Sometimes it happens one needs to set a device as a nat/router middlebox. Here is the (self-explanatory) commands needed on a GNU OS to set up a NAT/router functionalities.
#!/bin/bash OUTER_IF="wlan0" INNER_IF="eth0" sysctl net.ipv4.ip_forward=1 sysctl -p iptables -t nat -A POSTROUTING --out-interface $OUTER_IF -j MASQUERADE iptables -A FORWARD --in-interface $INNER_IF -j ACCEPT
Obviously, you also need to assign IP address. You can choose between setting up a DHCP or some good ol’ fashioned static address, e.g.:
sudo ip add add 192.168.0.1/24 dev $INNER_IF