OMAP Wireless Connectivity WLAN AP No Security

Purpose

This section will demonstrate how to configure the EVM to be a non secured AP. in addition the connection path will be demonstrated using the sniffer log.

Hardware Setup

Configuring AP

In order to configure the EVM as an AP, some configuration must be taken care of. The configuration of the AP involves two files:

• hostapd.conf - for configuring the connection parameters (security type, SSID, etc...)
• udhcpd.conf - fot configuring the DHCP of the AP

Both of the files are located under /etc.

Step 1 - Configuring hostapd.conf

First, we will back up the existing hostapd.conf file by invoking:

mv /etc/hostapd.conf /etc/hostapd.conf.bak

Create a new hostapd.conf with the following content:

1. Replace ssid field to the name you pick for the AP

Access Point configuration - Band support

1. hw_mode=g - to support bg band
2. hw_mode=b - to support b only band
3. ieee80211n=1 - to support 802.11n band

interface=wlan0
driver=nl80211
channel=1
hw_mode=g
preamble=1
dtim_period=2
beacon_int=100
logger_syslog=-1
logger_syslog_level=2
logger_stdout=-1
logger_stdout_level=2
dump_file=/tmp/hostapd.dump
ctrl_interface=/var/run/hostapd
ctrl_interface_group=0
supported_rates=60 90 120 180 240 360 480 540
basic_rates=60 90 120 180 240
ssid=MAC_AP
max_num_sta=5
macaddr_acl=0
auth_algs=3
ieee80211d=0
uapsd_advertisement_enabled=1
wep_rekey_period=0
own_ip_addr=127.0.0.1
wpa_group_rekey=0
wpa_strict_rekey=0
wpa_gmk_rekey=0
wpa_ptk_rekey=0
#ap_table_max_size=255
#ap_table_expiration_time=60
eap_server=1
disassoc_low_ack=1
ap_max_inactivity=4294967295

The editing above can be done by vi editor as follows:

1. vi /etc/hostapd.conf

2. The editor will be opened. Type the character 'i' to switch to editing mode.
3. Copy and paste the above content into the editor.
4. Hit 'esc' button to stop editing.
5. Type the sequence ":wq" in order to save and quit.

Step 2 - Configuring udhcpd.conf

First, we will back up the existing udhcpd.conf file by invoking:

mv /etc/udhcpd.conf /etc/udhcpd.conf.bak

Create a new udhcpd.conf with the following content:

# Sample udhcpd configuration file (/etc/udhcpd.conf)
# The start and end of the IP lease block
start 		192.168.0.20	#default: 192.168.0.20
end		192.168.0.254	#default: 192.168.0.254
# The interface that udhcpd will use
interface   wlan0		#default: eth0
#Examles
opt	dns	8.8.8.8  8.8.4.4 # public google dns servers
option	subnet	255.255.255.0
opt	router	192.168.0.1
option	lease	864000		# 10 days of

The editing above can be done by vi editor as follows:

1. vi /etc/udhcpd.conf

2. The editor will be opened. Type the character 'i' to switch to editing mode.
3. Copy and paste the above content into the editor.
4. Hit 'esc' button to stop editing.
5. Type the sequence ":wq" in order to save and quit.

Step 3 - Running hostapd and udhcpd

In order to run the Soft AP, We will run:

• hostapd (SoftAP functionality)
• udhcpd to operate the dhcp server
• iptables to enable the NAT (Network Address Translation)

The commands to do the above, are:

echo 1 > /proc/sys/net/ipv4/ip_forward
ifconfig wlan0 192.168.0.1
hostapd -B /etc/hostapd.conf -P /var/run/hostapd.pid
udhcpd /etc/udhcpd.conf
iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE

The IP address assigned for wlan0 interface (ifconfig wlan0 192.168.0.1) should match the "router" field IP in the udhcpd.conf file we edited above.
The expected result is:

root@am180x-evm:/# echo 1 > /proc/sys/net/ipv4/ip_forward
root@am180x-evm:/# ifconfig wlan0 192.168.0.1
wl1271: firmware booted (Rev 6.1.5.50.69)
ADDRCONF(NETDEV_UP): wlan0: link is not ready
root@am180x-evm:/# hostapd -B /etc/hostapd.conf -P /var/run/hostapd.pid
Configuration file: /etc/hostapd.conf
wl1271: down
wl1271: firmware booted (Rev 6.2.1.0.54)
Using interface wlan0 with hwaddr de:ad:be:ef:00:00 and ssid 'MAC_AP'
root@am180x-evm:/# udhcpd /etc/udhcpd.conf
root@am180x-evm:/# iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE

Step 4 - Connecting to the AP using PC

Now that the AP is up, the following sequence can be used to connect to the access point:

• Perform a scan on your station laptop and make sure that the AP SSID is visible. In our example it is called MAC_AP.
• Connect to the AP.
• Ping the AP to make sure it is working. In out example we set the Access Point IP address to 192.168.0.1, so we can invoke:

ping 192.168.0.1

The expected result would be something like:

PING 192.168.0.1 (192.168.0.1) 56(84) bytes of data.
64 bytes from 192.168.0.1: icmp_seq=1 ttl=64 time=1.93 ms
64 bytes from 192.168.0.1: icmp_seq=2 ttl=64 time=2.06 ms
64 bytes from 192.168.0.1: icmp_seq=3 ttl=64 time=2.13 ms

Step 5 - Exit From AP Mode

In order to exit from the AP mode, we need to kill both hostapd and udhcpd processes. We will invoke ps command in order to list the running processes:

root@am180x-evm:/# ps
  PID USER       VSZ STAT COMMAND
    1 root      1624 S    init [5]   
    2 root         0 SW   [kthreadd]
    3 root         0 SW   [ksoftirqd/0]
    6 root         0 SW<  [khelper]
...
 2655 root      4848 S    hostapd -B /etc/hostapd.conf -P /var/run/hostapd.pid 
 2657 root      2900 S    udhcpd /etc/udhcpd.conf 

Now we will use the command kill in order to kill the processes as follows:

kill <hostapd PID>
kill <udhcpd PID>

In the example above, the PID's of hostapd and udhcpd are 2655 and 2657 respectively, so we would run:

kill 2655
kill 2657

The expected result is:

netconsole: network logging stopped, interface mon.wlan0 unregistered
wl1271: down

Then return the original configuration files

rm /etc/hostapd.conf
rm /etc/udhcpd.conf
mv /etc/hostapd.conf.bak /etc/hostapd.conf
mv /etc/udhcpd.conf.bak /etc/udhcpd.conf