Add the release tag to the docker image

2021-10-27 00:48:47 -07:00
27 changed files with 925 additions and 1862 deletions
--- a/.github/dependabot.yml
+++ b/.github/dependabot.yml
@@ -1,19 +0,0 @@
-# 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"
--- a/.github/workflows/docker-hub-build-push.yml
+++ b/.github/workflows/docker-hub-build-push.yml
@@ -0,0 +1,31 @@
+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 and push the latest image
+        run: |
+          docker buildx build --push \
+            --tag shizunge/endlessh-go:latest \
+            --platform linux/amd64,linux/arm/v7,linux/arm64 .
+      - name: extract tag string
+        run: echo "RELEASE_VERSION=${GITHUB_REF#refs/*/}" >> $GITHUB_ENV
+      - name: tag image
+        run: docker tag shizunge/endlessh-go:latest shizunge/endlessh-go:$RELEASE_VERSION
+      - name: push tagged image
+        run: docker push shizunge/endlessh-go:$RELEASE_VERSION
--- a/.github/workflows/docker-hub-description.yml
+++ b/.github/workflows/docker-hub-description.yml
@@ -1,22 +0,0 @@
-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: ${{ github.event.repository.description }}
--- a/.github/workflows/on-pull-request.yml
+++ b/.github/workflows/on-pull-request.yml
@@ -1,48 +0,0 @@
-name: On pull request
-
-on:
-  pull_request:
-    branches:
-      - 'main'
-    paths-ignore:
-      - 'dashboard/*'
-      - 'examples/*'
-      - 'README.md'
-      - 'LICENSE'
-  workflow_dispatch:
-
-env:
-  PLATFORMS: "linux/amd64,linux/arm64,linux/arm/v7"
-  
-jobs:
-  build_container_image:
-    name: Build Docker image
-    runs-on: ubuntu-latest
-    steps:
-      - name: Checkout code
-        uses: actions/checkout@v5
-      - name: Set up QEMU
-        uses: docker/setup-qemu-action@v3
-      - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@v3.11.1
-      - name: Docker meta
-        id: meta
-        uses: docker/metadata-action@v5
-        with:
-          images: |
-            ghcr.io/${{ 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
-
-
--- a/.github/workflows/on-push.yml
+++ b/.github/workflows/on-push.yml
@@ -1,62 +0,0 @@
-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
-
-
--- a/.github/workflows/on-release.yml
+++ b/.github/workflows/on-release.yml
@@ -1,49 +0,0 @@
-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
--- a/.gitignore
+++ b/.gitignore
@@ -1 +0,0 @@
-endlessh-go
--- a/15
+++ b/15
@@ -1,20 +1,19 @@
-FROM golang AS build
+FROM golang:alpine AS build

-RUN mkdir /endlessh
-ADD . /endlessh
-WORKDIR /endlessh
+ADD . /go/src/app
+WORKDIR /go/src/app
 RUN go mod tidy
-RUN CGO_ENABLED=0 go build -o endlessh .
+RUN go build -o endlessh .

-FROM gcr.io/distroless/base
+FROM alpine:latest

 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 /endlessh/endlessh /endlessh
+COPY --from=build /go/src/app/endlessh /usr/bin/endlessh
 EXPOSE 2222 2112
 USER nobody
-ENTRYPOINT  ["/endlessh"]
+ENTRYPOINT  ["/usr/bin/endlessh"]
 CMD ["-logtostderr", "-v=1"]
--- a/README.md
+++ b/README.md
@@ -1,19 +1,10 @@
 # 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](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.
+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.

 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.

@@ -29,7 +20,7 @@ go build .
 Alternatively, you can use the [docker image](https://hub.docker.com/r/shizunge/endlessh-go):

 ```
-docker run -d -p 2222:2222 shizunge/endlessh-go -logtostderr -v=1
+sudo docker run -d -p 2222:2222 shizunge/endlessh-go
 ```

 It listens to port `2222` by default.
@@ -40,69 +31,50 @@ 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 stderr. You can set different log destinations via CLI arguments.
-
-Also check out [examples](./examples/README.md) for the setup of the full stack.
+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.

 ## Usage

-`./endlessh-go --help`
+Usage of `./endlessh-go`

-```
-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
-```
+* -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

 ## Metrics

-Endlessh-go exports the following Prometheus metrics.
+This golang implementation exports the following Prometheus metrics.

 | Metric                               | Type  | Description  |
 |--------------------------------------|-------|--------------|
@@ -110,27 +82,21 @@ Endlessh-go 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`: 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> |
+| 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> |

 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 [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.
+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.

 ## 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)
--- a/client.go
+++ b/client.go
@@ -0,0 +1,111 @@
+// 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()
+}
--- a/client/client.go
+++ b/client/client.go
@@ -1,102 +0,0 @@
-// 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)
-}
--- a/dashboard/endlessh.json
+++ b/dashboard/endlessh.json
--- a/BIN
+++ b/BIN
--- a/examples/README.md
+++ b/examples/README.md
@@ -1,18 +0,0 @@
-# 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.
--- a/examples/docker-maxmind/README.md
+++ b/examples/docker-maxmind/README.md
@@ -1,16 +0,0 @@
-## 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.
--- a/examples/docker-maxmind/docker-compose.yml
+++ b/examples/docker-maxmind/docker-compose.yml
@@ -1,35 +0,0 @@
-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:
--- a/examples/docker-simple/README.md
+++ b/examples/docker-simple/README.md
@@ -1,22 +0,0 @@
-## 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.
--- a/examples/docker-simple/docker-compose.yml
+++ b/examples/docker-simple/docker-compose.yml
@@ -1,59 +0,0 @@
-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:
--- a/examples/docker-simple/grafana-datasource.yml
+++ b/examples/docker-simple/grafana-datasource.yml
@@ -1,6 +0,0 @@
-apiVersion: 1
-
-datasources:
-  - name: Prometheus
-    type: prometheus
-    url: http://prometheus:9090
--- a/examples/docker-simple/prometheus.yml
+++ b/examples/docker-simple/prometheus.yml
@@ -1,5 +0,0 @@
-scrape_configs:
-  - job_name: 'endlessh'
-    scrape_interval: 60s
-    static_configs:
-      - targets: ['endlessh:2112']
--- a/geoip/geoip.go
+++ b/geoip/geoip.go
@@ -1,4 +1,4 @@
-// Copyright (C) 2021-2024 Shizun Ge
+// 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
@@ -14,44 +14,67 @@
 // along with this program.  If not, see <https://www.gnu.org/licenses/>.
 //

-package geoip
+package main

 import (
 	"encoding/json"
 	"fmt"
 	"io/ioutil"
-	"net"
 	"net/http"
 	"strings"

-	"github.com/oschwald/geoip2-golang"
 	"github.com/pierrre/geohash"
 )

-type GeoOption struct {
-	GeoipSupplier     string
-	MaxMindDbFileName string
+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"`
 }

-func composeLocation(country string, region string, city string) 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
+	}
+
 	var locations []string
-	for _, s := range []string{country, region, city} {
+	for _, s := range []string{geo.CountryName, geo.RegionName, geo.City} {
 		if strings.TrimSpace(s) != "" {
 			locations = append(locations, s)
 		}
 	}
 	location := strings.Join(locations, ", ")
 	if location == "" {
-		return "Unknown"
+		location = "Unknown"
 	}
-	return location
-}
-
-func composeCountry(country string) string {
+	country := geo.CountryName
 	if country == "" {
-		return "Unknown"
+		country = "Unknown"
 	}
-	return country
+	gh := geohash.EncodeAuto(geo.Latitude, geo.Longitude)
+
+	return gh, country, location, nil
 }

 type ipapi struct {
@@ -68,9 +91,9 @@ type ipapi struct {
 	Longitude   float64 `json:"lon"`
 }

-func geohashAndLocationFromIpapi(ipAddr string) (string, string, string, error) {
+func geohashAndLocationFromIpapi(address string) (string, string, string, error) {
 	var geo ipapi
-	response, err := http.Get("http://ip-api.com/json/" + ipAddr)
+	response, err := http.Get("http://ip-api.com/json/" + address)
 	if err != nil {
 		return "s000", "Unknown", "Unknown", err
 	}
@@ -87,62 +110,37 @@ func geohashAndLocationFromIpapi(ipAddr 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", ipAddr, geo.Status, geo.Message)
+		return "s000", "Unknown", "Unknown", fmt.Errorf("failed to query %v via ip-api: status: %v, message: %v", address, geo.Status, geo.Message)
 	}

-	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 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 + ")"
-			}
+	var locations []string
+	for _, s := range []string{geo.CountryName, geo.RegionName, geo.City} {
+		if strings.TrimSpace(s) != "" {
+			locations = append(locations, s)
 		}
 	}
-	gh := geohash.EncodeAuto(latitude, longitude)
-	country := composeCountry(countryName)
-	location := composeLocation(countryName, "", cityName)
+	location := strings.Join(locations, ", ")
+	if location == "" {
+		location = "Unknown"
+	}
+	country := geo.CountryName
+	if country == "" {
+		country = "Unknown"
+	}
+	gh := geohash.EncodeAuto(geo.Latitude, geo.Longitude)

 	return gh, country, location, nil
 }

-func GeohashAndLocation(ipAddr string, option GeoOption) (string, string, string, error) {
-	switch option.GeoipSupplier {
+func geohashAndLocation(address string, geoipSupplier string) (string, string, string, error) {
+	switch geoipSupplier {
 	case "off":
 		return "s000", "Geohash off", "Geohash off", nil
 	case "ip-api":
-		return geohashAndLocationFromIpapi(ipAddr)
-	case "max-mind-db":
-		return geohashAndLocationFromMaxMindDb(ipAddr, option.MaxMindDbFileName)
+		return geohashAndLocationFromIpapi(address)
+	case "freegeoip":
+		return geohashAndLocationFromFreegeoip(address)
 	default:
-		return "s000", "Unknown", "Unknown", fmt.Errorf("unknown geoipSupplier %v.", option.GeoipSupplier)
+		return "s000", "Unknown", "Unknown", fmt.Errorf("unknown geoipSupplier %v.", geoipSupplier)
 	}
 }
--- a/geoip/country.go
+++ b/geoip/country.go
@@ -1,264 +0,0 @@
-// 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},
-}
--- a/go.mod
+++ b/go.mod
@@ -1,25 +1,21 @@
 module endlessh-go

-go 1.24.2
+go 1.17

 require (
-	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
+	github.com/golang/glog v1.0.0
+	github.com/pierrre/geohash v1.0.0
+	github.com/prometheus/client_golang v1.11.0
 )

 require (
 	github.com/beorn7/perks v1.0.1 // 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
+	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
 )
--- a/go.sum
+++ b/go.sum
@@ -1,76 +1,156 @@
+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=
 github.com/broady/gogeohash v0.0.0-20120525094510-7b2c40d64042 h1:iEdmkrNMLXbM7ecffOAtZJQOQUTE4iMonxrb5opUgE4=
 github.com/broady/gogeohash v0.0.0-20120525094510-7b2c40d64042/go.mod h1:f1L9YvXvlt9JTa+A17trQjSMM6bV40f+tHjB+Pi+Fqk=
-github.com/cespare/xxhash/v2 v2.3.0 h1:UL815xU9SqsFlibzuggzjXhog7bL6oX9BbNZnL2UFvs=
-github.com/cespare/xxhash/v2 v2.3.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
-github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
-github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/cespare/xxhash/v2 v2.1.1 h1:6MnRN8NT7+YBpUIWxHtefFZOKTAPgGjpQSxqLNn0+qY=
+github.com/cespare/xxhash/v2 v2.1.1/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/fanixk/geohash v0.0.0-20150324002647-c1f9b5fa157a h1:Fyfh/dsHFrC6nkX7H7+nFdTd1wROlX/FxEIWVpKYf1U=
 github.com/fanixk/geohash v0.0.0-20150324002647-c1f9b5fa157a/go.mod h1:UgNw+PTmmGN8rV7RvjvnBMsoTU8ZXXnaT3hYsDTBlgQ=
-github.com/golang/glog v1.2.5 h1:DrW6hGnjIhtvhOIiAKT6Psh/Kd/ldepEa81DKeiRJ5I=
-github.com/golang/glog v1.2.5/go.mod h1:6AhwSGph0fcJtXVM/PEHPqZlFeoLxhs7/t5UDAwmO+w=
-github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
-github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
-github.com/klauspost/compress v1.18.0 h1:c/Cqfb0r+Yi+JtIEq73FWXVkRonBlf0CRNYc8Zttxdo=
-github.com/klauspost/compress v1.18.0/go.mod h1:2Pp+KzxcywXVXMr50+X0Q/Lsb43OQHYWRCY2AiWywWQ=
-github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
-github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=
-github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
-github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
-github.com/kylelemons/godebug v1.1.0 h1:RPNrshWIDI6G2gRW9EHilWtl7Z6Sb1BR0xunSBf0SNc=
-github.com/kylelemons/godebug v1.1.0/go.mod h1:9/0rRGxNHcop5bhtWyNeEfOS8JIWk580+fNqagV/RAw=
-github.com/mmcloughlin/geohash v0.10.0 h1:9w1HchfDfdeLc+jFEf/04D27KP7E2QmpDu52wPbJWRE=
-github.com/mmcloughlin/geohash v0.10.0/go.mod h1:oNZxQo5yWJh0eMQEP/8hwQuVx9Z9tjwFUqcTB1SmG0c=
-github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 h1:C3w9PqII01/Oq1c1nUAm88MOHcQC9l5mIlSMApZMrHA=
-github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822/go.mod h1:+n7T8mK8HuQTcFwEeznm/DIxMOiR9yIdICNftLE1DvQ=
-github.com/oschwald/geoip2-golang v1.13.0 h1:Q44/Ldc703pasJeP5V9+aFSZFmBN7DKHbNsSFzQATJI=
-github.com/oschwald/geoip2-golang v1.13.0/go.mod h1:P9zG+54KPEFOliZ29i7SeYZ/GM6tfEL+rgSn03hYuUo=
-github.com/oschwald/maxminddb-golang v1.13.0 h1:R8xBorY71s84yO06NgTmQvqvTvlS/bnYZrrWX1MElnU=
-github.com/oschwald/maxminddb-golang v1.13.0/go.mod h1:BU0z8BfFVhi1LQaonTwwGQlsHUEu9pWNdMfmq4ztm0o=
-github.com/pierrre/assert v0.9.0 h1:eIKXsqcLSeLAOXYGHreen2D5CTZ2/N0/cJBNdxuVLdM=
-github.com/pierrre/assert v0.9.0/go.mod h1:3tthe4L3xYU4biRPVTFo9t2YRO4Dg3+zrLyMS4YanCE=
-github.com/pierrre/compare v1.4.13 h1:b6gi3OgN1emmD1Ly37m+B/Pbq6tac+w3lNGT5xu4I10=
-github.com/pierrre/compare v1.4.13/go.mod h1:+ie0ecM2nS32oLck0FWDstwIUSZ0YF4KBIaACOvKhJM=
-github.com/pierrre/geohash v1.1.3 h1:3u+EbHm2FZQnZCu3E2SaeryIQYtA/eH1YYzDpFm/42c=
-github.com/pierrre/geohash v1.1.3/go.mod h1:K5UlVmtRxicTXgp6eShrlAOk2Neu9zOe76C/ug7RIZ8=
-github.com/pierrre/go-libs v0.17.0 h1:bjxd9unioV/YDkUW7obETp2IFct0kO9HePURn81UL8s=
-github.com/pierrre/go-libs v0.17.0/go.mod h1:920odOqc5mZREW9GFWg056mjQ2prNVRGUZO7HRS2Jlc=
-github.com/pierrre/pretty v0.14.3 h1:I100hHs1C/MCd3M0D/hIV7J2OXl7amLD0uP2jnB7mRw=
-github.com/pierrre/pretty v0.14.3/go.mod h1:HTaFDNtT9ELVK5pODLfXRLiEiyIx3MmQUL5UadrR3/0=
-github.com/pires/go-proxyproto v0.8.1 h1:9KEixbdJfhrbtjpz/ZwCdWDD2Xem0NZ38qMYaASJgp0=
-github.com/pires/go-proxyproto v0.8.1/go.mod h1:ZKAAyp3cgy5Y5Mo4n9AlScrkCZwUy0g3Jf+slqQVcuU=
-github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/go-kit/kit v0.8.0/go.mod h1:xBxKIO96dXMWWy0MnWVtmwkA9/13aqxPnvrjFYMA2as=
+github.com/go-kit/kit v0.9.0/go.mod h1:xBxKIO96dXMWWy0MnWVtmwkA9/13aqxPnvrjFYMA2as=
+github.com/go-kit/log v0.1.0/go.mod h1:zbhenjAZHb184qTLMA9ZjW7ThYL0H2mk7Q6pNt4vbaY=
+github.com/go-logfmt/logfmt v0.3.0/go.mod h1:Qt1PoO58o5twSAckw1HlFXLmHsOX5/0LbT9GBnD5lWE=
+github.com/go-logfmt/logfmt v0.4.0/go.mod h1:3RMwSq7FuexP4Kalkev3ejPJsZTpXXBr9+V4qmtdjCk=
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+github.com/golang/protobuf v1.4.0-rc.4.0.20200313231945-b860323f09d0/go.mod h1:WU3c8KckQ9AFe+yFwt9sWVRKCVIyN9cPHBJSNnbL67w=
+github.com/golang/protobuf v1.4.0/go.mod h1:jodUvKwWbYaEsadDk5Fwe5c77LiNKVO9IDvqG2KuDX0=
+github.com/golang/protobuf v1.4.2/go.mod h1:oDoupMAO8OvCJWAcko0GGGIgR6R6ocIYbsSw735rRwI=
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-gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
-gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=
-gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
-gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v2 v2.2.1/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
+gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
+gopkg.in/yaml.v2 v2.2.4/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
+gopkg.in/yaml.v2 v2.2.5/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
+gopkg.in/yaml.v2 v2.3.0/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
--- a/main.go
+++ b/main.go
@@ -1,4 +1,4 @@
-// Copyright (C) 2021-2024 Shizun Ge
+// 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
@@ -17,124 +17,104 @@
 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"
-	proxyproto "github.com/pires/go-proxyproto"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
 )

-func startSending(maxClients int64, bannerMaxLength int64, records chan<- metrics.RecordEntry) chan *client.Client {
-	clients := make(chan *client.Client, maxClients)
+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())
 	go func() {
-		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
-		}
+		glog.Infof("Starting Prometheus on %v:%v, entry point is /%v", connHost, prometheusPort, prometheusEntry)
+		http.ListenAndServe(connHost+":"+prometheusPort, nil)
 	}()
 }

-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", "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))
+	connHost := flag.String("host", "0.0.0.0", "Listening address")
+	connPort := flag.String("port", "2222", "Listening port")
 	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")
-	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.")
+	geoipSupplier := flag.String("geoip_supplier", "off", "Supplier to obtain Geohash of IPs. Possible values are \"off\", \"ip-api\", \"freegeoip\"")

 	flag.Usage = func() {
 		fmt.Fprintf(flag.CommandLine.Output(), "Usage of %v \n", os.Args[0])
@@ -143,38 +123,56 @@ func main() {
 	flag.Parse()

 	if *prometheusEnabled {
-		if *connType == "tcp6" && *prometheusHost == "0.0.0.0" {
-			*prometheusHost = "[::]"
-		}
-		metrics.InitPrometheus(*prometheusHost, *prometheusPort, *prometheusEntry)
+		initPrometheus(*connHost, *prometheusPort, *prometheusEntry)
 	}

-	records := metrics.StartRecording(*maxClients, *prometheusEnabled, *prometheusCleanUnseenSeconds,
-		geoip.GeoOption{
-			GeoipSupplier:     *geoipSupplier,
-			MaxMindDbFileName: *maxMindDbFileName,
-		})
-	clients := startSending(*maxClients, *bannerMaxLength, records)
-
+	rand.Seed(time.Now().UnixNano())
 	interval := time.Duration(*intervalMs) * time.Millisecond
 	// Listen for incoming connections.
 	if *connType == "tcp6" && *connHost == "0.0.0.0" {
 		*connHost = "[::]"
 	}
-	if len(connPorts) == 0 {
-		connPorts = append(connPorts, defaultPort)
+	l, err := net.Listen(*connType, *connHost+":"+*connPort)
+	if err != nil {
+		glog.Errorf("Error listening: %v", err)
+		os.Exit(1)
 	}
-	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,
+	// 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
 			}
+			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()
 }
--- a/metrics/metrics.go
+++ b/metrics/metrics.go
@@ -1,195 +0,0 @@
-// 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
-}
--- a/metrics/priority_queue.go
+++ b/metrics/priority_queue.go
@@ -1,94 +0,0 @@
-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
-}