Scribbles for my bad memory

Background

Yesterday, my PopOS system broke unexpectedly. The refresh install option failed, and attempting to reinstall while preserving the old /var and /home partitions was unsuccessful.

Solution: Fresh Custom Installation

Performed a clean custom installation with:

• /boot/efi - formatted
• / - formatted
• /recovery - formatted

This approach worked successfully, then migrated data from old partitions.

Partition Migration Process

Tools Used

parted --list    # Get partition information
blkid           # Get partition UUIDs

Note: Couldn't stop GDM or enter single-user mode (system would hang). Performed migration on running system instead.

1. Home Partition Migration (/dev/nvme0n1p8)

sudo mv /home /home.bak          # Backup current home
sudo mkdir /home
sudo mount /dev/nvme0n1p8 /home
ls /home                         # Confirm correct partition
sudo blkid /dev/nvme0n1p8       # Get UUID
sudo vi /etc/fstab

Added to /etc/fstab:

UUID=32e4ed56-6ed9-4f14-9585-ffff54f997b2 /home ext4 defaults 0 2

Rebooted to verify system stability.

2. Backup Partition Setup (/dev/nvme0n1p10)

sudo parted --list
sudo blkid /dev/nvme0n1p10
sudo vi /etc/fstab

Added to /etc/fstab:

UUID=8aba0dd5-7058-4036-8a08-fcd1e0e002bc /backup ext4 defaults 0 2

sudo mount -a                   # Test mount configuration

3. Var Partition Migration (/dev/nvme0n1p7)

# Mount old var partition and backup data
sudo mkdir /mnt/var
sudo mount /dev/nvme0n1p7 /mnt/var
sudo tar -czpvf /backup/old-var-backup.tar.gz -C /mnt var

or backup docker/crontabs only

sudo tar -czpvf /backup/old-docker-backup.tar.gz -C /mnt var/lib/docker
sudo tar -czpvf /backup/old-cron-backup.tar.gz -C /mnt var/spool/cron

# Prepare new var partition
sudo umount /mnt/var
sudo mkfs.ext4 /dev/nvme0n1p7   # Format old var partition

# Copy current var data to new partition
sudo mkdir /mnt/new-var
sudo mount /dev/nvme0n1p7 /mnt/new-var
sudo cp -av /var/* /mnt/new-var/

# Update fstab and switch to new partition
sudo blkid /dev/nvme0n1p7
sudo vi /etc/fstab              # Add var partition entry
sudo mv /var /var.old && sudo mkdir /var && sudo mount -a

Restore old var data

# update system
apt update && apt upgrade

sudo apt purge nano # enable vi EDITOR in visudo
sudo apt install curl

# re-enable davidwei ALL=(ALL:ALL) NOPASSWD:ALL

# install docker
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor --yes -o /usr/share/keyrings/docker-archive-keyring.gpg
echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"| sudo tee /etc/apt/sources.list.d/docker.list > /dev/null # add docker apt source
sudo apt update && sudo apt install docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin

# add current user to docker group
sudo usermod -aG docker davidwei

# restore old docker/cron data
# 1. Stop Docker services properly
sudo systemctl stop docker.socket
sudo systemctl stop docker.service

# 2. Extract docker data in one command
sudo tar -xzpf /backup/old-var-backup.tar.gz -C / var/lib/docker
sudo tar -xzpf /backup/old-var-backup.tar.gz -C / var/spoon/cron

or if there are spearate backups:

sudo tar -xzpf /backup/old-var-backup.tar.gz -C / var/lib/docker
sudo tar -xzpf /backup/old-var-backup.tar.gz -C / var/spool/cron/crontabs

sudo chmod og+rx /var/spool/cron/crontabs/
sudo chown davidwei:davidwei /var/spool/cron/crontabs/davidwei
sudo systemctl restart cron

# 3. Start Docker services
sudo systemctl start docker.service
sudo systemctl start docker.socket

# 4. Verify
docker volume ls
docker images
docker ps -a

# re-install tailscale / set no-expiry / rename to xps / change cloudflare dns to new IP
curl -fsSL https://tailscale.com/install.sh | sh

# re-install google-chrome
sudo dpkg -i ~/Downloads/google-chrome-stable_current_amd64.deb

# reinstall other utils
sudo apt install tree ncdu vim gnome-sushi mc clang ninja-build mesa-utils libgtk-3-dev cmake mysql-client-core-8.0 libstdc++-12-dev build-essential pkg-config htop mc ssh meld

# reinstall fcitx
sudo apt install fcitx5-rime fcitx5-chinese-addons

Key Lessons Learned

• Fresh installation with custom partitioning was more reliable than trying to preserve old partitions during install
• System migration on a running system worked fine when rescue mode wasn't accessible
• Always backup critical data before formatting partitions
• Test each partition mount configuration before proceeding to the next step

Status: Migration completed successfully. System running normally with all data preserved.

Need to share changes from a GitHub PR (even closed ones)? Just add .diff or .patch to the PR URL:

Original URL:

https://github.com/owner/repo/pull/123

For diff format:

https://github.com/owner/repo/pull/123.diff

For patch format:

https://github.com/owner/repo/pull/123.patch

Both work for open, closed, or merged PRs. Perfect for code reviews, investigations, or sharing changes with others.

For LLM/AI analysis: Use .diff format - it's cleaner and more standardized than .patch which includes extra email headers.

Problem

Rider's WinForms Designer locks files, preventing builds. It is super annoying!

Solution

1. File → Settings (Ctrl+Alt+S)
2. Tools → Windows Forms Designer
3. Uncheck "Enable Windows Forms Designer"
4. Apply and restart Rider

Emergency Fix

Kill locked processes:

taskkill /IM dotnet.exe /F

Alternative

Use Visual Studio for form design, Rider for code.

使用 Apache Guacamole 和 PopOS 搭建基于网页浏览器的无客户端远程桌面访问系统的完整指南。

概述

• Guacamole: 基于 Web 的远程桌面网关（HTML5，无需安装客户端软件）
• 目标系统: PopOS 配置 xrdp 服务器
• 访问方式: 任何设备通过浏览器访问
• 支持协议: RDP、VNC、SSH、Telnet、Kubernetes 连接

1. PopOS RDP 服务器配置

安装和配置 xrdp

# 安装 xrdp（比 GNOME 自带的远程桌面更稳定）
sudo apt update
sudo apt install xrdp

# 启动并设置开机自启
sudo systemctl enable xrdp
sudo systemctl start xrdp

# 验证服务状态
sudo systemctl status xrdp

解决 PolicyKit 权限问题

创建文件 /etc/polkit-1/localauthority/50-local.d/45-allow-colord.pkla：

[Allow Colord All Users]
Identity=unix-user:*
Action=org.freedesktop.color-manager.*
ResultAny=no
ResultInactive=no
ResultActive=yes

[Allow PackageKit All Users]
Identity=unix-user:*
Action=org.freedesktop.packagekit.*
ResultAny=no
ResultInactive=no
ResultActive=yes

可选：防火墙配置

# 如果使用 Docker 和局域网 IP，通常不需要开放端口
# 只有需要外部访问时才开放
sudo ufw allow 3389

2. Guacamole Docker 配置

更新的 Docker Compose 配置

services:
  guacdb:
    container_name: guacamoledb
    image: mariadb:10.11
    restart: unless-stopped
    environment:
      MYSQL_ROOT_PASSWORD: 'MariaDBRootPass2024'
      MYSQL_DATABASE: 'guacamole_db'
      MYSQL_USER: 'guacamole_user'
      MYSQL_PASSWORD: 'MariaDBUserPass2024'
    volumes:
      - db-data:/var/lib/mysql
    networks:
      - guacamole-network

  guacd:
    container_name: guacd
    image: guacamole/guacd:1.6.0
    restart: unless-stopped
    devices:
      - /dev/snd:/dev/snd # 映射声音设备
    networks:
      - guacamole-network

  guacamole:
    container_name: guacamole
    image: guacamole/guacamole:1.6.0
    restart: unless-stopped
    ports:
      - "8080:8080"
    environment:
      GUAC_AUDIO: "audio/L16"  # 改用更好的音频格式
      GUAC_AUDIO_RATE: "44100"  # 设置音频采样率
      GUACD_HOSTNAME: "guacd"
      MYSQL_HOSTNAME: "guacdb"
      MYSQL_DATABASE: "guacamole_db"
      MYSQL_USER: "guacamole_user"
      MYSQL_PASSWORD: "MariaDBUserPass2024"
      TOTP_ENABLED: "true"
      WEBAPP_CONTEXT: "ROOT"  # 允许直接通过 http://localhost:8080 访问
    depends_on:
      - guacdb
      - guacd
    networks:
      - guacamole-network

networks:
  guacamole-network:
    driver: bridge

volumes:
  db-data:

数据库初始化

# 1. 创建目录并设置
mkdir guacamole
cd guacamole

# 2. 生成数据库初始化文件
docker run --rm guacamole/guacamole:1.6.0 /opt/guacamole/bin/initdb.sh --mysql > initdb.sql

# 3. 启动服务
docker-compose up -d

# 4. 等待数据库准备就绪
sleep 30

# 5. 导入数据库架构
docker exec -i guacamoledb mysql -u root -pMariaDBRootPass2024 guacamole_db < initdb.sql

# 6. 验证表已创建
docker exec -it guacamoledb mysql -u root -pMariaDBRootPass2024 -e "USE guacamole_db; SHOW TABLES;"

3. Guacamole 配置

初始设置

1. 访问 Guacamole：http://localhost:8080（注意：没有 /guacamole 后缀！）
2. 默认登录：guacadmin / guacadmin
3. 重要：立即更改默认密码

创建 RDP 连接

1. 前往 设置 → 连接 → 新建连接

2. 编辑连接：

   • 名称：PopOS 桌面（或任意名称）
   • 协议：RDP

3. 参数：

   • 主机名：使用实际局域网 IP（例如：192.168.1.100）
   • 端口：3389
   • 用户名：你的 PopOS 用户名
   • 密码：你的 PopOS 密码

4. 可选设置：

   • 安全模式：any 或 rdp
   • 忽略服务器证书：✓（勾选）
   • 禁用身份验证：✓（如果需要）

Guacamole 代理参数

• 通常保持空白（主机名、端口、加密字段）
• 只有在 guacd 运行在不同服务器时才需要配置

4. 关键网络配置说明

⚠️ Docker 网络注意事项

• 在连接主机名中使用 IP 地址，不要用域名
• 如果使用 Tailscale/VPN：使用物理网络 IP，不要用 VPN IP
• 容器 DNS 解析可能指向无法访问的网络
• Docker 可以通过局域网 IP 访问主机端口，无需防火墙规则

IP 地址查找示例

# 查找你的 PopOS IP
ip addr show | grep "inet 192"
# 在 Guacamole 连接中使用这个 IP，不要用 localhost 或域名

5. 测试

验证 RDP 服务

# 在 PopOS 上测试本地 RDP
telnet localhost 3389

测试 Guacamole 连接

1. 登录 Guacamole Web 界面
2. 点击你的连接
3. 应该能在浏览器中看到 PopOS 桌面

故障排除

常见问题

• PolicyKit 密码提示：添加上述 polkit 配置
• 黑屏：在本地popOS上退出登录

调试命令

# 检查 xrdp 状态
sudo systemctl status xrdp

# 检查端口监听
sudo netstat -tlnp | grep 3389

# 检查 Guacamole 日志
docker logs guacamole
docker logs guacd

# 重启 PolicyKit（如果需要）
sudo systemctl restart polkitd
# 或者简单重启
sudo reboot

生产环境增强

Nginx 反向代理（可选）

添加 HTTPS 和自定义域名访问，支持 WebSocket：

server {
    listen 443 ssl;
    server_name your-domain.com;
    
    location / {
        proxy_pass http://localhost:8080;
        proxy_buffering off;
        proxy_http_version 1.1;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection $http_connection;
        access_log off;
    }
}

性能说明

• 优秀适用场景：办公工作、编程、系统管理
• 良好适用场景：局域网内一般桌面使用
• 不适合场景：高帧率游戏、视频播放
• 最佳环境：低延迟的本地网络

支持的协议

• RDP：Windows/Linux 远程桌面
• VNC：跨平台图形界面访问
• SSH：终端访问和文件传输
• Telnet：传统终端协议
• Kubernetes：容器编排访问

安全考虑

• 更改 Guacamole 默认密码 （问题不大，有二次验证）
• 使用 HTTPS（添加反向代理）

实用价值

通过这个配置，你可以：

• 在任何地方用任何设备（手机、平板、电脑）通过浏览器访问你的桌面
• 统一的 Web 入口管理所有远程连接
• 无需在每个设备安装各种客户端软件
• 搭建个人的"云工作台"

本配置已经在 PopOS 22.04 上通过测试

主要参考来源：

• Jeppson Tech Blog

A quick guide to set up clientless remote desktop access via web browser using Apache Guacamole and PopOS.

Overview

• Guacamole: Web-based remote desktop gateway (HTML5, no client software needed)
• Target: PopOS with xrdp server
• Access: Any device with a web browser
• Supports: RDP, VNC, SSH, Telnet, Kubernetes connections

1. PopOS RDP Server Setup

Install and Configure xrdp

# Install xrdp (more reliable than GNOME Remote Desktop)
sudo apt update
sudo apt install xrdp

# Start and enable service
sudo systemctl enable xrdp
sudo systemctl start xrdp

# Verify service
sudo systemctl status xrdp
sudo netstat -tlnp | grep 3389

Fix PolicyKit Permission Issues

Create /etc/polkit-1/localauthority/50-local.d/45-allow-colord.pkla:

[Allow Colord All Users]
Identity=unix-user:*
Action=org.freedesktop.color-manager.*
ResultAny=no
ResultInactive=no
ResultActive=yes

[Allow PackageKit All Users]
Identity=unix-user:*
Action=org.freedesktop.packagekit.*
ResultAny=no
ResultInactive=no
ResultActive=yes

Optional: Firewall Configuration

# Usually NOT needed if using Docker with LAN IP
# Only open if external access required
sudo ufw allow 3389

2. Guacamole Docker Setup

Updated Docker Compose Configuration

services:
  guacdb:
    container_name: guacamoledb
    image: mariadb:10.11
    restart: unless-stopped
    environment:
      MYSQL_ROOT_PASSWORD: 'MariaDBRootPass2024'
      MYSQL_DATABASE: 'guacamole_db'
      MYSQL_USER: 'guacamole_user'
      MYSQL_PASSWORD: 'MariaDBUserPass2024'
    volumes:
      - db-data:/var/lib/mysql
    networks:
      - guacamole-network

  guacd:
    container_name: guacd
    image: guacamole/guacd:1.6.0
    restart: unless-stopped
    networks:
      - guacamole-network

  guacamole:
    container_name: guacamole
    image: guacamole/guacamole:1.6.0
    restart: unless-stopped
    ports:
      - "8080:8080"
    environment:
      GUACD_HOSTNAME: "guacd"
      MYSQL_HOSTNAME: "guacdb"
      MYSQL_DATABASE: "guacamole_db"
      MYSQL_USER: "guacamole_user"
      MYSQL_PASSWORD: "MariaDBUserPass2024"
      TOTP_ENABLED: "true"
      WEBAPP_CONTEXT: "ROOT"  # Access via http://localhost:8080
    depends_on:
      - guacdb
      - guacd
    networks:
      - guacamole-network

networks:
  guacamole-network:
    driver: bridge

volumes:
  db-data:

Database Initialization (Correct Method)

# 1. Create directory and setup
mkdir guacamole
cd guacamole

# 2. Generate database initialization file
docker run --rm guacamole/guacamole:1.6.0 /opt/guacamole/bin/initdb.sh --mysql > initdb.sql

# 3. Start services
docker-compose up -d

# 4. Wait for database to be ready
sleep 30

# 5. Import database schema (no docker cp needed!)
docker exec -i guacamoledb mysql -u root -pMariaDBRootPass2024 guacamole_db < initdb.sql

# 6. Verify tables created
docker exec -it guacamoledb mysql -u root -pMariaDBRootPass2024 -e "USE guacamole_db; SHOW TABLES;"

3. Guacamole Configuration

Initial Setup

1. Access Guacamole: http://localhost:8080 (note: no /guacamole suffix!)
2. Default login: guacadmin / guacadmin
3. Important: Change default password immediately

Create RDP Connection

1. Go to Settings → Connections → New Connection

2. Edit Connection:

   • Name: PopOS Desktop (or any name)
   • Protocol: RDP

3. Parameters:

   • Hostname: Use actual LAN IP (e.g., 192.168.1.100)
   • Port: 3389
   • Username: Your PopOS username
   • Password: Your PopOS password

4. Optional Settings:

   • Security mode: any or rdp
   • Ignore server certificate: ✓ (check)
   • Disable authentication: ✓ (if needed)

Guacamole Proxy Parameters

• Usually leave empty (Hostname, Port, Encryption fields)
• Only configure if guacd runs on different server

4. Critical Network Configuration Notes

⚠️ Docker Networking Gotchas

• Use IP addresses, not domain names in connection hostname
• If using Tailscale/VPN: Use physical network IP, not VPN IP
• Container DNS resolution may point to unreachable networks
• Docker can access host ports via LAN IP without firewall rules

Example IP Discovery

# Find your PopOS IP
ip addr show | grep "inet 192"
# Use this IP in Guacamole connection, not localhost or domain names

5. Testing

Verify RDP Service

# On PopOS, test local RDP
telnet localhost 3389

Test Guacamole Connection

1. Login to Guacamole web interface
2. Click your connection
3. Should see PopOS desktop in browser

Troubleshooting

Common Issues

• "Non-numeric character in element length": Version mismatch or network issue
• "Connection refused": Check xrdp service and firewall
• PolicyKit password prompts: Add polkit configuration above
• Black screen: Try different security mode settings
• Slow performance: Normal on high-latency networks, excellent on LAN

Debug Commands

# Check xrdp status
sudo systemctl status xrdp

# Check port listening
sudo netstat -tlnp | grep 3389

# Check Guacamole logs
docker logs guacamole
docker logs guacd

# Restart PolicyKit (if needed)
sudo systemctl restart polkitd
# Or simply reboot
sudo reboot

Production Enhancements

Nginx Reverse Proxy (Optional)

Add HTTPS and custom domain access:

server {
    listen 443 ssl;
    server_name your-domain.com;
    
    location / {
        proxy_pass http://localhost:8080;
		proxy_buffering off;
		proxy_http_version 1.1;
		proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
		proxy_set_header Upgrade $http_upgrade;
		proxy_set_header Connection $http_connection;
		access_log off;
    }
}

Performance Notes

• Excellent for: Office work, programming, system administration
• Good for: General desktop use on LAN
• Not ideal for: High-framerate gaming, video streaming
• Best on: Local network with low latency

Supported Protocols

• RDP: Windows/Linux remote desktop
• VNC: Cross-platform graphical access
• SSH: Terminal access with file transfer
• Telnet: Legacy terminal protocol
• Kubernetes: Container orchestration access

Security Considerations

• Change default Guacamole passwords
• Use HTTPS in production (add reverse proxy)
• Consider VPN access for external connections
• Regularly update Docker images
• PolicyKit configuration limits privilege escalation

Setup tested on PopOS 22.04 with Guacamole 1.6.0 via Docker

Key Sources:

• Jeppson Tech Blog
• Docker best practices and real-world testing