Share Internet via Ad-Hoc

• On Computer 1, connected to the internet via cable:

   # ifconfig wlan0 down
   # iwconfig wlan0 mode Ad-Hoc
   # ifconfig wlan0 192.168.0.1 up
   # iwconfig wlan0 essid rede
   # iwconfig wlan0 key 123456789A
  

• On Computer 2:

  # ifconfig wlan0 down
  # iwconfig wlan0 mode Ad-Hoc
  # ifconfig wlan0 192.168.0.2 up
  # iwconfig wlan0 essid rede
  # iwconfig wlan0 key 123456789A
  # route add default gw 192.168.0.1
  # sh -c "echo 'nameserver 8.8.8.8' >> /etc/resolv.conf"
  

The Ad-Hoc network is already configured. You can now ping between both machines.

To share the internet, we need to add some rules to the firewall.

1. Install iptables:

   # pacman -S iptables
   

2. Configure iptables:

   # iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
   # iptables -A FORWARD -i eth0 -o wlan0 -m state --state ESTABLISHED,RELATED -j ACCEPT
   # iptables -A FORWARD -i wlan0 -o eth0 -j ACCEPT
   # sh -c "echo 1 > /proc/sys/net/ipv4/ip_forward"
   # /etc/rc.d/iptables save
   # /etc/rc.d/iptables restart