Convert your old laptop into wireless access point using Ubuntu 14.04

STEP 1. Intall iw and check if your device supports AP mode

sudo aptitude install iw
iw list
iw wlan0 info
iwconfig

Install hostapd and enable AP

sudo apt-get install hostapd

Extract provided example conf to /etc/hostapd/hostapd.conf

zcat /usr/share/doc/hostapd/examples/hostapd.conf.gz | sudo tee -a /etc/hostapd/hostapd.conf

Setup hostapd.conf

sudo nano /etc/hostapd/hostapd.conf

interface=wlan0
ssid=Wireless
hw_mode=g
wpa=2
wpa_passphrase=PASS
wpa_key_mgmt=WPA-PSK WPA-EAP WPA-PSK-SHA256 WPA-EAP-SHA256

Setup wireless interface

sudo nano /etc/network/interfaces

auto wlan0
iface wlan0 inet static
hostapd /etc/hostapd/hostapd.conf
address 192.168.X.1
netmask 255.255.255.0

Enable forwarding

sudo nano /etc/sysctl.conf
net.ipv4.ip_forward=1

Enable firewall (iptables)

iptables -t nat -A POSTROUTING -s 192.168.X.0/24 ! -d 192.168.X.0/24 -j MASQUERADE