Privacy Policy — yeoyou sync

Sun, 07 Jun 2026 02:00:00 +0000

Last updated: June 2026

Summary

yeoyou sync does not collect, store, or transmit any personal data to us or any third party.

What we collect

Nothing. yeoyou sync has no accounts, no analytics, no crash reporting, and no remote servers operated by us.

All data stays on your device and your own home server.

What the app accesses

Permission	Purpose	Sent to
Photos & Videos	Read files to back up	Your home server only
Wi-Fi state	Check connection before syncing	Never transmitted
Internet	Transfer files to your server	Your home server only

Your files are sent directly from your phone to the server you configured. We never see them.

Data stored on your device

Server connection info (IP address, alias) — stored locally in the app database
List of already-synced files — stored locally to avoid re-uploading

This data never leaves your device except to your own server.

Third-party services

None. yeoyou sync does not use any third-party SDKs, analytics, or advertising libraries.

Children’s privacy

yeoyou sync does not knowingly collect any information from children under 13.

Changes to this policy

If we make material changes, we will update the “Last updated” date above.

Contact

developer@yeoyou.net

Setting up Windows for developers with WSL2

Thu, 10 Sep 2020 13:29:21 +0000

Many developers use Mac. That would be for building iOS apps. But there are more competetive laptops with Windows. If you do not need to build iOS apps, Windows is actually a great option for developing, thanks to WSL2. Following this article, you can have a professional development environment without a hitch.

This includes…

Git, Git bash
Windows Terminal
WSL2
- Using Linux GUI apps
- Ssh to WSL
Docker
VSCode
Defender Antivirus Exclusion

Windows version and build

Wnd+R, type winver, enter will give you the version info like above. If you have already version 2004 (OS build 19041), you are ready to go.

May 2020 update (version 2004 or build 19041) will support WSL2 and Docker will use WSL backend as a docker engine by default. Windows Home edition is also okay since you can now use Docker.

If your Windows does not show 2004 update for some reason, try this link to update.

Developer mode

Symlinks needs Administrator privilege or developer mode.

A git repo with symlinks will needs this

Find more about using Symlinks in Windows

Git and Git-bash

Now git is a must have when you develop.

Install Git with Git bash

Let’s download here and install or update if you have already

C:\>git update-git-for-windows

If you don’t mind overriding DOS command, you can use bash command in command window

Choose autocrlf as input

and enable symlinks while installing

** symlinks need developer mode or administrator

Don’t worry if you missed the symlink setting. You can set anytime later

C:\>git config --global core.autocrlf input
C:\>git config --global core.symlinks true

Don’t forget to set your info

C:\>git config --global user.name "Your Name"
C:\>git config --global user.email "your-email-addr@your.domain"

About autoclrf

Should be input.

Converting LF to CRLF when checking out might seem to be nice but most files can be used in docker when you develop. And it will complain about CRLF.

Don’t worry about LF only files unless you are using Notepad.

Setting up RSA key

Github, Gitlab or Bitbucket (or more) use RSA key for authentication.

If you have your public key registered to the git service, you don’t have to provide username and password.

C:\>ssh-keygen -t RSA -b 2048

and enter a few times to answer using default value

C:\>type %USERPROFILE%\.ssh\id_rsa.pub

and copy paste the public key to your git service.

This is not only for Windows but you will need in in WSL as well. After install WSL, do that again in WSL side.

Windows Terminal

In MS Store, you can install Windows Terminal

CamingoCode font

I like CamingoCode. It is quite slick and clear monospaced font and provides distinctive I, l and 1 glyphs. Download TTF files from the link above and install by right clicking on each TTF files.

You can add this to the profile of the Windows Terminal setting.

	      	      "fontFace": "CamingoCode",
	      	      "fontSize": "9",

Using Git-bash

Add following to profiles.list array in the Terminal setting.

            {
                "guid": "{abc00000-0000-0000-0000-000000000000}",
                "name": "Git-Bash",
                "commandline": "%PROGRAMFILES%\\Git\\bin\\bash.exe",
                "icon": "%PROGRAMFILES%\\Git\\mingw64\\share\\git\\git-for-windows.ico",
                "fontFace": "CamingoCode",
                "fontSize": "9",
                "startingDirectory" : "~"
            },

WSL2

Windows Subsystem for Linux has been recently added support for version 2. It provides better file I/O performance and an actual Linux kernel. You cannot use the host disk for WSL2 local files like in WSL1.

Using WSL2 is not quite different to using Hyper-V VM, but you can share the host (Windows) memory with the guest (Linux) so you can optimize memory usage as you are using only one OS. (Oracle Virtualbox also does this as well but you cannot use it with Docker at the same time :/)

And more importantly, Docker supports WSL2 now and it routes all the exported ports from the container to your host network.

** Windows 10 Home edition also supports WSL2.

** You still need the virtualisation support in your BIOS or UEFI setting.

Installing WSL

You can refer the official document for details but could just follow my sequence.

Open the elevated powershell. Right click the start button and choose Windows PowerShell (Admin)

Enable WSL

C:\> dism.exe /online /enable-feature /featurename:Microsoft-Windows-Subsystem-Linux /all /norestart

Enable the ‘Virtual Machine Platform’ optional component

C:\> dism.exe /online /enable-feature /featurename:VirtualMachinePlatform /all /norestart

Install kernel update
Download the WSL2 kernel and install. Refer to the official document for details.
Install Ubuntu
You can use another Linux distro but I prefer ubuntu. Using MS store, install the distro
Set WSL 2 as your default version
```
C:\> wsl --set-default-version 2
```
Set default username
Running Ubuntu from the start menu will need you to input the username and password for the first time once

Accessing WSL directories

By default, WSL drive is shared by \\wsl$\<distro name> like \\wsl$\Ubuntu-20.04. Cmd+R, type \\wsl$ and enter will show the Linux root directories.

You can also map the drive by right click the directory.

Sudo without password

You can use sudo without password in your WSL

$ sudo visudo

will show the editor and you can add

<username> ALL=(ALL) NOPASSWD:ALL

at last.

Replace <username> with yours and ^x, y, enter to save and quit Nano.

Managing WSL memory

WSL2 shares your host memory but without a limit, it could drain your host memory.

It is required to set the maximum at half of your entire memory. It will not use the maximum memory unless required.

Limiting maximum memory usage

Create %USERPROFILE%\.wslconfig with the following content

[wsl2]
memory=4GB

Reclaiming WSL2 memory

On an MS blog article, it says

In order to return as much memory to the host as possible, we periodically compact memory to ensure free memory is available in contiguous blocks.

WSL kernel tries to return memory as much as possible but Linux still caches memory and WSL does not try to clear since it would affect the performance.

If you want to give more memory to host, try this command on WSL,

$ echo 1 | sudo tee /proc/sys/vm/drop_caches

or on Windows, you can do

C:\>bash -c "echo 1 | sudo tee /proc/sys/vm/drop_caches"

SSH to WSL

Since WSL2 is a linux VM, you can install sshd in it. But to connect to the machine you will need the IP address.

One of the issue on Hyper-v/WSL2 is you cannot make the VM’s IP address static. When the network connection has been changed, the host virtual network interface address are changed so the guest address is also changed. This would not happen so often but if it changed, you need to get the new address again.

Recently I have found a nice article to solve this issue.

You can install Openssh server in Windows side and set the default shell as bash(WSL2).

Following powershell commands will install Openssh server

Add-WindowsCapability -Online -Name OpenSSH.Server~~~~0.0.1.0
Set-Service -Name sshd -StartupType 'Automatic'
Start-Service sshd
New-ItemProperty -Path "HKLM:\SOFTWARE\OpenSSH" -Name DefaultShell -Value "C:\WINDOWS\System32\bash.exe" -PropertyType String -Force

And try

C:\>ssh localhost

It will show ssh prompt to login with your Windows login password.

If you have got used to Putty or Kitty, now you can use it as a terminal.

Tmux is a command line session manager. Visit the Official Wiki if you are interested.

ssh without the password

If you register your public key (id_rsa.pub usually) to .ssh/authorized_keys file, you can connect without the password.

But if you belong to the Administrators group, you should add the public key to %programdata%/ssh/administrators_authorized_keys.

Using Linux GUI Apps

GUI is not supported in WSL. But if you can use XServer, Linux GUI apps can be used in Windows side. Try VCXSrv project. It’s an opensource X11 server. Download it here and install.

Launching X server

Run XLaunch and it will ask some settings. Don’t forget to turn on Disable access control. If you save the setting on the Desktop, you can use the config file to launch the server without setting it again.

When you launch vcxsrv for the first time, Windows Security Alert will ask if you allow that but by default, private access is only allowed but you actually need both private and public.

If you have just allowed only private, or not sure, check Windows firewall.

And allow all the 4 items in the Windows Defender Firewall with Advanced Security if you haven’t yet.

You will have this icon in the system tray.

Setting DISPLAY env variable

You will also need to set DISPLAY env var in the WSL side. Because the host network address is not fixed, you might need to run the following before you use. Save the following to like ~/setDisplay and run source ~/setDisplay or jusr . ~/setDisplay.

$ export DISPLAY=$(awk '/nameserver / {print $2; exit}' /etc/resolv.conf 2>/dev/null):0
$ export LIBGL_ALWAYS_INDIRECT=1

Trying a Linux app

$ sudo apt install stacer
$ export DISPLAY=$(awk '/nameserver / {print $2; exit}' /etc/resolv.conf 2>/dev/null):0
$ export LIBGL_ALWAYS_INDIRECT=1
$ stacer

Those commands will install Stacer and launch in Windows side

Docker Desktop

Installing Docker on Windows is simple. Just download it here and install.

Since it provide a predefined service like an app, many projects utilise Docker in their project. But Using docker in Windows could be challenging due to the difference of the file system.

There is a nice blog article from Docker.

Even if your project does not require Docker, it would be beneficial.

For example, if you are not a ruby developer but if you want to use ruby for like writing a jekyll blog. You can use Docker to do that without installing all the ruby tools.

Moreover, you can install apps and Docker can start it always. How about getting a local music player for local files, Airsonic (Docker hub)

Limiting container memory

Using docker-compose is easier to manage the containers.

You can manage multiple containers and save all the options in the file and creating, start, stop and removing are quite handy. Conatainers can be named using container_name BTW.

If you have not used it yet, please leran more about docker-compose

Use docker-compose version 2 (2.4 is latest at the point of writing this article) if you are not using Swarm.

mem_limit: 512m will limit the memory usage to 512M

** This can also be done by --memory=512m using docker

VSCode

vscode seems like being a de facto standard. If you’re not a big fan of the other fancy editors, you can use this.

There is a nice document from MS

Where should the project files be placed

If your project is using docker and watching your source code and try to rebuild, it will not be working in Windows. This could be challenging to know the reason why.

If you are using windows dev tools you can keep source files in Windows side.

If you want to avoid hassles, just stay only in the WSL side.

Defender Antivirus Exclusion

You can put the all repo, project files in one directory in your home directory such as Projects. Usually it could create many automatically generated files in it.

For example, node_modules, .bundle, vendor, build or so on.

You can speed up by excluding Antivirus scanning.

If you feel some building process is quite slow, you can turn on the task manager and locate Antimalware Service Executable and if that consumes CPU over 10%, consider adding some more exclusion.

Optionals

Chocolatey, package manager

It has so less hassles to install all the tools manually. It is like using Homebrew (brew) in mac.

Chocolatey Official Site

Using Node.js in Windows side

If you are a frontend developer or nodejs developer, you would have already Node.js installed. The latest Node.js installer actually includes build tools and package manager for Windows, Chocolatey. Don’t forget to install necessary tools. Unless you would have some error while building binary packages.

When it is used in Gitbash, it is better. Even if your projects uses bash scripts which is usually not supported in Windows, you can still run it with git-bash.

You will need to exclude npm/yarn cache from Defender Antivirus setting.

%APPDATA%\npm-cache
%LOCALAPPDATA%\Yarn

Say Hello to Windows

Thanks to WSL2, Windows machine is also have been developer friendly. Docker performance it not worse than OSX and you can use it on Home Edition too. It actually has a better multiple display experience than OSX and Cleartype will give you a better font rendering in full HD display (might be a personal preference though). Edge browser is now chromium based.

I still don’t like too many rebooting but I would choose next dev machine as a Windows laptop :)

Setting up Algo VPN in Oracle cloud

Sat, 01 Aug 2020 10:41:01 +0000

Using VPN abroad sometimes has advantages but paying a VPN service subscription could cost more than it worth.

However, what if you already have a VPS aboard? There seems to be a free VPS hosting nowadays.

As I told in the previous post, I tried to set Algo VPN server in Oracle Cloud.

Hope this dump to help you.

Disclaimer

Please use your VPN server in your own responsibility. I am not responsible any of the consequences of using Oracle Cloud or VPN.

Create an instance

Check Oracle Cloud and Sign up.
- Choose your home region where you intend to be.
Sign into the web console and click Create a VM instance.
- Choose ubuntu minimal and upload your public key
  - Check how to create ssh key if you don’t have one.
Click create and you will see above details.
- Memo the public IP.

Now You can connect into the instance using ssh client.

Install Algo VPN server

Connect to the instance created above and follow the following instructions to install the VPN server.

Apt upgrade and install dependencies

$ sudo apt update && sudo apt upgrade -y
$ sudo apt install -y python3-virtualenv unzip vim

Install your editor as well above like vim or nano.

Download Algo

$ wget https://github.com/trailofbits/algo/archive/master.zip
$ unzip master.zip

Set virtualenv

$ cd algo-master
$ python3 -m virtualenv --python="$(command -v python3)" .env &&
  source .env/bin/activate &&
  python3 -m pip install -U pip virtualenv &&
  python3 -m pip install -r requirements.txt

Config users

Edit config.cfg to add users

$ vi config.cfg

I recommend you to use like the following since sharing accounts is told to cause some issues

users:
  - phone
  - phone2
  - tablet
  - tablet2
  - laptop
  - laptop2
  - desktop
  - desktop2
  - server
  - server2
  - guest
  - guest2

Start deployment

It’s an interactive script. You need to choose options and the script will get the job done.

$ ./algo

The first question is the most important Put 11 since you are using the localhost which you are using for the installation

[Cloud prompt]
What provider would you like to use?
--> 11. Install to existing Ubuntu 18.04 or 20.04 server (for more advanced users)

Most of the following would be okay for their default (just enter) but you will need the followings two answered differently

[Retain the PKI prompt]
Do you want to retain the keys (PKI)? (required to add users in the future, but less secure)
[y/N]
--> Y

[local : pause]
Enter the public IP address or domain name of your server: (IMPORTANT! This is used to verify the certificate)
[localhost]

---> [Put the public IP adress of your instance]

And it will start to install the VPN server and then it show the server details.

'#                       Congratulations!                         #'
'#                  Your Algo server is running.                  #'
'# Config files and certificates are in the ./configs/ directory. #'
'#           Go to https://whoer.net/ after connecting            #'
'#     and ensure that all your traffic passes through the VPN.   #'
'#                  Local DNS resolver 172.29.**.**               #'
'#     The p12 and SSH keys password for new users is *********   #'
'#     The CA key password is ****************                    #'

If something went wrong, it’s recommended to restart the whole procedure from the top. Terminate the instance and recreate the instance.

Copy credentials from the Algo server

Now it’s okay to disconnect the ssh connection to the VPN server.

From your local env (eg. laptop), run scp to copy files from the server Replace vpnserver to your VPN server IP.

$ scp -r ubuntu@vpnserver:algo-master/configs .

Now you can use credentials for the VPN server in the configs directory.

Open the ports for the VPN

VPN server itself is ready now but there is still one more step left. The ports are usually closed so it should be allowed manually.

Add Security List for VPN

Sign into the web console.

Go to Networking > Virtual Cloud Networks
Click the VCN name in the right plan to see the details
Click the Security Lists in the Resources in the Left pane
Click Create Security List
Put details in the popup
- Name: VPN
- Additional Ingress Rule: Ingress Rule 1
  - Source CIDR: 0.0.0.0/0
  - Destination Port Range: 4160
- Additional Ingress Rule: Ingress Rule 2
  - Source CIDR: 0.0.0.0/0
  - IP Protocol: UDP
  - Destination Port Range: 51820,500,4500
Click Create Security List to confirm

Bind the Security List to the Public Subnet

Go to the Instace Details (Compute > Instaces > Instance Details)
Click Subnet of Primary VNIC
Click Add Security List
Select the VPN in the security list pull down in the popup
Click Add Security List to confirm

Client settings

Let me share how I connect my iPad

Get the WireGuard in Appstore. (iOS12 or higher is required)
Open the PNG QR code file of the user such as configs/localhost/wireguard/tablet.png configs directory is the one you copied in the previous step
Launch WireGuard and touch + button to Create from QR code
Take the QR code and name it like tablet
turn on the connection

That’s it.

Go to the browser and search for my ip to confirm your ip is of the one of the VPN server.

WireGuard app is available for Mac and Windows10 as well so you can do similar

Troubleshooting

When the server is not available, WireGuard app silently fails so network is not available.

Turn off the connection switch in the WireGuard and resolve the server issue and retry.

Hello! Starting kenny.yeoyou.net

Fri, 31 Jul 2020 12:57:05 +0000

Hello there, I’m Kenny. A Korean developer working in Sydney.

I’ve been working for 20 years on IT/Programming here, Tokyo and Seoul. I’d like to share my recent learnings on the latest technology.

Stay tuned. The first coming post would be about setting a private VPN server on Oracle cloud.

BTW, I’m recently working with JS and loving it. Still new to Ruby but love Jekill and Gihub. Here is my little promise.

(async () => {
  const content = await setTheAlgoVpnOnOracleiCloud({
    regionName: 'South Korea North',
    due: 'ASAP'
  });
  const post = await dumpTheWalkthrough({
    target: 'Github blog',
    author: 'kennyhyun',
    content
   });
  await publishContents(post);
  console.log('You can make your own private VPN server now');
})();

Head-ups:

See ya