Merge pull request #181 from firstred/proxy-protocol

Add PROXY protocol support

.github/dependabot.yml

@@ -0,0 +1,19 @@
+# To get started with Dependabot version updates, you'll need to specify which
+# package ecosystems to update and where the package manifests are located.
+# Please see the documentation for all configuration options:
+# https://docs.github.com/github/administering-a-repository/configuration-options-for-dependency-updates
+
+version: 2
+updates:
+  - package-ecosystem: "gomod"
+    directory: "/" # Location of package manifests
+    schedule:
+      interval: "weekly"
+  - package-ecosystem: "github-actions"
+    directory: "/" # Location of package manifests
+    schedule:
+      interval: "weekly"
+  - package-ecosystem: "docker"
+    directory: "/" # Location of package manifests
+    schedule:
+      interval: "weekly"

.github/workflows/docker-hub-build-push.yml

@@ -1,25 +0,0 @@
-name: build docker image and push to docker hub
-
-on:
-  release:
-    types: # This configuration does not affect the page_build event above
-      - created
-
-jobs:
-  build:
-    runs-on: ubuntu-latest
-    steps:
-      - name: checkout code
-        uses: actions/checkout@v2
-      - name: install buildx
-        id: buildx
-        uses: crazy-max/ghaction-docker-buildx@v1
-        with:
-          version: latest
-      - name: login to docker hub
-        run: echo "${{ secrets.DOCKER_PASSWORD }}" | docker login -u "${{ secrets.DOCKER_USERNAME }}" --password-stdin
-      - name: build the image
-        run: |
-          docker buildx build --push \
-            --tag shizunge/endlessh-go:latest \
-            --platform linux/amd64,linux/arm/v7,linux/arm64 .

.github/workflows/docker-hub-description.yml

@@ -0,0 +1,22 @@
+name: Update Docker Hub description
+
+on:
+  release:
+    types:
+      - created
+  workflow_dispatch:
+
+jobs:
+  publish:
+    name: Update Docker Hub description
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout Code
+        uses: actions/checkout@v5
+      - name: Update Docker Hub description
+        uses: peter-evans/dockerhub-description@v4
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_PASSWORD }}
+          repository: ${{ github.repository }}
+          short-description: ${{ github.event.repository.description }}

.github/workflows/on-pull-request.yml

@@ -0,0 +1,48 @@
+name: On pull request
+
+on:
+  pull_request:
+    branches:
+      - 'main'
+    paths-ignore:
+      - 'dashboard/*'
+      - 'examples/*'
+      - 'README.md'
+      - 'LICENSE'
+  workflow_dispatch:
+
+env:
+  PLATFORMS: "linux/amd64,linux/arm64,linux/arm/v7"
+  
+jobs:
+  build_container_image:
+    name: Build Docker image
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v5
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v3
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3.11.1
+      - name: Docker meta
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: |
+            ghcr.io/${{ github.repository }}-development
+          tags: |
+            type=raw,value=dev-{{date 'X'}}
+            type=raw,value=latest
+            type=ref,event=branch
+            type=edge,branch=main
+      - name: Build 
+        uses: docker/build-push-action@v6.18.0
+        with:
+          platforms: ${{ env.PLATFORMS }}
+          push: false
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+          provenance: false
+
+

.github/workflows/on-push.yml

@@ -0,0 +1,62 @@
+name: On push
+
+on:
+  push:
+    branches-ignore:
+      - 'release'
+      - 'dependabot/**'
+    paths-ignore:
+      - 'dashboard/*'
+      - 'examples/*'
+      - 'README.md'
+      - 'LICENSE'
+  workflow_dispatch:
+
+env:
+  PLATFORMS: "linux/amd64,linux/arm64,linux/arm/v7"
+  
+jobs:
+  build_and_push:
+    name: Build and push Docker image
+    runs-on: ubuntu-latest
+    if: ${{ github.actor != 'dependabot[bot]' }}
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v5
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v3
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3.11.1
+      - name: Login to Docker Hub
+        uses: docker/login-action@v3.5.0
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_PASSWORD }}
+      - name: Login to GitHub Container Registry
+        uses: docker/login-action@v3.5.0
+        with:
+          registry: ghcr.io
+          username: ${{ github.repository_owner }}
+          password: ${{ github.token }}
+      - name: Docker meta
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: |
+            ${{ github.repository }}-development
+            ghcr.io/${{ github.repository }}-development
+          tags: |
+            type=raw,value=dev-{{date 'X'}}
+            type=raw,value=latest
+            type=ref,event=branch
+            type=edge,branch=main
+      - name: Build and push ${{ github.repository }}:${{ steps.git.outputs.image_tag }}
+        uses: docker/build-push-action@v6.18.0
+        with:
+          platforms: ${{ env.PLATFORMS }}
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+          provenance: false
+
+

.github/workflows/on-release.yml

@@ -0,0 +1,49 @@
+name: On release
+
+on:
+  release:
+    types: # This configuration does not affect the page_build event above
+      - created
+env:
+  PLATFORMS: "linux/amd64,linux/arm64,linux/arm/v7"
+  
+jobs:
+  build_and_push:
+    name: Build and push Docker image
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v5
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v3
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3.11.1
+      - name: Login to docker hub
+        uses: docker/login-action@v3.5.0
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_PASSWORD }}
+      - name: Login to GitHub Container Registry
+        uses: docker/login-action@v3.5.0
+        with:
+          registry: ghcr.io
+          username: ${{ github.repository_owner }}
+          password: ${{ github.token }}
+      - name: Docker meta
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: |
+            ${{ github.repository }}
+            ghcr.io/${{ github.repository }}
+          tags: |
+            type=ref,event=branch
+            type=ref,event=tag
+      - name: Build and push
+        uses: docker/build-push-action@v6.18.0
+        with:
+          platforms: ${{ env.PLATFORMS }}
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+          provenance: false

.gitignore

@@ -0,0 +1 @@
+endlessh-go

Dockerfile

@@ -1,19 +1,20 @@
-FROM golang:alpine AS build
+FROM golang AS build
 
-ADD . /go/src/app
-WORKDIR /go/src/app
+RUN mkdir /endlessh
+ADD . /endlessh
+WORKDIR /endlessh
 RUN go mod tidy
-RUN go build -o endlessh .
+RUN CGO_ENABLED=0 go build -o endlessh .
 
-FROM alpine:latest
+FROM gcr.io/distroless/base
 
 LABEL org.opencontainers.image.title=endlessh-go
 LABEL org.opencontainers.image.description="Endlessh: an SSH tarpit"
 LABEL org.opencontainers.image.vendor="Shizun Ge"
 LABEL org.opencontainers.image.licenses=GPLv3
 
-COPY --from=build /go/src/app/endlessh /usr/bin/endlessh
+COPY --from=build /endlessh/endlessh /endlessh
 EXPOSE 2222 2112
 USER nobody
-ENTRYPOINT  ["/usr/bin/endlessh"]
+ENTRYPOINT  ["/endlessh"]
 CMD ["-logtostderr", "-v=1"]

README.md

@@ -1,10 +1,19 @@
 # endlessh-go
 
+[![Release](https://img.shields.io/github/release/shizunge/endlessh-go.svg?label=Release)](https://github.com/shizunge/endlessh-go/releases/latest)
+[![License](https://img.shields.io/badge/License-GPLv3-blue)](https://github.com/shizunge/endlessh-go/blob/main/LICENSE)
+[![Image Size](https://img.shields.io/docker/image-size/shizunge/endlessh-go/latest.svg?label=Image%20Size)](https://hub.docker.com/r/shizunge/endlessh-go)
+[![Docker Pulls](https://img.shields.io/docker/pulls/shizunge/endlessh-go.svg?label=Docker%20Pulls&logo=Docker)](https://hub.docker.com/r/shizunge/endlessh-go)
+[![Build](https://img.shields.io/github/actions/workflow/status/shizunge/endlessh-go/on-push.yml?label=Build&branch=main&logo=GitHub)](https://github.com/shizunge/endlessh-go/actions/workflows/on-push.yml)
+[![CodeFactor Grade](https://img.shields.io/codefactor/grade/github/shizunge/endlessh-go?label=CodeFactor&logo=CodeFactor)](https://www.codefactor.io/repository/github/shizunge/endlessh-go)
+
 A golang implementation of [endlessh](https://nullprogram.com/blog/2019/03/22/) exporting Prometheus metrics, visualized by a Grafana dashboard.
 
+![screenshot](https://github.com/shizunge/endlessh-go/raw/main/dashboard/screenshot.png)
+
 ## Introduction
 
-Endlessh is a great idea that not only blocks the brute force SSH attacks, but also wastes attackers time as a kind of counter-attack. Besides trapping the attackers, I also want to visualize the Geolocations and other statistics of the sources of attacks. Unfortunately the wonderful original [C implementation of endlessh](https://github.com/skeeto/endlessh) only provides text based log, but I do not like the solution that writing extra scripts to parse the log outputs, then exporting the results to a dashboard, because it would introduce extra layers in my current setup and it would depend on the format of the text log file rather than some structured data. Thus I create this golang implementation of endlessh to export [Prometheus](https://prometheus.io/) metrics and a [Grafana](https://grafana.com/) dashboard to visualize them.
+[Endlessh](https://nullprogram.com/blog/2019/03/22/) is a great idea that not only blocks the brute force SSH attacks, but also wastes attackers time as a kind of counter-attack. Besides trapping the attackers, I also want to visualize the Geolocations and other statistics of the sources of attacks. Unfortunately the wonderful original [C implementation of endlessh](https://github.com/skeeto/endlessh) only provides text based log, but I do not like the solution that writes extra scripts to parse the log outputs, then exports the results to a dashboard, because it would introduce extra layers in my current setup and it would depend on the format of the text log file rather than some structured data. Thus I create this golang implementation of endlessh to export [Prometheus](https://prometheus.io/) metrics and a [Grafana](https://grafana.com/) dashboard to visualize them.
 
 If you want a dashboard of sources of attacks and do not mind the endlessh server, besides trapping the attackers, does extra things including: translating IP to Geohash, exporting Prometheus metrics, and using more memory (about 10MB), this is the solution for you.
 
@@ -20,7 +29,7 @@ go build .
 Alternatively, you can use the [docker image](https://hub.docker.com/r/shizunge/endlessh-go):
 
 ```
-sudo docker run -d -p 2222:2222 shizunge/endlessh-go
+docker run -d -p 2222:2222 shizunge/endlessh-go -logtostderr -v=1
 ```
 
 It listens to port `2222` by default.
@@ -31,50 +40,69 @@ Then you can try to connect to the endlessh server. Your SSH client should hang
 ssh -p 2222 localhost
 ```
 
-If you want log like the [C implementation](https://github.com/skeeto/endlessh), you need to set both CLI arguments `-logtostderr` and `-v=1`, then the log will go to the stderr. You can set different log destinations via CLI arguments.
+If you want log like the [C implementation](https://github.com/skeeto/endlessh), you need to set both CLI arguments `-logtostderr` and `-v=1`, then the log will go to stderr. You can set different log destinations via CLI arguments.
+
+Also check out [examples](./examples/README.md) for the setup of the full stack.
 
 ## Usage
 
-Usage of `./endlessh-go`
+`./endlessh-go --help`
 
-* -alsologtostderr
-  * log to standard error as well as files
-* -conn_type string
-  * Connection type. Possible values are tcp, tcp4, tcp6 (default "tcp")
-* -enable_prometheus
-  * Enable prometheus
-* -geoip_supplier string
-  * Supplier to obtain Geohash of IPs. Possible values are "off", "ip-api", "freegeoip" (default "off")
-* -host string
-  * Listening address (default "0.0.0.0")
-* -interval_ms int
-  * Message millisecond delay (default 1000)
-* -line_length int
-  * Maximum banner line length (default 32)
-* -log_backtrace_at value
-  * when logging hits line file:N, emit a stack trace
-* -log_dir string
-  * If non-empty, write log files in this directory
-* -logtostderr
-  * log to standard error instead of files
-* -max_clients int
-  * Maximum number of clients (default 4096)
-* -port string
-  * Listening port (default "2222")
-* -prometheus_entry string
-  * Entry point for prometheus (default "metrics")
-* -prometheus_port string
-  * The port for prometheus (default "2112")
-* -stderrthreshold value
-  * logs at or above this threshold go to stderr
-* -v value
-  * log level for V logs
-* -vmodule value
-  * comma-separated list of pattern=N settings for file-filtered logging
+```
+Usage of ./endlessh-go
+  -alsologtostderr
+        log to standard error as well as files
+  -conn_type string
+        Connection type. Possible values are tcp, tcp4, tcp6 (default "tcp")
+  -enable_prometheus
+        Enable prometheus
+  -geoip_supplier string
+        Supplier to obtain Geohash of IPs. Possible values are "off", "ip-api", "max-mind-db" (default "off")
+  -host string
+        SSH listening address (default "0.0.0.0")
+  -interval_ms int
+        Message millisecond delay (default 1000)
+  -line_length int
+        Maximum banner line length (default 32)
+  -log_backtrace_at value
+        when logging hits line file:N, emit a stack trace
+  -log_dir string
+        If non-empty, write log files in this directory
+  -log_link string
+        If non-empty, add symbolic links in this directory to the log files
+  -logbuflevel int
+        Buffer log messages logged at this level or lower (-1 means don't buffer; 0 means buffer INFO only; ...). Has limited applicability on non-prod platforms.
+  -logtostderr
+        log to standard error instead of files
+  -max_clients int
+        Maximum number of clients (default 4096)
+  -max_mind_db string
+        Path to the MaxMind DB file.
+  -port value
+        SSH listening port. You may provide multiple -port flags to listen to multiple ports. (default "2222")
+  -prometheus_clean_unseen_seconds int
+        Remove series if the IP is not seen for the given time. Set to 0 to disable. (default 0)
+  -prometheus_entry string
+        Entry point for prometheus (default "metrics")
+  -prometheus_host string
+        The address for prometheus (default "0.0.0.0")
+  -prometheus_port string
+        The port for prometheus (default "2112")
+  -proxy_protocol_enabled
+        Enable PROXY protocol support. This causes the server to expect PROXY protocol headers on incoming connections.
+  -proxy_protocol_read_header_timeout_ms int
+        Timeout for reading the PROXY protocol header in milliseconds. If the connection does not send a valid PROXY protocol header in this time, the header is ignored. (default 200)
+  -stderrthreshold value
+        logs at or above this threshold go to stderr (default 2)
+  -v value
+        log level for V logs
+  -vmodule value
+        comma-separated list of pattern=N settings for file-filtered logging
+```
 
 ## Metrics
 
-This golang implementation exports the following Prometheus metrics.
+Endlessh-go exports the following Prometheus metrics.
 
 | Metric                               | Type  | Description  |
 |--------------------------------------|-------|--------------|
@@ -82,21 +110,27 @@ This golang implementation exports the following Prometheus metrics.
 | endlessh_client_closed_count_total   | count | Total number of clients that stopped connecting to this host. |
 | endlessh_sent_bytes_total            | count | Total bytes sent to clients that tried to connect to this host. |
 | endlessh_trapped_time_seconds_total  | count | Total seconds clients spent on endlessh. |
-| endlessh_client_open_count           | count | Number of connections of clients. <br> Labels: <br> <ul><li> `ip`: IP of the client </li> <li>  `country`: Country of the IP </li> <li>  `location`: Country, Region, and City </li> <li>  `geohash`: Geohash of the location </li></ul> |
-| endlessh_client_trapped_time_seconds | count | Seconds a client spends on endlessh. <br> Labels: <br> <ul><li>  `ip`: IP of the client </li></ul> |
+| endlessh_client_open_count           | count | Number of connections of clients. <br> Labels: <br> <ul><li> `ip`: Remote IP of the client </li> <li> `local_port`: Local port the program listens to </li> <li> `country`: Country of the IP </li> <li> `location`: Country, Region, and City </li> <li> `geohash`: Geohash of the location </li></ul> |
+| endlessh_client_trapped_time_seconds | count | Seconds a client spends on endlessh. <br> Labels: <br> <ul><li> `ip`: Remote IP of the client </li> <li> `local_port`: Local port the program listens to </li></ul> |
 
 The metrics is off by default, you can turn it via the CLI argument `-enable_prometheus`.
 
 It listens to port `2112` and entry point is `/metrics` by default. The port and entry point can be changed via CLI arguments.
 
-The endlessh-go server stores the geohash of attackers as a label on `endlessh_client_open_count`, which is also off by default. You can turn it on via the CLI argument `-geoip_supplier`. The endlessh-go uses service from either [ip-api](https://ip-api.com/) or [freegeoip](https://freegeoip.live/), which may enforce a query rate and limit commercial use. Visit their website for their terms and policies.
+The endlessh-go server stores the geohash of attackers as a label on `endlessh_client_open_count`, which is also off by default. You can turn it on via the CLI argument `-geoip_supplier`. The endlessh-go uses service from [ip-api](https://ip-api.com/), which may enforce a query rate and limit commercial use. Visit their website for their terms and policies.
+
+You could also use an offline GeoIP database from [MaxMind](https://www.maxmind.com) by setting `-geoip_supplier` to _max-mind-db_ and `-max_mind_db` to the path of the database file.
 
 ## Dashboard
 
-![screenshot](dashboard/screenshot.png)
-
 The dashboard requires Grafana 8.2.
 
 You can import the dashboard from Grafana.com using ID [15156](https://grafana.com/grafana/dashboards/15156)
 
+The dashboard visualizes data for the selected time range.
+
 The IP addresses are clickable and link you to the [ARIN](https://www.arin.net/) database.
+
+## Contacts
+
+If you have any problems or questions, please contact me through a [GitHub issue](https://github.com/shizunge/endlessh-go/issues)

client.go

@@ -1,111 +0,0 @@
-// Copyright (C) 2021 Shizun Ge
-//
-// This program is free software: you can redistribute it and/or modify
-// it under the terms of the GNU General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-//
-// This program is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU General Public License for more details.
-//
-// You should have received a copy of the GNU General Public License
-// along with this program.  If not, see <https://www.gnu.org/licenses/>.
-//
-
-package main
-
-import (
-	"math/rand"
-	"net"
-	"sync/atomic"
-	"time"
-
-	"github.com/golang/glog"
-	"github.com/prometheus/client_golang/prometheus"
-)
-
-var letterBytes = []byte(" abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ01234567890!@#$%^&*()-=_+[]{}|;:',./<>?")
-
-func randStringBytes(n int64) []byte {
-	b := make([]byte, n+1)
-	for i := range b {
-		b[i] = letterBytes[rand.Intn(len(letterBytes))]
-	}
-	b[n] = '\n'
-	return b
-}
-
-type client struct {
-	conn              net.Conn
-	last              time.Time
-	next              time.Time
-	start             time.Time
-	interval          time.Duration
-	geoipSupplier     string
-	geohash           string
-	country           string
-	location          string
-	bytesSent         int
-	prometheusEnabled bool
-}
-
-func NewClient(conn net.Conn, interval time.Duration, maxClient int64, geoipSupplier string, prometheusEnabled bool) *client {
-	addr := conn.RemoteAddr().(*net.TCPAddr)
-	atomic.AddInt64(&numCurrentClients, 1)
-	atomic.AddInt64(&numTotalClients, 1)
-	geohash, country, location, err := geohashAndLocation(addr.IP.String(), geoipSupplier)
-	if err != nil {
-		glog.Warningf("Failed to obatin the geohash of %v: %v.", addr.IP, err)
-	}
-	if prometheusEnabled {
-		clientIP.With(prometheus.Labels{
-			"ip":       addr.IP.String(),
-			"geohash":  geohash,
-			"country":  country,
-			"location": location}).Inc()
-	}
-	glog.V(1).Infof("ACCEPT host=%v port=%v n=%v/%v\n", addr.IP, addr.Port, numCurrentClients, maxClient)
-	return &client{
-		conn:              conn,
-		last:              time.Now(),
-		next:              time.Now().Add(interval),
-		start:             time.Now(),
-		interval:          interval,
-		geohash:           geohash,
-		country:           country,
-		location:          location,
-		bytesSent:         0,
-		prometheusEnabled: prometheusEnabled,
-	}
-}
-
-func (c *client) Send(bannerMaxLength int64) error {
-	defer func(c *client) {
-		addr := c.conn.RemoteAddr().(*net.TCPAddr)
-		millisecondsSpent := time.Now().Sub(c.last).Milliseconds()
-		c.last = time.Now()
-		c.next = time.Now().Add(c.interval)
-		atomic.AddInt64(&numTotalMilliseconds, millisecondsSpent)
-		if c.prometheusEnabled {
-			clientSeconds.With(prometheus.Labels{"ip": addr.IP.String()}).Add(float64(millisecondsSpent) / 1000)
-		}
-	}(c)
-	length := rand.Int63n(bannerMaxLength)
-	bytesSent, err := c.conn.Write(randStringBytes(length))
-	if err != nil {
-		return err
-	}
-	c.bytesSent += bytesSent
-	atomic.AddInt64(&numTotalBytes, int64(bytesSent))
-	return nil
-}
-
-func (c *client) Close() {
-	addr := c.conn.RemoteAddr().(*net.TCPAddr)
-	atomic.AddInt64(&numCurrentClients, -1)
-	atomic.AddInt64(&numTotalClientsClosed, 1)
-	glog.V(1).Infof("CLOSE host=%v port=%v time=%v bytes=%v\n", addr.IP, addr.Port, time.Now().Sub(c.start).Seconds(), c.bytesSent)
-	c.conn.Close()
-}

client/client.go

@@ -0,0 +1,102 @@
+// Copyright (C) 2021-2024 Shizun Ge
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+//
+
+package client
+
+import (
+	"math/rand"
+	"net"
+	"strconv"
+	"sync/atomic"
+	"time"
+
+	"github.com/golang/glog"
+)
+
+var (
+	numCurrentClients int64
+	letterBytes       = []byte(" abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ01234567890!@#$%^&*()-=_+[]{}|;:',./<>?")
+)
+
+func randStringBytes(n int64) []byte {
+	b := make([]byte, n+1)
+	for i := range b {
+		b[i] = letterBytes[rand.Intn(len(letterBytes))]
+	}
+	b[n] = '\n'
+	return b
+}
+
+type Client struct {
+	conn      net.Conn
+	next      time.Time
+	start     time.Time
+	last      time.Time
+	interval  time.Duration
+	bytesSent int
+}
+
+func NewClient(conn net.Conn, interval time.Duration, maxClients int64) *Client {
+	for numCurrentClients >= maxClients {
+		time.Sleep(interval)
+	}
+	atomic.AddInt64(&numCurrentClients, 1)
+	addr := conn.RemoteAddr().(*net.TCPAddr)
+	glog.V(1).Infof("ACCEPT host=%v port=%v n=%v/%v\n", addr.IP, addr.Port, numCurrentClients, maxClients)
+	return &Client{
+		conn:      conn,
+		next:      time.Now().Add(interval),
+		start:     time.Now(),
+		last:      time.Now(),
+		interval:  interval,
+		bytesSent: 0,
+	}
+}
+
+func (c *Client) RemoteIpAddr() string {
+	return c.conn.RemoteAddr().(*net.TCPAddr).IP.String()
+}
+
+func (c *Client) LocalPort() string {
+	return strconv.Itoa(c.conn.LocalAddr().(*net.TCPAddr).Port)
+}
+
+func (c *Client) Send(bannerMaxLength int64) (int, error) {
+	if time.Now().Before(c.next) {
+		time.Sleep(c.next.Sub(time.Now()))
+	}
+	c.next = time.Now().Add(c.interval)
+	length := rand.Int63n(bannerMaxLength)
+	bytesSent, err := c.conn.Write(randStringBytes(length))
+	if err != nil {
+		return 0, err
+	}
+	c.bytesSent += bytesSent
+	return bytesSent, nil
+}
+
+func (c *Client) MillisecondsSinceLast() int64 {
+	millisecondsSpent := time.Now().Sub(c.last).Milliseconds()
+	c.last = time.Now()
+	return millisecondsSpent
+}
+
+func (c *Client) Close() {
+	addr := c.conn.RemoteAddr().(*net.TCPAddr)
+	glog.V(1).Infof("CLOSE host=%v port=%v time=%v bytes=%v\n", addr.IP, addr.Port, time.Now().Sub(c.start).Seconds(), c.bytesSent)
+	c.conn.Close()
+	atomic.AddInt64(&numCurrentClients, -1)
+}

examples/README.md

@@ -0,0 +1,18 @@
+# Examples
+
+> The default container user has uid 65534.
+
+## [docker-simple](./docker-simple)
+
+An example how to setup endlessh-go, Prometheus, and Grafana using [docker compose](https://docs.docker.com/compose/).
+
+## [docker-maxmind](./docker-maxmind)
+
+An example how to setup endlessh-go with the Maxmind GeoIP Database.
+
+## FAQ
+### Bind to privileged ports (<1024) in a container
+
+You need to add capability `NET_BIND_SERVICE` to the program.
+
+If you are using docker, this can be done via cli argument [`--cap-add`](https://docs.docker.com/engine/reference/run/#runtime-privilege-and-linux-capabilities) or [`cap_add`](https://docs.docker.com/compose/compose-file/compose-file-v3/#cap_add-cap_drop) in the docker compose file.

examples/docker-maxmind/README.md

@@ -0,0 +1,16 @@
+## docker compose
+
+This is an example how to setup endlessh-go with the Maxmind GeoIP Database using [docker compose](https://docs.docker.com/compose/). The reference of the compose file can be found [here](https://docs.docker.com/compose/compose-file/).
+
+To start the stack, in the _examples_ folder, run:
+
+```
+docker-compose up -d
+```
+
+The GeoIP Database will be saved in a mounted volume in: `./geo-data`. And the endlessh-go container will use this database to do the location lookups.
+
+This example exposes the following ports. Except the SSH port, you should not expose other ports to public without protections (not included in this example) in production.
+
+-   **2222**: The SSH port. You may test endlessh-go by running `ssh -p 2222 localhost`. Your SSH client should hang. View the log of endlessh-go by running `docker logs endlessh`.
+-   **2112**: The Prometheus metrics exported by endlessh-go. Go to [http://localhost:2112/metrics](http://localhost:2112/metrics) in your web browser to view the metrics.

examples/docker-maxmind/docker-compose.yml

@@ -0,0 +1,35 @@
+services:
+
+  endlessh:
+    container_name: endlessh
+    image: shizunge/endlessh-go:latest
+    restart: unless-stopped
+    #user: root
+    command:
+      - "-logtostderr"
+      - "-v=1"
+      - "-geoip_supplier=max-mind-db"
+      - "-max_mind_db=/geo-data/GeoLite2-City.mmdb"
+    networks:
+      - example_network
+    ports:
+      - 2222:2222 # SSH port
+      - 127.0.0.1:2112:2112 # Prometheus metrics port
+    volumes:
+      - ./geo-data/:/geo-data/:ro # geoip data
+
+  geoipupdate:
+    image: ghcr.io/maxmind/geoipupdate:v5
+    container_name: geoipupdate
+    restart: unless-stopped
+    security_opt: [ "no-new-privileges:true" ]
+    volumes:
+      - ./geo-data/:/usr/share/GeoIP/
+    environment:
+      - GEOIPUPDATE_EDITION_IDS=GeoLite2-City
+      - GEOIPUPDATE_FREQUENCY=72
+      - GEOIPUPDATE_ACCOUNT_ID=xxxxxx
+      - GEOIPUPDATE_LICENSE_KEY=xxxxxx
+
+networks:
+  example_network:

examples/docker-simple/README.md

@@ -0,0 +1,22 @@
+## docker compose
+
+This is an example how to setup endlessh-go, Prometheus, and Grafana using [docker compose](https://docs.docker.com/compose/). The reference of the compose file can be found [here](https://docs.docker.com/compose/compose-file/).
+
+*prometheus.yml* is used as a [Prometheus configuration](https://prometheus.io/docs/prometheus/latest/configuration/configuration/).
+
+*grafana-datasource.yml* is used to provision a data source for Grafana to ease the setup, though Grafana data source can also be setup manually.
+
+To start the stack, in the *examples* folder, run:
+
+```
+docker-compose up -d
+```
+
+This example exposes the following ports. Except the SSH port, you should not expose other ports to public without protections (not included in this example) in production.
+
+* **2222**: The SSH port. You may test endlessh-go by running `ssh -p 2222 localhost`. Your SSH client should hang. View the log of endlessh-go by running `docker logs endlessh`.
+* **2112**: The Prometheus metrics exported by endlessh-go. Go to [http://localhost:2112/metrics](http://localhost:2112/metrics) in your web browser to view the metrics.
+* **9090**: Prometheus web interface. Go to [http://localhost:9090](http://localhost:9090) in your web browser for Prometheus. You can check whether the target of endlessh-go is up (Click Status, then Targets).
+* **3000**: Grafana. Go to [http://localhost:3000](http://localhost:3000) in your web browser for Grafana. Use username *examples* and password *examples* to login.
+
+In this example, we do not provision a dashboard for Grafana. You need to manually load the endlessh-go dashboard, by either importing it from the Grafana.com using ID [15156](https://grafana.com/grafana/dashboards/15156), or pasting the dashboard JSON text to the text area. See the [Grafana documentation](https://grafana.com/docs/grafana/latest/dashboards/export-import/) about import. Then select *Prometheus* as the data source.

examples/docker-simple/docker-compose.yml

@@ -0,0 +1,59 @@
+services:
+
+  endlessh:
+    container_name: endlessh
+    image: shizunge/endlessh-go:latest
+    restart: always
+    command:
+      - -interval_ms=1000
+      - -logtostderr
+      - -v=1
+      - -enable_prometheus
+      - -geoip_supplier=ip-api
+    networks:
+      - example_network
+    ports:
+      - 2222:2222 # SSH port
+      - 127.0.0.1:2112:2112 # Prometheus metrics port
+
+  prometheus:
+    image: prom/prometheus:latest
+    container_name: prometheus
+    restart: always
+    command:
+      - --config.file=/etc/prometheus/prometheus.yml
+      - --storage.tsdb.path=/prometheus
+      - --storage.tsdb.retention.time=45d
+      - --web.console.libraries=/usr/share/prometheus/console_libraries
+      - --web.console.templates=/usr/share/prometheus/consoles
+      - --web.enable-admin-api
+    networks:
+      - example_network
+    ports:
+      - 127.0.0.1:9090:9090
+    volumes:
+      - ./prometheus.yml:/etc/prometheus/prometheus.yml
+      - prometheus:/prometheus
+
+  grafana:
+    image: grafana/grafana:latest
+    container_name: grafana
+    restart: always
+    networks:
+      - example_network
+    ports:
+      - 127.0.0.1:3000:3000
+    environment:
+      - GF_SECURITY_ADMIN_USER=examples
+      - GF_SECURITY_ADMIN_PASSWORD=examples
+    volumes:
+      - grafana_var:/var/lib/grafana/
+      - ./grafana-datasource.yml:/etc/grafana/provisioning/datasources/prometheus.yml
+
+networks:
+  example_network:
+
+
+volumes:
+  prometheus:
+  grafana_var:

examples/docker-simple/grafana-datasource.yml

@@ -0,0 +1,6 @@
+apiVersion: 1
+
+datasources:
+  - name: Prometheus
+    type: prometheus
+    url: http://prometheus:9090

examples/docker-simple/prometheus.yml

@@ -0,0 +1,5 @@
+scrape_configs:
+  - job_name: 'endlessh'
+    scrape_interval: 60s
+    static_configs:
+      - targets: ['endlessh:2112']

geoip/country.go

@@ -0,0 +1,264 @@
+// Copyright (C) 2023-2024 Shizun Ge
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+//
+
+package geoip
+
+// Map country's ISO to their capital's latitude and longitude.
+// Country's ISO see https://en.wikipedia.org/wiki/ISO_3166-1_alpha-2
+type location struct {
+	Latitude  float64
+	Longitude float64
+}
+
+var countryToLocation = map[string]location{
+	"AD": {42.5, 1.5},
+	"AE": {24.4511, 54.3969},
+	"AF": {34.5328, 69.1658},
+	"AG": {17.1211, -61.8447},
+	"AI": {18.2167, -63.05},
+	"AL": {41.33, 19.82},
+	"AM": {40.1814, 44.5144},
+	"AO": {-8.8383, 13.2344},
+	"AR": {-34.5997, -58.3819},
+	"AS": {-14.274, -170.7046},
+	"AT": {48.2083, 16.3725},
+	"AU": {-35.2931, 149.1269},
+	"AW": {12.5186, -70.0358},
+	"AZ": {40.3667, 49.8352},
+	"BA": {43.8563, 18.4132},
+	"BB": {13.0975, -59.6167},
+	"BD": {23.7289, 90.3944},
+	"BE": {50.8353, 4.3314},
+	"BF": {12.3686, -1.5275},
+	"BG": {42.6979, 23.3217},
+	"BH": {26.225, 50.5775},
+	"BI": {-3.3825, 29.3611},
+	"BJ": {6.402, 2.518},
+	"BL": {17.8958, -62.8508},
+	"BM": {32.2942, -64.7839},
+	"BN": {4.9167, 114.9167},
+	"BO": {-16.4942, -68.1475},
+	"BR": {-15.7939, -47.8828},
+	"BS": {25.0667, -77.3333},
+	"BT": {27.4833, 89.6333},
+	"BW": {-24.6569, 25.9086},
+	"BY": {53.9022, 27.5618},
+	"BZ": {17.25, -88.7675},
+	"CA": {45.4247, -75.695},
+	"CD": {-4.3317, 15.3139},
+	"CF": {4.3732, 18.5628},
+	"CG": {-4.2667, 15.2833},
+	"CH": {46.948, 7.4474},
+	"CI": {5.3364, -4.0267},
+	"CK": {-21.207, -159.771},
+	"CL": {-33.45, -70.6667},
+	"CM": {3.8578, 11.5181},
+	"CN": {39.904, 116.4075},
+	"CO": {4.6126, -74.0705},
+	"CR": {9.9333, -84.0833},
+	"CU": {23.1367, -82.3589},
+	"CV": {14.9177, -23.5092},
+	"CW": {12.108, -68.935},
+	"CX": {-10.4167, 105.7167},
+	"CY": {35.1725, 33.365},
+	"CZ": {50.0833, 14.4167},
+	"DE": {52.5167, 13.3833},
+	"DJ": {11.595, 43.1481},
+	"DK": {55.6805, 12.5615},
+	"DM": {15.3, -61.3833},
+	"DO": {18.4764, -69.8933},
+	"DZ": {36.7764, 3.0586},
+	"EC": {-0.22, -78.5125},
+	"EE": {59.4372, 24.745},
+	"EG": {30.0444, 31.2358},
+	"ER": {15.3333, 38.9167},
+	"ES": {40.4167, -3.7167},
+	"ET": {9.0272, 38.7369},
+	"FI": {60.1756, 24.9342},
+	"FJ": {-18.1333, 178.4333},
+	"FK": {-51.7, -57.85},
+	"FM": {6.9178, 158.185},
+	"FO": {62, -6.7833},
+	"FR": {48.8566, 2.3522},
+	"GA": {0.3901, 9.4544},
+	"GB": {51.5072, -0.1275},
+	"GD": {12.0444, -61.7417},
+	"GE": {41.7225, 44.7925},
+	"GF": {4.933, -52.33},
+	"GH": {5.6037, -0.187},
+	"GI": {36.1324, -5.3781},
+	"GL": {64.175, -51.7333},
+	"GM": {13.4531, -16.5775},
+	"GN": {9.538, -13.6773},
+	"GP": {16.0104, -61.7055},
+	"GQ": {3.7521, 8.7737},
+	"GR": {37.9842, 23.7281},
+	"GS": {-54.2833, -36.5},
+	"GT": {14.6099, -90.5252},
+	"GU": {13.4745, 144.7504},
+	"GW": {11.8592, -15.5956},
+	"GY": {6.7833, -58.1667},
+	"HK": {22.3069, 114.1831},
+	"HN": {14.0942, -87.2067},
+	"HR": {45.8131, 15.9772},
+	"HT": {18.5425, -72.3386},
+	"HU": {47.4983, 19.0408},
+	"ID": {-6.2146, 106.8451},
+	"IE": {53.3497, -6.2603},
+	"IL": {31.7833, 35.2167},
+	"IM": {54.15, -4.4819},
+	"IN": {28.6139, 77.209},
+	"IQ": {33.35, 44.4167},
+	"IR": {35.7, 51.4167},
+	"IS": {64.1475, -21.935},
+	"IT": {41.8931, 12.4828},
+	"JE": {49.1858, -2.11},
+	"JM": {17.9714, -76.7931},
+	"JO": {31.95, 35.9333},
+	"JP": {35.6839, 139.7744},
+	"KE": {-1.2864, 36.8172},
+	"KG": {42.8667, 74.5667},
+	"KH": {11.5696, 104.921},
+	"KI": {1.3382, 173.0176},
+	"KM": {-11.7036, 43.2536},
+	"KN": {17.2983, -62.7342},
+	"KP": {39.03, 125.73},
+	"KR": {37.56, 126.99},
+	"KW": {29.375, 47.98},
+	"KY": {19.2866, -81.3744},
+	"KZ": {51.1333, 71.4333},
+	"LA": {17.9667, 102.6},
+	"LB": {33.8869, 35.5131},
+	"LC": {14.0167, -60.9833},
+	"LI": {47.1397, 9.5219},
+	"LK": {6.9, 79.9164},
+	"LR": {6.3106, -10.8047},
+	"LS": {-29.31, 27.48},
+	"LT": {54.6833, 25.2833},
+	"LU": {49.6106, 6.1328},
+	"LV": {56.9475, 24.1069},
+	"LY": {32.8752, 13.1875},
+	"MA": {26.0928, -10.6089},
+	"MC": {43.7396, 7.4069},
+	"MD": {47.0228, 28.8353},
+	"ME": {42.4397, 19.2661},
+	"MF": {18.0706, -63.0847},
+	"MG": {-18.9386, 47.5214},
+	"MH": {7.0918, 171.3802},
+	"MK": {41.9833, 21.4333},
+	"ML": {12.6458, -7.9922},
+	"MM": {16.795, 96.16},
+	"MN": {47.9214, 106.9055},
+	"MP": {15.2137, 145.7546},
+	"MQ": {14.6104, -61.08},
+	"MR": {18.0858, -15.9785},
+	"MS": {16.7928, -62.2106},
+	"MT": {35.8978, 14.5125},
+	"MU": {-20.1667, 57.5},
+	"MV": {4.175, 73.5083},
+	"MW": {-13.9833, 33.7833},
+	"MX": {19.4333, -99.1333},
+	"MY": {3.1478, 101.6953},
+	"MZ": {-25.9153, 32.5764},
+	"NA": {-22.57, 17.0836},
+	"NC": {-22.2625, 166.4443},
+	"NE": {13.5086, 2.1111},
+	"NF": {-29.0569, 167.9617},
+	"NG": {9.0556, 7.4914},
+	"NI": {12.15, -86.2667},
+	"NL": {52.08, 4.31},
+	"NO": {59.9111, 10.7528},
+	"NP": {27.7167, 85.3667},
+	"NR": {-0.5477, 166.9209},
+	"NU": {-19.056, -169.921},
+	"NZ": {-41.2889, 174.7772},
+	"OM": {23.6139, 58.5922},
+	"PA": {9, -79.5},
+	"PE": {-12.06, -77.0375},
+	"PF": {-17.5334, -149.5667},
+	"PG": {-9.4789, 147.1494},
+	"PH": {14.6, 120.9833},
+	"PK": {33.6989, 73.0369},
+	"PL": {52.23, 21.0111},
+	"PM": {46.7811, -56.1764},
+	"PN": {-25.0667, -130.0833},
+	"PR": {18.4037, -66.0636},
+	"PT": {38.708, -9.139},
+	"PW": {7.5006, 134.6242},
+	"PY": {-25.3, -57.6333},
+	"QA": {25.3, 51.5333},
+	"RE": {-20.8789, 55.4481},
+	"RO": {44.4, 26.0833},
+	"RS": {44.8167, 20.4667},
+	"RU": {55.7558, 37.6178},
+	"RW": {-1.9536, 30.0606},
+	"SA": {24.65, 46.71},
+	"SB": {-9.4333, 159.95},
+	"SC": {-4.6236, 55.4544},
+	"SD": {15.6031, 32.5265},
+	"SE": {59.3294, 18.0686},
+	"SG": {1.3, 103.8},
+	"SH": {-15.9251, -5.7179},
+	"SI": {46.05, 14.5167},
+	"SK": {48.1447, 17.1128},
+	"SL": {8.4833, -13.2331},
+	"SM": {43.932, 12.4484},
+	"SN": {14.7319, -17.4572},
+	"SO": {2.0408, 45.3425},
+	"SR": {5.8667, -55.1667},
+	"SS": {4.85, 31.6},
+	"ST": {0.3333, 6.7333},
+	"SV": {13.6989, -89.1914},
+	"SX": {18.0256, -63.0492},
+	"SY": {33.5131, 36.2919},
+	"SZ": {-26.3208, 31.1617},
+	"TC": {21.4664, -71.136},
+	"TD": {12.11, 15.05},
+	"TG": {6.1319, 1.2228},
+	"TH": {13.75, 100.5167},
+	"TJ": {38.5731, 68.7864},
+	"TL": {-8.5536, 125.5783},
+	"TM": {37.95, 58.3833},
+	"TN": {36.8008, 10.18},
+	"TO": {-21.1347, -175.2083},
+	"TR": {39.93, 32.85},
+	"TT": {10.6667, -61.5167},
+	"TV": {-8.5243, 179.1942},
+	"TZ": {-6.8, 39.2833},
+	"UA": {50.45, 30.5236},
+	"UG": {0.3136, 32.5811},
+	"US": {38.9047, -77.0163},
+	"UY": {-34.8667, -56.1667},
+	"UZ": {41.3, 69.2667},
+	"VA": {41.9033, 12.4534},
+	"VC": {13.1667, -61.2333},
+	"VE": {10.5, -66.9333},
+	"VG": {18.4167, -64.6167},
+	"VI": {18.3419, -64.9332},
+	"VN": {21.0245, 105.8412},
+	"VU": {-17.7333, 168.3167},
+	"WF": {-13.2825, -176.1736},
+	"WS": {-13.8333, -171.8333},
+	"XG": {31.5069, 34.456},
+	"XK": {42.6633, 21.1622},
+	"XR": {78.2167, 15.6333},
+	"XW": {31.7764, 35.2269},
+	"YE": {15.35, 44.2},
+	"YT": {-12.7871, 45.275},
+	"ZA": {-25.7464, 28.1881},
+	"ZM": {-15.4167, 28.2833},
+	"ZW": {-17.8292, 31.0522},
+}

geoip/geoip.go

@@ -1,4 +1,4 @@
-// Copyright (C) 2021 Shizun Ge
+// Copyright (C) 2021-2024 Shizun Ge
 //
 // This program is free software: you can redistribute it and/or modify
 // it under the terms of the GNU General Public License as published by
@@ -14,67 +14,44 @@
 // along with this program.  If not, see <https://www.gnu.org/licenses/>.
 //
 
-package main
+package geoip
 
 import (
 	"encoding/json"
 	"fmt"
 	"io/ioutil"
+	"net"
 	"net/http"
 	"strings"
 
+	"github.com/oschwald/geoip2-golang"
 	"github.com/pierrre/geohash"
 )
 
-type freegeoip struct {
-	Ip          string  `json:"ip"`
-	CountryCode string  `json:"country_code"`
-	CountryName string  `json:"country_name"`
-	RegionCode  string  `json:"region_code"`
-	RegionName  string  `json:"region_name"`
-	City        string  `json:"city"`
-	Zipcode     string  `json:"zipcode"`
-	Latitude    float64 `json:"latitude"`
-	Longitude   float64 `json:"longitude"`
-	MetroCode   int     `json:"metro_code"`
-	AreaCode    int     `json:"area_code"`
+type GeoOption struct {
+	GeoipSupplier     string
+	MaxMindDbFileName string
 }
 
-func geohashAndLocationFromFreegeoip(address string) (string, string, string, error) {
-	var geo freegeoip
-	response, err := http.Get("https://freegeoip.live/json/" + address)
-	if err != nil {
-		return "s000", "Unknown", "Unknown", err
-	}
-	defer response.Body.Close()
-
-	body, err := ioutil.ReadAll(response.Body)
-	if err != nil {
-		return "s000", "Unknown", "Unknown", err
-	}
-
-	err = json.Unmarshal(body, &geo)
-	if err != nil {
-		return "s000", "Unknown", "Unknown", err
-	}
-
+func composeLocation(country string, region string, city string) string {
 	var locations []string
-	for _, s := range []string{geo.CountryName, geo.RegionName, geo.City} {
+	for _, s := range []string{country, region, city} {
 		if strings.TrimSpace(s) != "" {
 			locations = append(locations, s)
 		}
 	}
 	location := strings.Join(locations, ", ")
 	if location == "" {
-		location = "Unknown"
+		return "Unknown"
 	}
-	country := geo.CountryName
-	if country == "" {
-		country = "Unknown"
-	}
-	gh := geohash.EncodeAuto(geo.Latitude, geo.Longitude)
+	return location
+}
 
-	return gh, country, location, nil
+func composeCountry(country string) string {
+	if country == "" {
+		return "Unknown"
+	}
+	return country
 }
 
 type ipapi struct {
@@ -91,9 +68,9 @@ type ipapi struct {
 	Longitude   float64 `json:"lon"`
 }
 
-func geohashAndLocationFromIpapi(address string) (string, string, string, error) {
+func geohashAndLocationFromIpapi(ipAddr string) (string, string, string, error) {
 	var geo ipapi
-	response, err := http.Get("http://ip-api.com/json/" + address)
+	response, err := http.Get("http://ip-api.com/json/" + ipAddr)
 	if err != nil {
 		return "s000", "Unknown", "Unknown", err
 	}
@@ -110,37 +87,62 @@ func geohashAndLocationFromIpapi(address string) (string, string, string, error)
 	}
 
 	if geo.Status != "success" {
-		return "s000", "Unknown", "Unknown", fmt.Errorf("failed to query %v via ip-api: status: %v, message: %v", address, geo.Status, geo.Message)
+		return "s000", "Unknown", "Unknown", fmt.Errorf("failed to query %v via ip-api: status: %v, message: %v", ipAddr, geo.Status, geo.Message)
 	}
 
-	var locations []string
-	for _, s := range []string{geo.CountryName, geo.RegionName, geo.City} {
-		if strings.TrimSpace(s) != "" {
-			locations = append(locations, s)
-		}
-	}
-	location := strings.Join(locations, ", ")
-	if location == "" {
-		location = "Unknown"
-	}
-	country := geo.CountryName
-	if country == "" {
-		country = "Unknown"
-	}
 	gh := geohash.EncodeAuto(geo.Latitude, geo.Longitude)
+	country := composeCountry(geo.CountryName)
+	location := composeLocation(geo.CountryName, geo.RegionName, geo.City)
 
 	return gh, country, location, nil
 }
 
-func geohashAndLocation(address string, geoipSupplier string) (string, string, string, error) {
-	switch geoipSupplier {
+func geohashAndLocationFromMaxMindDb(ipAddr, maxMindDbFileName string) (string, string, string, error) {
+	db, err := geoip2.Open(maxMindDbFileName)
+	if err != nil {
+		return "s000", "Unknown", "Unknown", err
+	}
+	defer db.Close()
+	// If you are using strings that may be invalid, check that ip is not nil
+	ip := net.ParseIP(ipAddr)
+	cityRecord, err := db.City(ip)
+	if err != nil {
+		return "s000", "Unknown", "Unknown", err
+	}
+	countryName := cityRecord.Country.Names["en"]
+	cityName := cityRecord.City.Names["en"]
+	latitude := cityRecord.Location.Latitude
+	longitude := cityRecord.Location.Longitude
+	iso := cityRecord.Country.IsoCode
+	if latitude == 0 && longitude == 0 {
+		// In case of using Country DB, city is not available.
+		loc, ok := countryToLocation[iso]
+		if ok {
+			latitude = loc.Latitude
+			longitude = loc.Longitude
+		} else {
+			if iso != "" {
+				// For debugging, adding the iso to the country name.
+				countryName = countryName + " (" + iso + ")"
+			}
+		}
+	}
+	gh := geohash.EncodeAuto(latitude, longitude)
+	country := composeCountry(countryName)
+	location := composeLocation(countryName, "", cityName)
+
+	return gh, country, location, nil
+}
+
+func GeohashAndLocation(ipAddr string, option GeoOption) (string, string, string, error) {
+	switch option.GeoipSupplier {
 	case "off":
 		return "s000", "Geohash off", "Geohash off", nil
 	case "ip-api":
-		return geohashAndLocationFromIpapi(address)
-	case "freegeoip":
-		return geohashAndLocationFromFreegeoip(address)
+		return geohashAndLocationFromIpapi(ipAddr)
+	case "max-mind-db":
+		return geohashAndLocationFromMaxMindDb(ipAddr, option.MaxMindDbFileName)
 	default:
-		return "s000", "Unknown", "Unknown", fmt.Errorf("unknown geoipSupplier %v.", geoipSupplier)
+		return "s000", "Unknown", "Unknown", fmt.Errorf("unknown geoipSupplier %v.", option.GeoipSupplier)
 	}
 }

go.mod

@@ -1,21 +1,25 @@
 module endlessh-go
 
-go 1.17
+go 1.24.2
 
 require (
-	github.com/golang/glog v1.0.0
-	github.com/pierrre/geohash v1.0.0
-	github.com/prometheus/client_golang v1.11.0
+	github.com/golang/glog v1.2.5
+	github.com/oschwald/geoip2-golang v1.13.0
+	github.com/pierrre/geohash v1.1.3
+	github.com/prometheus/client_golang v1.23.2
 )
 
 require (
 	github.com/beorn7/perks v1.0.1 // indirect
-	github.com/cespare/xxhash/v2 v2.1.1 // indirect
-	github.com/golang/protobuf v1.4.3 // indirect
-	github.com/matttproud/golang_protobuf_extensions v1.0.1 // indirect
-	github.com/prometheus/client_model v0.2.0 // indirect
-	github.com/prometheus/common v0.26.0 // indirect
-	github.com/prometheus/procfs v0.6.0 // indirect
-	golang.org/x/sys v0.0.0-20210603081109-ebe580a85c40 // indirect
-	google.golang.org/protobuf v1.26.0-rc.1 // indirect
+	github.com/cespare/xxhash/v2 v2.3.0 // indirect
+	github.com/kr/text v0.2.0 // indirect
+	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
+	github.com/oschwald/maxminddb-golang v1.13.0 // indirect
+	github.com/pires/go-proxyproto v0.8.1 // indirect
+	github.com/prometheus/client_model v0.6.2 // indirect
+	github.com/prometheus/common v0.66.1 // indirect
+	github.com/prometheus/procfs v0.16.1 // indirect
+	go.yaml.in/yaml/v2 v2.4.2 // indirect
+	golang.org/x/sys v0.35.0 // indirect
+	google.golang.org/protobuf v1.36.8 // indirect
 )

go.sum

@@ -1,156 +1,76 @@
-cloud.google.com/go v0.34.0/go.mod h1:aQUYkXzVsufM+DwF1aE+0xfcU+56JwCaLick0ClmMTw=
 github.com/Codefor/geohash v0.0.0-20140723084247-1b41c28e3a9d h1:iG9B49Q218F/XxXNRM7k/vWf7MKmLIS8AcJV9cGN4nA=
 github.com/Codefor/geohash v0.0.0-20140723084247-1b41c28e3a9d/go.mod h1:RVnhzAX71far8Kc3TQeA0k/dcaEKUnTDSOyet/JCmGI=
 github.com/TomiHiltunen/geohash-golang v0.0.0-20150112065804-b3e4e625abfb h1:wumPkzt4zaxO4rHPBrjDK8iZMR41C1qs7njNqlacwQg=
 github.com/TomiHiltunen/geohash-golang v0.0.0-20150112065804-b3e4e625abfb/go.mod h1:QiYsIBRQEO+Z4Rz7GoI+dsHVneZNONvhczuA+llOZNM=
-github.com/alecthomas/template v0.0.0-20160405071501-a0175ee3bccc/go.mod h1:LOuyumcjzFXgccqObfd/Ljyb9UuFJ6TxHnclSeseNhc=
-github.com/alecthomas/template v0.0.0-20190718012654-fb15b899a751/go.mod h1:LOuyumcjzFXgccqObfd/Ljyb9UuFJ6TxHnclSeseNhc=
-github.com/alecthomas/units v0.0.0-20151022065526-2efee857e7cf/go.mod h1:ybxpYRFXyAe+OPACYpWeL0wqObRcbAqCMya13uyzqw0=
-github.com/alecthomas/units v0.0.0-20190717042225-c3de453c63f4/go.mod h1:ybxpYRFXyAe+OPACYpWeL0wqObRcbAqCMya13uyzqw0=
-github.com/alecthomas/units v0.0.0-20190924025748-f65c72e2690d/go.mod h1:rBZYJk541a8SKzHPHnH3zbiI+7dagKZ0cgpgrD7Fyho=
-github.com/beorn7/perks v0.0.0-20180321164747-3a771d992973/go.mod h1:Dwedo/Wpr24TaqPxmxbtue+5NUziq4I4S80YR8gNf3Q=
-github.com/beorn7/perks v1.0.0/go.mod h1:KWe93zE9D1o94FZ5RNwFwVgaQK1VOXiVxmqh+CedLV8=
 github.com/beorn7/perks v1.0.1 h1:VlbKKnNfV8bJzeqoa4cOKqO6bYr3WgKZxO8Z16+hsOM=
 github.com/beorn7/perks v1.0.1/go.mod h1:G2ZrVWU2WbWT9wwq4/hrbKbnv/1ERSJQ0ibhJ6rlkpw=
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+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

main.go

@@ -1,4 +1,4 @@
-// Copyright (C) 2021 Shizun Ge
+// Copyright (C) 2021-2024 Shizun Ge
 //
 // This program is free software: you can redistribute it and/or modify
 // it under the terms of the GNU General Public License as published by
@@ -17,104 +17,124 @@
 package main
 
 import (
+	"endlessh-go/client"
+	"endlessh-go/geoip"
+	"endlessh-go/metrics"
 	"flag"
 	"fmt"
-	"math/rand"
 	"net"
-	"net/http"
 	"os"
+	"strings"
 	"time"
 
 	"github.com/golang/glog"
-	"github.com/prometheus/client_golang/prometheus"
-	"github.com/prometheus/client_golang/prometheus/promhttp"
+	proxyproto "github.com/pires/go-proxyproto"
 )
 
-var (
-	numCurrentClients     int64
-	numTotalClients       int64
-	numTotalClientsClosed int64
-	numTotalBytes         int64
-	numTotalMilliseconds  int64
-	totalClients          prometheus.CounterFunc
-	totalClientsClosed    prometheus.CounterFunc
-	totalBytes            prometheus.CounterFunc
-	totalSeconds          prometheus.CounterFunc
-	clientIP              *prometheus.CounterVec
-	clientSeconds         *prometheus.CounterVec
-)
-
-func initPrometheus(connHost, prometheusPort, prometheusEntry string) {
-	totalClients = prometheus.NewCounterFunc(
-		prometheus.CounterOpts{
-			Name: "endlessh_client_open_count_total",
-			Help: "Total number of clients that tried to connect to this host.",
-		}, func() float64 {
-			return float64(numTotalClients)
-		},
-	)
-	totalClientsClosed = prometheus.NewCounterFunc(
-		prometheus.CounterOpts{
-			Name: "endlessh_client_closed_count_total",
-			Help: "Total number of clients that stopped connecting to this host.",
-		}, func() float64 {
-			return float64(numTotalClientsClosed)
-		},
-	)
-	totalBytes = prometheus.NewCounterFunc(
-		prometheus.CounterOpts{
-			Name: "endlessh_sent_bytes_total",
-			Help: "Total bytes sent to clients that tried to connect to this host.",
-		}, func() float64 {
-			return float64(numTotalBytes)
-		},
-	)
-	totalSeconds = prometheus.NewCounterFunc(
-		prometheus.CounterOpts{
-			Name: "endlessh_trapped_time_seconds_total",
-			Help: "Total seconds clients spent on endlessh.",
-		}, func() float64 {
-			return float64(numTotalMilliseconds) / 1000
-		},
-	)
-	clientIP = prometheus.NewCounterVec(
-		prometheus.CounterOpts{
-			Name: "endlessh_client_open_count",
-			Help: "Number of connections of clients.",
-		},
-		[]string{"ip", "geohash", "country", "location"},
-	)
-	clientSeconds = prometheus.NewCounterVec(
-		prometheus.CounterOpts{
-			Name: "endlessh_client_trapped_time_seconds",
-			Help: "Seconds a client spends on endlessh.",
-		},
-		[]string{"ip"},
-	)
-	prometheus.MustRegister(totalClients)
-	prometheus.MustRegister(totalClientsClosed)
-	prometheus.MustRegister(totalBytes)
-	prometheus.MustRegister(totalSeconds)
-	prometheus.MustRegister(clientIP)
-	prometheus.MustRegister(clientSeconds)
-	http.Handle("/"+prometheusEntry, promhttp.Handler())
+func startSending(maxClients int64, bannerMaxLength int64, records chan<- metrics.RecordEntry) chan *client.Client {
+	clients := make(chan *client.Client, maxClients)
 	go func() {
-		glog.Infof("Starting Prometheus on %v:%v, entry point is /%v", connHost, prometheusPort, prometheusEntry)
-		http.ListenAndServe(connHost+":"+prometheusPort, nil)
+		for {
+			c, more := <-clients
+			if !more {
+				return
+			}
+			go func() {
+				bytesSent, err := c.Send(bannerMaxLength)
+				remoteIpAddr := c.RemoteIpAddr()
+				localPort := c.LocalPort()
+				millisecondsSpent := c.MillisecondsSinceLast()
+				if err != nil {
+					c.Close()
+					records <- metrics.RecordEntry{
+						RecordType:        metrics.RecordEntryTypeStop,
+						IpAddr:            remoteIpAddr,
+						LocalPort:         localPort,
+						MillisecondsSpent: millisecondsSpent,
+					}
+					return
+				}
+				clients <- c
+				records <- metrics.RecordEntry{
+					RecordType:        metrics.RecordEntryTypeSend,
+					IpAddr:            remoteIpAddr,
+					LocalPort:         localPort,
+					MillisecondsSpent: millisecondsSpent,
+					BytesSent:         bytesSent,
+				}
+			}()
+		}
+	}()
+	return clients
+}
+
+func startAccepting(maxClients int64, connType, connHost, connPort string, interval time.Duration, clients chan<- *client.Client, records chan<- metrics.RecordEntry, proxyProtocolEnabled bool, proxyProtocolReadHeaderTimeout int) {
+	go func() {
+		l, err := net.Listen(connType, connHost+":"+connPort)
+		if err != nil {
+			glog.Errorf("Error listening: %v", err)
+			os.Exit(1)
+		}
+
+		// Wrap the listener in a proxy protocol listener
+		if proxyProtocolEnabled {
+			l = &proxyproto.Listener{Listener: l, ReadHeaderTimeout: time.Duration(proxyProtocolReadHeaderTimeout) * time.Millisecond}
+		}
+
+		// Close the listener when the application closes.
+		defer l.Close()
+
+		glog.Infof("Listening on %v:%v", connHost, connPort)
+		for {
+			// Listen for an incoming connection.
+			conn, err := l.Accept()
+			if err != nil {
+				glog.Errorf("Error accepting connection from port %v: %v", connPort, err)
+				os.Exit(1)
+			}
+			c := client.NewClient(conn, interval, maxClients)
+			remoteIpAddr := c.RemoteIpAddr()
+			records <- metrics.RecordEntry{
+				RecordType: metrics.RecordEntryTypeStart,
+				IpAddr:     remoteIpAddr,
+				LocalPort:  connPort,
+			}
+			clients <- c
+		}
 	}()
 }
 
+type arrayStrings []string
+
+func (a *arrayStrings) String() string {
+	return strings.Join(*a, ", ")
+}
+
+func (a *arrayStrings) Set(value string) error {
+	*a = append(*a, value)
+	return nil
+}
+
+const defaultPort = "2222"
+
+var connPorts arrayStrings
+
 func main() {
 	intervalMs := flag.Int("interval_ms", 1000, "Message millisecond delay")
 	bannerMaxLength := flag.Int64("line_length", 32, "Maximum banner line length")
 	maxClients := flag.Int64("max_clients", 4096, "Maximum number of clients")
 	connType := flag.String("conn_type", "tcp", "Connection type. Possible values are tcp, tcp4, tcp6")
-	connHost := flag.String("host", "0.0.0.0", "Listening address")
-	connPort := flag.String("port", "2222", "Listening port")
+	connHost := flag.String("host", "0.0.0.0", "SSH listening address")
+	flag.Var(&connPorts, "port", fmt.Sprintf("SSH listening port. You may provide multiple -port flags to listen to multiple ports. (default %q)", defaultPort))
 	prometheusEnabled := flag.Bool("enable_prometheus", false, "Enable prometheus")
+	prometheusHost := flag.String("prometheus_host", "0.0.0.0", "The address for prometheus")
 	prometheusPort := flag.String("prometheus_port", "2112", "The port for prometheus")
 	prometheusEntry := flag.String("prometheus_entry", "metrics", "Entry point for prometheus")
-	geoipSupplier := flag.String("geoip_supplier", "off", "Supplier to obtain Geohash of IPs. Possible values are \"off\", \"ip-api\", \"freegeoip\"")
+	prometheusCleanUnseenSeconds := flag.Int("prometheus_clean_unseen_seconds", 0, "Remove series if the IP is not seen for the given time. Set to 0 to disable. (default 0)")
+	geoipSupplier := flag.String("geoip_supplier", "off", "Supplier to obtain Geohash of IPs. Possible values are \"off\", \"ip-api\", \"max-mind-db\"")
+	maxMindDbFileName := flag.String("max_mind_db", "", "Path to the MaxMind DB file.")
+	proxyProtocolEnabled := flag.Bool("proxy_protocol_enabled", false, "Enable PROXY protocol support. This causes the server to expect PROXY protocol headers on incoming connections.")
+	proxyProtocolReadHeaderTimeout := flag.Int("proxy_protocol_read_header_timeout_ms", 200, "Timeout for reading the PROXY protocol header in milliseconds. If the connection does not send a valid PROXY protocol header in this time, the header is ignored.")
 
 	flag.Usage = func() {
 		fmt.Fprintf(flag.CommandLine.Output(), "Usage of %v \n", os.Args[0])
@@ -123,56 +143,38 @@ func main() {
 	flag.Parse()
 
 	if *prometheusEnabled {
-		initPrometheus(*connHost, *prometheusPort, *prometheusEntry)
+		if *connType == "tcp6" && *prometheusHost == "0.0.0.0" {
+			*prometheusHost = "[::]"
+		}
+		metrics.InitPrometheus(*prometheusHost, *prometheusPort, *prometheusEntry)
 	}
 
-	rand.Seed(time.Now().UnixNano())
+	records := metrics.StartRecording(*maxClients, *prometheusEnabled, *prometheusCleanUnseenSeconds,
+		geoip.GeoOption{
+			GeoipSupplier:     *geoipSupplier,
+			MaxMindDbFileName: *maxMindDbFileName,
+		})
+	clients := startSending(*maxClients, *bannerMaxLength, records)
+
 	interval := time.Duration(*intervalMs) * time.Millisecond
 	// Listen for incoming connections.
 	if *connType == "tcp6" && *connHost == "0.0.0.0" {
 		*connHost = "[::]"
 	}
-	l, err := net.Listen(*connType, *connHost+":"+*connPort)
-	if err != nil {
-		glog.Errorf("Error listening: %v", err)
-		os.Exit(1)
+	if len(connPorts) == 0 {
+		connPorts = append(connPorts, defaultPort)
 	}
-	// Close the listener when the application closes.
-	defer l.Close()
-	glog.Infof("Listening on %v:%v", *connHost, *connPort)
-
-	clients := make(chan *client, *maxClients)
-	go func() {
-		for {
-			c, more := <-clients
-			if !more {
-				return
+	for _, connPort := range connPorts {
+		startAccepting(*maxClients, *connType, *connHost, connPort, interval, clients, records, *proxyProtocolEnabled, *proxyProtocolReadHeaderTimeout)
+	}
+	for {
+		if *prometheusCleanUnseenSeconds <= 0 {
+			time.Sleep(time.Duration(1<<63 - 1))
+		} else {
+			time.Sleep(time.Second * time.Duration(60))
+			records <- metrics.RecordEntry{
+				RecordType: metrics.RecordEntryTypeClean,
 			}
-			if time.Now().Before(c.next) {
-				time.Sleep(c.next.Sub(time.Now()))
-			}
-			err := c.Send(*bannerMaxLength)
-			if err != nil {
-				c.Close()
-				continue
-			}
-			go func() { clients <- c }()
-		}
-	}()
-	listener := func() {
-		for {
-			// Listen for an incoming connection.
-			conn, err := l.Accept()
-			if err != nil {
-				glog.Errorf("Error accepting: %v", err)
-				os.Exit(1)
-			}
-			// Handle connections in a new goroutine.
-			for numCurrentClients >= *maxClients {
-				time.Sleep(interval)
-			}
-			clients <- NewClient(conn, interval, *maxClients, *geoipSupplier, *prometheusEnabled)
 		}
 	}
-	listener()
 }

metrics/metrics.go

@@ -0,0 +1,195 @@
+// Copyright (C) 2024 Shizun Ge
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+//
+
+package metrics
+
+import (
+	"endlessh-go/geoip"
+	"net/http"
+	"os"
+	"time"
+	"strings"
+	"net"
+
+	"github.com/golang/glog"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+)
+
+var (
+	pq                 *UpdatablePriorityQueue
+	totalClients       *prometheus.CounterVec
+	totalClientsClosed *prometheus.CounterVec
+	totalBytes         *prometheus.CounterVec
+	totalSeconds       *prometheus.CounterVec
+	clientIP           *prometheus.CounterVec
+	clientSeconds      *prometheus.CounterVec
+)
+
+func InitPrometheus(prometheusHost, prometheusPort, prometheusEntry string) {
+	pq = NewUpdatablePriorityQueue()
+	totalClients = prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "endlessh_client_open_count_total",
+			Help: "Total number of clients that tried to connect to this host.",
+		}, []string{"local_port"},
+	)
+	totalClientsClosed = prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "endlessh_client_closed_count_total",
+			Help: "Total number of clients that stopped connecting to this host.",
+		}, []string{"local_port"},
+	)
+	totalBytes = prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "endlessh_sent_bytes_total",
+			Help: "Total bytes sent to clients that tried to connect to this host.",
+		}, []string{"local_port"},
+	)
+	totalSeconds = prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "endlessh_trapped_time_seconds_total",
+			Help: "Total seconds clients spent on endlessh.",
+		}, []string{"local_port"},
+	)
+	clientIP = prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "endlessh_client_open_count",
+			Help: "Number of connections of clients.",
+		},
+		[]string{"ip", "local_port", "geohash", "country", "location"},
+	)
+	clientSeconds = prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "endlessh_client_trapped_time_seconds",
+			Help: "Seconds a client spends on endlessh.",
+		},
+		[]string{"ip", "local_port"},
+	)
+	promReg := prometheus.NewRegistry()
+	promReg.MustRegister(totalClients)
+	promReg.MustRegister(totalClientsClosed)
+	promReg.MustRegister(totalBytes)
+	promReg.MustRegister(totalSeconds)
+	promReg.MustRegister(clientIP)
+	promReg.MustRegister(clientSeconds)
+	handler := promhttp.HandlerFor(promReg, promhttp.HandlerOpts{EnableOpenMetrics: true})
+	http.Handle("/"+prometheusEntry, handler)
+	go func() {
+
+		if strings.HasPrefix(prometheusHost, "unix:") {
+			socketPath := prometheusHost[5:] // trim the "unix:" prefix
+			glog.Infof("Starting Prometheus on Unix socket %v, entry point is /%v", socketPath, prometheusEntry)
+			serveOnUnixSocket(socketPath)
+		} else {
+			ipPort := prometheusHost+":"+prometheusPort
+			glog.Infof("Starting Prometheus on IP port %v, entry point is /%v", ipPort, prometheusEntry)
+			serveOnIpPort(ipPort)
+		}
+		
+	}()
+}
+
+func serveOnUnixSocket(socketPath string) {
+	_ = os.Remove(socketPath) // allow failure
+	unixListener, err := net.Listen("unix", socketPath)
+	if err != nil {
+		glog.Errorf("Error starting Prometheus on socket %v: %v", socketPath, err)
+		os.Exit(1)
+	}
+	if err := http.Serve(unixListener, nil); err != nil {
+		glog.Errorf("Error starting Prometheus at socket %v: %v", socketPath, err)
+		os.Exit(1)
+	}
+}
+
+func serveOnIpPort(ipPort string) {
+	if err := http.ListenAndServe(ipPort, nil); err != nil {
+		glog.Errorf("Error starting Prometheus at IP port %v: %v", ipPort, err)
+		os.Exit(1)
+	}
+}
+
+const (
+	RecordEntryTypeStart = iota
+	RecordEntryTypeSend  = iota
+	RecordEntryTypeStop  = iota
+	RecordEntryTypeClean = iota
+)
+
+type RecordEntry struct {
+	RecordType        int
+	IpAddr            string
+	LocalPort         string
+	MillisecondsSpent int64
+	BytesSent         int
+}
+
+func StartRecording(maxClients int64, prometheusEnabled bool, prometheusCleanUnseenSeconds int, geoOption geoip.GeoOption) chan RecordEntry {
+	records := make(chan RecordEntry, maxClients)
+	go func() {
+		for {
+			r, more := <-records
+			if !more {
+				return
+			}
+			if !prometheusEnabled {
+				continue
+			}
+			switch r.RecordType {
+			case RecordEntryTypeStart:
+				geohash, country, location, err := geoip.GeohashAndLocation(r.IpAddr, geoOption)
+				if err != nil {
+					glog.Warningf("Failed to obtain the geohash of %v: %v.", r.IpAddr, err)
+				}
+				clientIP.With(prometheus.Labels{
+					"ip":         r.IpAddr,
+					"local_port": r.LocalPort,
+					"geohash":    geohash,
+					"country":    country,
+					"location":   location}).Inc()
+				totalClients.With(prometheus.Labels{"local_port": r.LocalPort}).Inc()
+				pq.Update(r.IpAddr, time.Now())
+			case RecordEntryTypeSend:
+				secondsSpent := float64(r.MillisecondsSpent) / 1000
+				clientSeconds.With(prometheus.Labels{
+					"ip":         r.IpAddr,
+					"local_port": r.LocalPort}).Add(secondsSpent)
+				totalSeconds.With(prometheus.Labels{"local_port": r.LocalPort}).Add(secondsSpent)
+				totalBytes.With(prometheus.Labels{"local_port": r.LocalPort}).Add(float64(r.BytesSent))
+				pq.Update(r.IpAddr, time.Now())
+			case RecordEntryTypeStop:
+				secondsSpent := float64(r.MillisecondsSpent) / 1000
+				clientSeconds.With(prometheus.Labels{
+					"ip":         r.IpAddr,
+					"local_port": r.LocalPort}).Add(secondsSpent)
+				totalSeconds.With(prometheus.Labels{"local_port": r.LocalPort}).Add(secondsSpent)
+				totalClientsClosed.With(prometheus.Labels{"local_port": r.LocalPort}).Inc()
+				pq.Update(r.IpAddr, time.Now())
+			case RecordEntryTypeClean:
+				top := pq.Peek()
+				deadline := time.Now().Add(-time.Second * time.Duration(prometheusCleanUnseenSeconds))
+				for top != nil && top.Value.Before(deadline) {
+					clientIP.DeletePartialMatch(prometheus.Labels{"ip": top.Key})
+					clientSeconds.DeletePartialMatch(prometheus.Labels{"ip": top.Key})
+					pq.Pop()
+					top = pq.Peek()
+				}
+			}
+		}
+	}()
+	return records
+}

metrics/priority_queue.go

@@ -0,0 +1,94 @@
+package metrics
+
+import (
+	"container/heap"
+	"time"
+)
+
+// Pair represents a key-value pair with a timestamp
+type Pair struct {
+	Key     string
+	Value   time.Time
+	HeapIdx int // Index in the heap for efficient updates
+}
+
+// PriorityQueue is a min-heap implementation for Pairs
+type PriorityQueue []*Pair
+
+// Len returns the length of the priority queue
+func (pq PriorityQueue) Len() int { return len(pq) }
+
+// Less compares two pairs based on their values (timestamps)
+func (pq PriorityQueue) Less(i, j int) bool {
+	return pq[i].Value.Before(pq[j].Value)
+}
+
+// Swap swaps two pairs in the priority queue
+func (pq PriorityQueue) Swap(i, j int) {
+	pq[i], pq[j] = pq[j], pq[i]
+	pq[i].HeapIdx = i
+	pq[j].HeapIdx = j
+}
+
+// Push adds a pair to the priority queue
+func (pq *PriorityQueue) Push(x interface{}) {
+	pair := x.(*Pair)
+	pair.HeapIdx = len(*pq)
+	*pq = append(*pq, pair)
+}
+
+// Pop removes the pair with the minimum value (timestamp) from the priority queue
+func (pq *PriorityQueue) Pop() interface{} {
+	old := *pq
+	n := len(old)
+	pair := old[n-1]
+	pair.HeapIdx = -1 // for safety
+	*pq = old[0 : n-1]
+	return pair
+}
+
+// UpdatablePriorityQueue represents the data structure with the priority queue
+type UpdatablePriorityQueue struct {
+	pq     PriorityQueue
+	keyMap map[string]*Pair
+}
+
+// NewUpdatablePriorityQueue initializes a new UpdatablePriorityQueue
+func NewUpdatablePriorityQueue() *UpdatablePriorityQueue {
+	return &UpdatablePriorityQueue{
+		pq:     make(PriorityQueue, 0),
+		keyMap: make(map[string]*Pair),
+	}
+}
+
+// Update adds or updates a key-value pair in the data structure
+func (ds *UpdatablePriorityQueue) Update(key string, value time.Time) {
+	if pair, ok := ds.keyMap[key]; ok {
+		// Key exists, update the time
+		pair.Value = value
+		heap.Fix(&ds.pq, pair.HeapIdx)
+	} else {
+		// Key does not exist, create a new entry
+		pair := &Pair{Key: key, Value: value}
+		heap.Push(&ds.pq, pair)
+		ds.keyMap[key] = pair
+	}
+}
+
+// Peek returns the entry with the minimal time
+func (ds *UpdatablePriorityQueue) Peek() *Pair {
+	if ds.pq.Len() == 0 {
+		return nil
+	}
+	return ds.pq[0]
+}
+
+// Pop removes the entry with the minimal time
+func (ds *UpdatablePriorityQueue) Pop() *Pair {
+	if ds.pq.Len() == 0 {
+		return nil
+	}
+	pair := heap.Pop(&ds.pq).(*Pair)
+	delete(ds.keyMap, pair.Key)
+	return pair
+}