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

1. Set up the static IP addresses
   1. Device IP: 192.168.1.x/24 (each participant has number from 1 to 254)
   2. Mask: 255.255.255.0
   3. Gateway IP: 192.168.1.253
2. Open the wireshark
   1. use an “arp || icmp” as in a filter (that will show only ARP and ping messages)
3. Ping the other people IPs
4. Take a look at the ARP table in computer
   1. command “arp -a” in windows
   2. 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:

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

Now time to verify:

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

Interconnected LAN networks

1. Install wireguard in openwrt
2. Then set it up with helpful instructions from this page

1. we will find commands on the fly
   1. ip route add
   2. ip addr add
   3. and others:D

1. VPN project - two sites

1. first with 10.1.1.0/24 network, VPN server
2. second with 10.1.2.0/24 network, VPN client
3. 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