diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
deleted file mode 100644
index 7d77234..0000000
--- a/.github/workflows/build.yml
+++ /dev/null
@@ -1,35 +0,0 @@
-name: Build Images
-
-on:
-  push:
-
-jobs:
-  docker:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Log into DockerHub
-        if: github.event_name != 'pull_request'
-        uses: docker/login-action@v3
-        with:
-          username: ${{ github.actor }}
-          password: ${{ secrets.DOCKERHUB_TOKEN }}
-
-      - name: Set up QEMU
-        uses: docker/setup-qemu-action@v3
-
-      - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@v3
-
-      - name: Docker meta
-        id: meta
-        uses: docker/metadata-action@v5
-        with:
-          images: ${{ github.actor }}/ufw-docker-agent
-
-      - name: Build and push
-        uses: docker/build-push-action@v6
-        with:
-          push: ${{ github.event_name != 'pull_request' }}
-          platforms: linux/amd64,linux/arm64/v8
-          tags: ${{ steps.meta.outputs.tags }}
-          labels: ${{ steps.meta.outputs.labels }}
diff --git a/.github/workflows/testing.yml b/.github/workflows/testing.yml
deleted file mode 100644
index 5d9119e..0000000
--- a/.github/workflows/testing.yml
+++ /dev/null
@@ -1,16 +0,0 @@
-name: Unit Testing ufw-docker
-on: [push, pull_request]
-jobs:
-  test:
-    name: Unit Testing
-    runs-on: ubuntu-latest
-    steps:
-    - uses: actions/checkout@v2
-    - name: Checkout submodules
-      shell: bash
-      run: |
-        auth_header="$(git config --local --get http.https://github.com/.extraheader)"
-        git submodule sync --recursive
-        git -c "http.extraheader=$auth_header" -c protocol.version=2 submodule update --init --force --recursive --depth=1
-    - name: Test ufw-docker
-      run: ./test.sh
diff --git a/Dockerfile b/Dockerfile
index b63c63e..e9095d0 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,29 +1,19 @@
-FROM ubuntu:24.04
+FROM ubuntu:20.04
 
-ARG docker_version="27.3.1"
-ARG use_iptables_legacy=false
+ARG docker_version="19.03.12"
 
 ENV DEBIAN_FRONTEND=noninteractive
 RUN apt-get update \
-    && apt-get install -y ca-certificates curl gnupg lsb-release \
-    && mkdir -p /etc/apt/keyrings \
-    && curl -fsSL https://download.docker.com/linux/ubuntu/gpg | gpg --dearmor -o /etc/apt/keyrings/docker.gpg \
-    && echo "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.gpg]" \
-            "https://download.docker.com/linux/ubuntu" "$(lsb_release -cs) stable" \
-            | tee /etc/apt/sources.list.d/docker.list > /dev/null \
+    && apt-get install -y --no-install-recommends apt-transport-https \
+               ca-certificates curl software-properties-common gnupg dirmngr \
+    && apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 9DC858229FC7DD38854AE2D88D81803C0EBFCD88 \
+    && add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu \
+                          $(lsb_release -cs) stable" \
     && apt-get update \
     && apt-get install -y --no-install-recommends locales ufw \
-    && apt-get install -y --no-install-recommends "docker-ce=$(apt-cache madison docker-ce | grep -m1 -F "${docker_version}" | cut -d'|' -f2 | tr -d '[[:blank:]]')" \
+    && ( apt-get install -y --no-install-recommends "docker-ce=5:${docker_version}~*" || \
+         apt-get install -y --no-install-recommends "docker-ce=${docker_version}~*" ) \
     && locale-gen en_US.UTF-8 \
-    && if "$use_iptables_legacy"; then \
-          apt-get -y install arptables ebtables \
-          && update-alternatives --install /usr/sbin/arptables arptables /usr/sbin/arptables-legacy 100 \
-          && update-alternatives --install /usr/sbin/ebtables ebtables /usr/sbin/ebtables-legacy 100 \
-          && update-alternatives --set iptables /usr/sbin/iptables-legacy \
-          && update-alternatives --set ip6tables /usr/sbin/ip6tables-legacy \
-          && update-alternatives --set arptables /usr/sbin/arptables-legacy \
-          && update-alternatives --set ebtables /usr/sbin/ebtables-legacy; \
-       fi \
     && apt-get clean autoclean \
     && apt-get autoremove --yes \
     && rm -rf /var/lib/{apt,dpkg,cache,log}/
diff --git a/README.md b/README.md
index 1d836f1..ff4c96b 100644
--- a/README.md
+++ b/README.md
@@ -2,7 +2,7 @@ To Fix The Docker and UFW Security Flaw Without Disabling Iptables
 ==================
 
 [![Build Status](https://travis-ci.org/chaifeng/ufw-docker.svg)](https://travis-ci.org/chaifeng/ufw-docker)
-[![chaifeng/ufw-docker-agent](https://img.shields.io/docker/pulls/chaifeng/ufw-docker-agent)](https://hub.docker.com/r/chaifeng/ufw-docker-agent)
+![chaifeng/ufw-docker-agent](https://img.shields.io/docker/pulls/chaifeng/ufw-docker-agent)
 
 - [English](#tldr)
 - [中文](#太长不想读)
@@ -18,7 +18,7 @@ UFW is a popular iptables front end on Ubuntu that makes it easy to manage firew
 The issue is:
 
 1. UFW is enabled on a server that provides external services, and all incoming connections that are not allowed are blocked by default.
-2. Run a Docker container on the server and use the `-p` option to publish ports for that container on all IP addresses.
+2. Run a Docker container on the server and use the `-p` option to publish ports for that container on all IP addresses. 
    For example: `docker run -d --name httpd -p 0.0.0.0:8080:80 httpd:alpine`, this command will run an httpd service and publish port 80 of the container to port 8080 of the server.
 3. UFW will not block all external requests to visit port 8080. Even the command `ufw deny 8080` will not prevent external access to this port.
 4. This problem is actually quite serious, which means that a port that was originally intended to provide services internally is exposed to the public network.
@@ -43,7 +43,7 @@ Almost all of these solutions are similar. It requires to disable docker's iptab
 
 The solutions that we can find on internet are very similar and not elegant, I hope a new solution can:
 
-- Don't need to disable Docker's iptables and let Docker to manage it's network.
+- Don't need to disable Docker's iptables and let Docker to manage it's network. 
   We don't need to manually maintain iptables rules for any new Docker networks, and avoid potential side effects after disabling iptables in Docker.
 - The public network cannot access ports that published by Docker. Even if the port is published on all IP addresses using an option like `-p 8080:80`. Containers and internal networks can visit each other normally.
   Although it is possible to have Docker publish a container's port to the server's private IP address, the port will not be accessed on the public network. But, this server may have multiple private IP addresses, and these private IP addresses may also change.
@@ -193,22 +193,6 @@ Con:
 
 Doesn't support older versions of Ubuntu, and the command is a bit more complicated. But you can use my script.
 
-### IPv6
-
-[Enable IPv6 support](https://forums.docker.com/t/docker-user-chain-for-ip6tables/133961/3) in Docker by specifying ULA range (RFC 4193) in `/etc/docker/daemon.json`
-```json
-{
-  "experimental": true,
-  "ipv6": true,
-  "ip6tables": true,
-  "fixed-cidr-v6": "fd00:dead:beef::/48"
-}
-```
-
-Restart Docker
-```shell
-systemctl restart docker
-```
 
 ### Conclusion
 
@@ -226,7 +210,7 @@ Download `ufw-docker` script
 
     sudo wget -O /usr/local/bin/ufw-docker \
       https://github.com/chaifeng/ufw-docker/raw/master/ufw-docker
-    sudo chmod +x /usr/local/bin/ufw-docker
+    chmod +x /usr/local/bin/ufw-docker
 
 Then using the following command to modify the `after.rules` file of `ufw`
 
@@ -236,36 +220,6 @@ This command does the following things:
 - Back up the file `/etc/ufw/after.rules`
 - Append the rules of UFW and Docker at the end of the file
 
-#### IPv6 support
-
-`ufw-docker` also supports IPv6 networks and will update `/etc/ufw/after6.rules` when necessary.
-
-### Using the `--docker-subnets` option
-
-You can use the `--docker-subnets` option to customize which subnets will be allowed to communicate with Docker containers.
-This option applies to both IPv4 and IPv6 networks.
-
-* If the option is **not provided**, only standard private LAN subnets will be used
-  (IPv4: `10.0.0.0/8`, `172.16.0.0/12`, `192.168.0.0/16`; IPv6: `fd00::/8`)
-* If `--docker-subnets` is given **without any arguments**, all Docker network subnets will be detected and used automatically.
-  **Note:** If you add or remove Docker networks, you need to run `ufw-docker install --docker-subnets` again to update the firewall rules according to the latest network configuration.
-* If one or more subnets are specified, only these subnets will be used (you can list multiple subnets, separated by spaces; each should be in CIDR format).
-  The subnets can include networks not managed by Docker itself.
-
-#### Examples
-
-    # Use default private LAN subnets (IPv4: 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16; IPv6: fd00::/8)
-    ufw-docker install
-
-    # Auto-detect and use all Docker network subnets (both IPv4 and IPv6)
-    ufw-docker install --docker-subnets
-
-    # Only allow these specified subnets to communicate with Docker containers
-    ufw-docker install --docker-subnets 192.168.207.0/24 10.207.0.0/16 fd00:cf::/64
-
-
-You can use the same options with `ufw-docker check` to preview the changes before applying them.
-
 #### Install for Docker Swarm mode
 
 We can only use this script on manager nodes to manage firewall rules when using in Swarm mode.
@@ -305,10 +259,6 @@ Expose the `443` port of the container `httpd` and the protocol is `tcp`
 
     ufw-docker allow httpd 443/tcp
 
-Expose the `443` port of the container `httpd` and the protocol is `tcp` and the network is `foobar-external-network` when the container `httpd` is attached to multiple networks
-
-    ufw-docker allow httpd 443/tcp foobar-external-network
-
 Expose all published ports of the container `httpd`
 
     ufw-docker allow httpd
@@ -335,7 +285,7 @@ Remove rules from all nodes related to the service `web`
 
 ### Try it out
 
-We use [Vagrant](https://www.vagrantup.com/) to set up a local testing environment.
+We use [Vagrant](https://www.vagrantup.com/) to set up a local testing environment. 
 
 Run the following command to create 1 master node and 2 worker nodes
 
@@ -452,7 +402,7 @@ UFW 是 Ubuntu 上很流行的一个 iptables 前端，可以非常方便的管
 
     COMMIT
     # END UFW AND DOCKER
-
+ 
 然后重启 UFW，`sudo systemctl restart ufw`。现在外部就已经无法访问 Docker 发布出来的任何端口了，但是容器内部以及私有网络地址上可以正常互相访问，而且容器也可以正常访问外部的网络。**可能由于某些未知原因，重启 UFW 之后规则也无法生效，请重启服务器。**
 
 如果希望允许外部网络访问 Docker 容器提供的服务，比如有一个容器的服务端口是 `80`。那就可以用以下命令来允许外部网络访问这个服务：
@@ -548,19 +498,6 @@ UFW 是 Ubuntu 上很流行的一个 iptables 前端，可以非常方便的管
 
 不支持老版本的 Ubuntu，而且命令的使用上可能也会比较复杂。
 
-### 支持 IPv6
-
-要让 Docker Engine [启用 IPv6 的支持](https://forums.docker.com/t/docker-user-chain-for-ip6tables/133961/3). 你需要在 `/etc/docker/daemon.json` 文件中启用相关设置，并分配一个 ULA（唯一本地地址，RFC 4193）地址段作为 IPv6 网络范围。
-
-```json
-{
-  "experimental": true,
-  "ipv6": true,
-  "ip6tables": true,
-  "fixed-cidr-v6": "fd00:dead:beef::/48"
-}
-```
-
 #### 结论
 
 如果我们正在使用老版本的 Ubuntu，我们可以使用 `ufw-user-input`。但是要小心避免把不该暴露的服务暴露出去。
@@ -587,33 +524,6 @@ UFW 是 Ubuntu 上很流行的一个 iptables 前端，可以非常方便的管
 - 备份文件 `/etc/ufw/after.rules`
 - 把 UFW 和 Docker 的相关规则添加到文件 `after.rules` 的末尾
 
-#### IPv6 支持
-
-`ufw-docker` 也支持 IPv6 网络，并会在需要时自动更新 `/etc/ufw/after6.rules` 文件。
-
-### 使用 `--docker-subnets` 选项
-
-你可以使用 `--docker-subnets` 选项，自定义允许与 Docker 容器通信的子网。
-该选项同时适用于 IPv4 和 IPv6 网络。
-
-* 如果**未指定**该选项，只会使用标准的私有局域网子网
-  （IPv4：`10.0.0.0/8`、`172.16.0.0/12`、`192.168.0.0/16`；IPv6：`fd00::/8`）
-* 如果指定了 `--docker-subnets` 但**未带参数**，会自动检测并使用所有 Docker 网络的子网。
-  **注意：** 如果你对 Docker 网络进行了新增或删除操作，需要重新运行 `ufw-docker install --docker-subnets`，以便根据最新的网络配置更新防火墙规则。
-* 如果指定了一个或多个子网，则只会使用这些子网（你可以用空格分隔多个子网，每个子网应为 CIDR 格式）。
-  这些子网可以包括非 Docker 管理的网络。
-
-#### 示例
-
-    # 使用默认的私有局域网子网（IPv4：10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16；IPv6：fd00::/8）
-    ufw-docker install
-
-    # 自动检测并使用所有 Docker 网络的子网（同时支持 IPv4 和 IPv6）
-    ufw-docker install --docker-subnets
-
-    # 仅允许这些指定的子网与 Docker 容器通信
-    ufw-docker install --docker-subnets 192.168.207.0/24 10.207.0.0/16 fd00:cf::/64
-
 #### 为 Docker Swarm 环境安装
 
 仅仅可以在管理节点上使用 `ufw-docker` 这个脚本来管理防火墙规则。
@@ -653,10 +563,6 @@ UFW 是 Ubuntu 上很流行的一个 iptables 前端，可以非常方便的管
 
     ufw-docker allow httpd 443/tcp
 
-如果容器 `httpd` 绑定到多个网络上，暴露其 `443` 端口，协议为 `tcp`，网络为 `foobar-external-network`
-
-    ufw-docker allow httpd 443/tcp foobar-external-network
-
 把容器 `httpd` 的所有映射端口都暴露出来
 
     ufw-docker allow httpd
diff --git a/Vagrantfile b/Vagrantfile
index baf5815..1499184 100644
--- a/Vagrantfile
+++ b/Vagrantfile
@@ -3,59 +3,25 @@
 # -*- mode: ruby -*-
 # vi: set ft=ruby :
 
-ENV['VAGRANT_NO_PARALLEL']="true"
-
 Vagrant.configure('2') do |config|
-  ubuntu_version = File.readlines("Dockerfile").filter { |line|
-    line.start_with?("FROM ")
-  }.first.match(/\d\d\.\d\d/)[0]
 
-  docker_version = File.readlines("Dockerfile").filter { |line|
-    line.start_with?("ARG docker_version=")
-  }.first.match(/"([\d\.]+)"/)[1]
-
-  config.vm.box = "chaifeng/ubuntu-#{ubuntu_version}-docker-#{docker_version}"
+  config.vm.box = "chaifeng/ubuntu-20.04-docker-19.03.11"
+  #config.vm.box = "chaifeng/ubuntu-16.04-docker-18.03"
 
   config.vm.provider 'virtualbox' do |vb|
     vb.memory = '1024'
     vb.default_nic_type = "virtio"
   end
 
-  config.vm.provider 'parallels' do |prl|
-    prl.memory = '1024'
-    prl.check_guest_tools = false
-  end
-
   ip_prefix="192.168.56"
-  ip6_prefix="fd00:a:b"
-  worker_count=1
 
-  def env_true?(env_name)
-    value = ENV[env_name] || 'false'
-    true_values  = %w[true yes on 1]
-    down = value.strip.downcase
-    return 'true' if true_values.include?(down)
-    'false'
-  end
-
-  def env_true_str?(env_name)
-    env_true?(env_name).to_s
-  end
-
-  config.vm.provision 'setup', preserve_order: true, type: 'shell', privileged: false, inline: <<-SHELL
-    byobu-ctrl-a screen
-  SHELL
-
-  config.vm.provision 'docker-daemon-config',  type: 'shell', inline: <<-SHELL
+  config.vm.provision 'docker-daemon-config', type: 'shell', inline: <<-SHELL
     set -eu
-    [[ -f /etc/profile.d/editor.sh ]] || echo 'export EDITOR=vim' > /etc/profile.d/editor.sh
-    if [[ "$(hostname)" = @(master|node?) && ! -f /etc/docker/daemon.json ]]; then
+    if [[ ! -f /etc/docker/daemon.json ]]; then
       echo '{' >> /etc/docker/daemon.json
       echo '  "insecure-registries": ["localhost:5000", "#{ip_prefix}.130:5000"]' >> /etc/docker/daemon.json
       [[ -n "#{ENV['DOCKER_REGISTRY_MIRROR']}" ]] &&
         echo '  , "registry-mirrors": ["#{ENV['DOCKER_REGISTRY_MIRROR']}"]' >> /etc/docker/daemon.json
-      #{env_true_str?('ENABLE_DOCKER_IPV6')} &&
-       echo '  ,"ip6tables": true, "ipv6": true, "fixed-cidr-v6": "#{ip6_prefix}:deaf::/64"' >> /etc/docker/daemon.json
       echo '}' >> /etc/docker/daemon.json
       if type systemctl &>/dev/null; then
         systemctl restart docker
@@ -65,49 +31,41 @@ Vagrant.configure('2') do |config|
     fi
   SHELL
 
-  config.vm.provision 'ufw-docker', preserve_order: true, type: 'shell', inline: <<-SHELL
-    set -xeuo pipefail
+  config.vm.provision 'ufw-docker', type: 'shell', inline: <<-SHELL
+    set -euo pipefail
     export DEBUG=true
     lsb_release -is | grep -Fi ubuntu
+    /vagrant/ufw-docker check || {
+      ufw allow OpenSSH
+      ufw allow from #{ip_prefix}.128/28 to any
 
-    declare -a subnets=(--docker-subnets 192.168.56.128/28 10.0.0.0/8 172.16.0.0/12)
-    #{env_true_str?('ENABLE_DOCKER_IPV6')} &&
-      subnets+=(fd00:a:b:deaf::/64 fd05:8f23:c937:1::/64 fd05:8f23:c937:2::/64 fd05:8f23:c937::/64)
-    if [[ "$(hostname)" = @(master|node?) ]]; then
-      /vagrant/ufw-docker check "${subnets[@]-}" >/dev/null 2>&1 || {
-        ufw allow OpenSSH
-        ufw allow from #{ip_prefix}.128/28 to any
-        #{env_true_str?('ENABLE_DOCKER_IPV6')} &&
-          ufw allow from #{ip6_prefix}:0:cafe::/80 to any
+      yes | ufw enable || true
+      ufw status | grep '^Status: active'
 
-        yes | ufw enable || true
-        ufw status | grep '^Status: active'
+      /vagrant/ufw-docker install
 
-        /vagrant/ufw-docker install "${subnets[@]-}"
+      sed -i -e 's,192\.168\.0\.0/16,#{ip_prefix}.128/28,' /etc/ufw/after.rules
+
+      systemctl restart ufw
 
-        systemctl restart ufw
-      }
       [[ -L /usr/local/bin/ufw-docker ]] || ln -s /vagrant/ufw-docker /usr/local/bin/
-    fi
+
+      iptables -I DOCKER-USER 4 -p udp -j LOG --log-prefix '[UFW DOCKER] '
+    }
   SHELL
 
   private_registry="#{ip_prefix}.130:5000"
 
   config.vm.define "master" do |master|
-    master_ip_address = "#{ip_prefix}.130"
     master.vm.hostname = "master"
-    master.vm.network "private_network", ip: "#{master_ip_address}"
-    if env_true?('ENABLE_DOCKER_IPV6')
-      master.vm.network "private_network", ip: "#{ip6_prefix}:0:cafe::130", type: "static", netmast: 64, auto_config: true
-    end
+    master.vm.network "private_network", ip: "#{ip_prefix}.130"
 
-    master.vm.provision "unit-testing", preserve_order: true, type: 'shell', privileged: false, inline: <<-SHELL
+    master.vm.provision "unit-testing", type: 'shell', inline: <<-SHELL
         set -euo pipefail
-        [[ -n "#{ENV['DISABLE_UNIT_TESTING']}" ]] ||
-           /vagrant/test.sh
+        /vagrant/test.sh
     SHELL
 
-    master.vm.provision "docker-registry", preserve_order: true, type: 'docker' do |d|
+    master.vm.provision "docker-registry", type: 'docker' do |d|
       d.run "registry",
             image: "registry:2",
             args: "-p 5000:5000",
@@ -117,35 +75,31 @@ Vagrant.configure('2') do |config|
 
     ufw_docker_agent_image = "#{private_registry}/chaifeng/ufw-docker-agent:test"
 
-    master.vm.provision "docker-build-ufw-docker-agent", preserve_order: true, type: 'shell', inline: <<-SHELL
-      set -xeuo pipefail
-      suffix="$(iptables --version | grep -o '\\(nf_tables\\|legacy\\)')"
-      if [[ "$suffix" = legacy ]]; then use_iptables_legacy=true; else use_iptables_legacy=false; fi
-      docker build --build-arg use_iptables_legacy="${use_iptables_legacy:-false}" -t "#{ufw_docker_agent_image}-${suffix}" /vagrant
-      docker push "#{ufw_docker_agent_image}-${suffix}"
+    master.vm.provision "docker-build-ufw-docker-agent", type: 'shell', inline: <<-SHELL
+      set -euo pipefail
+      docker build -t #{ufw_docker_agent_image} /vagrant
+      docker push #{ufw_docker_agent_image}
 
-      echo "export UFW_DOCKER_AGENT_IMAGE=#{ufw_docker_agent_image}-${suffix}" > /etc/profile.d/ufw-docker.sh
+      echo "export UFW_DOCKER_AGENT_IMAGE=#{ufw_docker_agent_image}" > /etc/profile.d/ufw-docker.sh
       echo "export DEBUG=true" >> /etc/profile.d/ufw-docker.sh
 
       echo "Defaults env_keep += UFW_DOCKER_AGENT_IMAGE" > /etc/sudoers.d/98_ufw-docker
       echo "Defaults env_keep += DEBUG" >> /etc/sudoers.d/98_ufw-docker
     SHELL
 
-    master.vm.provision "swarm-init", preserve_order: true, type: 'shell', privileged: false, inline: <<-SHELL
+    master.vm.provision "swarm-init", type: 'shell', inline: <<-SHELL
       set -euo pipefail
       docker info | fgrep 'Swarm: active' && exit 0
 
-      docker swarm init --advertise-addr "#{master_ip_address}"
+      docker swarm init --advertise-addr eth1
       docker swarm join-token worker --quiet > /vagrant/.vagrant/docker-join-token
     SHELL
 
-    master.vm.provision "build-webapp", preserve_order: true, type: 'shell', privileged: false, inline: <<-SHELL
-        set -xeuo pipefail
+    master.vm.provision "build-webapp", type: 'shell', inline: <<-SHELL
+        set -euo pipefail
         docker build -t #{private_registry}/chaifeng/hostname-webapp - <<\\DOCKERFILE
 FROM httpd:alpine
 
-RUN printf "Listen %s\\n" 7000 8080 >> /usr/local/apache2/conf/httpd.conf
-
 RUN { echo '#!/bin/sh'; \\
     echo 'set -e; (echo -n "${name:-Hi} "; hostname;) > /usr/local/apache2/htdocs/index.html'; \\
     echo 'exec "$@"'; \\
@@ -157,8 +111,8 @@ DOCKERFILE
         docker push #{private_registry}/chaifeng/hostname-webapp
     SHELL
 
-    master.vm.provision "local-webapp", preserve_order: true, type: 'shell', inline: <<-SHELL
-        set -xeuo pipefail
+    master.vm.provision "local-webapp", type: 'shell', inline: <<-SHELL
+        set -euo pipefail
         for name in public:18080 local:8000; do
             webapp="${name%:*}_webapp"
             port="${name#*:}"
@@ -171,70 +125,26 @@ DOCKERFILE
         ufw-docker allow public_webapp
     SHELL
 
-    master.vm.provision "multiple-network", preserve_order: true, type: 'shell', inline: <<-SHELL
-      set -xeuo pipefail
-      declare -a docker_opts=()
-
-      if ! docker network ls | grep -F foo-internal; then
-          ! #{env_true_str?('ENABLE_DOCKER_IPV6')} || docker_opts=(--ipv6 --subnet fd05:8f23:c937:1::/64)
-          docker network create --internal "${docker_opts[@]}" foo-internal
-      fi
-      if ! docker network ls | grep -F bar-external; then
-          ! #{env_true_str?('ENABLE_DOCKER_IPV6')} || docker_opts=(--ipv6 --subnet fd05:8f23:c937:2::/64)
-          docker network create "${docker_opts[@]}" bar-external
-      fi
-
-      for app in internal-multinet-app:7000 public-multinet-app:17070; do
-          if ! docker inspect "${app%:*}" &>/dev/null; then
-              docker run -d --restart unless-stopped --name "${app%:*}" \
-                         -p "${app#*:}":80 --env name="${app}" \
-                         --network foo-internal \
-                         192.168.56.130:5000/chaifeng/hostname-webapp
-              docker network connect bar-external "${app%:*}"
-          fi
-      done
-
-      ufw-docker allow public-multinet-app 80 bar-external
-      ufw-docker allow internal-multinet-app 80 foo-internal
-    SHELL
-
-    master.vm.provision "swarm-webapp", preserve_order: true, type: 'shell', inline: <<-SHELL
-        set -xeuo pipefail
-        declare -a docker_opts=()
-        if #{env_true_str?('ENABLE_DOCKER_IPV6')}; then
-            docker inspect ip6net >/dev/null ||
-               docker network create --driver overlay --ipv6 ip6net
-            docker_opts+=(--network ip6net)
-        fi
+    master.vm.provision "swarm-webapp", type: 'shell', inline: <<-SHELL
+      set -euo pipefail
         for name in public:29090 local:9000; do
             webapp="${name%:*}_service"
             port="${name#*:}"
             if docker service inspect "$webapp" &>/dev/null; then docker service rm "$webapp"; fi
-            docker service create --name "$webapp" "${docker_opts[@]}" \
-                --publish "${port}:80" --env name="$webapp" --replicas #{worker_count} #{private_registry}/chaifeng/hostname-webapp
+            docker service create --name "$webapp" \
+                --publish "${port}:80" --env name="$webapp" --replicas 3 #{private_registry}/chaifeng/hostname-webapp
         done
 
         ufw-docker service allow public_service 80/tcp
-
-        docker service inspect "public_multiport" ||
-            docker service create --name "public_multiport" "${docker_opts[@]}" \
-                --publish "40080:80" --publish "47000:7000" --publish "48080:8080" \
-                --env name="public_multiport" --replicas #{worker_count + 1} #{private_registry}/chaifeng/hostname-webapp
-
-        ufw-docker service allow public_multiport 80/tcp
-        ufw-docker service allow public_multiport 8080/tcp
     SHELL
   end
 
-  1.upto worker_count do |ip|
+  1.upto 2 do |ip|
     config.vm.define "node#{ip}" do | node |
       node.vm.hostname = "node#{ip}"
       node.vm.network "private_network", ip: "#{ip_prefix}.#{ 130 + ip }"
-      if env_true?('ENABLE_DOCKER_IPV6')
-        node.vm.network "private_network", ip: "#{ip6_prefix}:0:cafe::#{ 130 + ip }", type: "static", netmast: 64, auto_config: true
-      end
 
-      node.vm.provision "node#{ip}-swarm-join", preserve_order: true, type: 'shell', inline: <<-SHELL
+      node.vm.provision "swarm-join", type: 'shell', inline: <<-SHELL
         set -euo pipefail
         docker info | fgrep 'Swarm: active' && exit 0
 
@@ -244,92 +154,24 @@ DOCKERFILE
     end
   end
 
-  config.vm.define "node-internal" do |node|
-    node.vm.hostname = "node-internal"
-    node.vm.network "private_network", ip: "#{ip_prefix}.142"
-    if env_true?('ENABLE_DOCKER_IPV6')
-      node.vm.network "private_network", ip: "#{ip6_prefix}:0:cafe::142", type: "static", netmast: 64, auto_config: true
-    end
-  end
-
   config.vm.define "external" do |external|
     external.vm.hostname = "external"
     external.vm.network "private_network", ip: "#{ip_prefix}.127"
-    if env_true?('ENABLE_DOCKER_IPV6')
-      external.vm.network "private_network", ip: "#{ip6_prefix}:0:eeee::127", type: "static", netmast: 64, auto_config: true
-    end
 
-    external.vm.provision "testing", preserve_order: true, type: 'shell', privileged: false, inline: <<-SHELL
-        set -xuo pipefail
-        error_count=0
-        function test-webapp() {
-          local actual=""
+    external.vm.provision "testing", type: 'shell', inline: <<-SHELL
+        set -euo pipefail
+        set -x
+        server="http://#{ip_prefix}.130"
+        function test-webapp() { timeout 3 curl --silent "$@"; }
+        test-webapp "$server:18080"
+        ! test-webapp "$server:8000"
 
-          if [[ "$#" -eq 2 ]]; then
-            local expect_fail='!'
-            url="$2"
-          else
-            url="$1"
-          fi
+        test-webapp "$server:29090"
+        ! test-webapp "$server:9000"
 
-          timeout 3 curl --silent "$url" || actual='!'
-
-          if [[ "${expect_fail:-}" = "${actual}" ]]; then
-            echo "OK: '$url' is ${expect_fail:+NOT }accessible${expect_fail:+ (should NOT be)}."
-          else
-            echo "FAIL: '$url' is ${expect_fail:+}${expect_fail:-NOT }accessible${expect_fail:-}."
-            (( ++ error_count ))
-            return 1
-          fi
-        } 2>/dev/null
-
-        function run_tests() {
-          local server="$1"
-          test-webapp "$server:18080"
-          test-webapp ! "$server:8000"
-
-          test-webapp "$server:17070" # multiple networks app
-          test-webapp ! "$server:7000" # internal multiple networks app
-
-          # Docker Swarm
-          test-webapp ! "$server:9000"
-          test-webapp ! "$server:47000"
-        }
-        function run_tests_ipv4() {
-          local server="$1"
-          # Docker Swarm
-          test-webapp "$server:29090"
-
-          test-webapp "$server:40080"
-          test-webapp "$server:48080"
-
-        }
-        function run_tests_ipv6() {
-          local server="$1"
-
-          echo TODO: It seems that Docker Swarm does not support IPv6 well >&2
-
-          test-webapp ! "$server:29090" # it is accessible via IPv4
-          test-webapp ! "$server:40080" # it is accessible via IPv4
-          test-webapp ! "$server:48080" # it is accessible via IPv4
-
-        }
-
-        run_tests "http://#{ip_prefix}.130"
-        run_tests_ipv4 "http://#{ip_prefix}.130"
-
-        if #{env_true_str?('ENABLE_DOCKER_IPV6')}; then
-          run_tests "http://[#{ip6_prefix}:0:cafe::130]"
-          run_tests_ipv6 "http://[#{ip6_prefix}:0:cafe::130]"
-        fi
-        {
         echo "====================="
-        if [[ "$error_count" -eq 0 ]]; then echo "      TEST DONE      "
-        else echo "   TESTS FAIL: ${error_count}"
-        fi
+        echo "      TEST DONE      "
         echo "====================="
-        exit "${error_count}"
-        } 2>/dev/null
     SHELL
   end
 end
diff --git a/test/bach b/test/bach
index 27885eb..ff94833 160000
--- a/test/bach
+++ b/test/bach
@@ -1 +1 @@
-Subproject commit 27885eb79c11e4652dede994c886ae5f9e30994f
+Subproject commit ff948334df72f25410d03cbff72b5eaa5e9de409
diff --git a/test/ufw-docker-service.test.sh b/test/ufw-docker-service.test.sh
index c536d31..dd74bb6 100755
--- a/test/ufw-docker-service.test.sh
+++ b/test/ufw-docker-service.test.sh
@@ -284,7 +284,6 @@ test-ufw-docker--service-delete-matches-assert() {
     docker service update --update-parallelism=0 \
            --env-add ufw_docker_agent_image="${ufw_docker_agent_image}" \
            --env-add "ufw_public_abcd1234=webapp/deny" \
-           --env-add "DEBUG=false" \
            --image "${ufw_docker_agent_image}" \
            "${ufw_docker_agent}"
 }
diff --git a/test/ufw-docker.test.sh b/test/ufw-docker.test.sh
index 52ab301..35b3919 100755
--- a/test/ufw-docker.test.sh
+++ b/test/ufw-docker.test.sh
@@ -12,20 +12,12 @@ source "$working_dir"/bach/bach.sh
     @mocktrue ufw status
     @mocktrue grep -Fq "Status: active"
 
-    @mock iptables --version
-    @mocktrue grep -F '(legacy)'
-
-    @mocktrue docker -v
-    @mock docker -v === @stdout Docker version 0.0.0, build dummy
-
-    @mockpipe remove_blank_lines
+    @ignore remove_blank_lines
     @ignore echo
     @ignore err
 
     DEFAULT_PROTO=tcp
     GREP_REGEXP_INSTANCE_NAME="[-_.[:alnum:]]\\+"
-
-    UFW_DOCKER_AGENT_IMAGE=chaifeng/ufw-docker-agent:090502-legacy
 }
 
 function ufw-docker() {
@@ -38,41 +30,6 @@ function load-ufw-docker-function() {
     @load_function "$working_dir/../ufw-docker" "$1"
 }
 
-test-ufw-docker-init-legacy() {
-    @mocktrue grep -F '(legacy)'
-    @source <(@sed '/PATH=/d' "$working_dir/../ufw-docker") help
-}
-test-ufw-docker-init-legacy-assert() {
-    iptables --version
-    test -n chaifeng/ufw-docker-agent:090502-legacy
-    trap on-exit EXIT INT TERM QUIT ABRT ERR
-    @dryrun cat
-}
-
-
-test-ufw-docker-init-nf_tables() {
-    @mockfalse grep -F '(legacy)'
-    @source <(@sed '/PATH=/d' "$working_dir/../ufw-docker") help
-}
-test-ufw-docker-init-nf_tables-assert() {
-    iptables --version
-    test -n chaifeng/ufw-docker-agent:090502-nf_tables
-    trap on-exit EXIT INT TERM QUIT ABRT ERR
-    @dryrun cat
-}
-
-
-test-ufw-docker-init() {
-    UFW_DOCKER_AGENT_IMAGE=chaifeng/ufw-docker-agent:100917
-    @source <(@sed '/PATH=/d' "$working_dir/../ufw-docker") help
-}
-test-ufw-docker-init-assert() {
-    test -n chaifeng/ufw-docker-agent:100917
-    trap on-exit EXIT INT TERM QUIT ABRT ERR
-    @dryrun cat
-}
-
-
 test-ufw-docker-help() {
     ufw-docker help
 }
@@ -91,23 +48,11 @@ test-ufw-docker-without-parameters-assert() {
 
 test-ufw-is-disabled() {
     @mockfalse grep -Fq "Status: active"
-    @mock iptables --version === @stdout 'iptables v1.8.4 (legacy)'
 
     ufw-docker
 }
 test-ufw-is-disabled-assert() {
-    die "UFW is disabled or you are not root user, or mismatched iptables legacy/nf_tables, current iptables v1.8.4 (legacy)"
-    ufw-docker--help
-}
-
-
-test-docker-is-installed() {
-    @mockfalse docker -v
-
-    ufw-docker
-}
-test-docker-is-installed-assert() {
-    die "Docker executable not found."
+    die "UFW is disabled or you are not root user."
     ufw-docker--help
 }
 
@@ -128,14 +73,6 @@ test-ufw-docker-install-assert() {
 }
 
 
-test-ufw-docker-install--docker-subnets() {
-    ufw-docker install --docker-subnets
-}
-test-ufw-docker-install--docker-subnets-assert() {
-    ufw-docker--install --docker-subnets
-}
-
-
 test-ufw-docker-check() {
     ufw-docker check
 }
@@ -144,14 +81,6 @@ test-ufw-docker-check-assert() {
 }
 
 
-test-ufw-docker-check--docker-subnets() {
-    ufw-docker check --docker-subnets
-}
-test-ufw-docker-check--docker-subnets-assert() {
-    ufw-docker--check --docker-subnets
-}
-
-
 test-ufw-docker-service() {
     ufw-docker service allow httpd
 }
@@ -214,7 +143,7 @@ test-ufw-docker-list-httpd() {
     ufw-docker list httpd
 }
 test-ufw-docker-list-httpd-assert() {
-    ufw-docker--list 'httpd-container-name\(/v6\)\?' "" tcp ""
+    ufw-docker--list httpd-container-name "" tcp
 }
 
 
@@ -223,7 +152,7 @@ test-ufw-docker-allow-httpd() {
     ufw-docker allow httpd
 }
 test-ufw-docker-allow-httpd-assert() {
-    ufw-docker--allow httpd-container-name "" tcp ""
+    ufw-docker--allow httpd-container-name "" tcp
 }
 
 
@@ -232,7 +161,7 @@ test-ufw-docker-allow-httpd-80() {
     ufw-docker allow httpd 80
 }
 test-ufw-docker-allow-httpd-80-assert() {
-    ufw-docker--allow httpd-container-name 80 tcp ""
+    ufw-docker--allow httpd-container-name 80 tcp
 }
 
 
@@ -241,7 +170,7 @@ test-ufw-docker-allow-httpd-80tcp() {
     ufw-docker allow httpd 80/tcp
 }
 test-ufw-docker-allow-httpd-80tcp-assert() {
-    ufw-docker--allow httpd-container-name 80 tcp ""
+    ufw-docker--allow httpd-container-name 80 tcp
 }
 
 
@@ -250,7 +179,7 @@ test-ufw-docker-allow-httpd-80udp() {
     ufw-docker allow httpd 80/udp
 }
 test-ufw-docker-allow-httpd-80udp-assert() {
-    ufw-docker--allow httpd-container-name 80 udp ""
+    ufw-docker--allow httpd-container-name 80 udp
 }
 
 
@@ -262,12 +191,21 @@ test-ASSERT-FAIL-ufw-docker-allow-httpd-INVALID-port() {
 }
 
 
+test-ufw-docker-list-httpd() {
+    @mock ufw-docker--instance-name httpd === @stdout httpd-container-name
+    ufw-docker list httpd
+}
+test-ufw-docker-list-httpd-assert() {
+    ufw-docker--list httpd-container-name "" tcp
+}
+
+
 test-ufw-docker-delete-allow-httpd() {
     @mock ufw-docker--instance-name httpd === @stdout httpd-container-name
     ufw-docker delete allow httpd
 }
 test-ufw-docker-delete-allow-httpd-assert() {
-    ufw-docker--delete 'httpd-container-name\(/v6\)\?' "" tcp ""
+    ufw-docker--delete httpd-container-name "" tcp
 }
 
 
@@ -284,31 +222,7 @@ function setup-ufw-docker--allow() {
     load-ufw-docker-function ufw-docker--allow
 
     @mocktrue docker inspect instance-name
-    @mock docker inspect --format '{{range $name, $net := .NetworkSettings.Networks}}{{if $net.IPAddress}}{{$name}} {{$net.IPAddress}}{{"\n"}}{{end}}{{if $net.GlobalIPv6Address}}{{$name}} {{$net.GlobalIPv6Address}}{{"\n"}}{{end}}{{end}}' instance-name === @stdout "default 172.18.0.3"
-    @mock docker inspect --format='{{range $p, $conf := .NetworkSettings.Ports}}{{with $conf}}{{$p}}{{"\n"}}{{end}}{{end}}' instance-name === @stdout 5000/tcp 8080/tcp 5353/udp
-}
-
-function setup-IPv6-ufw-docker--allow() {
-    load-ufw-docker-function ufw-docker--allow
-
-    @mocktrue docker inspect instance-name
-    @mock docker inspect --format '{{range $name, $net := .NetworkSettings.Networks}}{{if $net.IPAddress}}{{$name}} {{$net.IPAddress}}{{"\n"}}{{end}}{{if $net.GlobalIPv6Address}}{{$name}} {{$net.GlobalIPv6Address}}{{"\n"}}{{end}}{{end}}' instance-name === @stdout "default 172.18.0.3" "default fd00:cf::42"
-    @mock docker inspect --format='{{range $p, $conf := .NetworkSettings.Ports}}{{with $conf}}{{$p}}{{"\n"}}{{end}}{{end}}' instance-name === @stdout 5000/tcp 8080/tcp 5353/udp
-}
-
-function setup-ufw-docker--allow--multinetwork() {
-    load-ufw-docker-function ufw-docker--allow
-
-    @mocktrue docker inspect instance-name
-    @mock docker inspect --format '{{range $name, $net := .NetworkSettings.Networks}}{{if $net.IPAddress}}{{$name}} {{$net.IPAddress}}{{"\n"}}{{end}}{{if $net.GlobalIPv6Address}}{{$name}} {{$net.GlobalIPv6Address}}{{"\n"}}{{end}}{{end}}' instance-name === @stdout "default 172.18.0.3" "awesomenet 172.19.0.7"
-    @mock docker inspect --format='{{range $p, $conf := .NetworkSettings.Ports}}{{with $conf}}{{$p}}{{"\n"}}{{end}}{{end}}' instance-name === @stdout 5000/tcp 8080/tcp 5353/udp
-}
-
-function setup-IPv6-ufw-docker--allow--multinetwork() {
-    load-ufw-docker-function ufw-docker--allow
-
-    @mocktrue docker inspect instance-name
-    @mock docker inspect --format '{{range $name, $net := .NetworkSettings.Networks}}{{if $net.IPAddress}}{{$name}} {{$net.IPAddress}}{{"\n"}}{{end}}{{if $net.GlobalIPv6Address}}{{$name}} {{$net.GlobalIPv6Address}}{{"\n"}}{{end}}{{end}}' instance-name === @stdout "default 172.18.0.3" "default fd00:cf::42" "awesomenet 172.19.0.7" "awesomenet fd00:cf::207"
+    @mock docker inspect --format='{{range .NetworkSettings.Networks}}{{.IPAddress}}{{"\n"}}{{end}}' instance-name === @stdout 172.18.0.3
     @mock docker inspect --format='{{range $p, $conf := .NetworkSettings.Ports}}{{with $conf}}{{$p}}{{"\n"}}{{end}}{{end}}' instance-name === @stdout 5000/tcp 8080/tcp 5353/udp
 }
 
@@ -355,7 +269,7 @@ test-ufw-docker--allow-instance-and-match-the-port() {
     ufw-docker--allow instance-name 5000 tcp
 }
 test-ufw-docker--allow-instance-and-match-the-port-assert() {
-    ufw-docker--add-rule instance-name 172.18.0.3 5000 tcp default
+    ufw-docker--add-rule instance-name 172.18.0.3 5000 tcp
 }
 
 
@@ -365,9 +279,9 @@ test-ufw-docker--allow-instance-all-published-port() {
     ufw-docker--allow instance-name "" ""
 }
 test-ufw-docker--allow-instance-all-published-port-assert() {
-    ufw-docker--add-rule instance-name 172.18.0.3 5000 tcp default
-    ufw-docker--add-rule instance-name 172.18.0.3 8080 tcp default
-    ufw-docker--add-rule instance-name 172.18.0.3 5353 udp default
+    ufw-docker--add-rule instance-name 172.18.0.3 5000 tcp
+    ufw-docker--add-rule instance-name 172.18.0.3 8080 tcp
+    ufw-docker--add-rule instance-name 172.18.0.3 5353 udp
 }
 
 
@@ -377,116 +291,14 @@ test-ufw-docker--allow-instance-all-published-tcp-port() {
     ufw-docker--allow instance-name "" tcp
 }
 test-ufw-docker--allow-instance-all-published-tcp-port-assert() {
-    ufw-docker--add-rule instance-name 172.18.0.3 5000 tcp default
-    ufw-docker--add-rule instance-name 172.18.0.3 8080 tcp default
-    ufw-docker--add-rule instance-name 172.18.0.3 5353 udp default # FIXME
-}
-
-
-test-ufw-docker--allow-instance-all-published-port-multinetwork() {
-    setup-ufw-docker--allow--multinetwork
-
-    ufw-docker--allow instance-name "" ""
-}
-test-ufw-docker--allow-instance-all-published-port-multinetwork-assert() {
-    ufw-docker--add-rule  instance-name  172.18.0.3  5000  tcp  default
-    ufw-docker--add-rule  instance-name  172.19.0.7  5000  tcp  awesomenet
-    ufw-docker--add-rule  instance-name  172.18.0.3  8080  tcp  default
-    ufw-docker--add-rule  instance-name  172.19.0.7  8080  tcp  awesomenet
-    ufw-docker--add-rule  instance-name  172.18.0.3  5353  udp  default
-    ufw-docker--add-rule  instance-name  172.19.0.7  5353  udp  awesomenet
-}
-
-test-ufw-docker--allow-instance-all-published-port-multinetwork-select-network() {
-    setup-ufw-docker--allow--multinetwork
-
-    ufw-docker--allow instance-name "" "" awesomenet
-}
-test-ufw-docker--allow-instance-all-published-port-multinetwork-select-network-assert() {
-    ufw-docker--add-rule  instance-name  172.19.0.7  5000  tcp  awesomenet
-    ufw-docker--add-rule  instance-name  172.19.0.7  8080  tcp  awesomenet
-    ufw-docker--add-rule  instance-name  172.19.0.7  5353  udp  awesomenet
-}
-
-
-test-IPv6-ufw-docker--allow-instance-and-match-the-port() {
-    setup-IPv6-ufw-docker--allow
-
-    ufw-docker--allow instance-name 5000 tcp
-}
-test-IPv6-ufw-docker--allow-instance-and-match-the-port-assert() {
-    ufw-docker--add-rule instance-name 172.18.0.3 5000 tcp default
-    ufw-docker--add-rule instance-name/v6 fd00:cf::42 5000 tcp default
-}
-
-
-test-IPv6-ufw-docker--allow-instance-all-published-port() {
-    setup-IPv6-ufw-docker--allow
-
-    ufw-docker--allow instance-name "" ""
-}
-test-IPv6-ufw-docker--allow-instance-all-published-port-assert() {
-    ufw-docker--add-rule instance-name 172.18.0.3 5000 tcp default
-    ufw-docker--add-rule instance-name/v6 fd00:cf::42 5000 tcp default
-    ufw-docker--add-rule instance-name 172.18.0.3 8080 tcp default
-    ufw-docker--add-rule instance-name/v6 fd00:cf::42 8080 tcp default
-    ufw-docker--add-rule instance-name 172.18.0.3 5353 udp default
-    ufw-docker--add-rule instance-name/v6 fd00:cf::42 5353 udp default
-}
-
-
-test-IPv6-ufw-docker--allow-instance-all-published-tcp-port() {
-    setup-IPv6-ufw-docker--allow
-
-    ufw-docker--allow instance-name "" tcp
-}
-test-IPv6-ufw-docker--allow-instance-all-published-tcp-port-assert() {
-    ufw-docker--add-rule instance-name 172.18.0.3 5000 tcp default
-    ufw-docker--add-rule instance-name/v6 fd00:cf::42 5000 tcp default
-    ufw-docker--add-rule instance-name 172.18.0.3 8080 tcp default
-    ufw-docker--add-rule instance-name/v6 fd00:cf::42 8080 tcp default
-    ufw-docker--add-rule instance-name 172.18.0.3 5353 udp default # FIXME
-    ufw-docker--add-rule instance-name/v6 fd00:cf::42 5353 udp default # FIXME
-}
-
-
-test-IPv6-ufw-docker--allow-instance-all-published-port-multinetwork() {
-    setup-IPv6-ufw-docker--allow--multinetwork
-
-    ufw-docker--allow instance-name "" ""
-}
-test-IPv6-ufw-docker--allow-instance-all-published-port-multinetwork-assert() {
-    ufw-docker--add-rule  instance-name  172.18.0.3  5000  tcp  default
-    ufw-docker--add-rule instance-name/v6 fd00:cf::42 5000 tcp default
-    ufw-docker--add-rule  instance-name  172.19.0.7  5000  tcp  awesomenet
-    ufw-docker--add-rule instance-name/v6 fd00:cf::207 5000 tcp awesomenet
-    ufw-docker--add-rule  instance-name  172.18.0.3  8080  tcp  default
-    ufw-docker--add-rule instance-name/v6 fd00:cf::42 8080 tcp default
-    ufw-docker--add-rule  instance-name  172.19.0.7  8080  tcp  awesomenet
-    ufw-docker--add-rule instance-name/v6 fd00:cf::207 8080 tcp awesomenet
-    ufw-docker--add-rule  instance-name  172.18.0.3  5353  udp  default
-    ufw-docker--add-rule instance-name/v6 fd00:cf::42 5353 udp default
-    ufw-docker--add-rule  instance-name  172.19.0.7  5353  udp  awesomenet
-    ufw-docker--add-rule instance-name/v6 fd00:cf::207 5353 udp awesomenet
-}
-
-test-IPv6-ufw-docker--allow-instance-all-published-port-multinetwork-select-network() {
-    setup-IPv6-ufw-docker--allow--multinetwork
-
-    ufw-docker--allow instance-name "" "" awesomenet
-}
-test-IPv6-ufw-docker--allow-instance-all-published-port-multinetwork-select-network-assert() {
-    ufw-docker--add-rule  instance-name  172.19.0.7  5000  tcp  awesomenet
-    ufw-docker--add-rule instance-name/v6 fd00:cf::207 5000 tcp awesomenet
-    ufw-docker--add-rule  instance-name  172.19.0.7  8080  tcp  awesomenet
-    ufw-docker--add-rule instance-name/v6 fd00:cf::207 8080 tcp awesomenet
-    ufw-docker--add-rule  instance-name  172.19.0.7  5353  udp  awesomenet
-    ufw-docker--add-rule instance-name/v6 fd00:cf::207 5353 udp awesomenet
+    ufw-docker--add-rule instance-name 172.18.0.3 5000 tcp
+    ufw-docker--add-rule instance-name 172.18.0.3 8080 tcp
+    ufw-docker--add-rule instance-name 172.18.0.3 5353 udp # FIXME
 }
 
 
 test-ufw-docker--add-rule-a-non-existing-rule() {
-    @mockfalse ufw-docker--list webapp 5000 tcp ""
+    @mockfalse ufw-docker--list webapp 5000 tcp
 
     load-ufw-docker-function ufw-docker--add-rule
     ufw-docker--add-rule webapp 172.18.0.4 5000 tcp
@@ -495,54 +307,29 @@ test-ufw-docker--add-rule-a-non-existing-rule-assert() {
     ufw route allow proto tcp from any to 172.18.0.4 port 5000 comment "allow webapp 5000/tcp"
 }
 
-test-ufw-docker--add-rule-a-non-existing-rule-with-network() {
-    @mockfalse ufw-docker--list webapp 5000 tcp default
-
-    load-ufw-docker-function ufw-docker--add-rule
-    ufw-docker--add-rule webapp 172.18.0.4 5000 tcp default
-}
-test-ufw-docker--add-rule-a-non-existing-rule-with-network-assert() {
-    ufw route allow proto tcp from any to 172.18.0.4 port 5000 comment "allow webapp 5000/tcp default"
-}
-
 
 test-ufw-docker--add-rule-modify-an-existing-rule() {
-    @mocktrue ufw-docker--list webapp 5000 tcp default
-    @mock ufw --dry-run route allow proto tcp from any to 172.18.0.4 port 5000 comment "allow webapp 5000/tcp default" === @echo
+    @mocktrue ufw-docker--list webapp 5000 tcp
+    @mocktrue ufw --dry-run route allow proto tcp from any to 172.18.0.4 port 5000 comment "allow webapp 5000/tcp"
     @mockfalse grep "^Skipping"
 
     load-ufw-docker-function ufw-docker--add-rule
-    ufw-docker--add-rule webapp 172.18.0.4 5000 tcp default
+    ufw-docker--add-rule webapp 172.18.0.4 5000 tcp
 }
 test-ufw-docker--add-rule-modify-an-existing-rule-assert() {
-    ufw-docker--delete webapp 5000 tcp default
+    ufw-docker--delete webapp 5000 tcp
 
-    ufw route allow proto tcp from any to 172.18.0.4 port 5000 comment "allow webapp 5000/tcp default"
-}
-
-
-test-IPv6-ufw-docker--add-rule-modify-an-existing-rule() {
-    @mocktrue ufw-docker--list webapp/v6 5000 tcp default
-    @mock ufw --dry-run route allow proto tcp from any to fd00:cf::42 port 5000 comment "allow webapp/v6 5000/tcp default" === @echo
-    @mockfalse grep "^Skipping"
-
-    load-ufw-docker-function ufw-docker--add-rule
-    ufw-docker--add-rule webapp/v6 fd00:cf::42 5000 tcp default
-}
-test-IPv6-ufw-docker--add-rule-modify-an-existing-rule-assert() {
-    ufw-docker--delete webapp/v6 5000 tcp default
-
-    ufw route allow proto tcp from any to fd00:cf::42 port 5000 comment "allow webapp/v6 5000/tcp default"
+    ufw route allow proto tcp from any to 172.18.0.4 port 5000 comment "allow webapp 5000/tcp"
 }
 
 
 test-ufw-docker--add-rule-skip-an-existing-rule() {
-    @mocktrue ufw-docker--list webapp 5000 tcp ""
+    @mocktrue ufw-docker--list webapp 5000 tcp
     @mocktrue ufw --dry-run route allow proto tcp from any to 172.18.0.4 port 5000 comment "allow webapp 5000/tcp"
     @mocktrue grep "^Skipping"
 
     load-ufw-docker-function ufw-docker--add-rule
-    ufw-docker--add-rule webapp 172.18.0.4 5000 tcp ""
+    ufw-docker--add-rule webapp 172.18.0.4 5000 tcp
 }
 test-ufw-docker--add-rule-skip-an-existing-rule-assert() {
     @do-nothing
@@ -550,16 +337,17 @@ test-ufw-docker--add-rule-skip-an-existing-rule-assert() {
 
 
 test-ufw-docker--add-rule-modify-an-existing-rule-without-port() {
-    @mocktrue ufw-docker--list webapp "" tcp ""
-    @mock ufw --dry-run route allow proto tcp from any to 172.18.0.4 comment "allow webapp" === @echo
+    @mocktrue ufw-docker--list webapp "" tcp
+
+    @mocktrue ufw --dry-run route allow proto tcp from any to 172.18.0.4 comment "allow webapp"
     @mockfalse grep "^Skipping"
 
     load-ufw-docker-function ufw-docker--add-rule
 
-    ufw-docker--add-rule webapp 172.18.0.4 "" tcp ""
+    ufw-docker--add-rule webapp 172.18.0.4 "" tcp
 }
 test-ufw-docker--add-rule-modify-an-existing-rule-without-port-assert() {
-    ufw-docker--delete webapp "" tcp ""
+    ufw-docker--delete webapp "" tcp
 
     ufw route allow proto tcp from any to 172.18.0.4 comment "allow webapp"
 }
@@ -577,7 +365,7 @@ test-ufw-docker--instance-name-found-a-name() {
 }
 test-ufw-docker--instance-name-found-a-name-assert() {
     docker inspect --format="{{.Name}}" foo
-    @dryrun echo -n foo
+    echo -n foo
 }
 
 
@@ -596,14 +384,11 @@ test-ufw-docker--instance-name-found-an-id-assert() {
 
 test-ufw-docker--list-name() {
     @mocktrue ufw status numbered
-    @mockfalse grep "# allow foo\\( [[:digit:]]\\+\\/\\(tcp\\|udp\\)\\)\\( [[:graph:]]*\\)\$"
-    @mockfalse grep "# allow foo\\( [[:digit:]]\\+\\/\\(tcp\\|udp\\)\\)\$"
-
     load-ufw-docker-function ufw-docker--list
     ufw-docker--list foo
 }
 test-ufw-docker--list-name-assert() {
-    grep "# allow foo\$"
+    grep "# allow foo\\( [[:digit:]]\\+\\/\\(tcp\\|udp\\)\\)\\?\$"
 }
 
 test-ufw-docker--list-name-udp() {
@@ -612,7 +397,7 @@ test-ufw-docker--list-name-udp() {
     ufw-docker--list foo "" udp
 }
 test-ufw-docker--list-name-udp-assert() {
-    grep "# allow foo\\( [[:digit:]]\\+\\/\\(tcp\\|udp\\)\\)\\( [[:graph:]]*\\)\$"
+    grep "# allow foo\\( [[:digit:]]\\+\\/\\(tcp\\|udp\\)\\)\\?\$"
 }
 
 
@@ -622,7 +407,7 @@ test-ufw-docker--list-name-80() {
     ufw-docker--list foo 80
 }
 test-ufw-docker--list-name-80-assert() {
-    grep "# allow foo\\( 80\\/tcp\\)\\( [[:graph:]]*\\)\$"
+    grep "# allow foo\\( 80\\/tcp\\)\\?\$"
 }
 
 
@@ -632,29 +417,7 @@ test-ufw-docker--list-name-80-udp() {
     ufw-docker--list foo 80 udp
 }
 test-ufw-docker--list-name-80-udp-assert() {
-    grep "# allow foo\\( 80\\/udp\\)\\( [[:graph:]]*\\)\$"
-}
-
-
-test-ufw-docker--list-grep-without-network() {
-    @mocktrue ufw status numbered
-    load-ufw-docker-function ufw-docker--list
-    ufw-docker--list foo 80 udp
-}
-test-ufw-docker--list-grep-without-network-assert() {
-    grep "# allow foo\\( 80\\/udp\\)\\( [[:graph:]]*\\)\$"
-}
-
-
-test-ufw-docker--list-grep-without-network-and-port() {
-    @mocktrue ufw status numbered
-    @mockfalse grep "# allow foo\\( 80\\/tcp\\)\\( [[:graph:]]*\\)\$"
-
-    load-ufw-docker-function ufw-docker--list
-    ufw-docker--list foo 80
-}
-test-ufw-docker--list-grep-without-network-and-port-assert() {
-    grep "# allow foo\\( 80\\/tcp\\)\$"
+    grep "# allow foo\\( 80\\/udp\\)\\?\$"
 }
 
 
@@ -671,7 +434,7 @@ test-ufw-docker--list-number-assert() {
 
 test-ufw-docker--delete-empty-result() {
     @mock ufw-docker--list-number webapp 80 tcp === @stdout ""
-    @mockpipe sort -rn
+    @mock sort -rn
 
     load-ufw-docker-function ufw-docker--delete
     ufw-docker--delete webapp 80 tcp
@@ -683,7 +446,7 @@ test-ufw-docker--delete-empty-result-assert() {
 
 test-ufw-docker--delete-all() {
     @mock ufw-docker--list-number webapp 80 tcp === @stdout 5 8 9
-    @mockpipe sort -rn
+    @mock sort -rn
 
     load-ufw-docker-function ufw-docker--delete
     ufw-docker--delete webapp 80 tcp
diff --git a/ufw-docker b/ufw-docker
index ad0c8e6..197c2d7 100755
--- a/ufw-docker
+++ b/ufw-docker
@@ -5,50 +5,28 @@ set -euo pipefail
 LANG=en_US.UTF-8
 LANGUAGE=en_US:
 LC_ALL=en_US.UTF-8
-PATH="/bin:/usr/bin:/sbin:/usr/sbin:/snap/bin/"
+PATH="/bin:/usr/bin:/sbin:/usr/sbin"
 
 GREP_REGEXP_INSTANCE_NAME="[-_.[:alnum:]]\\+"
 DEFAULT_PROTO=tcp
 
 ufw_docker_agent=ufw-docker-agent
-ufw_docker_agent_image="${UFW_DOCKER_AGENT_IMAGE:-chaifeng/${ufw_docker_agent}:250702-nf_tables}"
-
-if [[ "${ufw_docker_agent_image}" = *-@(legacy|nf_tables) ]]; then
-    if iptables --version | grep -F '(legacy)' &>/dev/null; then
-        ufw_docker_agent_image="${ufw_docker_agent_image%-*}-legacy"
-    else
-        ufw_docker_agent_image="${ufw_docker_agent_image%-*}-nf_tables"
-    fi
-fi
-
-test -n "$ufw_docker_agent_image"
+ufw_docker_agent_image="${UFW_DOCKER_AGENT_IMAGE:-chaifeng/${ufw_docker_agent}:200812}"
 
 function ufw-docker--status() {
-    ufw-docker--list "$GREP_REGEXP_INSTANCE_NAME\(/v6\)\?"
+    ufw-docker--list "$GREP_REGEXP_INSTANCE_NAME"
 }
 
 function ufw-docker--list() {
     local INSTANCE_NAME="$1"
     local INSTANCE_PORT="${2:-}"
     local PROTO="${3:-${DEFAULT_PROTO}}"
-    local NETWORK="${4:-}"
-    local params_count="$#"
 
     if [[ -z "$INSTANCE_PORT" ]]; then
         INSTANCE_PORT="[[:digit:]]\\+"
         PROTO="\\(tcp\\|udp\\)"
     fi
-
-    if [[ -z "$NETWORK" ]]; then
-       NETWORK="[[:graph:]]*"
-    fi
-
-    local ufw_output
-    ufw_output="$(ufw status numbered)"
-
-    grep "# allow ${INSTANCE_NAME}\\( ${INSTANCE_PORT}\\/${PROTO}\\)\\( ${NETWORK}\\)\$" <<< "$ufw_output" ||
-        grep "# allow ${INSTANCE_NAME}\\( ${INSTANCE_PORT}\\/${PROTO}\\)\$" <<< "$ufw_output" ||
-        grep "# allow ${INSTANCE_NAME}\$" <<< "$ufw_output"
+    ufw status numbered | grep "# allow ${INSTANCE_NAME}\\( ${INSTANCE_PORT}\\/${PROTO}\\)\\?\$"
 }
 
 function ufw-docker--list-number() {
@@ -66,15 +44,13 @@ function ufw-docker--allow() {
     local INSTANCE_NAME="$1"
     local INSTANCE_PORT="$2"
     local PROTO="$3"
-    local NETWORK="${4:-}"
-    local NETWORK_ADDRESSES PORT_PROTO_LIST PROT_PROTO IP SUFFIX
 
     docker inspect "$INSTANCE_NAME" &>/dev/null ||
         die "Docker instance \"$INSTANCE_NAME\" doesn't exist."
 
-    mapfile -t NETWORK_ADDRESSES < <(docker inspect --format '{{range $name, $net := .NetworkSettings.Networks}}{{if $net.IPAddress}}{{$name}} {{$net.IPAddress}}{{"\n"}}{{end}}{{if $net.GlobalIPv6Address}}{{$name}} {{$net.GlobalIPv6Address}}{{"\n"}}{{end}}{{end}}' "$INSTANCE_NAME" 2>/dev/null | remove_blank_lines)
+    mapfile -t INSTANCE_IP_ADDRESSES < <(docker inspect --format='{{range .NetworkSettings.Networks}}{{.IPAddress}}{{"\n"}}{{end}}' "$INSTANCE_NAME" 2>/dev/null | remove_blank_lines)
 
-    [[ -z "${NETWORK_ADDRESSES:-}" ]] && die "Could not find a running instance \"$INSTANCE_NAME\"."
+    [[ -z "${INSTANCE_IP_ADDRESSES:-}" ]] && die "Could not find a running instance \"$INSTANCE_NAME\"."
 
     mapfile -t PORT_PROTO_LIST < <(docker inspect --format='{{range $p, $conf := .NetworkSettings.Ports}}{{with $conf}}{{$p}}{{"\n"}}{{end}}{{end}}' "$INSTANCE_NAME" | remove_blank_lines)
 
@@ -83,26 +59,19 @@ function ufw-docker--allow() {
         return 1
     fi
 
-    local count=0
+    RETVAL=1
     for PORT_PROTO in "${PORT_PROTO_LIST[@]}"; do
         if [[ -z "$INSTANCE_PORT" || "$PORT_PROTO" = "${INSTANCE_PORT}/${PROTO}" ]]; then
-            for item in "${NETWORK_ADDRESSES[@]}"; do
-                INSTANCE_NETWORK="${item% *}"
-                IP="${item#* }"
-                if [[ -n "$NETWORK" ]] && [[ "$NETWORK" != "$INSTANCE_NETWORK" ]]; then
-                    continue
-                fi
-                if [[ "$IP" = *:* ]]; then SUFFIX="/v6"; else SUFFIX=""; fi
-                ufw-docker--add-rule "${INSTANCE_NAME}${SUFFIX}" "$IP" "${PORT_PROTO%/*}" "${PORT_PROTO#*/}" "${INSTANCE_NETWORK}"
-                (( ++count ))
+            for IP in "${INSTANCE_IP_ADDRESSES[@]}"; do
+                ufw-docker--add-rule "$INSTANCE_NAME" "$IP" "${PORT_PROTO%/*}" "${PORT_PROTO#*/}"
+                RETVAL="$?"
             done
         fi
     done
-    if [[ "$count" -eq 0 ]]; then
+    if [[ "$RETVAL" -ne 0 ]]; then
         err "Fail to add rule(s), cannot find the published port ${INSTANCE_PORT}/${PROTO} of instance \"${INSTANCE_NAME}\" or cannot update outdated rule(s)."
-        return 1
     fi
-    return 0
+    return "$RETVAL"
 }
 
 function ufw-docker--add-service-rule() {
@@ -123,11 +92,10 @@ function ufw-docker--add-rule() {
     local INSTANCE_IP_ADDRESS="$2"
     local PORT="$3"
     local PROTO="$4"
-    local NETWORK="${5:-}"
 
     declare comment
 
-    echo "allow ${INSTANCE_NAME} ${PORT}/${PROTO} ${NETWORK}"
+    echo "allow ${INSTANCE_NAME} ${PORT}/${PROTO}"
     typeset -a UFW_OPTS
     UFW_OPTS=(route allow proto "${PROTO}"
               from any to "$INSTANCE_IP_ADDRESS")
@@ -136,15 +104,12 @@ function ufw-docker--add-rule() {
         UFW_OPTS+=(port "${PORT}")
         comment="$comment ${PORT}/${PROTO}"
     }
-    [[ -n "$NETWORK" ]] && {
-        comment="$comment ${NETWORK}"
-    }
     UFW_OPTS+=(comment "$comment")
 
-    if ufw-docker--list "$INSTANCE_NAME" "$PORT" "$PROTO" "$NETWORK" &>/dev/null; then
+    if ufw-docker--list "$INSTANCE_NAME" "$PORT" "$PROTO" &>/dev/null; then
         ufw --dry-run "${UFW_OPTS[@]}" | grep "^Skipping" && return 0
         err "Remove outdated rule."
-        ufw-docker--delete "$INSTANCE_NAME" "$PORT" "$PROTO" "$NETWORK"
+        ufw-docker--delete "$INSTANCE_NAME" "$PORT" "$PROTO"
     fi
     echo ufw "${UFW_OPTS[@]}"
     ufw "${UFW_OPTS[@]}"
@@ -286,7 +251,6 @@ function ufw-docker--service-delete() {
     docker service update --update-parallelism=0 \
            --env-add ufw_docker_agent_image="${ufw_docker_agent_image}" \
            --env-add "${service_env}" \
-           --env-add DEBUG="${DEBUG-}" \
            --image "${ufw_docker_agent_image}" \
            "${ufw_docker_agent}"
 }
@@ -296,78 +260,36 @@ function ufw-docker--raw-command() {
 }
 
 after_rules="/etc/ufw/after.rules"
-after6_rules="/etc/ufw/after6.rules"
 
 function ufw-docker--check() {
-    err "\\n########## iptables -n -L DOCKER-USER ##########"
-    iptables -n -L DOCKER-USER
+  err "\\n########## iptables -n -L DOCKER-USER ##########"
+  iptables -n -L DOCKER-USER
 
-    err "\\n\\n########## diff $after_rules ##########"
-    ufw-docker--check-install "$@" && err "\\nCheck IPv4 firewall rules done."
-
-    if command -v ip6tables >/dev/null 2>&1; then
-        err "\\n########## ip6tables -n -L DOCKER-USER ##########"
-        ip6tables -n -L DOCKER-USER
-
-        err "\\n\\n########## diff $after6_rules ##########"
-        ufw-docker--check-install_ipv6 "$@" && err "\\nCheck IPv6 firewall rules done."
-    fi
+  err "\\n\\n########## diff $after_rules ##########"
+  ufw-docker--check-install && err "\\nCheck done."
 }
 
 declare -a files_to_be_deleted
 
 function rm-on-exit() {
-    [[ $# -gt 0 ]] && files_to_be_deleted+=("$@")
+  [[ $# -gt 0 ]] && files_to_be_deleted+=("$@")
 }
 
 function on-exit() {
-    for file in "${files_to_be_deleted[@]:-}"; do
-        [[ -f "$file" ]] && rm -r "$file"
-    done
-    files_to_be_deleted=()
+  for file in "${files_to_be_deleted[@]:-}"; do
+    [[ -f "$file" ]] && rm -r "$file"
+  done
+  files_to_be_deleted=()
 }
 
 trap on-exit EXIT INT TERM QUIT ABRT ERR
 
-function ufw-docker--list-docker-subnets() {
-    local ipversion="$1"
-    shift || true
-    if [[ -z "${1-}" ]]; then
-        docker network ls --format '{{.ID}}' |
-        while read -r net; do
-            docker network inspect "$net" --format '{{range .IPAM.Config}}{{.Subnet}}{{"\n"}}{{end}}'
-        done
-    else
-        printf "%s\n" "$@"
-     fi |
-        while read -r cidr; do
-            if [[ "${ipversion}" = "IPv4" && "$cidr" = *.* ]] || [[ "${ipversion}" = "IPv6" && "$cidr" = *:* ]]
-            then echo "$cidr"
-            fi
-        done |
-        sort
-}
-
 function ufw-docker--check-install() {
-    declare -a cidr_list
-    declare cidr
-    if [[ -z "${1-}" ]]; then
-        cidr_list=(10.0.0.0/8 172.16.0.0/12 192.168.0.0/16)
-    elif [[ "${1-}" = '--docker-subnets' ]]; then
-        shift || true
-        mapfile -t cidr_list < <(ufw-docker--list-docker-subnets IPv4 "$@")
-    fi
-    if [[ -z "${cidr_list:-}" ]]; then
-        err "ERROR: Could not find any IPv4 subnets used by docker engine\n"
-        exit 1
-    fi
+	after_rules_tmp="${after_rules_tmp:-$(mktemp)}"
+	rm-on-exit "$after_rules_tmp"
 
-    after_rules_tmp="${after_rules_tmp:-$(mktemp)}"
-    rm-on-exit "$after_rules_tmp"
-
-    sed "/^# BEGIN UFW AND DOCKER/,/^# END UFW AND DOCKER/d" "$after_rules" > "$after_rules_tmp"
-    {
-        cat <<-\EOF
+	sed "/^# BEGIN UFW AND DOCKER/,/^# END UFW AND DOCKER/d" "$after_rules" > "$after_rules_tmp"
+	>> "${after_rules_tmp}" cat <<-\EOF
 	# BEGIN UFW AND DOCKER
 	*filter
 	:ufw-user-forward - [0:0]
@@ -375,26 +297,18 @@ function ufw-docker--check-install() {
 	:DOCKER-USER - [0:0]
 	-A DOCKER-USER -j ufw-user-forward
 
-	EOF
-
-        for cidr in "${cidr_list[@]}"; do
-	          echo "-A DOCKER-USER -j RETURN -s ${cidr}"
-        done
-
-        cat <<-\EOF
+	-A DOCKER-USER -j RETURN -s 10.0.0.0/8
+	-A DOCKER-USER -j RETURN -s 172.16.0.0/12
+	-A DOCKER-USER -j RETURN -s 192.168.0.0/16
 
 	-A DOCKER-USER -p udp -m udp --sport 53 --dport 1024:65535 -j RETURN
 
-	EOF
-
-        for cidr in "${cidr_list[@]}"; do
-	          echo "-A DOCKER-USER -j ufw-docker-logging-deny -p tcp -m tcp --tcp-flags FIN,SYN,RST,ACK SYN -d ${cidr}"
-        done
-        for cidr in "${cidr_list[@]}"; do
-	          echo "-A DOCKER-USER -j ufw-docker-logging-deny -p udp -m udp --dport 0:32767 -d ${cidr}"
-        done
-
-        cat <<-\EOF
+	-A DOCKER-USER -j ufw-docker-logging-deny -p tcp -m tcp --tcp-flags FIN,SYN,RST,ACK SYN -d 192.168.0.0/16
+	-A DOCKER-USER -j ufw-docker-logging-deny -p tcp -m tcp --tcp-flags FIN,SYN,RST,ACK SYN -d 10.0.0.0/8
+	-A DOCKER-USER -j ufw-docker-logging-deny -p tcp -m tcp --tcp-flags FIN,SYN,RST,ACK SYN -d 172.16.0.0/12
+	-A DOCKER-USER -j ufw-docker-logging-deny -p udp -m udp --dport 0:32767 -d 192.168.0.0/16
+	-A DOCKER-USER -j ufw-docker-logging-deny -p udp -m udp --dport 0:32767 -d 10.0.0.0/8
+	-A DOCKER-USER -j ufw-docker-logging-deny -p udp -m udp --dport 0:32767 -d 172.16.0.0/12
 
 	-A DOCKER-USER -j RETURN
 
@@ -404,159 +318,55 @@ function ufw-docker--check-install() {
 	COMMIT
 	# END UFW AND DOCKER
 	EOF
-    } >> "${after_rules_tmp}"
-    diff -u --color=auto "$after_rules" "$after_rules_tmp"
-}
 
-function ufw-docker--check-install_ipv6() {
-    declare -a cidr6_list
-    declare cidr
-    if [[ -z "${1-}" ]]; then
-        cidr6_list=(fd00::/8)
-    elif [[ "${1-}" = '--docker-subnets' ]]; then
-        shift || true
-        mapfile -t cidr6_list < <(ufw-docker--list-docker-subnets IPv6 "$@")
-    fi
-    if [[ -z "${cidr6_list:-}" ]]; then
-        err "INFO: Could not find any IPv6 subnets used by docker engine, will disable IPv6 support.\n"
-        return 0
-    fi
-
-    after6_rules_tmp="${after6_rules_tmp:-$(mktemp)}"
-    rm-on-exit "$after6_rules_tmp"
-
-    sed "/^# BEGIN UFW AND DOCKER/,/^# END UFW AND DOCKER/d" "$after6_rules" > "$after6_rules_tmp"
-    {
-        cat <<-\EOF
-	# BEGIN UFW AND DOCKER
-	*filter
-	:ufw6-user-forward - [0:0]
-	:ufw6-docker-logging-deny - [0:0]
-	:DOCKER-USER - [0:0]
-	-A DOCKER-USER -j ufw6-user-forward
-
-	EOF
-
-        for cidr in "${cidr6_list[@]}"; do
-	          echo "-A DOCKER-USER -j RETURN -s ${cidr}"
-        done
-
-        cat <<-\EOF
-	-A DOCKER-USER -p udp -m udp --sport 53 --dport 1024:65535 -j RETURN
-	EOF
-
-        for cidr in "${cidr6_list[@]}"; do
-	          echo "-A DOCKER-USER -j ufw6-docker-logging-deny -p tcp -m tcp --tcp-flags FIN,SYN,RST,ACK SYN -d ${cidr}"
-	          echo "-A DOCKER-USER -j ufw6-docker-logging-deny -p udp -m udp --dport 0:32767 -d ${cidr}"
-        done
-
-        cat <<-\EOF
-
-	-A DOCKER-USER -j RETURN
-
-	-A ufw6-docker-logging-deny -m limit --limit 3/min --limit-burst 10 -j LOG --log-prefix "[UFW DOCKER BLOCK] "
-	-A ufw6-docker-logging-deny -j DROP
-
-	COMMIT
-	# END UFW AND DOCKER
-	EOF
-    } >> "${after6_rules_tmp}"
-    diff -u --color=auto "$after6_rules" "$after6_rules_tmp"
+	diff -u --color=auto "$after_rules" "$after_rules_tmp"
 }
 
 function ufw-docker--install() {
-    local changed=false
-    if ! ufw-docker--check-install "$@"; then
-        changed=true
-        local after_rules_bak
-        after_rules_bak="${after_rules}-ufw-docker~$(date '+%Y-%m-%d-%H%M%S')~"
-        err "\\nBacking up $after_rules to $after_rules_bak"
-        cp "$after_rules" "$after_rules_bak"
-        cat "$after_rules_tmp" > "$after_rules"
+  if ! ufw-docker--check-install; then
+	  local after_rules_bak
+    after_rules_bak="${after_rules}-ufw-docker~$(date '+%Y-%m-%d-%H%M%S')~"
+	  err "\\nBacking up $after_rules to $after_rules_bak"
+	  cp "$after_rules" "$after_rules_bak"
+	  cat "$after_rules_tmp" > "$after_rules"
+    err "Please restart UFW service manually by using the following command:"
+    if type systemctl &>/dev/null; then
+      err "    sudo systemctl restart ufw"
+    else
+      err "    sudo service ufw restart"
     fi
-
-    if ! ufw-docker--check-install_ipv6 "$@"; then
-        changed=true
-        local after6_rules_bak
-        after6_rules_bak="${after6_rules}-ufw-docker~$(date '+%Y-%m-%d-%H%M%S')~"
-        err "\\nBacking up $after6_rules to $after6_rules_bak"
-        cp "$after6_rules" "$after6_rules_bak"
-        cat "$after6_rules_tmp" > "$after6_rules"
-    fi
-
-    if "$changed"; then
-        err "Please restart UFW service manually by using the following command:"
-        if type systemctl &>/dev/null; then
-            err "    sudo systemctl restart ufw"
-        else
-            err "    sudo service ufw restart"
-        fi
-    fi
-}
-
-function ufw-docker--install--help() {
-    cat <<HELP
-ufw-docker $1 --docker-subnets [SUBNET1 SUBNET2 …]
-
-Specify which subnets should be used when configuring firewall rules for Docker containers and any allowed networks that communicate with containers.
-
-  - If this option is not provided, only standard private LAN subnets are used (RFC1918 for IPv4 and fd00::/8 for IPv6).
-  - If --docker-subnets is given without any arguments, all Docker network subnets will be automatically detected and used.
-  - If one or more subnets are specified, these subnets will be used for firewall rules, and they can include any networks that need to communicate with containers—not just the subnets configured by the Docker engine.
-    You can specify multiple subnets separated by spaces (each in CIDR format).
-
-Examples:
-  - ufw-docker $1
-    Use only standard private subnets (default behavior).
-      - IPv4 subnets: 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16
-      - IPv6 subnet: fd00::/8
-
-  - ufw-docker $1 --docker-subnets
-    Auto-detect and use all Docker network subnets.
-
-  - ufw-docker $1 --docker-subnets 10.207.0.0/16 192.168.207.0/24 fd00:cf::/64
-    Use only the specified subnets, including those outside of Docker’s own configuration, for all networks that should be allowed to communicate with containers.
-HELP
+  fi
 }
 
 function ufw-docker--help() {
-    cat <<-EOF >&2
+	cat <<-EOF >&2
 	Usage:
-	  ufw-docker <list|allow> [docker-instance-id-or-name [port[/tcp|/udp]] [network]]
-	  ufw-docker delete allow [docker-instance-id-or-name [port[/tcp|/udp]] [network]]
+	  ufw-docker <list|allow> [docker-instance-id-or-name [port[/tcp|/udp]]]
+	  ufw-docker delete allow [docker-instance-id-or-name [port[/tcp|/udp]]]
 
 	  ufw-docker service allow <swarm-service-id-or-name <port</tcp|/udp>>>
 	  ufw-docker service delete allow <swarm-service-id-or-name>
 
-	  ufw-docker <install|check> [--docker-subnets [SUBNET0 SUBNET1 ...]]
-
 	  ufw-docker <status|install|check|help>
 
 	Examples:
 	  ufw-docker help
-	  ufw-docker check --help
-	  ufw-docker install --help
 
-	  ufw-docker check                         # Check the installation of firewall rules
-	  ufw-docker check --docker-subnets        # Auto-detect and use all Docker network subnets
-	  ufw-docker check --docker-subnets 192.168.207.0/24 10.207.0.0/16 fd00:cf::/64
-
-	  ufw-docker install                      # Install firewall rules
-	  ufw-docker install --docker-subnets     # Auto-detect and use all Docker network subnets
-	  ufw-docker install --docker-subnets 192.168.207.0/24 10.207.0.0/16 fd00:cf::/64
+	  ufw-docker check           # Check the installation of firewall rules
+	  ufw-docker install         # Install firewall rules
 
 	  ufw-docker status
 
 	  ufw-docker list httpd
 
+
 	  ufw-docker allow httpd
 	  ufw-docker allow httpd 80
 	  ufw-docker allow httpd 80/tcp
-	  ufw-docker allow httpd 80/tcp default
 
 	  ufw-docker delete allow httpd
 	  ufw-docker delete allow httpd 80/tcp
-          ufw-docker delete allow httpd 80/tcp default
+
 
 	  ufw-docker service allow httpd 80/tcp
 
@@ -580,11 +390,7 @@ function die() {
 # __main__
 
 if ! ufw status 2>/dev/null | grep -Fq "Status: active" ; then
-    die "UFW is disabled or you are not root user, or mismatched iptables legacy/nf_tables, current $(iptables --version)"
-fi
-
-if ! docker -v &> /dev/null; then
-  die "Docker executable not found."
+    die "UFW is disabled or you are not root user."
 fi
 
 ufw_action="${1:-help}"
@@ -612,31 +418,16 @@ case "$ufw_action" in
         if [[ "$INSTANCE_PORT" = */udp ]]; then
             PROTO=udp
         fi
-        shift || true
-
-        NETWORK="${1:-}"
 
         INSTANCE_PORT="${INSTANCE_PORT%/*}"
-        ;;&
-    delete|list)
-        "ufw-docker--$ufw_action" "$INSTANCE_NAME\\(/v6\\)\\?" "$INSTANCE_PORT" "$PROTO" "$NETWORK"
-        ;;
-    allow)
-        "ufw-docker--$ufw_action" "$INSTANCE_NAME" "$INSTANCE_PORT" "$PROTO" "$NETWORK"
+
+        "ufw-docker--$ufw_action" "$INSTANCE_NAME" "$INSTANCE_PORT" "$PROTO"
         ;;
     service|raw-command|add-service-rule)
         shift || true
         "ufw-docker--$ufw_action" "$@"
         ;;
-    install|check)
-        shift || true
-        if [[ "${1-}" = @(help|-h|--help) ]]; then
-            ufw-docker--install--help "$ufw_action"
-            exit
-        fi
-        "ufw-docker--$ufw_action" "$@"
-        ;;
-    status)
+    status|install|check)
         ufw-docker--"$ufw_action"
         ;;
     *)