Hi! welcome to our workshop! Today we'd like to show a few things that you can do with computer networks!

• Set up the static IP addresses
  • Device IP: 192.168.1.x/24 (each participant has number from 1 to 254)
  • Mask: 255.255.255.0
  • Gateway IP: 192.168.1.253
• Open the wireshark
  • use an “arp || icmp” as in a filter (that will show only ARP and ping messages)
• Ping the other people IPs
• Take a look at the ARP table in computer
  • command “arp -a” in windows
  • command “arp -n” in linux (net-tools have to be installed)

Local area network (4 participants)

Each group (2-3 people) has it's own router (with OpenWRT). One person should set up the router, together with rest of group, from one computer over the web interface (accessible over 192.168.1.1 - and later over 10.1.x.1 address from browser).

Set up following stuff:

• Set different network IP addresses (IPv4)
  • First router - 10.1.1.0/24
  • Second router - 10.1.2.0/24
  • Third router - 10.1.3.0/24
  • Fourth router - 10.1.4.0/24
• Reconnect to the router (so that Your computer gets NEW ip from router)
• Connect WAN port of all routers to common switch
• Set up WAN interfaces (static IPs)
  • First router - 10.1.5.1/24
  • Second router - 10.1.5.2/24
  • Third router - 10.1.5.3/24
  • Fourth router - 10.1.5.4/24
• Set up firewalls
  • Forwarding between LAN and WAN has to be always allowed
  • Disable the masquerade

Now time to verify:

• Ping people in the same subnet (behind the same router)
• Ping people in the other subnet (behind the other router)
• Traceroute the people in the other subnet, and take a look what are the routers the packet goes through
• Take a look with wireshark at all the packets

Interconnected LAN networks

• Install wireguard in openwrt
• Then set it up with helpful instructions from this page

• we will find commands on the fly
  • ip route add
  • ip addr add
  • and others:D

1. VPN project - two sites
   • first with 10.1.1.0/24 network, VPN server
   • second with 10.1.2.0/24 network, VPN client
   • first has 10.1.3.1/30, second has 10.1.3.2/30

Server:

[Interface]
PrivateKey = yourPrivateKey
Address = 10.1.3.1/30
ListenPort = 51820
PostUp = ip route add 10.1.2.0/24 via 10.1.3.2

[Peer]
PublicKey = OtherpartyPublicKey
AllowedIPs = 10.1.2.0/24, 10.1.3.2/32

Client:

[Interface]
Address = 10.1.3.2/30
PrivateKey = yourPrivateKey
PostUp = ip route add 10.1.1.0/24 via 10.1.3.1

[Peer]
PublicKey = OtherPartyPublickey
Endpoint = publicIP:51820
AllowedIPs = 10.1.1.0/24, 10.1.3.1/32
PersistentKeepalive = 21

Generate private and public key for VPN server

wg genkey | tee privatekey | wg pubkey > publickey; cat publickey; cat privatekey