Linux make WiFi hotspot/wireless Routing

Reference: http://blog.csdn.net/u011641885/article/details/49512199
1. Tools/Materials
Desktop with wireless card (RT3070 wireless card with USB interface), wired network card
Installing the Linux operating system, I'm using ubuntu14.04
2. Methods/Steps
A. Check to confirm that the wireless network card supports master mode
Execute command: IW list
In the command execution results if you see the following (AP, Ap/vlan), it means that the network card is supported for the AP to do the routing
Supported interface modes:
* IBSS
* Managed
* AP
* Ap/vlan
* Monitor
* Mesh Point

B. Installing HOSTAPD
I compiled it manually, the directory is in/home/edward/opt/edward/hostapd/
Modify the HOSTAPD configuration file vim/etc/dhcp/dhcpd.conf
Change this file to read as follows:
Ctrl_interface=/var/run/hostapd
Interface=wlan0
driver=nl80211
Ssid=emma
Hw_mode=g
channel=10
Macaddr_acl=0
Auth_algs=3
wpa=2
wpa_passphrase=fah191430
Wpa_key_mgmt=wpa-psk
Wpa_pairwise=tkip
Rsn_pairwise=tkip CCMP

AP hotspot name is Emma, password is fah191430
Then turn on HOSTAPD and go to the/HOME/EDWARD/OPT/EDWARD/HOSTAPD/HOSTAPD directory
sudo./hostapd-b/etc/hostapd.conf
The following error was found:
Configuration File:/etc/hostapd/hostapd.conf
Nl80211:could not configure driver mode
Nl80211:deinit Ifname=wlan0 disabled_11b_rates=0
NL80211 driver initialization failed.
Wlan0:interface State uninitialized->disabled
Wlan0:ap-disabled
Wlan0:ctrl-event-terminating
Hostapd_free_hapd_data:interface Wlan0 wasn ' t started
Workaround:
Change the state of the NetworkManager, turn off WiFi, and soft lock
sudo nmcli nm wifi off
sudo rfkill unblock WLAN
And then start the HOSTAPD service.
sudo hostapd-b/etc/hostapd.conf

C. Installing the configuration DHCP server
sudo apt-get install Isc-dhcp-server
Modifying a configuration file/etc/dhcp/dhcpd.conf
Option Domain-name-servers 218.85.157.99;
Subnet 192.168.1.0 netmask 255.255.255.0 {//NOTE: Here 192.168.1.0 cannot be written 192.168.1.1
Range 192.168.1.77 192.168.1.250;
Option routers 192.168.1.3; Gateway to write this machine's wlan0 IP
Option broadcast-address 192.168.1.255;
}
Start the DHCP server
Configure IP and subnet masks for network cards before starting
sudo ifconfig wlan0 192.168.1.3 netmask 255.255.255.0 up
Sudo/etc/init.d/isc-dhcp-server restart

D.iptables Configuring forwarding Rules
Linux forwarding needs to be turned on before configuring forwarding
Temporary change, resume after reboot
sudo sysctl-w net.ipv4.ip_forward=1
Permanent change
Vim/etc/sysctl.conf
#添加或修改这样一段:
Net.ipv4.conf.default.rp_filter = 1
#然后执行命令
Sysctl-p
Use Iptables to set up forwarding
Iptables-t nat-i postrouting-o Eth0-j Masquerade
Iptables-a forward-s 192.168.1.0/24-j ACCEPT
Iptables-a forward-d 192.168.1.0/24-j ACCEPT
The first of these means that the forwarding packet will be sent from the eth0 (external network) This network card, the other two means only forwarding 192.168.1.0/24 this network segment over the packet,
This network segment is exactly wlan0 other devices connected to the network segment assigned by the machine

Linux make WiFi hotspot/wireless Routing