SCREENSHOT 4. Most every Access Point has a facility to allow
Internet users to access servers that sit in the Access Point’s
local network.
{{0x10,0x11,0x12,0x13,0x14,0x15,0x16,0x17,0x18,0x
19,0x1A,0x1B,0x1C}},\
{{0x20,0x21,0x22,0x23,0x24,0x25,0x26,0x27,0x28,0x
29,0x2A,0x2B,0x2C}},\
{{0x30,0x31,0x32,0x33,0x34,0x35,0x36,0x37,0x38,0xSCREENSHOT 5. The Microchip folks that engineered the TCP/IP
stack have taken much of the head scratching out of embedded
networking. This set of Web pages is a fantastic tutorial on sending
mail, uploading files, and coding interactive Web pages.
46 SERVO 03.2010
39,0x3A,0x3B,0x3C}},\
}
#define END_OF_MY_DEFAULT_WEP_KEYS_LONG
Note that the 128-bit WEP key I entered matches the
AP’s WEP key entry in Screenshot 3. There are four key
index strings that we can alter. I chose to replace the first
WEP key string to match the first WEP key string in our AP.
The TCP/IP driver needs to know that. So, we identify the
selected key index in this manner:
/* Valid Key Index: 0, 1, 2, 3 */
#define MY_DEFAULT_WEP_KEY_INDEX (0u)
The final step in setting up ZG2100M wireless security
is defining the WEP authorization type:
/* Valid WEP auth: kZGAuthAlgOpen */
/* kZGAuthAlgShared */
#define MY_DEFAULT_WEP_AUTH kZGAuthAlgOpen
Take a quick look at Screenshot 3 again and note that
I selected Auto in the AP’s Authentication configuration
slot. Selecting Open would have also worked here as we
can specify the authentication type in both our TCP/IP
firmware and the AP configuration.
Now our ZG2100M data flow is relatively secure. If
your ZG2100M-equipped mechanical animals roam on your
residential range, you’ll most likely want them to be able to
get on the Internet and your local network through your
current (and hopefully secured) home network setup. That’s
where being able to configure the ZG2100M for WEP and
other security methods become important. Now you know
that you can monitor and control your ZG2100M-based
devices while keeping your home network and device data
secure.
Here’s where the cool stuff comes into play. Take a
look at Screenshot 4. The PC(Server) is really our
ZG2100M which has been given the IP address of
192.168.1.101 by the AP’s DHCP server. The unknown
prefix is telling us that a NetBIOS name was not associated
with the device (our ZG2100M) that accepted the lease to
the DHCP-assigned IP address. Not a problem. In this
application environment, we can operate without a
NetBIOS name.
What we’ve done in Screenshot 4 is open up an
Internet worm hole in the AP to allow our ZG2100M to act
as an Internet-enabled Telnet server. A remote Internet host
can access the ZG2100M Telnet server application which is
part of the free TCP/IP stack and is running on the
PIC24FJ128GA010 by opening a Telnet session using the
AP’s IP address coupled with the port addresses shown in
Screenshot 4. The same can be done if you wanted a
Fred Eady can be reached via email at fred@edtp.com
