student_access_vpn

Student access with VPN

Finally, you can also access the mini-Internet through a VPN. In the file config/l2_hosts.txt, the lines starting with vpn correspond to a L2-VPN server which will be automatically installed instead of a normal host. A L2-VPN is connected to a L2 switch (the one written in C4 of the configuration file), and every user connected to this L2-VPN will be virtually connected to that L2 switch.

To use the VPN, a student must first install OpenVPN and run it with the following command (on Ubuntu 18 and 20):

sudo openvpn --config client.conf

We provide the client.conf file below, where VPN_IP must be replaced by the IP address of the server hosting the mini-Internet. VPN_PORT defines to which VPN server we want to connect to. You can find the port of the VPN servers by looking at their configuration file, which is located here: groups/gX/vpn/vpn_Y/server.conf with X the group number and Y the VPN ID for that group.

client
remote VPN_IP VPN_PORT
dev tap
proto udp
resolv-retry infinite
nobind
persist-key
persist-tun
ca ca.crt
cipher AES-256-CBC
verb 3
auth-user-pass

The file ca.crt is automatically generated during the mini-Internet setup. It is available in the directory groups/gX/vpn/vpn_Y and must be given to the student. Finally, the username is groupX (X is the group number) and the password is the same than the one used to access the proxy container through SSH.

When connected, the student should see an interface called tap0 with a corresponding IP address. This interface is directly connected to the mini-Internet.

❗ VPN access from other operating systems than Linux/Ubuntu (such as Windows) might also be possible but was not tested by us.