Page 263 - Hacking Roomba

244 Part III — More Complex Interfacing

and the WiMicro will be on that network. This makes finding it a bit easier. The IP address
range used on this network is the default one used when there’s no DHCP server or static
IP address configured: the 169.254/16 network. /16 means the broadcast ping address is
169.254.255.255 and either device’s IP address must start with 169.254.
When you’re on the LTRX_IBSS net, the steps to find the WiMicro address are:

1. Determine your own IP address.
2. Broadcast ping 169.254.255.255.
3. Look at responses and pick the one that isn’t yours.
Listing 12-1 shows an example of doing this on a Unix-like OS. The ifconfig command
gives the IP address of the computer called demo: 169.254.86.198. The ping command
then shows two devices responding, the demo computer and something else at 169.265.78.119.
That’s the WiMicro. From this point you can use the web interface or telnet interface to con-
figure it.

If you don’t have a Wi-Fi access point but do have a computer with wireless access, you can
keep the WiMicro in ad-hoc mode and connect directly to its LTRX_IBSS wireless network. This
enables you to experiment with a Wi-Fi Roomba without needing the Wi-Fi router normally
required.

Listing 12-1: Finding the WiMicro with ping

demo% ifconfig en1
en1: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST>
mtu 1500
inet6 fe80::20d:93ff:fe86:fb49%en1 prefixlen 64 scopeid
0x5
inet 169.254.86.198 netmask 0xffff0000 broadcast
169.254.255.255
ether 00:0d:93:86:fb:49
media: autoselect status: active
supported media: autoselect
demo% ping 169.254.255.255
PING 169.254.255.255 (169.254.255.255): 56 data bytes
64 bytes from 169.254.86.198: icmp_seq=0 ttl=255 time=0.240 ms
64 bytes from 169.254.78.119: icmp_seq=0 ttl=64 time=2.208 ms
(DUP!)
64 bytes from 169.254.86.198: icmp_seq=1 ttl=255 time=0.247 ms
64 bytes from 169.254.78.119: icmp_seq=1 ttl=64 time=2.304 ms
(DUP!)
^C
-- - 169.254.255.255 ping statistics -- -
2 packets transmitted, 2 packets received, +2 duplicates, 0%
packet loss
round-trip min/avg/max/stddev = 0.240/1.250/2.304/1.007 ms