Skillaz Secure Chat

Peer-to-peer chat application for network communication with ability to setup data transmission limitations, separated groups and multiple-users-on-one-machine support.

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Table of Contents

• Problem
• Solution
• Quick Start
• Launch installers

Problem

Imagine, you have a single terminal server that you use to access some protected environment, for example, RDP-server. Also you have a lot of sensitive data under that protected environment. In common case limited access to that information is allowed and needed, but if a big bunch of data would be exported from protected environment it will be fatal.

RDP server allows you to setup data in- and out- transmission rules, but it has no flexibility in these settings. You can't allow send X bytes of data from RDP server, you may only block or allow it. And this behaviour does not match our requirements.

Solution

Skillaz Secure Chat (SSC) allows you to setup communication between RDP server and client machines through network with flexible limitations.

For now, SSC able to setup these limitations:

• Message length (symbols count)
• TBD...

Quick start

1. Download latest release installer for your operation system
2. Install on machines you want to setup communication between (see installation sections for different operation systems below)
3. Open specific TCP port on machine, where you want to access to (Default: 63211).
4. Go to app installation folder and open appsettings.yaml, fill up KnownPeers section with IP addresses of machines, you installed SSC into.
   • Also you may setup other parameters to fit into your requirements
5. Launch SSC on both machines.

Secret codes

To setup communications between two machines you need to make security code that was randomly generated at the first application launch to match onto both applications you want to connect. If you have 123456 secret code on the first machine, you should set equal secret code on the second machine. Then they will be connected and you could see it in list of connected users.

This allows to create groups of users that able to move from one group to another by changing their secret code if they are located in same network.

Application settings

Application has built-in settings that could be override in config file appsettings.yaml. Note that you should create it and place in directory with application executable to apply settings override.

MaxChatMessageLength: 3000 # max chat message length available to transfer through chat
ListenerTcpPort: 63211 # server tcp/ip port to listen incoming connections
ClientTcpPort: 63211 # client tcp/ip port to connect to remote servers
LogLevel: Off # global log level for all application users (used if this level is higher than user-specific in usersettings.yaml)
KnownRemotePeers:
  - 1.2.3.4:63211 # List of remote peers to connect

User settings

When user launch application for the first time file usersettings.yaml generates automatically.

File creates in these folders:

Linux: /home/<username>/.local/share/ssc/usersettings.yaml
MacOS: /Users/<username>/.local/share/ssc/usersettings.yaml
Windows: C:\Users\<username>\AppData\Local\ssc\usersettings.yaml

With this content:

UserId: 00000000-0000-0000-0000-000000000000 # unique user identifier (GUID). Not recommended to change.
Name: "user_name" # username (default - your username providing by OS). Can be changed through GUI
SecretCode: 123456 # secret code. Can be changed through GUI
LogLevel: "Info" # log level

Logs

Default logs directories:

Linux: /home/<username>/.local/share/ssc/logs
MacOS: /Users/<username>/.local/share/ssc/logs
Windows: C:\Users\<username>\AppData\Local\ssc\logs

Available log levels (to setup in usersettings.yaml):

• Trace
• Debug
• Info
• Warning
• Error
• Fatal

Launch installers

Windows

1. Launch .exe installer
2. Go through installation wizard till the end
3. Launch installed application

Linux (Ubuntu)

1. On target machine execute this:

   sudo dpkg -i <path to .deb file on target machine>

2. To show this app into applications menu you need to execute:

   sudo cp /usr/share/Skillaz.SecureChat/linux-installer/ssc.desktop /usr/share/applications/ssc.desktop

Linux (Fedora)

1. On target machine execute this:

   sudo rpm -i <path to .rpm file on target machine>

2. To show this app into applications menu you need to execute:

   sudo cp /usr/share/Skillaz.SecureChat/linux-installer/ssc.desktop /usr/share/applications/ssc.desktop

MacOS

1. Open .dmg package on target machine
2. Move SSC app to Applications folder
3. Because unsinged apps are blocked by macOS we should disable quarantine for downloaded app:

   sudo xattr -d com.apple.quarantine "/Applications/SSC.app"

4. Launch SSC

Manual Build Installers

Windows

Prerequirements

• Inno Script Studio or InnoSetup

Create .exe installer

1. Prepare binaries by this command:

   dotnet publish -c Release -r win-x64 --self-contained

2. Launch Inno Script Studio
3. Compile windows-installer/installer.iss to produce installer .exe file
4. Send .exe file to target machine

Linux DEB package

Prerequirements

• dotnet deb

  dotnet tool install --global dotnet-deb
  dotnet deb install

Create .deb package

1. Go to sources folder

   cd src

2. Execute this to create deb package:

   dotnet deb -r ubuntu-x64 -c Release

3. Next move this package to target machine:

   scp -i <path to pkey file for ssh authorization> <path to .deb> <remote login>@<target machine remote address>:<target file path .deb file>

Linux RPM package

Prerequirements

• dotnet rpm

  dotnet tool install --global dotnet-rpm
  dotnet rpm install

Create .rpm package

1. Go to sources folder

   cd src

2. Execute this to create rpm package:

   dotnet rpm -r fedora-x64 -c Release

3. Next move this package to target machine:

   scp -i <path to pkey file for ssh authorization> <path to .rpm> <remote login>@<target machine remote address>:<target file path .rpm file>

MacOS

Prerequirements

• Macbook (or other OSX machine)
• create-dmg utility

Prepare .app package

1. Firstly, prepare binaries for publishing on target machine:

   dotnet publish -c Release -r osx-x64 --self-contained

2. Next move content of generated osx-x64 folder to osx-installer/SSC.app/Contents/MacOS/osx-x64 folder.

3. If you created the .app on Windows, make sure to run chmod +x osx-installer/SSC.app/Contents/MacOS/Skillaz.SecureChat from a Unix machine. Otherwise, the app will not start on macOS.

4. Create dmg package this way:

   create-dmg \
   --volname "Skillaz Secure Chat" \
   --volicon "src/osx-installer/SSC.app/Contents/Resources/logo.icns" \
   --icon "SSC.app" 30 60 \
   --hide-extension "SSC.app" \
   --app-drop-link 280 60 \
   --no-internet-enable \
   "Skillaz.SecureChat.osx-x64.dmg" \
   "src/osx-installer/SSC.app"

5. Next, launch this command to setup external volume icon:

   src/osx-installer/set-ex-icon src/osx-installer/SSC.app/Contents/Resources/logo.icns Skillaz.SecureChat.osx-x64.dmg

6. Distribute this dmg package to target users

You may also check official instruction how to build and distribute .app packages by Avalonia: link