1. Building Distributed
Networks using VPNs
David R Newman

2. VPN – Virtual Private Network
A Definition
VPN – Virtual Private Network “
A virtual network that is constructed across the Internet (or other public network) to connect two or more parts of a private network. ”

3. OSI Model

4. Types of VPN On top of Data Link Layer On top of Network Layer
L2TP/IPsec - Layer 2 Tunnelling Protocol / Internet Protocol security
VPLS – Virtual Private LAN Service
On top of Network Layer
PPTP – Point-to-Point Tunnelling Protocol
PPP – Point-to-Point Protocol
SSH – Secure Shell
VPRN – Virtual Private Routed Network
DTLS – Data Transport Layer Security
TLS – Transport Layer Security
E.g. OpenVPN

5. Server and Clients

6. OpenVPN Interfaces

7. Why OpenVPN? Open Source
High connection speed (relative to available bandwidth)
Secure
Makes it is easy to bypass NATs and Firewalls
Well-supported by OpenWRT
Extensively configurable

8. OpenVPN Server (1) server 10.13.112.112 255.255.255.252
local
port 5044
proto udp
dev tap55
ca /etc/openvpn/package_managment/node_control_2015.crt
cert /etc/openvpn/package_managment/server- node_control_2015.crt
key /etc/openvpn/package_managment/server- node_control_2015.crt.key
dh /etc/openvpn/dh1024.pem
push "route "
push "route "
push "dhcp-option DNS "

9. OpenVPN Server (2) client-to-client keepalive 10 120 user openvpn
group openvpn
persist-key
persist-tun
log /var/log/openvpn/server55.log
status /var/log/openvpn/server55-status.log
verb 3
script-security 3 system
client-connect "/etc/openvpn/client-routes/connect- node308"
client-disconnect "/etc/openvpn/client- routes/disconnect-node308"

10. OpenVPN Client remote sown-auth2.ecs.soton.ac.uk 5044
proto udp
dev tap
ca /etc/sown/node_control_2015.crt
cert /etc/sown/client.crt
key /etc/sown/client.key
client
nobind
resolv-retry infinite
user nobody
group nogroup
persist-key
verb 3
script-security 2
down /etc/sown/events/tunnel_down
up /etc/sown/events/tunnel_up

11. Further Reading OSI vs. TCP/IP Model Picking a VPN
between-osi-seven-layer-network-model-and-tcpip
Picking a VPN
ikev2/
OpenVPN Documentation
OpenVPN on OpenWRT
Wide Area Wi-Fi

12. Future SOWN Talks 17th November 2016 After Christmas
Firmware Development for Embedded Devices – Chris Malton
After Christmas
A Mechanism for Global Distributed Authentication – David Newman
Administering the SOWN Network – David Newman and Chris Malton

13. Questions?