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Reene
Reene

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[Intranet penetration][Ngrok]Expose local services to achieve front-end and back-end debugging

#network #networking #intranet

Intro

Achieve front-end and back-end debugging when outside the local network. Besides a)building vpn in aws [aws vpn],b)reverse ssh tunnel, there introduce another method which is more simple to expose local service, to make private cloud have access to local service.

0.Using Ngrok (intranet penetration tool)

Ngrok is a lightweight intranet penetration tool that can quickly expose local services to the public network. It is very suitable for scenarios where the host does not have a public IP.

1. Configure Ngrok in your mechine

1). Check the system architecture

Run the following command in the terminal to confirm system architecture:

uname -m
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  • x86_64: 64-bit architecture.
  • arm or aarch64: ARM architecture

2).Download the correct Ngrok binary

x86_64:

wget https://bin.equinox.io/c/bNyj1mQVY4c/ngrok-v3-stable-linux-amd64.tgz
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ARM64：

wget https://bin.equinox.io/c/bNyj1mQVY4c/ngrok-v3-stable-linux-arm64.tgz
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3). Unzip the file

Unzip the file you just downloaded:

There I use the ubuntu(aarch64)

tar -xvzf ngrok-v3-stable-linux-arm64.tgz
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Once the unzip is complete, you should see a file called ngrok.

4). Install Ngrok

Move the unzipped file to your system's global path, such as /usr/local/bin:

sudo mv ngrok /usr/local/bin
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5). Verify the installation

Check that the installation was successful:

ngrok version
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If successful, it will display output similar to the following:

ngrok version 3.x.x
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2. Get an authtoken

Register an Ngrok account and get an authtoken : https://dashboard.ngrok.com/

  • go to the setting, and configure payment method, and then choose free tier.

After finish setting, go to token.
Authenticate the ngrok agent. only have to do this once. The Authtoken is saved in the default configuration file.

ngrok config add-authtoken <your-token>
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3. Run Ngrok again

Now we can use Ngrok normally. For example, to start an SSH tunnel (port 22):

ngrok tcp 22
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If successful, Ngrok will output an address similar to the following:

Forwarding tcp://0.tcp.ngrok.io:12345 -> localhost:22
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  • Edit ssh_config 
sudo vim /etc/ssh/sshd_config PermitRootLogin yes PasswordAuthentication yes KbdInteractiveAuthentication yes UsePAM yes #PubkeyAuthentication yes
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Image description
now we can access our SSH service from the outside using the following command:

ssh user@0.tcp.ngrok.io -p 12345
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  • user: Replace with your host's SSH username (e.g. ubuntu).
  • tcp.eu.ngrok.io and 12345: from the address and port provided by Ngrok.

4.Configuring Ngrok to Auto-Start on Ubuntu Virtual Machine

This guide explains how to configure Ngrok to start automatically on boot with persistent settings on an Ubuntu virtual machine.

 # Step 1: Create an Ngrok Configuration File mkdir -p $HOME/.ngrok2 nano $HOME/.ngrok2/ngrok.yml # Add the following content to ngrok.yml: version: "2" authtoken: your-authtoken tunnels: ssh: proto: tcp addr: 22 # Or use: mkdir -p $HOME/.ngrok2 && cat <<EOF > $HOME/.ngrok2/ngrok.yml version: "2" authtoken: your-authtoken tunnels: ssh: proto: tcp addr: 22 EOF # Save the file and test the configuration ngrok start --config=$HOME/.ngrok2/ngrok.yml --all # Step 2: Create a Systemd Service File sudo nano /etc/systemd/system/ngrok.service # Add the following content to the service file: [Unit] Description=Ngrok Service After=network.target [Service] ExecStart=/usr/local/bin/ngrok start --config=/home/<username>/.ngrok2/ngrok.yml --all Restart=on-failure User=<username> WorkingDirectory=/home/<username> Environment="PATH=/usr/local/bin:/usr/bin:/bin" [Install] WantedBy=multi-user.target # Save and exit the file # Step 3: Enable and Start the Service sudo systemctl daemon-reload sudo systemctl stop ngrok sudo systemctl start ngrok sudo systemctl status ngrok # Enable the service to start on boot sudo systemctl enable ngrok # Step 4: Verify Ngrok Auto-Start on Boot sudo reboot # After rebooting, check the Ngrok service status sudo systemctl status ngrok # Confirm Ngrok is running and its tunnels are active # Ngrok’s web interface is available by default at http://127.0.0.1:4040
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go to dashboard:https://dashboard.ngrok.com/agents

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