How to build a wifi LAN with static IP addresses

In this little tutorial I'm going to use wireless connections but be aware that most of this stuff is valid for ethernet-cabled connections as well. I'll consider just this two simple cases, for more advanced stuff the answer is google.

CASE #1 (2 computers and a modem):

Requirements: #2 pc with wifi network cards



In this specific case we can build an "ad-hoc" network (i.e. point-to-point).
You can use either the software bundled with your wifi card or windows tutorial to create a nwe network. In this process you have to choose a SSID (that is the name of your network) and the security level (see Appendix1).
Once you terminate, you'd better set fixed addresses to your computers so to have a greater control over your network and if needed easily add new functions or spot problems.
If you use Windows XP (for Vista the procedure is similar) you should go to the control panel/ network connections/ wireless connection the click it with the right button ---> Properties ---> Select IP Protocol (or TCP/IP v4) e click on Properties
Then select the manual config and complete as follows:

for PC1
IP address: 192.168.0.1 /*this is the UNIQUE address of the computer, so you must not have duplicates on the net*/
Subnet mask: 255.255.255.0 /*automatically filled*/
Gateway: 192.168.0.1 /*this is the address of the computer with the modem connected to the internet (look at the pic)*/

for PC2
IP address: 192.168.0.2
Subnet mask: 255.255.255.0
Gateway: 192.168.0.1

for both:
if you can and it works select the autoconfiguration for DNS, otherwise fill them manually with the DNS of your ISP or your custom ones.


More on the same topic:
a) if both the computers can indipendently connect to the internet then set themselves as gateway (i.e. for 192.168.0.1 set 192.168.0.1 as gateway and for 192.168.0.2 set 192.168.0.2 as gateway)

b)if you use an external modem/router instead of an internal/USB modem it needs its own IP address so be careful while assigning IPs to the computers (remember that you've to avoid duplicates!). Then, in the pc directly connected to it set the router address as gateway, while nothing changes for the other pc


CASE #2:

Minimal Requirements:
-#1 wi-fi Access Point
-#1 adsl modem/router (note that the wifi access point may embed an adsl modem so you don't need another device, this is the case of the following example)
- at most 253 computers with wifi cards

Now we're going to analyse a network of this kind (AP= Access Point):



The starting point is similar to the one in the previous case: you have to access to the Access Point (see Appendix2) and create a new wifi network, so choose the SSID and security level (again, see Appendix1). Moreover you'll have to set the parameters of your internet connection in the appropriate page.

Now repeat the steps described in the case 1 to set the IP addresses, and dns (BEWARE OF THE AP ADDRESS).
As regards Gateways, in this example PC #2,3,4,6 need 192.168.0.1 (the AP) as gateway, while PC #5 is a kinda weird case because it's connected via ethernet cable to PC #4 so it requires the ip address of PC#4 to be set as gateway. (be aware of the fact that PC#4 always needs pc#5 to be turned on and the ethernet connection to be estabilished to be able to connect to the internet. It would have been better to connect it directly to the AP either via wifi or via ethernet).

Finally, the printer connected to PC#6 can be shared through the network. (even in this case it would have been better to plug the printer directly to the printer server in the AP (if present) so to avoid any dependence on a specific computer).
To share the printer with windows just go to the "printers" folder in the control panel and click on "Add a new printer"---> follow the path to add a network printer and write the address of pc #6 when required.
If you use Linux the procedure may be similar but I don't want to explain it here (Linux users are generally pro nerds so they can walk on their own legs).


Appendix 1 (Security):

Security is one of the main issues of wifi networks because you're sending your data over everyone's air, so anyone can easily eavesdrop what you're currently doing. For this reason some ciphering methods has been developed. I'll list them from the most secure downward.

WPA2 (most secure, if available ENABLE it!)
WPA (relatively secure)
WEP (unsecure, it can be hacked in few minutes exposing your whole LAN to undesirable people)
Open (no ciphering at all! you're exposed to everyone if you don't use some other authentication methods)


Appendix 2 (Debugging and tricks):

a)Are my devices in communication?
You can easily see if 2 devices can communitate with each other: Open the Command Prompt (Terminal if you use linux) and type: ping IP /*whare IP is the ip address of the device we want to contact*/
if you can see the response time (measured in ms) then you're done: the 2 devices can communicate

b)How to access to the AP or router?
APs and routers have a configuration page accessible through HTTP connection: this means you can open your favourite browser and by typing http://IP (as above IP must be replace with the device ip address) you acces to the control page.
Generally you have to perform an authentication with login and password, so have a look at the manual budled with your device. APs and routers usually use standard combinations such as admin/admin or similar

c)uhm... nice network but.... how can I share files?
I'm going to explain it in future

d) Wannabe a lamer too! Tell me how to crack WEP!!!
Nope (for now ...)