If you have a wireless internet device connected to your laptop, then you can use your laptop as an internet gate way in  your  LAN . Other computers can  access internet through your  laptop.  If your internet is fast you can  run a small office over that wify connection.

Let me explain how it possible.

So you need  two NIC’s in your computer  and running  Linux operating system.

Your Laptop configuration:

wlan0   -> This will be connected to public internet and you can access internet from your laptop
eth0   ->  This will connect to your lan or  switch , let us assign an ip for it  10.0.0.100

Now  perform the following commands.

# echo 1 > /proc/sys/net/ipv4/ip_forward

# /sbin/iptables -t nat -A POSTROUTING -o wlan0 -j MASQUERADE

# /sbin/iptables -A FORWARD -i wlan0 -o eth0 -m state –state RELATED,ESTABLISHED -j ACCEPT

# /sbin/iptables -A FORWARD -i eth0 -o wlan0 -j ACCEPT

Now go to nearest computer and configure an ip address on range  10.0.0.100/24 , make sure to use gateway ip   10.0.0.100 . You can also use public name servers 4.2.2.1 and 4.2.2.2

Now  access internet and surf the world. Enjoy it. If you need to use this  after a reboot , make sure the above iptable rules must be saved.