Quincy

Quincy is a VPN client and server implementation using the QUIC protocol.

Design

Quincy uses the QUIC protocol implemented by quinn to create an encrypted tunnnel between clients and the server.

This tunnel serves two purposes:

• authentication using a reliable bidirectional stream
• data transfer using unreliable datagrams (for lower latency and avoidance of multiple reliability layers)

After a connection is established and the client is authenticated, a TUN interface is spawned using an IP address provided by the server.

When all is set up, multiple tasks are spawned (on both the client and the server), with 2 of them being the most important:

• authentication task - responsible for sending the session token in the specified interval
• connection task - responsible for relaying packets between the TUN interface and the QUIC tunnel

These tasks run in parallel using the tokio runtime for added efficiency and throughput.

Usage

Quincy is split into 3 binaries:

• client: The VPN client
• server: The VPN server
• users: A utility binary meant for managing the users file

Client

The Quincy client requires a separate configuration file, an example of which can be found in examples/client.toml:

# The address and port the Quincy server is available at
connection_string = "quincy:55555"

[authentication]
# The username used for authentication
username = "test"
# The password used for authentication
password = "test"
# A list of trusted certificates the server can use or have its certificate signed by
trusted_certificates = ["examples/cert/ca_cert.pem"]

[connection]
# The MTU used by the QUIC tunnel and the spawned TUN interface
mtu = 1400

[log]
# The log level
level = "info"

With the configuration file in place, the client can be started using the following command:

$ client --config-path examples/client.toml

Routes are set up by default on some systems (Linux) and not set-up at all on others (MacOS).

Server

The Quincy server requires a separate configuration file, an example of which can be found in examples/server.toml:

# Section representing tunnel configuration
[tunnels.tun0]
# Name of the tunnel (currently not used as the name of the interface)
name = "tun0"
# Path to the certificate used for TLS
certificate_file = "examples/cert/server_cert.pem"
# Path to the certificate key used for TLS
certificate_key_file = "examples/cert/server_key.pem"
# The address of the tunnel endpoint and base address of the address pool available to clients
address_tunnel = "10.0.0.1"
# Netmask used to generate the address pool available to clients
address_mask = "255.255.255.0"
# Path to the file containing user credentials
users_file = "examples/users"

[connection]
# The MTU used by the QUIC tunnel and the spawned TUN interface
mtu = 1400

[log]
# The log level
level = "info"

With the configuration file in place, the client can be started using the following command:

$ server --config-path examples/server.toml

Users

The users utility can be used to manage entries the users file. The users file contains usernames and password hashes in the following format (examples/users):

test:$argon2id$v=19$m=19456,t=2,p=1$S9rMLOcz/dnYN4cnyc/TJg$ES0p+DErLfcWoUJ2tvZlxZSSIGYNUEe0ZpKBDz7MOj0

The following command can be used to add users to this file:

$ users --add examples/users

The prompts will look something like this:

Enter the username: test 
Enter password for user 'test': 
Confirm password for user 'test': 

A similar command can be used to remove users from the file:

$ users --remove examples/users

The prompt will again look something like this:

Enter the username: test