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.traefik.yml
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displayName: Bot Filter
type: middleware
import: github.com/hoelee/traefik-botfilter
summary: Rejects common scans and temporarily bans suspicious clients using bounded per-IP scoring.
testData:
statusCode: 403
requireUserAgent: true
requireAccept: true
requireHost: true
browserValidation: true
whitelistCIDRs:
- 192.168.0.0/16
- 10.0.0.0/8
temporaryBanMinutes: 15
blockedUserAgents:
- curl
- wget
- python
blockedPaths:
- /.env
- /.git
- /wp-login.php
- /xmlrpc.php
- /phpmyadmin
blockedExtensions:
- .env
- .bak
- .zip
LICENSE
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Apache License
Version 2.0, January 2004
http://www.apache.org/licenses/
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README.md
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# Traefik Bot Filter
`traefik-botfilter` is a dependency-free Traefik middleware plugin for public
sites that are receiving scanners or unsophisticated HTTP floods. It blocks
known scan paths before they reach the upstream and keeps a bounded, local
per-client score cache for temporary bans.
It is deliberately a **request filter**, not a bot-management service. A
distributed attacker that sends valid browser-like requests from many IPs
needs an upstream CDN/WAF or firewall as well.
## What it does
- Immediately rejects and temporarily bans configured scanner paths, file
extensions, and User-Agent tokens.
- Optionally requires `User-Agent`, `Accept`, and `Host`. A failed required
check is immediately cached as a temporary ban, so repeated requests do not
reach Kiwix.
- Adds scores in a configurable sliding window. Defaults implement the stated
model: empty UA `+40`, missing Accept `+20`, bad path `+50`, blocked UA
`+80`, first request directly to `/content/` `+15`, and an upstream `404`
`+40`.
- Bans when the score reaches `scoreThreshold` (default `100`). A blocked scan
path always bans immediately, independently of the score threshold.
- Applies conservative browser plausibility checks. It detects internally
inconsistent browser User-Agents, but does not claim to distinguish every
automation client from a real browser. That requires a JavaScript challenge
at a CDN/WAF layer.
- Bounds memory with `maxTrackedIPs` (default `50,000`) and
`maxScoreEventsPerIP` (default `16`), with lock-safe access and no cleanup
goroutine.
- Never trusts `X-Forwarded-For` unless `clientIPHeader` is explicitly set
**and** the TCP peer is in `trustedProxyCIDRs`.
## Important fixes before enabling it
Your Kiwix service currently publishes `6001:8080`. Requests to that port go
straight to Kiwix and bypass this middleware, rate limiting, and Traefik
access controls. Remove this line unless you need a separate protected private
listener:
```yaml
kiwix:
# ports:
# - "6001:8080"
```
Also narrow the current error middleware. `400-599` makes every ordinary
Kiwix 404 and upstream 502 call `host.docker.internal:44440`, which adds work
and obscures the original failure. Keep it only for rate-limit responses:
```yaml
cp-ratelimit-errorpages:
errors:
status:
- "429-429"
service: srv-error
query: "/{status}.html"
```
The access log supplied with this request contains 57,141 requests with an
empty User-Agent (`"-"`), including thousands of `404` and `502` responses.
With `requireUserAgent: true`, those requests are rejected at Traefik before
they consume Kiwix CPU.
## Configuration
Add the following to the dynamic file provider configuration. The middleware
must be attached to each public Kiwix router.
```yaml
http:
middlewares:
botfilter:
plugin:
botfilter:
statusCode: 403
requireUserAgent: true
requireAccept: true
requireHost: true
browserValidation: true
whitelistCIDRs:
- 192.168.0.0/16
- 10.0.0.0/8
temporaryBanMinutes: 15
scoreThreshold: 100
scoreWindowMinutes: 15
maxTrackedIPs: 50000
maxScoreEventsPerIP: 16
blockedUserAgents:
- curl
- wget
- python
- Go-http-client
- masscan
- sqlmap
- zgrab
- nikto
blockedPaths:
- /.env
- /.git
- /wp-login.php
- /xmlrpc.php
- /phpmyadmin
blockedExtensions:
- .env
- .bak
- .zip
# This weak signal contributes only 15 points. Direct links to a
# Kiwix article remain possible; they are not banned by themselves.
randomArticlePatterns:
- /content/
# Leave both unset when Traefik accepts traffic directly. If a CDN
# or load balancer is in front, configure its exact source CIDRs and
# ensure it overwrites this header.
# clientIPHeader: X-Forwarded-For
# trustedProxyCIDRs:
# - 203.0.113.0/24
# Do not turn this on during an attack unless short diagnostics are
# needed: per-request disk logging can itself become expensive.
logBlockedRequests: false
```
Apply it before `cp-ratelimit` so rejected requests do not consume the
rate-limiter's work. Keep the narrowed errors middleware as the outer wrapper
for the rate limiter:
```yaml
http:
routers:
rtr-default-wiki:
# ... existing rule/service fields ...
middlewares:
- cp-ratelimit-errorpages
- botfilter
- cp-ratelimit
```
Use the same middleware list on `rtr-wiki` and `rtr-yes` if they expose Kiwix.
## Install in Traefik
### Production: remote plugin
The module name in `.traefik.yml` is intentionally the one requested here.
Create the public repository `github.com/hoelee/traefik-botfilter`, push this
directory, and create the immutable Git tag `v0.1.0`. Then put this in the
**static** Traefik configuration (`traefik.yml`), not `dynamic.yml`:
```yaml
experimental:
plugins:
botfilter:
moduleName: github.com/hoelee/traefik-botfilter
version: v0.1.0
```
Restart Traefik after changing static plugin configuration. Do not retag an
existing version; publish `v0.1.1` for later changes.
### Test locally first
Traefik local plugins need the Go module at the exact module path below
`/plugins-local/src`. On the Synology host, copy or clone this repository to:
```text
/volume1/docker/traefik-plugins/src/github.com/hoelee/traefik-botfilter
```
Add this readonly mount to the Traefik service:
```yaml
volumes:
- /volume1/docker/traefik-plugins:/plugins-local:ro
```
And use this static configuration instead of the remote `plugins` block:
```yaml
experimental:
localPlugins:
botfilter:
moduleName: github.com/hoelee/traefik-botfilter
```
Restart Traefik and confirm its startup log says that the `botfilter` plugin
loaded before exposing the public router.
## Option reference
| Option | Default | Meaning |
| --- | ---: | --- |
| `statusCode` | `403` | HTTP status for rejected requests (`400`–`599`). |
| `temporaryBanMinutes` | `15` | In-memory ban duration. |
| `scoreThreshold` | `100` | Score at which a client is banned. |
| `scoreWindowMinutes` | `15` | Sliding window for score events. |
| `maxTrackedIPs` | `50000` | Hard maximum size of the per-IP state map. |
| `maxScoreEventsPerIP` | `16` | Bound on score events retained per client. |
| `requireUserAgent` | `false` | Immediately ban missing User-Agent requests. |
| `requireAccept` | `false` | Immediately ban missing Accept requests. |
| `requireHost` | `false` | Immediately ban missing Host requests. |
| `browserValidation` | `false` | Score implausible Mozilla-family header combinations. |
| `whitelistCIDRs` | none | Clients that bypass all checks and cache updates. |
| `clientIPHeader` | empty | Optional header used only from `trustedProxyCIDRs`. |
| `trustedProxyCIDRs` | none | TCP peer ranges allowed to supply the client-IP header. |
| `randomArticlePatterns` | `/content/` | First-request path prefixes that add `randomArticleScore`. |
| `logBlockedRequests` | `false` | Opt-in rejected-request logging. |
All listed score fields are configurable: `emptyUserAgentScore`,
`missingAcceptScore`, `blockedUserAgentScore`, `badPathScore`,
`randomArticleScore`, `notFoundScore`, and `fakeBrowserScore`. Set a score to
`0` to disable that one signal; scanner-path and required-header rejections
still ban immediately.
## Operational limits and recommended defences
This plugin protects Kiwix from the malformed-header/scanner pattern in the
log, but it cannot stop a botnet that rotates IPs and perfectly imitates
browser headers. For that case:
1. Put the hostname behind a CDN/WAF with bot challenge and request-rate rules.
2. Firewall the NAS so public clients cannot reach Kiwix's port `6001` or any
Traefik entry point other than the intended public port.
3. Do not expose the NAS origin address in DNS or other services; otherwise
attackers can bypass the CDN.
4. Keep Traefik access logs sampled or rotate them quickly during an incident.
Per-request synchronous disk logging becomes material at flood volume.
5. `deploy.resources` is commonly ignored by non-Swarm Docker Compose. Verify
resource limits with `docker inspect` on the NAS rather than assuming the
`deploy` block limits CPU.
The cache is intentionally local to a Traefik process and is reset on
container restart. That is appropriate for a low-overhead edge filter; use a
CDN/WAF or shared store if bans must survive restarts or be shared by multiple
Traefik replicas.
## Development
```text
go test ./...
go vet ./...
```
The implementation only uses the Go standard library, which reduces plugin
startup and supply-chain risk.
botfilter.go
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// Package botfilter is a Traefik middleware plugin that blocks known scans
// and applies a bounded, in-memory per-IP suspicion score.
package botfilter
import (
"bufio"
"context"
"fmt"
"io"
"net"
"net/http"
"net/netip"
"strconv"
"time"
)
type botFilter struct {
next http.Handler
config *compiledConfig
cache *clientCache
logger filterLogger
}
// New constructs a Traefik middleware. Its signature is the interface used
// by Traefik's Go plugin runtime.
func New(_ context.Context, next http.Handler, config *Config, name string) (http.Handler, error) {
if next == nil {
return nil, fmt.Errorf("botfilter: next handler is nil")
}
compiled, err := compileConfig(config)
if err != nil {
return nil, err
}
return &botFilter{
next: next,
config: compiled,
cache: newClientCache(compiled),
logger: filterLogger{name: name, enabled: compiled.LogBlockedRequests},
}, nil
}
func (b *botFilter) ServeHTTP(rw http.ResponseWriter, r *http.Request) {
now := time.Now()
addr := clientIP(r, b.config)
ip := addressString(addr)
if addressInPrefixes(addr, b.config.whitelist) {
b.next.ServeHTTP(rw, r)
return
}
if existing := b.cache.isBanned(ip, now); existing.banned {
b.reject(rw, ip, "temporary ban", existing)
return
}
match := inspectRequest(r, b.config)
paths := requestPaths(r)
decision := b.cache.observeRequest(ip, requestObservation{
at: now,
paths: paths,
points: match.points,
forceBan: match.forceBan,
})
if decision.banned {
reason := match.reason
if reason == "" {
reason = "suspicion score threshold"
}
b.reject(rw, ip, reason, decision)
return
}
recorder := &statusRecorder{ResponseWriter: rw}
b.next.ServeHTTP(recorder, r)
if result := b.cache.observeResponse(ip, recorder.statusCode(), b.config.NotFoundScore, time.Now()); result.banned {
b.logger.blocked(ip, "404 score threshold", result.score)
}
}
func (b *botFilter) reject(rw http.ResponseWriter, ip, reason string, decision cacheResult) {
b.logger.blocked(ip, reason, decision.score)
rw.Header().Set("Cache-Control", "no-store")
rw.Header().Set("Content-Type", "text/plain; charset=utf-8")
if decision.banUntil.After(time.Now()) {
seconds := int(time.Until(decision.banUntil).Seconds())
if seconds < 1 {
seconds = 1
}
rw.Header().Set("Retry-After", strconv.Itoa(seconds))
}
rw.WriteHeader(b.config.StatusCode)
_, _ = io.WriteString(rw, "request denied\n")
}
func addressString(addr netip.Addr) string {
if !addr.IsValid() {
return ""
}
return addr.String()
}
// statusRecorder keeps downstream response capabilities available while
// recording the final status used for 404 scoring.
type statusRecorder struct {
http.ResponseWriter
status int
}
func (r *statusRecorder) WriteHeader(status int) {
if r.status != 0 {
return
}
r.status = status
r.ResponseWriter.WriteHeader(status)
}
func (r *statusRecorder) Write(data []byte) (int, error) {
if r.status == 0 {
r.status = http.StatusOK
}
return r.ResponseWriter.Write(data)
}
func (r *statusRecorder) statusCode() int {
if r.status == 0 {
return http.StatusOK
}
return r.status
}
func (r *statusRecorder) Unwrap() http.ResponseWriter { return r.ResponseWriter }
func (r *statusRecorder) Flush() {
if r.status == 0 {
r.status = http.StatusOK
}
if flusher, ok := r.ResponseWriter.(http.Flusher); ok {
flusher.Flush()
}
}
func (r *statusRecorder) Hijack() (net.Conn, *bufio.ReadWriter, error) {
hijacker, ok := r.ResponseWriter.(http.Hijacker)
if !ok {
return nil, nil, http.ErrNotSupported
}
return hijacker.Hijack()
}
func (r *statusRecorder) Push(target string, options *http.PushOptions) error {
pusher, ok := r.ResponseWriter.(http.Pusher)
if !ok {
return http.ErrNotSupported
}
return pusher.Push(target, options)
}
func (r *statusRecorder) ReadFrom(source io.Reader) (int64, error) {
if r.status == 0 {
r.status = http.StatusOK
}
if readerFrom, ok := r.ResponseWriter.(io.ReaderFrom); ok {
return readerFrom.ReadFrom(source)
}
return io.Copy(struct{ io.Writer }{Writer: r.ResponseWriter}, source)
}
botfilter_test.go
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package botfilter
import (
"context"
"net/http"
"net/http/httptest"
"testing"
)
func TestRequiredHeaderCreatesTemporaryBan(t *testing.T) {
cfg := CreateConfig()
cfg.RequireUserAgent = true
cfg.RequireAccept = true
cfg.RequireHost = true
nextCalls := 0
handler, err := New(context.Background(), http.HandlerFunc(func(rw http.ResponseWriter, _ *http.Request) {
nextCalls++
rw.WriteHeader(http.StatusOK)
}), cfg, "test")
if err != nil {
t.Fatalf("New() error = %v", err)
}
first := httptest.NewRequest(http.MethodGet, "http://wiki.example/content/article", nil)
first.RemoteAddr = "203.0.113.11:54321"
first.Header.Set("Accept", "text/html")
first.Header.Del("User-Agent")
firstResponse := httptest.NewRecorder()
handler.ServeHTTP(firstResponse, first)
if firstResponse.Code != http.StatusForbidden {
t.Fatalf("first response status = %d, want %d", firstResponse.Code, http.StatusForbidden)
}
if firstResponse.Header().Get("Retry-After") == "" {
t.Fatal("first response did not include Retry-After")
}
second := httptest.NewRequest(http.MethodGet, "http://wiki.example/", nil)
second.RemoteAddr = "203.0.113.11:54321"
second.Header.Set("Accept", "text/html")
second.Header.Set("User-Agent", "Mozilla/5.0 Chrome/120.0 AppleWebKit/537.36 Safari/537.36")
secondResponse := httptest.NewRecorder()
handler.ServeHTTP(secondResponse, second)
if secondResponse.Code != http.StatusForbidden {
t.Fatalf("second response status = %d, want cached ban", secondResponse.Code)
}
if nextCalls != 0 {
t.Fatalf("next handler calls = %d, want 0", nextCalls)
}
}
func TestWhitelistBypassesFilter(t *testing.T) {
cfg := CreateConfig()
cfg.RequireUserAgent = true
cfg.WhitelistCIDRs = []string{"192.168.0.0/16"}
handler, err := New(context.Background(), http.HandlerFunc(func(rw http.ResponseWriter, _ *http.Request) {
rw.WriteHeader(http.StatusNoContent)
}), cfg, "test")
if err != nil {
t.Fatalf("New() error = %v", err)
}
request := httptest.NewRequest(http.MethodGet, "http://wiki.example/", nil)
request.RemoteAddr = "192.168.30.25:1234"
request.Header.Del("User-Agent")
response := httptest.NewRecorder()
handler.ServeHTTP(response, request)
if response.Code != http.StatusNoContent {
t.Fatalf("response status = %d, want whitelist to reach next handler", response.Code)
}
}
func TestEncodedScanPathBansBeforeUpstream(t *testing.T) {
cfg := CreateConfig()
cfg.RequireUserAgent = false
cfg.RequireAccept = false
nextCalls := 0
handler, err := New(context.Background(), http.HandlerFunc(func(rw http.ResponseWriter, _ *http.Request) {
nextCalls++
rw.WriteHeader(http.StatusOK)
}), cfg, "test")
if err != nil {
t.Fatalf("New() error = %v", err)
}
request := httptest.NewRequest(http.MethodGet, "http://wiki.example/foo/..%2F.env", nil)
request.RemoteAddr = "198.51.100.22:1234"
request.Header.Set("User-Agent", "Mozilla/5.0 Chrome/120.0 AppleWebKit/537.36 Safari/537.36")
response := httptest.NewRecorder()
handler.ServeHTTP(response, request)
if response.Code != http.StatusForbidden {
t.Fatalf("response status = %d, want %d", response.Code, http.StatusForbidden)
}
if nextCalls != 0 {
t.Fatalf("next handler calls = %d, want 0", nextCalls)
}
}
func Test404ScoreBansOnSubsequentRequest(t *testing.T) {
cfg := CreateConfig()
cfg.RequireUserAgent = false
cfg.RequireAccept = false
cfg.RandomArticlePatterns = nil
cfg.EmptyUserAgentScore = 0
cfg.MissingAcceptScore = 0
cfg.ScoreThreshold = 40
nextCalls := 0
handler, err := New(context.Background(), http.HandlerFunc(func(rw http.ResponseWriter, _ *http.Request) {
nextCalls++
rw.WriteHeader(http.StatusNotFound)
}), cfg, "test")
if err != nil {
t.Fatalf("New() error = %v", err)
}
first := httptest.NewRequest(http.MethodGet, "http://wiki.example/not-found", nil)
first.RemoteAddr = "198.51.100.23:1234"
first.Header.Set("User-Agent", "Mozilla/5.0 Chrome/120.0 AppleWebKit/537.36 Safari/537.36")
first.Header.Set("Accept", "text/html")
firstResponse := httptest.NewRecorder()
handler.ServeHTTP(firstResponse, first)
if firstResponse.Code != http.StatusNotFound {
t.Fatalf("first response status = %d, want 404", firstResponse.Code)
}
second := httptest.NewRequest(http.MethodGet, "http://wiki.example/another-miss", nil)
second.RemoteAddr = "198.51.100.23:1234"
second.Header.Set("User-Agent", "Mozilla/5.0 Chrome/120.0 AppleWebKit/537.36 Safari/537.36")
second.Header.Set("Accept", "text/html")
secondResponse := httptest.NewRecorder()
handler.ServeHTTP(secondResponse, second)
if secondResponse.Code != http.StatusForbidden {
t.Fatalf("second response status = %d, want cached ban after two 404s", secondResponse.Code)
}
if nextCalls != 1 {
t.Fatalf("next handler calls = %d, want 1", nextCalls)
}
}
func TestTrustedProxyHeaderSeparatesClients(t *testing.T) {
cfg := CreateConfig()
cfg.RequireUserAgent = true
cfg.ClientIPHeader = "X-Forwarded-For"
cfg.TrustedProxyCIDRs = []string{"127.0.0.0/8"}
nextCalls := 0
handler, err := New(context.Background(), http.HandlerFunc(func(rw http.ResponseWriter, _ *http.Request) {
nextCalls++
rw.WriteHeader(http.StatusNoContent)
}), cfg, "test")
if err != nil {
t.Fatalf("New() error = %v", err)
}
bad := httptest.NewRequest(http.MethodGet, "http://wiki.example/", nil)
bad.RemoteAddr = "127.0.0.1:1234"
bad.Header.Set("X-Forwarded-For", "198.51.100.61")
bad.Header.Del("User-Agent")
badResponse := httptest.NewRecorder()
handler.ServeHTTP(badResponse, bad)
if badResponse.Code != http.StatusForbidden {
t.Fatalf("bad client status = %d, want 403", badResponse.Code)
}
good := httptest.NewRequest(http.MethodGet, "http://wiki.example/", nil)
good.RemoteAddr = "127.0.0.1:1234"
good.Header.Set("X-Forwarded-For", "198.51.100.62")
good.Header.Set("User-Agent", "Mozilla/5.0 Chrome/120.0 AppleWebKit/537.36 Safari/537.36")
goodResponse := httptest.NewRecorder()
handler.ServeHTTP(goodResponse, good)
if goodResponse.Code != http.StatusNoContent {
t.Fatalf("good client status = %d, want 204", goodResponse.Code)
}
if nextCalls != 1 {
t.Fatalf("next handler calls = %d, want 1", nextCalls)
}
}
func TestCompileConfigRejectsInvalidCIDR(t *testing.T) {
cfg := CreateConfig()
cfg.WhitelistCIDRs = []string{"not-a-cidr"}
if _, err := compileConfig(cfg); err == nil {
t.Fatal("compileConfig() error = nil, want invalid CIDR error")
}
}
cache.go
+223
View File
@@ -0,0 +1,223 @@
package botfilter
import (
"sync"
"time"
)
type scoreEvent struct {
at time.Time
points int
}
type clientState struct {
banUntil time.Time
lastSeen time.Time
requests int
sawHome bool
sawStatic bool
sawFavicon bool
events []scoreEvent
}
type requestObservation struct {
at time.Time
paths []string
points int
forceBan bool
}
type cacheResult struct {
banned bool
banUntil time.Time
score int
}
// clientCache deliberately has no background goroutine. A middleware
// instance can be discarded on a Traefik reload without needing goroutine
// cleanup, and opportunistic cleanup keeps its memory use bounded.
type clientCache struct {
mu sync.Mutex
entries map[string]*clientState
maxEntries int
maxEvents int
scoreWindow time.Duration
banDuration time.Duration
threshold int
randomPaths []string
randomScore int
operations uint64
}
func newClientCache(cfg *compiledConfig) *clientCache {
return &clientCache{
entries: make(map[string]*clientState),
maxEntries: cfg.MaxTrackedIPs,
maxEvents: cfg.MaxScoreEventsPerIP,
scoreWindow: cfg.scoreWindow,
banDuration: cfg.banDuration,
threshold: cfg.ScoreThreshold,
randomPaths: append([]string(nil), cfg.randomPaths...),
randomScore: cfg.RandomArticleScore,
}
}
func (c *clientCache) isBanned(ip string, now time.Time) cacheResult {
if ip == "" {
return cacheResult{}
}
c.mu.Lock()
defer c.mu.Unlock()
state := c.entries[ip]
if state == nil || !state.banUntil.After(now) {
return cacheResult{}
}
return cacheResult{banned: true, banUntil: state.banUntil}
}
func (c *clientCache) observeRequest(ip string, observation requestObservation) cacheResult {
if ip == "" {
// An invalid peer address must never share a cache entry with another
// malformed request. The request can still be rejected by its headers.
return cacheResult{banned: observation.forceBan}
}
c.mu.Lock()
defer c.mu.Unlock()
c.operations++
c.cleanupLocked(observation.at)
state := c.entries[ip]
if state != nil && state.banUntil.After(observation.at) {
return cacheResult{banned: true, banUntil: state.banUntil}
}
if state == nil {
c.ensureCapacityLocked(observation.at)
state = &clientState{}
c.entries[ip] = state
}
c.pruneEventsLocked(state, observation.at)
points := observation.points + c.behaviorScoreLocked(state, observation.paths)
state.requests++
state.lastSeen = observation.at
if points > 0 {
state.events = append(state.events, scoreEvent{at: observation.at, points: points})
if len(state.events) > c.maxEvents {
state.events = append([]scoreEvent(nil), state.events[len(state.events)-c.maxEvents:]...)
}
}
score := sumScore(state.events)
if observation.forceBan || score >= c.threshold {
state.banUntil = observation.at.Add(c.banDuration)
return cacheResult{banned: true, banUntil: state.banUntil, score: score}
}
return cacheResult{score: score}
}
func (c *clientCache) observeResponse(ip string, status int, points int, now time.Time) cacheResult {
if ip == "" || status != 404 || points <= 0 {
return cacheResult{}
}
c.mu.Lock()
defer c.mu.Unlock()
state := c.entries[ip]
if state == nil || state.banUntil.After(now) {
return cacheResult{}
}
c.pruneEventsLocked(state, now)
state.lastSeen = now
state.events = append(state.events, scoreEvent{at: now, points: points})
if len(state.events) > c.maxEvents {
state.events = append([]scoreEvent(nil), state.events[len(state.events)-c.maxEvents:]...)
}
score := sumScore(state.events)
if score >= c.threshold {
state.banUntil = now.Add(c.banDuration)
return cacheResult{banned: true, banUntil: state.banUntil, score: score}
}
return cacheResult{score: score}
}
func (c *clientCache) behaviorScoreLocked(state *clientState, paths []string) int {
// The heuristic is intentionally weak: visiting a content page first is
// normal for a shared link, so it adds only the configured 15 points.
// It becomes useful in combination with malformed headers or 404 scans.
firstRequest := state.requests == 0
isContent := false
for _, requestPath := range paths {
if requestPath == "/" || requestPath == "/index.html" {
state.sawHome = true
}
if requestPath == "/favicon.ico" {
state.sawFavicon = true
}
if hasStaticAssetExtension(requestPath) {
state.sawStatic = true
}
if pathMatchesAny(requestPath, c.randomPaths) {
isContent = true
}
}
if firstRequest && isContent && !state.sawHome && !state.sawStatic && !state.sawFavicon {
return c.randomScore
}
return 0
}
func (c *clientCache) pruneEventsLocked(state *clientState, now time.Time) {
cutoff := now.Add(-c.scoreWindow)
first := 0
for first < len(state.events) && !state.events[first].at.After(cutoff) {
first++
}
if first > 0 {
state.events = append([]scoreEvent(nil), state.events[first:]...)
}
}
func (c *clientCache) cleanupLocked(now time.Time) {
// Full cleanup every 256 requests amortises the map scan while retaining
// recently scored clients for the entire score window.
if c.operations%256 != 0 {
return
}
cutoff := now.Add(-c.scoreWindow)
for ip, state := range c.entries {
if !state.banUntil.After(now) && !state.lastSeen.After(cutoff) {
delete(c.entries, ip)
}
}
}
func (c *clientCache) ensureCapacityLocked(now time.Time) {
if len(c.entries) < c.maxEntries {
return
}
// Evict the oldest non-banned entry first. If all entries are banned, the
// oldest ban is evicted; the cap remains a hard upper bound either way.
var oldestIP string
var oldestTime time.Time
for ip, state := range c.entries {
candidate := state.lastSeen
if state.banUntil.After(now) {
candidate = state.banUntil
}
if oldestIP == "" || candidate.Before(oldestTime) {
oldestIP, oldestTime = ip, candidate
}
}
if oldestIP != "" {
delete(c.entries, oldestIP)
}
}
func sumScore(events []scoreEvent) int {
total := 0
for _, event := range events {
total += event.points
}
return total
}
config.go
+168
View File
@@ -0,0 +1,168 @@
package botfilter
import (
"fmt"
"net/netip"
"net/textproto"
"strings"
"time"
)
// Config is the plugin configuration exposed by Traefik's dynamic file
// provider. All durations are expressed as integers because Traefik plugin
// configuration is deliberately kept YAML-friendly.
type Config struct {
StatusCode int `json:"statusCode,omitempty" yaml:"statusCode,omitempty" toml:"statusCode,omitempty"`
RequireUserAgent bool `json:"requireUserAgent,omitempty" yaml:"requireUserAgent,omitempty" toml:"requireUserAgent,omitempty"`
RequireAccept bool `json:"requireAccept,omitempty" yaml:"requireAccept,omitempty" toml:"requireAccept,omitempty"`
RequireHost bool `json:"requireHost,omitempty" yaml:"requireHost,omitempty" toml:"requireHost,omitempty"`
BrowserValidation bool `json:"browserValidation,omitempty" yaml:"browserValidation,omitempty" toml:"browserValidation,omitempty"`
WhitelistCIDRs []string `json:"whitelistCIDRs,omitempty" yaml:"whitelistCIDRs,omitempty" toml:"whitelistCIDRs,omitempty"`
TemporaryBanMinutes int `json:"temporaryBanMinutes,omitempty" yaml:"temporaryBanMinutes,omitempty" toml:"temporaryBanMinutes,omitempty"`
BlockedUserAgents []string `json:"blockedUserAgents,omitempty" yaml:"blockedUserAgents,omitempty" toml:"blockedUserAgents,omitempty"`
BlockedPaths []string `json:"blockedPaths,omitempty" yaml:"blockedPaths,omitempty" toml:"blockedPaths,omitempty"`
BlockedExtensions []string `json:"blockedExtensions,omitempty" yaml:"blockedExtensions,omitempty" toml:"blockedExtensions,omitempty"`
ScoreThreshold int `json:"scoreThreshold,omitempty" yaml:"scoreThreshold,omitempty" toml:"scoreThreshold,omitempty"`
ScoreWindowMinutes int `json:"scoreWindowMinutes,omitempty" yaml:"scoreWindowMinutes,omitempty" toml:"scoreWindowMinutes,omitempty"`
MaxTrackedIPs int `json:"maxTrackedIPs,omitempty" yaml:"maxTrackedIPs,omitempty" toml:"maxTrackedIPs,omitempty"`
MaxScoreEventsPerIP int `json:"maxScoreEventsPerIP,omitempty" yaml:"maxScoreEventsPerIP,omitempty" toml:"maxScoreEventsPerIP,omitempty"`
EmptyUserAgentScore int `json:"emptyUserAgentScore,omitempty" yaml:"emptyUserAgentScore,omitempty" toml:"emptyUserAgentScore,omitempty"`
MissingAcceptScore int `json:"missingAcceptScore,omitempty" yaml:"missingAcceptScore,omitempty" toml:"missingAcceptScore,omitempty"`
BlockedUserAgentScore int `json:"blockedUserAgentScore,omitempty" yaml:"blockedUserAgentScore,omitempty" toml:"blockedUserAgentScore,omitempty"`
BadPathScore int `json:"badPathScore,omitempty" yaml:"badPathScore,omitempty" toml:"badPathScore,omitempty"`
RandomArticleScore int `json:"randomArticleScore,omitempty" yaml:"randomArticleScore,omitempty" toml:"randomArticleScore,omitempty"`
NotFoundScore int `json:"notFoundScore,omitempty" yaml:"notFoundScore,omitempty" toml:"notFoundScore,omitempty"`
FakeBrowserScore int `json:"fakeBrowserScore,omitempty" yaml:"fakeBrowserScore,omitempty" toml:"fakeBrowserScore,omitempty"`
RandomArticlePatterns []string `json:"randomArticlePatterns,omitempty" yaml:"randomArticlePatterns,omitempty" toml:"randomArticlePatterns,omitempty"`
ClientIPHeader string `json:"clientIPHeader,omitempty" yaml:"clientIPHeader,omitempty" toml:"clientIPHeader,omitempty"`
TrustedProxyCIDRs []string `json:"trustedProxyCIDRs,omitempty" yaml:"trustedProxyCIDRs,omitempty" toml:"trustedProxyCIDRs,omitempty"`
LogBlockedRequests bool `json:"logBlockedRequests,omitempty" yaml:"logBlockedRequests,omitempty" toml:"logBlockedRequests,omitempty"`
}
// CreateConfig creates the default configuration. The defaults protect common
// public HTTP services without requiring a third-party dependency.
func CreateConfig() *Config {
return &Config{
StatusCode: 403,
TemporaryBanMinutes: 15,
ScoreThreshold: 100,
ScoreWindowMinutes: 15,
MaxTrackedIPs: 50000,
MaxScoreEventsPerIP: 16,
EmptyUserAgentScore: 40,
MissingAcceptScore: 20,
BlockedUserAgentScore: 80,
BadPathScore: 50,
RandomArticleScore: 15,
NotFoundScore: 40,
FakeBrowserScore: 40,
RandomArticlePatterns: []string{"/content/"},
}
}
type compiledConfig struct {
Config
banDuration time.Duration
scoreWindow time.Duration
whitelist []netip.Prefix
trustedProxies []netip.Prefix
blockedAgents []string
blockedPaths []string
blockedExts []string
randomPaths []string
clientIPHeader string
}
func compileConfig(input *Config) (*compiledConfig, error) {
if input == nil {
return nil, fmt.Errorf("botfilter: configuration is nil")
}
// Copy scalar fields and slices so a later configuration reload cannot
// mutate an already-running middleware instance.
cfg := *input
cfg.WhitelistCIDRs = append([]string(nil), input.WhitelistCIDRs...)
cfg.TrustedProxyCIDRs = append([]string(nil), input.TrustedProxyCIDRs...)
cfg.BlockedUserAgents = append([]string(nil), input.BlockedUserAgents...)
cfg.BlockedPaths = append([]string(nil), input.BlockedPaths...)
cfg.BlockedExtensions = append([]string(nil), input.BlockedExtensions...)
cfg.RandomArticlePatterns = append([]string(nil), input.RandomArticlePatterns...)
defaults := CreateConfig()
applyDefaults(&cfg, defaults)
if cfg.StatusCode < 400 || cfg.StatusCode > 599 {
return nil, fmt.Errorf("botfilter: statusCode must be between 400 and 599")
}
if cfg.TemporaryBanMinutes <= 0 {
return nil, fmt.Errorf("botfilter: temporaryBanMinutes must be greater than zero")
}
if cfg.ScoreThreshold <= 0 || cfg.ScoreWindowMinutes <= 0 {
return nil, fmt.Errorf("botfilter: scoreThreshold and scoreWindowMinutes must be greater than zero")
}
if cfg.MaxTrackedIPs <= 0 || cfg.MaxScoreEventsPerIP <= 0 {
return nil, fmt.Errorf("botfilter: maxTrackedIPs and maxScoreEventsPerIP must be greater than zero")
}
whitelist, err := parseCIDRs(cfg.WhitelistCIDRs, "whitelistCIDRs")
if err != nil {
return nil, err
}
trusted, err := parseCIDRs(cfg.TrustedProxyCIDRs, "trustedProxyCIDRs")
if err != nil {
return nil, err
}
return &compiledConfig{
Config: cfg,
banDuration: time.Duration(cfg.TemporaryBanMinutes) * time.Minute,
scoreWindow: time.Duration(cfg.ScoreWindowMinutes) * time.Minute,
whitelist: whitelist,
trustedProxies: trusted,
blockedAgents: normaliseTokens(cfg.BlockedUserAgents),
blockedPaths: normalisePaths(cfg.BlockedPaths),
blockedExts: normaliseExtensions(cfg.BlockedExtensions),
randomPaths: normalisePaths(cfg.RandomArticlePatterns),
clientIPHeader: textproto.CanonicalMIMEHeaderKey(strings.TrimSpace(cfg.ClientIPHeader)),
}, nil
}
func applyDefaults(cfg, defaults *Config) {
if cfg.StatusCode == 0 {
cfg.StatusCode = defaults.StatusCode
}
if cfg.TemporaryBanMinutes == 0 {
cfg.TemporaryBanMinutes = defaults.TemporaryBanMinutes
}
if cfg.ScoreThreshold == 0 {
cfg.ScoreThreshold = defaults.ScoreThreshold
}
if cfg.ScoreWindowMinutes == 0 {
cfg.ScoreWindowMinutes = defaults.ScoreWindowMinutes
}
if cfg.MaxTrackedIPs == 0 {
cfg.MaxTrackedIPs = defaults.MaxTrackedIPs
}
if cfg.MaxScoreEventsPerIP == 0 {
cfg.MaxScoreEventsPerIP = defaults.MaxScoreEventsPerIP
}
// Score fields deliberately do not receive fallback values here. Traefik
// starts from CreateConfig(), so omitted values retain their defaults, while
// an explicit YAML zero remains a useful way to disable one signal.
}
func parseCIDRs(values []string, field string) ([]netip.Prefix, error) {
result := make([]netip.Prefix, 0, len(values))
for _, value := range values {
value = strings.TrimSpace(value)
if value == "" {
continue
}
prefix, err := netip.ParsePrefix(value)
if err != nil {
return nil, fmt.Errorf("botfilter: invalid %s entry %q: %w", field, value, err)
}
result = append(result, prefix.Masked())
}
return result, nil
}
go.mod
+3
View File
@@ -0,0 +1,3 @@
module github.com/hoelee/traefik-botfilter
go 1.20
logger.go
+17
View File
@@ -0,0 +1,17 @@
package botfilter
import "log"
type filterLogger struct {
name string
enabled bool
}
func (l filterLogger) blocked(ip, reason string, score int) {
if !l.enabled {
return
}
// This is intentionally opt-in. Logging every rejected request during a
// flood can become a second source of CPU and disk pressure.
log.Printf("botfilter[%s]: blocked client=%s reason=%q score=%d", l.name, ip, reason, score)
}
matcher.go
+141
View File
@@ -0,0 +1,141 @@
package botfilter
import (
"net/http"
"strings"
)
type matchResult struct {
points int
forceBan bool
reason string
}
func inspectRequest(r *http.Request, cfg *compiledConfig) matchResult {
paths := requestPaths(r)
userAgent := strings.TrimSpace(r.UserAgent())
if cfg.RequireUserAgent && userAgent == "" {
return matchResult{points: cfg.EmptyUserAgentScore, forceBan: true, reason: "missing user-agent"}
}
if cfg.RequireAccept && !hasHeader(r, "Accept") {
return matchResult{points: cfg.MissingAcceptScore, forceBan: true, reason: "missing accept"}
}
if cfg.RequireHost && strings.TrimSpace(r.Host) == "" {
return matchResult{forceBan: true, reason: "missing host"}
}
if containsToken(strings.ToLower(userAgent), cfg.blockedAgents) {
return matchResult{points: cfg.BlockedUserAgentScore, forceBan: true, reason: "blocked user-agent"}
}
if matchesBlockedPath(paths, cfg.blockedPaths) {
return matchResult{points: cfg.BadPathScore, forceBan: true, reason: "blocked path"}
}
if matchesBlockedExtension(paths, cfg.blockedExts) {
return matchResult{points: cfg.BadPathScore, forceBan: true, reason: "blocked extension"}
}
result := matchResult{}
if userAgent == "" {
result.points += cfg.EmptyUserAgentScore
result.reason = "empty user-agent"
}
if !hasHeader(r, "Accept") {
result.points += cfg.MissingAcceptScore
result.reason = appendReason(result.reason, "missing accept")
}
if cfg.BrowserValidation && implausibleBrowser(r, userAgent) {
result.points += cfg.FakeBrowserScore
result.reason = appendReason(result.reason, "implausible browser headers")
}
return result
}
func containsToken(value string, tokens []string) bool {
for _, token := range tokens {
if strings.Contains(value, token) {
return true
}
}
return false
}
func matchesBlockedPath(paths, blockedPaths []string) bool {
for _, requestPath := range paths {
if pathMatchesAny(requestPath, blockedPaths) {
return true
}
}
return false
}
func matchesBlockedExtension(paths, extensions []string) bool {
for _, requestPath := range paths {
for _, extension := range extensions {
if strings.HasSuffix(requestPath, extension) {
return true
}
}
}
return false
}
func pathMatchesAny(requestPath string, rules []string) bool {
for _, rule := range rules {
if pathMatches(requestPath, rule) {
return true
}
}
return false
}
func hasStaticAssetExtension(requestPath string) bool {
for _, extension := range []string{".css", ".js", ".mjs", ".png", ".jpg", ".jpeg", ".gif", ".svg", ".webp", ".ico", ".woff", ".woff2"} {
if strings.HasSuffix(requestPath, extension) {
return true
}
}
return false
}
func implausibleBrowser(r *http.Request, userAgent string) bool {
ua := strings.ToLower(userAgent)
if !strings.Contains(ua, "mozilla/") {
return false
}
// Do not require optional browser client-hint or fetch-metadata headers:
// older browsers and privacy tools legitimately omit them. Instead reject
// internally inconsistent browser family declarations.
isChromium := strings.Contains(ua, "chrome/") || strings.Contains(ua, "crios/") || strings.Contains(ua, "edg/") || strings.Contains(ua, "opr/")
isFirefox := strings.Contains(ua, "firefox/")
isSafari := strings.Contains(ua, "safari/") && !isChromium
if !isChromium && !isFirefox && !isSafari {
return true
}
if isChromium && !strings.Contains(ua, "applewebkit/") {
return true
}
if isFirefox && !strings.Contains(ua, "gecko/") {
return true
}
if isSafari && (!strings.Contains(ua, "applewebkit/") || !strings.Contains(ua, "version/")) {
return true
}
if value := r.Header.Get("Sec-Fetch-Site"); value != "" {
switch value {
case "same-origin", "same-site", "cross-site", "none":
default:
return true
}
}
return false
}
func appendReason(current, next string) string {
if current == "" {
return next
}
return current + "; " + next
}
util.go
+127
View File
@@ -0,0 +1,127 @@
package botfilter
import (
"net"
"net/http"
"net/netip"
"net/url"
pathpkg "path"
"strings"
)
func clientIP(r *http.Request, cfg *compiledConfig) netip.Addr {
remote := parseRemoteAddress(r.RemoteAddr)
if cfg.clientIPHeader == "" || !addressInPrefixes(remote, cfg.trustedProxies) {
return remote
}
// A trusted reverse proxy must overwrite (not append to an untrusted
// client-provided value) this header. The left-most valid value is the
// original client in the conventional X-Forwarded-For representation.
for _, value := range strings.Split(r.Header.Get(cfg.clientIPHeader), ",") {
if addr, err := netip.ParseAddr(strings.TrimSpace(value)); err == nil {
return addr.Unmap()
}
}
return remote
}
func parseRemoteAddress(value string) netip.Addr {
host, _, err := net.SplitHostPort(strings.TrimSpace(value))
if err == nil {
value = host
}
addr, err := netip.ParseAddr(strings.Trim(strings.TrimSpace(value), "[]"))
if err != nil {
return netip.Addr{}
}
return addr.Unmap()
}
func addressInPrefixes(addr netip.Addr, prefixes []netip.Prefix) bool {
if !addr.IsValid() {
return false
}
for _, prefix := range prefixes {
if prefix.Contains(addr) {
return true
}
}
return false
}
func normaliseTokens(values []string) []string {
result := make([]string, 0, len(values))
for _, value := range values {
if token := strings.ToLower(strings.TrimSpace(value)); token != "" {
result = append(result, token)
}
}
return result
}
func normalisePaths(values []string) []string {
result := make([]string, 0, len(values))
for _, value := range values {
if path := normalisePath(value); path != "" {
result = append(result, path)
}
}
return result
}
func normaliseExtensions(values []string) []string {
result := make([]string, 0, len(values))
for _, value := range values {
value = strings.ToLower(strings.TrimSpace(value))
if value == "" {
continue
}
if !strings.HasPrefix(value, ".") {
value = "." + value
}
result = append(result, value)
}
return result
}
func normalisePath(value string) string {
value = strings.TrimSpace(value)
if value == "" {
return ""
}
value = strings.ReplaceAll(value, "\\", "/")
if !strings.HasPrefix(value, "/") {
value = "/" + value
}
return strings.ToLower(pathpkg.Clean(value))
}
func requestPaths(r *http.Request) []string {
values := []string{r.URL.Path, r.URL.EscapedPath()}
result := make([]string, 0, len(values)*3)
seen := make(map[string]struct{})
for _, value := range values {
for i := 0; i < 3 && value != ""; i++ {
normalised := normalisePath(value)
if _, ok := seen[normalised]; !ok {
seen[normalised] = struct{}{}
result = append(result, normalised)
}
decoded, err := url.PathUnescape(value)
if err != nil || decoded == value {
break
}
value = decoded
}
}
return result
}
func pathMatches(path, rule string) bool {
return path == rule || strings.HasPrefix(path, rule+"/")
}
func hasHeader(r *http.Request, name string) bool {
return strings.TrimSpace(r.Header.Get(name)) != ""
}