Hostap - complete wi-fi AP configuration

1. Configure wlan0 interface

   /etc/network/interfaces:
   auto wlan0
   iface wlan0 inet static
       address 192.168.22.1
       netmask 255.255.255.0

1. Install the package hostapd for managing wireless card in host mode

   sudo apt-get install hostapd

2. Configure hostap

   File /etc/hostapd/hostapd.conf:
   hw_mode=g
   channel=11
   driver=nl80211

   ssid=my-network-name
   interface=wlan0

   # possible MAC address restriction
   #macaddr_acl=0
   #accept_mac_file=/etc/hostapd.accept
   #deny_mac_file=/etc/hostapd.deny
   #ieee8021x=1    # Use 802.1X authentication

   # encryption
   wpa=2
   wpa_passphrase=my-secret-password
   wpa_key_mgmt=WPA-PSK
   wpa_pairwise=TKIP CCMP
   rsn_pairwise=CCMP
   ctrl_interface=/var/run/hostapd

   # Only root can configure hostapd
   ctrl_interface_group=0

3. Start hostapd

   sudo hostapd /etc/hostapd/hostapd.conf
   Debug mode: sudo hostapd -dd /etc/hostapd/hostapd.conf

   Possible errors:

   Interface is managed with NetworkManager - check it: nmcli d should tell that intergace is NOT managed
   Take it out from NetworkManager: sudo nmcli nm wifi off
   Another error:
   rfkill: WLAN soft blocked
   Could not set interface wlan0 flags (UP): Operation not possible due to RF-kill
   wlan0: Could not connect to kernel driver
   Solution:
   check interface state: rfkill list
   unblock interface with rfkill: sudo rfkill unblock wlan
   Hostap is already running
   nl80211: Could not configure driver mode
   nl80211 driver initialization failed.
   hostapd_free_hapd_data: Interface wlan0 wasn't started
   ps ax | grep hostap

4. Try to connect to your new network - you should not obtain an IP address yet

5. Setup masquerading

6. Configure DHCP and DNS:

   • With dnsmasq:
     Dnsmasq is not installed by default - only dnsmasq-base is, but it is not usable.

     sudo apt-get install dnsmasq
     /etc/dnsmasq.conf:
     interface=wlan0
     dhcp-range=192.168.22.2,192.168.22.100,2h
     #dhcp-host=11:22:33:44:55:66,192.168.1.2
     
     Dnsmasq must be set in NetworkManager in /etc/NetworkManager/NetworkManager.conf:
     dns=dnsmasq

   • Old approach: 

Autostart of hostapd

Add to the /etc/rc.local:
rfkill unblock wlan0 && hostapd /etc/hostapd/hostapd.conf

• Take out wlan interface from NetworkManager config (see error in Start hostapd): /etc/NetworkManager/NetworkManager.conf:

[keyfile]
unmanaged-devices=mac:<WLAN_MAC_ADDRESS>
Maybe the same there: no-auto-default=<WLAN_MAC_ADDRESS>

Bash script wifiup.sh:

#! /bin/bash
if [ `ps ax | grep hostap | grep -v grep | wc -l` -eq 0 ]; then
    echo `rfkill list` > /tmp/wifi-rfkill-on-start
    rfkill unblock wlan && hostapd /etc/hostapd/hostapd.conf & > /tmp/hostap.log
fi