How To: Internet Connection Sharing - Mack Connectivity Pack

[mack]

Hi all,

Here's my Connectivity Pack for sharing internet connection over PPP (bluetooth or USB). It works both ways. (sharing GPRS with your laptop, or sharing your broadband connection with your phone).

See previous discussions in this thread:
http://www.motorolafans.com/forums/v...ic.php?p=14968

Below is the README file of this package.

Admin, after all this kernel-tinkering, isn't it time I lose my "Newbie" status ?

If you test this package, post your feedbacks here. I tested it on my A780 but it should work on other ezx phones as well.

Mack


Mack's connectivity pack:
-------------------------

This package contains some hacks to add two features to the A780 (and probably other EZX-based phones):

1. Sharing the GPRS connection over bluetooth (PPP), to provide your laptop with internet access on the go, through the phone.

2. Sharing the broadband internet connection of your desktop/laptop with the phone, so the phone can get faster and cheaper net access rather than the GPRS connection.

For obvious reasons, you shouldn't use these two features at the same time.

Disclaimer: Some of this work is an ugly hack. I take no responsibility to any damage. If, without loss of generality, your phone dies, your GPRS charges rocket to $1M or your country suffers a massive earthquake, don't come to me

A Thank You note: This work is dedicated to Motorola for releasing these wonderful phones. Keep making linux-based open environment phones and I'm sure my next phone will be a Motorola too.

Installation:

0. Make sure you have a working PPP connection (such as LeoPPP), and a loader that runs .lin scripts.

1. Extract this package in /diska/.system/QTDownLoad:
cd /diska/.system/QTDownLoad/ ; tar zxvf /diska/MackConnectivityPack.tgz
(If you install in a different location, you'll have to edit the 'ln' line
of the {masq,unmasq,inet-bt,un-inet-bt} scripts, to link to the new dir.
Iptables will look for its components in /tmp/mack/iptables, so the
symlink is required).

2. Copy *.lin from this directory to /diska/MyPrograms/ or wherever you like
to run .lin files from:
cp /diska/.system/QTDownLoad/mack/iptables/*.lin /diska/MyPrograms/


Usage:

Sharing the GPRS connection with your laptop:

0. Create the PPP connection (over bluetooth or USB cable) and use the Data
menu in Setup to start a GPRS connection to your favorite operator.

1. Click 'Files' and browse to MyPrograms. Click MackNAT.lin. Nothing will
appear to happen, but the environment is set.

2. On your laptop, add a route to wherever you wish to connect through ppp0:

route add <address> dev ppp0

You could route ALL traffic through the GPRS connection:

route del default
route add default dev ppp0

but be warned that your laptop may decide to generate unexpected traffic
such as getting an OS update, and you'll end up paying for more traffic
than you meant. Therefore, I only add route to an IP address I plan to
ssh to, or a default route for a very limited time, to access some website.

3. Use the connection.

4. When done, just go back to MyPrograms and click MackUnNAT. Nothing will
appear to happen, but traffic from your laptop will no longer be routed
through GPRS.


Sharing your broadband connection with your phone:

0. Create the PPP connection (over bluetooth or USB cable).

1. When ppp0 is up and running, set your laptop to route and NAT the fake
GPRS IP, 10.1.1.1. Here's my script for doing 0+1:

#!/bin/sh
dund -n -P 5 -c <MY_A780_BT_ADDRESS> noauth 192.168.1.3:192.168.1.4 netmask 255.255.255.0 local
while ! ping -c 1 192.168.1.4 >/dev/null 2>&1 ; do echo -n "."; sleep 1; done
iptables -D FORWARD -i ppp0 -j ACCEPT >/dev/null 2>&1
iptables -I FORWARD -i ppp0 -j ACCEPT
iptables -D FORWARD -o ppp0 -j ACCEPT >/dev/null 2>&1
iptables -I FORWARD -o ppp0 -j ACCEPT
iptables -t nat -D POSTROUTING -s 10.1.1.1 -j MASQUERADE >/dev/null 2>&1
iptables -t nat -I POSTROUTING -s 10.1.1.1 -j MASQUERADE
route add 10.1.1.1 dev ppp0
echo Ready.

Note to the paranoids among us: if you wish to set separate firewall
rules for the fake GPRS traffic going through your laptop/desktop, note
that packets will appear as though coming from 10.1.1.1 rather than the
normal ppp0 address of the phone.

2. Make sure you don't have an active GPRS connection. (The script would
work even if you do have one active, but you won't be sure you're not
paying, because the fake gprsv0 won't be created). I also suggest you
don't try to mess with the Data menu in Setup while this mode is active,
since it'll talk to the fake dsm and yield unexpected results. If you
did enter this mode while a GPRS connection is active, you'll have to
restart your GPRS connection after leaving this mode.

3. Click 'Files' and browse to MyPrograms. Click MackInetBT.lin. Nothing will
appear to happen, but the connection should now be up.

4. Use the connection. Opera, Java, and anything else should go through the
fake GPRS interface. Note that kvm (java) will still ask you to choose
a network profile to go through. Just create a fake one and select it.
It doesn't matter what you write in it since the fake dsm will always tell
kvm that connection is successful.

By the way, if you wish to make sure you're using the BT connection rather
than a GPRS connection, try to connect some local server on your network,
which wouldn't be accessible through the internet. If you don't have one,
you can just browse to http://checkip.dyndns.org/ and see that your IP
address is not the one you usually get from your GPRS provider.

5. When done browsing, just go to MyPrograms and click MackUnInetBT.lin.
Everything will be back to normal, and you'll be able to start a real
GPRS connection again.


Implementation notes:

The first feature was easy to implement. I just added NAT support to the
phone's kernel, and added some iptables rules to activate it.

The second one was tricky. Its trivial to just add a default route from the
phone via ppp0, but some internal applications (Opera, kvm) insist on routing
through gprsv0. (Opera just bind()s the GPRS IP for its connection. KVM
takes a step further, and ioctl()s gprsv0 itself. I wonder why they do that...

So, you'd think its still easy. Just write a small kernel module that
replaces gprsv with a fake gprsv0, and compile ipt_ROUTE.o and reroute
packets from gprsv0 to ppp0. Well, wrong again. These applications insist
on checking with 'dsm', which asks tapisrv to check /dev/mux* for a live GPRS
connection. If they can't detect a live GPRS connection, they refuse to
connect().

I was left with no choice but to fake the dsm interface in order to tell
applications that the GPRS is on. The complete solution is a combination of
a fake (usermode) dsm, a fake (kernel mode) gprsv, and some netfilter
trickery to reroute fake gprsv0 traffic over ppp0.

I guess I could write a single kernel module that does all that, but since
my scripts work, I'll leave it at that for now.

Good luck.

Mack

[maxx_730]

Woot way to go! Thanks! Ohyeah you could connect to internet from laptop thru bluetooth already with MPT, but good to be able to do it outside windows.
Ps: you lose newbie status if you have more than 50 posts. So start postwhoring then!

[mack]

woot way to go! Thanks!
Ps: you lose newbie status if you have more than 50 posts. So start postwhoring then!

You're welcome. Let me know if it works for you.

As for newbie status - I know, but I figured some kernel hacking ought to be worth something.

[admin]

i'll make u still a newbie no matter what! xD

kidding

[intoxicated]

really want to try this but for some reason i can't get BTPPP connect to the pc after i reinstalled my windows :S
always get timeout from connecting...

[rpconnect]

beauty work mack!!! thanks!!!

has anyone else tried this on an e680/i? (I know this is a 780 thread, but I cant help but try out cool ideas, so i'm hoping other e680 users read this 780 thread as well) I am pretty sure that the fake gprsv0 device is coming up ("ip route list" shows gprsv0 as default) and the forwarding is working okay on the host as I can ping anwhere from the phone (i'm assuming that the ping will go via the defaulted gprsv0), but neither opera or the kvm is respecting the connection.

for reference, i did change all occurances from 10.1.1.1 to 10.1.1.101 to avoid confilcting w/ my router's internal ip address (in both the ip forwarding script on the host and inet-bt script on the phone), but since the ping seems to work (over the assumed default gprsv0) I don't know if this is a problem or not. any thoughts or suggestions would be most appreciated.

[intoxicated]

finally got my e680i btppp connected..
i am not quite sure how to do 1st step...

"When ppp0 is up and running, set your laptop to route and NAT the fake"

when i run the script thats given it says the dund command is not found..

[mightymop]

try to add and edit the lines:

iptables -D FORWARD -i ppp0 -j ACCEPT >/dev/null 2>&1
iptables -I FORWARD -i ppp0 -j ACCEPT
iptables -D FORWARD -o ppp0 -j ACCEPT >/dev/null 2>&1
iptables -I FORWARD -o ppp0 -j ACCEPT
iptables -t nat -D POSTROUTING -s 10.1.1.1 -j MASQUERADE >/dev/null 2>&1
iptables -t nat -I POSTROUTING -s 10.1.1.1 -j MASQUERADE
route add 10.1.1.1 dev ppp0

to your iptables-firewallscript...
restart the firewall so that the iptablesstuff is working...

start mack's script when bluetooth is connected..

#!/bin/sh

dund -n -P 5 -c <MY_A780_BT_ADDRESS> noauth 192.168.1.3:192.168.1.4 netmask 255.255.255.0 local

while ! ping -c 1 192.168.1.4 >/dev/null 2>&1 ; do echo -n "."; sleep 1; done

iptables -D FORWARD -i ppp0 -j ACCEPT >/dev/null 2>&1

iptables -I FORWARD -i ppp0 -j ACCEPT

iptables -D FORWARD -o ppp0 -j ACCEPT >/dev/null 2>&1

iptables -I FORWARD -o ppp0 -j ACCEPT

iptables -t nat -D POSTROUTING -s 10.1.1.1 -j MASQUERADE >/dev/null 2>&1

iptables -t nat -I POSTROUTING -s 10.1.1.1 -j MASQUERADE

route add 10.1.1.1 dev ppp0

echo Ready


(maybe without the iptables stuff, 'cause this is allready running at this time)




the phone will ask
for an SSP connection...
then take leoppp to get ppp over bluetooth running and then start
MackInetBT.lin. after this it works for me on my a780

[alebm]

I tried to work over belcarra usbnet connection with my e680i, native apps works flawless, but opera only says "connecting..." and doesn't stop(if the script is triggered from the console some numbers(1, 2 and 8 ) popups at random intervals of time)... I changed ppp0 of cell script to usbl0 and changed the ip of gw also(192.168.55.1 host computer IP). Cellphone has the 192.168.55.6 and gprs still with 10.1.1.1.

About the native apps, if I try to access host internal webserver it reports the 192...6 ip. There is no log file with opera attemps to access the server.
Realplayer seens to access something but I had no compatible file to test at this time.

logs:
192.168.55.6 - - [15/Sep/2005:03:21:37 -0300] "GET /inicio.shtml HTTP/1.0" 200 2545 "http://192.168.55.1:800/inicio.shtml" "Lynx/2.6 libwww" "-"

10.1.1.1 - - [15/Sep/2005:03:22:40 -0300] "GET /fotos/d.rm HTTP/1.1" 404 867 "-" "RMA/1.0 (compatible; RealMedia)" "-"

[intoxicated]

still not sure what i should do after i get leoppp connected thorugh BT
now i have my phone assigned to 192.168.1.11 and my pc as 192.168.1.2
how do i set your laptop to route and NAT the fake GPRS IP?