# Set up the connection in Linux

> Step-by-step Linux VPN client setup with IKEv2/StrongSwan and WireGuard - package installation, configuration import, and connecting to Niflheim server

Source: https://opennix.org/en/docs/niflheim/clients/linux/


## 1. Configure IPSEC

### Install the required packages

There are commands for installing IPSEC packages for different versions of Linux. Below is a list of the commands for the other distributions. 

#### Ubuntu

Use the following command to install the IPSEC package on Ubuntu:  

```shell
sudo apt-get install strongswan libstrongswan-standard-plugins
```
#### RHEL-based

Use the following command to install the IPSEC package on Rhel based:  

```shell
dnf install epel-release
dnf install strongswan
```

### Configuring the IPSEC connection

1.1 First of all, the user needs to copy the following files from the VPN server to their Linux client: 

- `/opt/niflheim/configs/<external_ip>/ipsec/.pki/certs/<user_name>.crt` to `/etc/ipsec.d/certs`
- `/opt/niflheim/configs/<external_ip>/ipsec/.pki/private/<user_name>.key` to `/etc/ipsec.d/private`
- `/opt/niflheim/configs/<external_ip>/ipsec/manual/cacert.pem` to `/etc/ipsec.d/cacerts`

Add the `<user_name>.key` file to `/etc/ipsec.secrets` in the following format:

1.2 The next step is to update IPSEC <SECRET>. This is done by adding <user_name>.key to /etc/ipsec.secrets:

```text
<external_ip> : ECDSA <user_name>.key
```

1.3.  Add the configuration from the file  `/opt/niflheim/configs/<external_ip>/ipsec/manual/<user_name>.conf` to `/etc/ipsec.conf`file.

1.4 IPSEC must be restarted with the following command:

```shell
sudo ipsec restart
```

The following command is used to connect to the network: 

```shell
sudo ipsec up <tunnel_name>
```
The next command is used to disconnect from the network:

```shell
sudo ipsec down <tunnel_name>
```

## 2. Configuring WireGuard Clien

### Install the required packages

2.1 First of all, the Wireguard Client must be installed according to the [official documentation](https://www.wireguard.com/install/).

2.2 To get the configuration file, the user needs to perform the following steps: 
 
- Connect to the virtual machine via ssh;
- Navigate to the `/opt/niflheim/configs/<external_ip>` directory;
- Copy the configuration file `wireguard/<user_name>.conf` to their computer.

### Setting up

After the user has copied the configuration file, they need to configure the client.

2.3. It is required to copy the configuration file taken from the server to the correct folder by executing the following command:

```shell
cp <user_name>.conf /etc/wireguard/wg0.conf

```
2.4 The WireGuard client must be started by running the following command:

```shell
sudo systemctl start wg-quick@wg0
```
2.5 If desired, you can add the client to the startup by executing the following command: 

```shell
sudo systemctl enable wg-quick@wg0
```