eth0: connected to internet
wlan0: local WLAN
# iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE # iptables -A INPUT -i wlan0 -j ACCEPT # echo 1 > /proc/sys/net/ipv4/ip_forward
# iptables -t nat -A POSTROUTING -j MASQUERADE
Filter (Used with FORWARD here) all incoming traffic from wlan0 and outgoing to eth0 except the specified MAC address (can add more MACs using the same command)
# iptables -P FORWARD DROP # iptables -A FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT # iptables -A FORWARD -i wlan0 -o eth0 -m mac --mac-source xx:xx:xx:xx:xx:xx -m state --state NEW -j ACCEPT