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WiFi Ad-hoc Network
This page describes how to establish a decentralized WiFi network.
A wireless ad-hoc network - also known as Independent Basic Service Set (IBSS) - consists of local wireless devices (nodes) discovering each other and forming a network, each able to forward data for other nodes. An access point is not required for managing this communication.
In the following examples, two wireless LAN clients will be configured as ad-hoc network nodes with static IP addressing. Before continuing, install the wireless-tools package.
Debian Method
On each node, open /etc/network/interfaces in a text editor:
$ su # sensible-editor /etc/network/interfaces
- Define stanzas for each node's wireless interface, setting the network SSID and the device's operating mode to ad-hoc:
Node A
auto wlan0 iface wlan0 inet static address 192.168.1.1 netmask 255.255.255.0 wireless-channel 1 wireless-essid MYNETWORK wireless-mode ad-hoc
Node B
auto wlan0 iface wlan0 inet static address 192.168.1.2 netmask 255.255.255.0 wireless-channel 1 wireless-essid MYNETWORK wireless-mode ad-hoc
- Save the file and exit the editor.
Raise the interface on each node:
# ifup wlan0
Scan for ad-hoc cells in range (necessary for some drivers to trigger IBSS scanning):
# iwlist wlan0 scan wlan0 Scan completed : Cell 01 - Address: 02:0F:B5:4F:74:ED ESSID:"MYNETWORK" Mode:Ad-Hoc Frequency:2.412 GHz (Channel 1) Quality=42/70 Signal level=-53 dBm Noise level=-95 dBm Encryption key:off Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 6 Mb/s 9 Mb/s; 12 Mb/s; 18 Mb/s; 24 Mb/s; 36 Mb/s 48 Mb/s; 54 Mb/s Extra:bcn_int=100
To test, ping node A from node B:
you@nodeB$ ping 192.168.1.1 PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data. 64 bytes from 192.168.1.1: icmp_seq=1 ttl=64 time=0.073 ms 64 bytes from 192.168.1.1: icmp_seq=2 ttl=64 time=0.061 ms 64 bytes from 192.168.1.1: icmp_seq=3 ttl=64 time=0.062 ms 64 bytes from 192.168.1.1: icmp_seq=4 ttl=64 time=0.063 ms --- 192.168.1.1 ping statistics --- 4 packets transmitted, 4 received, 0% packet loss, time 3001ms rtt min/avg/max/mdev = 0.061/0.064/0.073/0.010 ms
For general /etc/network/interfaces information, see the interfaces(5) man page.
Manual Method
On each node, bring the wireless interface down, change the device's operating mode and SSID, then raise the interface:
$ su # ifconfig wlan0 down # iwconfig wlan0 channel 1 essid MYNETWORK mode ad-hoc # ifconfig wlan0 up
Scan for ad-hoc cells in range (necessary for some drivers to trigger IBSS scanning):
iwlist wlan0 scan wlan0 Scan completed : Cell 01 - Address: 02:0F:B5:4F:74:ED ESSID:"MYNETWORK" Mode:Ad-Hoc Frequency:2.412 GHz (Channel 1) Quality=42/70 Signal level=-53 dBm Noise level=-95 dBm Encryption key:off Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 6 Mb/s 9 Mb/s; 12 Mb/s; 18 Mb/s; 24 Mb/s; 36 Mb/s 48 Mb/s; 54 Mb/s Extra:bcn_int=100
- On each node, assign an IP address to the wireless interface:
Node A
# ifconfig wlan0 192.168.1.1 netmask 255.255.255.0
Node B
# ifconfig wlan0 192.168.1.2 netmask 255.255.255.0
To test, ping node A from node B:
you@nodeB$ ping 192.168.1.1 PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data. 64 bytes from 192.168.1.1: icmp_seq=1 ttl=64 time=0.073 ms 64 bytes from 192.168.1.1: icmp_seq=2 ttl=64 time=0.061 ms 64 bytes from 192.168.1.1: icmp_seq=3 ttl=64 time=0.062 ms 64 bytes from 192.168.1.1: icmp_seq=4 ttl=64 time=0.063 ms --- 192.168.1.1 ping statistics --- 4 packets transmitted, 4 received, 0% packet loss, time 3001ms rtt min/avg/max/mdev = 0.061/0.064/0.073/0.010 ms
Troubleshooting
- The default operating frequency/channel (2.412 GHz: channel 1) is frequently congested. Try using a different channel in the event of difficulties.
- Wireless LAN devices compliant with IEEE 802.11 specifications will only support a maximum bit rate of 11 Mbit/s.
See Also
http://hostap.epitest.fi/ | hostapd is a daemon to turn a computer into an access point.