How to share your 3G connection

In an earlier post I was speculating how disruptive a Nokia N80 or other WLAN enabled phone could be as WLAN access point which lets several people share the same UMTS Internet connection. We are not quite there yet but there are other ways to share your 3G connection. The easiest but still somewhat complicated one is to use the Internet connection sharing functionality of Windows XP. Here’s a short description of how to do it:

Settings for the computer with the 3G connection:

To use the Internet sharing feature, the 3G ‘modem’ has to appear in the Windows Network settings as either a dial up modem or a network card. This is shown in figure 1. Sorry for the figures being in German but I think the icons in the windows should give you an idea where to look for the settings on your PC. Right click on the icon that represents the 3G connection and select ‘Properties’. In my particular case shown in figure 1, the phone is connected via Bluetooth. Phones being connected by a cable and PCMCIA cards (*) work fine as well as long as the connection appears as a dial up modem or network card to Windows. Next, click on the last tab of the dialog box and check the box which says that this connection will be shared with other users.

Next, select the network adapter to which the other computers are connected that want to share the connection. In my case, the other users are connected via the Ethernet port. Once you click on the ‘OK’ button the following will happen: Windows configures a fixed IP address (usually for the network card to which the other users are connected (**). This is shown in figure 2. Do not change this setting as otherwise the connection sharing will not work anymore.

Settings on the other computers:

Here, some manual settings are required as well. Go the ‘Windows Network Settings’ and select the network adapter which connects this computer to the one that shares its Internet connection. In my case this is the ‘LAN network adapter’ as shown in figure 3 (***). Go to the TCP/IP setting and set the following values: IP address: Set this to an address in the same subnet as the sharing computer (e.g. Standard Gateway and DNS Server: Set these IP addresses to the IP address of the sharing computer (e.g.

That’s it! Once the computers are connected with each other and the 3G connection is established all participants can use the single Internet connection. Enjoy!

And here’s the fine print 😉

(*) Personally, I don’t have experience with certain software, e.g. from Vodafone, which is supposed to make your life easier and integrate the connection management in their own graphical user interface. Therefore, feedback on this would be appreciated.

(**) If you sometimes use the fixed line LAN connection for other purposes, you have to deactivate the Internet sharing on your modem connection again and reset the IP settings of the LAN connection for automatic IP and DNS address retrieval.

(***) It should also be possible to be able to share an Internet connection via the Wireless LAN network adapter. In this case however, the WLAN network adapter needs to be configured for ‘Ad-hoc connections’ or a Wireless LAN access point has to be used. In both cases it is important to remember not to change the static IP address of the adapter (usually that Windows has configured when the Internet connection sharing was first activated.

3G Roaming – Pleasure with Pitfalls

Thanks to an international 3G subscription I have long ago given up searching for Wifi hotspots at the locations I travel to. Instead, as the Sprint guys put it, the 3G network is following me wherever I go. I see it the other way round. Wherever I go, the network is already there. While I have always managed so far to find good 3G or EDGE connectivity, there are some pitfalls which I wouldn’t have thought existed anymore three years after the commercial launch of the first UMTS networks. Here are some strange but true examples:

France: For a month or two now, Orange, the mobile operator that allows me to roam to its 3G network, seems to have a new software version running on their UMTS network in Paris. Since then, my almost brand new Nokia N70 behaves strangely and has trouble establishing a dedicated bearer during a packet session after some time of inactivity. This results in very long delays in the order of 10 seconds or more when I click on a link after some time of network inactivity. The only remedy is to trick the network into letting me have a dedicated channel continuously by constantly sending pings to a host on the network. While this helps for notebook use, I can’t use this trick while web browsing via the mobile phone. So I prefer using Organe’s EDGE network by forcing the mobile into GSM only mode. In other parts of the country things work flawlessly. This is probably due to the fact that Orange uses different UMTS access vendors in different parts of the country: Alcatel in Paris, Nortel and Nokia in other parts of the country. Well done, Orange!

Germany: Here, I have a greater choice of UMTS roaming partners: T-Mobile, E-Plus and O2. The first two work flawlessly with my Nokia N70. O2 also works well if the mobile can find the UMTS network. Sometimes, however, the mobile just refuses to see the network, especially after the mobile has lost coverage for some time like for example if I have parked the car in an underground garage. Switching the phone on or off does not change anything. Even a manual network search, which shows that the 3G network is available, does not force the mobile back into O2’s UMTS network. The only action that helps sometimes is to go back to the place where the phone has no GSM or UMTS coverage of O2’s network for a minute. It’s a repeatable phenomenon and I’ve only seen it in Germany and only with O2. Also, I have to restart the phone much more often than in other networks, about once per day, as after some time I can’t connect to the Internet anymore.

Austria: Again, I have several roaming partners for UMTS: T-Mobile, A1 and One. In the A1 network I have detected the strangest problem yet. With both my Nokia N70 and my somewhat older Sony Ericsson V800 I have problems to send data from the notebook to the network. An analysis with Wireshark, a network tracing tool, revealed that the network has problems with large IP packets in uplink direction. At first I thought it was a specific mobile problem in combination with the network components used in the A1 network. However, as two completely different phones have the same problem it seems to be a general network issue. What helps is to reduce the Maximum Transfer Size (MTU) of the notebook for dial up connections. After changing the MTU size to 480 bytes as described in this Microsoft bulletin, things worked a lot better. But quite frankly, I prefer using ONE’s network where things work as they should. Just in case I ever end up in a part of Austria where ONE’s network is not available, I still have my MTU jocker ready.

All of this is very strange as both of my UMTS phones are widely used in these countries. But I think it shows that 3G interoperability is still not where it should be. Nevertheless, things are not as bad as they might seem after describing these three cases for the following reasons: Even in the countries described above I have found at least one network in which things work flawlessly with my mobiles. In addition, here’s a list of countries where I didn’t encounter problems, at least not in the networks I used: Switzerland (GPRS and EDGE), Spain, Italy, Belgium (EDGE), The Netherlands, U.K. and Portugal.

Centrino WLAN vulnerabilities – Getting your virus with a malformed packet

Maybe it’s because we are used to getting patches to our PC every month or so now that the following story has not seen wide spread attention so far: Intel admits Centrino chipset driver issues: These allow attackers to send malformed wireless lan frames to insert and execute malicious code (read viruses).

This is scary for two reasons:

Firstly, no user interaction is required. This means that a user doesn’t even have to browse to a malicious webpage to get infected. It’s enough to have your WLAN card activated. Airports and conferences might become nice playgrounds for past time hackers and self replicating viri once an exploit for this hits the net.

Secondly, the fixes have to be installed manually. There is no auto update functionality like for example for Microsoft Windows patches which are downloaded and installed by the operating system once available. I’ve downloaded and installed the patch for a notebook with a Centrino 2200BG card. A 129 MB (MEGABYTE!) download. Incredible! At least it installed o.k. and the driver was updated. Then I downloaded the patch for another notebook which has a Centrino 2100 chipset. A refreshingly short 13 MB download… When executing the file it installed an update for the helper program but failed to update the driver for the chipset. The program showed no sign that the driver, where the real problem sits, was not updated. Perfect, the average user will never notice that… So I manually installed the driver update from the hardware settings. To make the day perfect, many notebook vendors have chosen to write their own wireless lan configuration utilities that interface with the driver in some way. Of course they could be broken if you install the driver. Take a look at F-Secure’s blog. Once an exploit for this hits the wild, it’s going to be big.

Speculation: Could the same scenario happen in the cellular world, too? In theory I could imagine this happening in the cellular world as well. Imagine that somebody finds a bug in the IP stack of mobile devices or in the mobile browser that could be exploited in the same way. Downloading fixes on such devices is still a procedure most device manufacturers have yet to come to terms with. For the moment, though, I think such a scenario is unlikely. Unlike in the PC world with a dominance of Windows and Intel Centrino chipsets the mobile space is much more diverse which would prevent or at least slow down such a scenario. Nokia with their Series 60 phones might have a good approach to this. No buffer overflows possible as per OS design and software and patches can be pushed to a device Over the Air (OTA) starting with S60 3rd edition.

Fon (almost) made a smart move in Germany

Today I read a post on Teltarif, a German website, that FON has partnered with a German DSL reseller to offer bundles for prospective Foneros. For those of you who haven’t heard of FON before, they are attempting to build the largest Wifi Hotspot network in the world with the help of private enthusiasts.

I like the idea of bundling FON with a DSL offer, as I think becoming a Fonero must be as easy as possible in order to be successful. At closer inspection, however, the bundle falls short of the "Buy our product and we will deliver a box which you just have to plug into your phone socket at home to become a hotspot". Instead, the offer only bundles a FON account, a Fon Wifi access point and a DSL data subscription provided by Interroute Germany.

What’s missing is the DSL line subscription and a DSL modem which you have to get separately. Apart from being too complicated for the average user who’s thinking about becoming a Fonero because he lives downtown or near a hotel, the hardware lineup is also not reflecting todays DSL landscape. While it was common to have a separate DSL modem and a separate Wifi router a couple of years ago, integrated Wifi routers + DSL modems are the norm these days.

Great first step FON, but now it’s time to put your software on an integrated Wifi router / DSL modem and find a reseller who is willing to do the final step and sell both the DSL data subscription and the DSL line in one package.

Podcast: US Wireless Carrier Landscape

As a frequent traveler, I’m amazed that each country seems to have it’s oddities when it comes to mobile carriers. In some countries, mobile voice and mobile data is very cheap while in others just accross the border, the world looks quite different. Debi Jones of and Mediaslaves has been nice enough to do the first in a series of podcasts discussing the state of wireless in different countries. Debi lives in California, so the US mobile landscape is the center of our discussions:

Part 1:

  • Coexistence of GSM and CDMA in the US
  • HSDPA deployment
  • Closed down CDMA handsets
  • The Nokia vs. Qualcomm battle
  • The Korean CDMA/UMTS situation
  • Price of wireless data

Podcast, MP3, 26 mins, 12 MB

Part 2:

  • Muni Wifi and combination of Cellular and Wifi Data plans
  • Wireless traveling in the US
  • A hotspot detector (check it out at
  • Wireless Instant Messaging, Yahoo Go!, Skype and Trillian
  • Verizon’s Walled Garden
  • Mobile phone multitasking on Nokia N-Series phones
  • Mobile phone design

Podcast, MP3, 28 mins, 13 MB

Some figures on Mobile Operator OPEX

Sometimes I find it really strange that a large part of wireless networks is everything but wireless. The only part which is really "wireless" is the radio channel between the user and the cell tower. Behind the base station data and voice is transferred over copper or fiber cables, or microwave links in some cases.

Kevin has come up with an interesting whitepaper on the evolution of the transmission network behind the base stations which is required to adapt the networks to the increasing demand for mobile data. Among many other things the following figures were quite interesting to me, especially when combined with an earlier post of mine on data usage of a mobile PC user and potential revenue generated per base station:

  • Cost of Running the Network: The percentage for running the network from the total operational expenditure (OPEX) is around 30%. On the other hand, 43% of the money goes to Marketing, Sales and Administration… (see figure 2 in the whitepaper). I wonder if (and where) the salaries of the various top executives (CEO, CTO, CMO,…) are included in the OPEX!? 😉
  • Backhaul Line Rental: On page 4, the whitepaper says that the line rental for a 2 MBit/s E-1 link used for most UMTS base stations today is about € 250.- per month. This amounts to about 1/3 of the 30% spent from the total OPEX on network operation.
  • Cost for Technical Personnel: The costs for technical personnel to run the network amounts to another third of the network operation costs. This is 10% of the overall OPEX. Not very much compared to the 43% for Marketing, Sales and Administration…

HSDPA backhaul over ADSL

Kevin Evans has put a post on his blog on HSDPA backhaul over ADSL. At first, it seems like a pretty good idea he says but has some second thoughts:

Kevin says Internet Service Providers (ISP) would probably be less than happy to connect HSDPA ADSL links to their  backbone. I agree! Cells where HSDPA is used heavily will pretty much use most of the bandwidth of an ADSL link for a considerable time per day. Consequently, such links would substantially increase the load of the ISPs ADSL backbone.

He then goes on to say that the alternative for mobile operators is to do their own ADSL backhauling. He thinks this is also not a good idea due to having to build an overlay network for backhauling next to the E-1s currently used for real time voice traffic. But why is it such a bad idea for operators to put their own ‘mini’ DSLAMs in central offices and have a little fiber there for backhauling? There is cost whatever you do, E-1, microwave, etc. so why not ADSL?

Some operators might have already decided to do this (speculation on my part). O2 Germany for example has said that they want to become an integrated fixed- and mobile telecommunication company, providing both high speed fixed line Internet access via DSL and high speed mobile Internet access via HSDPA. If they decide to build their own ADSL network, they can use it for both purposes.

As an alternative, Kevin suggests to use Ethernet for carrying both real time voice traffic and non real time background and streaming traffic generated by web browsing, podcast downloads, etc. But what about the distance you can cover with commercial Ethernet equipment today over phone cables?

When I first read about HSDPA over ADSL backhaul it immediately made sense to me due to the fact that ADSL has become a cheap technology to bridge larger distances than what is possible with other technologies. Have new long distance Ethernet technologies caught up in the meantime?

Whatever operators decide, I hope they decide quickly as HSDPA over 2 MBit/s E-1s is not going to make people happy.

It’s time for some mobile privacy!

I am sure that not even one person in a thousand has ever attempted to manage web browser cookies on the PC. I have to admit that I’ve been one of those 999 until recently. However, leaving the browser on its own to collect and send cookies as requested by web sites leaves the door wide open to advertisment companies and other institutions who love nothing more than to spy on where users are going in the web and what they are looking at. So I’ve set my cookie options in Firefox to only allow cookies from a few select web sites so I don’t have to log in everytime I go there. All other cookies are automatically deleted whenever I close the browser.

In the mobile world I would like to do the same thing. However, Opera for S60 has only very limited cookie privacy options. One can either delete all or none. Not good for me as I would like to keep some cookies like for example the one that keeps me logged into my mobile Flickr account.

Time for some action Opera!