Implementing Network Traffic Monitoring on a CentOS 7 Server Using vnStat

Sure, here is how to install and set up `vnStat` for monitoring network traffic on a CentOS 7 server, in English:

1. Install the EPEL repository (if it is not already installed):

  ```
  sudo yum install epel-release
  ```

2. Install `vnStat`:

  ```
  sudo yum install vnstat
  ```

3. After `vnStat` is installed, you need to initialize the `vnStat` database. First, check the available network interfaces using `ip link` or `ifconfig`.

4. Then initialize the database for the interface of interest (for example, `eth0`):

  ```
  sudo vnstat -u -i eth0
  ```

5. Start the `vnStat` service:

  ```
  sudo systemctl start vnstat
  sudo systemctl enable vnstat
  ```

Now you can check the traffic statistics using the `vnstat` command with no parameters. It will show you the day and month traffic statistics.

If you need a visual representation, you can use `vnStati` to generate statistics images. For example, the command `vnstati -vs -i eth0 -o ~/vnstat.png` will generate an overview statistics image for the `eth0` interface and save it to the `vnstat.png` file in your home directory.

Please note that `vnStat` and `vnStati` do not provide real-time monitoring. For real-time monitoring, you could use tools like `nload`, `iftop`, or `bmon`.