Today dawns a new chapter in my Internet connectivity.... well maybe not so drastic. In my my last article I mentioned my purchasing an Alltel 3G wireless internet card to replace my Wildblue Satellite Internet service. I have been using the air card for a couple of days now and am pleased enough with it that I canceled my Wildblue account. Now comes the fun part.... sharing the Internet connection with the rest of the machines in my office.

Follow up:

As it turns out it wasn't that complicated of a process. I have the Huawei EC 168 Air Card plugged into the USB port on my workstation which is running Linux Mint. I set up the connection the same way as outlined in the article mentioned above. The next step was to configure my workstation to act as gateway for the rest of the office. This process actually only involves two steps: making the workstation the DHCP server for the network and then configuring the ethernt port to NAT traffic from the other computers in the office to give them access to the Internet.

Installing the DHCP server is no big deal and I discovered a firewall application called Firestarter is the easiest way to configure the NAT. So the first thing I did was install the software.

sudo apt-get install firestarter dhcp3-server

Once the DHCP server is installed there is just a little bit of configuration that needs to be done to get it up and running. I followed the example given in How To Set Up A DHCP Server For Your LAN

And here is a copy of my file which you may use as an example:

ddns-update-style none;

option domain-name-servers 145.253.2.75, 193.174.32.18;

default-lease-time 86400;
max-lease-time 604800;

authoritative;

subnet 192.168.0.0 netmask 255.255.255.0 {
range 192.168.0.200 192.168.0.229;
option subnet-mask 255.255.255.0;
option broadcast-address 192.168.0.255;
option routers 192.168.0.210;
}

host hdtsrvr {
hardware ethernet 00:0B:CD:XX:XX:XX;
fixed-address 192.168.0.151;
default-lease-time 86400;
max-lease-time 86400;
}

host win2000 {
hardware ethernet 08:00:27:XX:XX:XX;
fixed-address 192.168.0.1;
default-lease-time 86400;
max-lease-time 86400;
}

My workstation's IP address is 192.168.0.210. I left it at this address instead of changing it to 192.168.0.1 because I already have NFS setup and didn't feel like going in and re-configuring all of that. Next I have assigned several machines a reserved IP addresses. It makes it easier for me to remember their address. The one thing the above mentioned article wasn't clear about was how to do that so that is what the host xxxxxx {...} is all about.

Once the configuration file is done and saved you need to reset the DHCP server by

/etc/init.d/dhcp3-server restart

You can check your configuration by renewing the IP lease of one of the computers on the network.

Next I tried to fired up the Firestarter firewall application. When I tried to open Firestarter from the menu nothing happened. I looked around and found an article on how to share your internet connection on ubuntu which used the process I am using and there was a comment that said there was a problem with how Firestarter found the DHCP server. So I ran sudo ln -sf /etc/init.d/dhcp3-server /etc/init.d/dhcpd. This didn't fix the problem opening Firestarter so I don't know if if is needed or not.

NOTE: There was also a configuration mentioned in this article that configured the interface DHCP listened to. DHCP seemed to be working before I did this so I am not sure that it is necessary.

Well Firestarter still didn't run so I opened up a terminal window and ran sudo firestarter which brought up the initial configuration wizzard. Appearently it needs to be running as root. I didn't take a screen shot of this but I set the Internet Connected Device to ppp0 and the Network Connected Device to eth1 which happens to be the ethernet card I am using at the moment. I'm not sure yet if there is anything else that needs to be configured but that is all I had to do to get it all to working. And it seems to work like a charm.

Tags: 3g wireless, alltel, internet connection sharing