraction (see "Counting method" in
+    [`SPEC.md`](../SPEC.md)).
+
+- `limit_hit`: the limit broken:
+    - `minute`, `hour` or `day` for a rate limit;
+    - `minute_bytes`, `hour_bytes` or `day_bytes` for a byte limit;
+    - `error_burst`.
+
+    A request whose bytes broke a limit was passed on whole, so its `action`
+    stays `forward`.
+
+- `rule_ids`: the rule file rules that matched, in order, up to the one that
+  refused.
+- `waf_score` and `waf_rule_ids`: the Core Rule Set's score and the rules that
+  matched, for a request it inspected.
+- `reputation`: the sources the client is on, in this order:
+    - blocklist URLs;
+    - the CrowdSec decision list's URL;
+    - DNS blocklist zones;
+    - `abuseipdb`.
+- `offence`: `limit`, for a request that broke a limit.
+- `ban_expires`: when the client's ban ends, for a request that made one or was
+  refused under one: a time, or `permanent`.
+
+## Timings
+
+All in milliseconds:
+
+- `duration_total`: from the request's headers being read to its log line;
+- `duration_checks`: to the end of the checks, before forwarding;
+- `duration_waf`: the part of that the Core Rule Set took;
+- `duration_upstream_connect`: from the hand-over to the app until there was a
+  connection;
+- `duration_upstream_first_byte`: until the first byte of the answer;
+- `duration_upstream_total`: until the end of the answer.

docs/rules.md

@@ -0,0 +1,67 @@
+# Rule files
+
+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
+
+A rule is a line of four fields separated by spaces or tabs: an id, a target, an
+action and a regex. The regex runs to the end of the line. Blank lines and lines
+starting with `#` are ignored.
+
+```
+# id           target      action  regex
+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 `_`, 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;
+    - `uri`: the path and the query together;
+    - `query`: the query as sent;
+    - `method`, `host`, `user_agent` and `referer`;
+    - `header:<Name>`: any one request header but `Host` and
+      `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 `$`. `(?i)` at its front makes it ignore case.
+
+## The default file
+
+The image ships one file, `share/rules.d/00-default.rules`, installed as
+`/etc/smallwebwaf/rules.d/00-default.rules`:
+
+```
+# 00-default.rules: probes no real visitor sends, anchored at the site root
+
+# id             target      action  regex
+env-file         path        ban     (?i)^/\.env(\.[a-z]+)?$
+vcs-dir          path        ban     (?i)^/\.(git|svn|hg|bzr)(/|$)
+secrets-dir      path        ban     (?i)^/\.(aws|ssh|docker|kube)/
+secret-file      path        ban     (?i)^/\.(htpasswd|htaccess|npmrc|netrc|pgpass|git-credentials|bash_history|DS_Store)$
+editor-dir       path        ban     (?i)^/\.(vscode|idea)/
+backup-file      path        ban     (?i)^/[^/]+\.(php(\.[a-z0-9]+|~)|sql(\.[a-z0-9]+)?)$
+log-file         path        ban     (?i)^/(debug|error|access)\.log$
+compose-file     path        ban     (?i)^/(docker-)?compose\.ya?ml$
+php-shell        path        ban     (?i)^/(shell|c99|r57|wso|alfa)\.php$
+scanner-agent    user_agent  ban     (?i)\b(sqlmap|nikto|nuclei|masscan|zgrab|wpscan)\b
+path-traversal   uri         block   (\.\./){2,}
+empty-agent      user_agent  log     ^$
+```
+
+## 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
+wp-probe         path        ban     (?i)^/(wp-login\.php|xmlrpc\.php|wp-admin/)
+```
+
+```dockerfile
+COPY 50-gitea.rules /etc/smallwebwaf/rules.d/50-gitea.rules
+```

docs/settings.md

@@ -0,0 +1,331 @@
+# Settings
+
+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.
+
+## 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, so `1K` is 1024 bytes. Examples: `512K`, `100M`, `5G`.
+- A count is a whole number of requests, such as `1000`.
+- A list is comma separated, with spaces around items ignored. An empty item is
+  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`
+  are the same. `xk` stands for Kosovo. A code that is not a country is refused,
+  such as `nk` (North Korea is `kp`) or the withdrawn `su`.
+- An AS number is `AS` and the number, in either case, such as `AS64496`.
+- A percentage is a whole number from 0 to 100.
+- A path prefix starts with `/`, such as `/assets/`.
+
+## Core
+
+- `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.
+- `SWWAF_LISTEN_ADDR` (default `:8080`): where `smallwebwaf` listens: `:` and a
+  port, such as `:9000`. Leave the host out (see "Ports" in
+  [`SPEC.md`](../SPEC.md)).
+- `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`): how many of its own bans `smallwebwaf`
+  keeps, a whole number above zero.
+
+## 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 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. A duration.
+- `SWWAF_STATE_COUNTER_INTERVAL` (default `15m`): how often every state file is
+  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 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, 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`,
+  `user`, `mail`, `daemon`, `auth`, `syslog`, `lpr`, `news`, `uucp`, `cron`,
+  `authpriv`, `ftp`, or `local0` to `local7`.
+- `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.
+
+## Metrics
+
+- `SWWAF_METRICS_TOP_N` (default `50`): how many AS numbers and how many
+  countries get series of their own. A whole number above zero.
+
+## Static lists
+
+- `SWWAF_ALLOW_NETS` (default empty): netblocks you trust, such as your
+  monitoring (see step 3 in [`SPEC.md`](../SPEC.md)).
+- `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 refused (see
+  step 3 in [`SPEC.md`](../SPEC.md)).
+
+## 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`. `off` stops
+  the start while a setting that needs a lookup is set:
+    - the two country lists;
+    - `SWWAF_ADD_LOOKUP_HEADERS`;
+    - the four biased threshold lists and `SWWAF_ASN_LIMIT_PERCENT_URL`;
+    - `SWWAF_UNKNOWN_LIMIT_PERCENT` below `100`;
+    - 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`.
+- `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
+  stops the start.
+
+## 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 with one AS number and percentage on each line, such as
+  `AS64496:50`. 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.
+- `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, 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`, 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 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 after an alert is sent its
+  repeats are held back. A duration or `off`.
+- `SWWAF_ALERT_MAX_PER_HOUR` (default `60`): the most alerts sent in an hour. A
+  whole number above zero, or `off`.
+
+## Anomaly thresholds
+
+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`;
+- `SWWAF_ANOMALY_CLIENT_BYTES_PER_MINUTE`;
+- `SWWAF_ANOMALY_CLIENT_BYTES_PER_HOUR`.
+
+The other scopes' names have another prefix before the same four endings, such
+as `REQUESTS_PER_MINUTE`:
+
+- `SWWAF_ANOMALY_NET_...`: per netblock around a client. Two settings give the
+  netblock's length:
+    - `SWWAF_ANOMALY_NET_V4_PREFIX` (default `24`, from 0 to 32) for an IPv4
+      client;
+    - `SWWAF_ANOMALY_NET_V6_PREFIX` (default `48`, from 0 to 128) for an IPv6
+      client.
+- `SWWAF_ANOMALY_ASN_...`: per AS number.
+- `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.
+
+## Settings given as files
+
+To give a token as a file, as "Tokens" under "Deployment" in
+[`SPEC.md`](../SPEC.md) describes, make the file on the host:
+
+```sh
+mkdir -p /srv/app/tokens
+openssl rand -hex 32 > /srv/app/tokens/metrics
+chown 65532:65532 /srv/app/tokens/metrics
+chmod 0400 /srv/app/tokens/metrics
+```
+
+Then mount its directory into the container read-only, and name the file:
+
+```sh
+docker run \
+    -v /srv/app/tokens:/etc/smallwebwaf/tokens:ro \
+    -e SWWAF_METRICS_TOKEN_FILE=/etc/smallwebwaf/tokens/metrics \
+    ...
+```
+
+## Fixed limits
+
+A few limits are fixed rather than settings:
+
+- 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;
+- at most 20,000 anomaly counters are kept;
+- each alert destination's queue holds at most 1,000 alerts.

docs/state-files.md

@@ -0,0 +1,104 @@
+# State 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: every ban an admin made, and up to `SWWAF_MAX_BANS` of
+those `smallwebwaf` made. Per entry:
+
+- `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.
+
+An entry an admin adds needs `netblock`, `start` and `expires`; `reason`,
+`notes` and `cause` may be left out, and 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"
+        }
+    ]
+}
+```
+
+"Bans" in [`SPEC.md`](../SPEC.md) says how an edit lifts, keeps or forgets a
+ban. The notes:
+
+- `asn`, `as_name` and `country`: the client's, added when the lookup answers
+  (empty when lookups are off);
+- for a broken limit, `kind` (`requests`, `bytes` or `refusals`), `limit`,
+  `window` and `count`: what the limit was on, the limit, its window and the
+  count reached;
+- `limit_percent` and `limit_percent_setting`: the client's percentage of that
+  limit and the setting that gave it, when a setting lowered it;
+- for a clear sign of attack, `rule_id` and `target`, or `trap_path`;
+- `reputation`: the sources the client was on, each with its `source` and, for
+  AbuseIPDB, its `score`;
+- `request`: the request that caused the ban, each text cut to 256 bytes:
+    - `time`, `method` and `host`;
+    - `path`, with its query string;
+    - `status` and `user_agent`;
+- `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`: 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`. Written every 15 minutes, a full file comes to
+  about 600 MiB of writes a day, and a hundred new bans a day add about 600 MiB
+  more.
+- `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/alerts/alerts.go

@@ -1,8 +1,8 @@
 // Package alerts sends alerts on bans, on traffic over an anomaly
 // threshold, on a source that fails and on a file with an error to each
 // destination set: to the webhook
-// SWWAF_ALERT_WEBHOOK_URL names, each as one JSON object, as the "Alert
+// SWWAF_ALERT_WEBHOOK_URL names, each as one JSON object, as "The JSON
-// webhook schema" section of SPEC.md describes, to the Slack incoming
+// object" in docs/alerts.md describes, to the Slack incoming
 // webhook SWWAF_ALERT_SLACK_WEBHOOK_URL names, as a message, and to the
 // ntfy topic SWWAF_ALERT_NTFY_URL names. A repeat within
 // SWWAF_ALERT_COOLDOWN is held back, and so is an alert past
@@ -149,11 +149,10 @@ type Params struct {
 }
 
 // Alert is one alert, as the webhook is sent it and alerts.json holds it,
-// with the fields of the "Alert webhook schema" section of SPEC.md. ASN,
+// with the fields of "The JSON object" in docs/alerts.md. ASN, ASName and
-// ASName and Country are, for a ban, the client's as the ban's notes give
+// Country are, for a ban, the client's as the ban's notes give them.
-// them.
 //
-//nolint:tagliatelle // SPEC.md's alert webhook schema names its fields in snake_case
+//nolint:tagliatelle // docs/alerts.md names the alert's fields in snake_case
 type Alert struct {
 	Instance string       `json:"instance"`
 	Time     time.Time    `json:"time"`

internal/anomaly/anomaly.go

@@ -1,8 +1,8 @@
 // Package anomaly counts requests and bytes over a minute and an hour, per
 // client, per surrounding netblock, per AS number, for the whole service
 // and per named netblock, and raises an anomaly alert for a count over its
-// threshold, as "Anomaly thresholds" under "Configuration surface" in
+// threshold, as "Anomaly thresholds" under "Settings" in SPEC.md
-// SPEC.md describes. It refuses and bans nothing. At most 20,000 counters
+// describes. It refuses and bans nothing. At most 20,000 counters
 // are kept, in memory, and written to alerts.json and read from it by the
 // state package.
 package anomaly

internal/metrics/metrics.go

@@ -1,6 +1,7 @@
-// Package metrics keeps smallwebwaf's Prometheus metrics, as the "Metrics
+// Package metrics keeps smallwebwaf's Prometheus metrics, as
-// endpoint" section of SPEC.md lists them, and serves them in the
+// docs/metrics.md lists them, and serves them in the Prometheus text
-// Prometheus text format. No metric carries a client's address.
+// format, as the "Metrics endpoint" section of SPEC.md requires. No
+// metric carries a client's address.
 package metrics
 
 import (

internal/ratelimit/ratelimit.go

@@ -206,7 +206,7 @@ type Hit struct {
 // Counts are a client's requests and bytes in the minute, the hour and
 // the day that end at a request, that request's included.
 //
-//nolint:tagliatelle // SPEC.md's request log names its fields in snake_case
+//nolint:tagliatelle // docs/request-log.md names the fields in snake_case
 type Counts struct {
 	Minute      float64 `json:"minute"`
 	Hour        float64 `json:"hour"`

internal/requestlog/requestlog.go

@@ -64,11 +64,10 @@ const LimitHitErrorBurst = "error_burst"
 const timeLayout = "2006-01-02T15:04:05.000Z07:00"
 
 // Line is one request's line in the request log. The field names, and
-// their order, are those of the "Request log" section of SPEC.md. A field
+// their order, are those of docs/request-log.md. A field that may not
-// that may not apply to a request is left out of its line when it does
+// apply to a request is left out of its line when it does not.
-// not.
 //
-//nolint:tagliatelle // SPEC.md's request log names its fields in snake_case
+//nolint:tagliatelle // docs/request-log.md names the fields in snake_case
 type Line struct {
 	Type string `json:"type"`
 

internal/state/state.go

@@ -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

@@ -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
+		// ban, made after the admin opened the file, is lost, as the
-		// while running" in SPEC.md says.
+		// "Persistent state" section of SPEC.md says.
 		time.Sleep(time.Nanosecond)
 		synctest.Wait()
 

internal/waf/waf.go

@@ -1,8 +1,8 @@
 // Package waf runs the OWASP Core Rule Set 4.25.0, through Coraza, on the
 // method, the URL with its query and the headers of a request, and on its
 // body while SWWAF_WAF_BODY_LIMIT is set, with the six changes smallwebwaf
-// makes to it, as "Attack detection" under "Configuration surface" in
+// makes to it, as "Attack detection" under "Settings" in SPEC.md describes
-// SPEC.md describes them. It reads no response.
+// them. It reads no response.
 //
 // smallwebwaf writes only to its state directory, so Coraza is built with
 // its no_fs_access tag, as the Dockerfile and script/build build it: of a

script/example-app

@@ -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

script/gitea-requests

@@ -2,11 +2,12 @@
 # script/gitea-requests: build the image and run gitea 1.27.3 behind it,
 # with every setting of smallwebwaf at its default but SWWAF_UPSTREAM_URL,
 # which names gitea's container. Then send through it the gitea requests
-# that reading gitea's source found the Core Rule Set refuses, and a short
+# that reading gitea's source found the Core Rule Set refuses, which
-# sample of gitea's ordinary use: signing in, pages of files and commits,
+# docs/gitea.md records, and a short sample of gitea's ordinary use:
-# a diff, the API, a push, clone and fetch over HTTP, and two container
+# signing in, pages of files and commits, a diff, the API, a push, clone
-# image pushes. Last, print each request smallwebwaf logged, with what it
+# and fetch over HTTP, and two container image pushes. Last, print each
-# did with it and the ids of the Core Rule Set's rules that matched it.
+# request smallwebwaf logged, with what it did with it and the ids of the
+# Core Rule Set's rules that matched it.
 # Every request comes from one client, docker's gateway, so more than
 # SWWAF_ERROR_BURST_THRESHOLD, 30, refusals in a minute would ban it, and
 # the requests after would show as banned. The containers, the network,