Some interesting questions and answers from my local Linux Group, the responses were written by Linux wireless expert Quentin Wright.

The first questioner wants temporary Internet access for a local community group:

I run a group in a venue without Internet access, I've been thinking of getting a USB 3G dongle (possibly with one of those USB->Ethernet hubs people like Three offer).

You could just get a pay-as-you-go SIM and a dongle.

I quite like the Netgear MBM621 which is an HSPDA/Ethernet modem and does NAT. Unfortunately they cost about 230 UKP new, and second-hand ones sell for nearly as much on eBay.

The next two questions are from the same author, who has connection problems with a mobile broadband USB dongle.

I have the T-Mobile web-n-walk mobile broadband USB stick which identifies itself as a Huawei E220/E270 HSDPA modem.

I recently downloaded and installed the latest version of the vodafone-mobile-connect (VMC) package for Fedora 10.

This installed okay after I had installed a few other things it required and it now runs, detects the Huawei and is quite happy to read and send text messages, which I previously had to do using a hand-crafted script.

But it will not set the device into internet mode, and although it installed lots of files in /usr/share/vodafone-mobile-connect/ I can't find what I have to change to make it work with the t-mobile network.

Not especially constructive I'm afraid, but it works out of the box with Ubuntu 9.04 using Network Manager. There is a look-up table of providers and their configurations installed by default - something different from VMC.

It may well work similarly with Fedora 11 as they said they were going to put the code in - I'll try it in the next day or so other distractions at work permitting.

I got rid of Network Manager because it interfered with other things (including the latest version of Firefox) and I mostly prefer to use scripts to handle my network connections (including changing /etc/hosts, and other things). Various colleagues who previously used 'NM' have now switched to 'wicd' which they find works where NM breaks in recent versions of linux. I don't know what's going on there.

Things have been particularly complicated with respect to networking since the transition to the Devicescape architecture in the kernel last year, coupled with the incorporation of the driver code from the more common wireless devices into the kernel as well.

These changes have in turn obliged the driver developers, the wpa-supplicant people, and the teams involved in the configuration utilities like Network Manager and wicd to catch up with the changes in the kernel. Further the distribution builders have had quite difficult decisions to make about the particular kernel build and other components to put into their release.

It's not sufficient to make a statement like "NM breaks with such-and-such a version of Linux". In reality a problem will relate to the combination of the specific kernel version, the particular device being used, as well as the versions of NM and wpa-supplicant.

Additionally in some distributions, like Debian, Mandrive and PCLinux OS, with some devices multiple conflicting drivers are loaded when particular devices are detected. In other distributions like Arch Linux, SUSE and Debian the firmware has to be copied into /lib/firmware. The symptom is that Network Manager appears to work, including acceptance of the key and even the appearance of a brief connection which then dies.

In endeavouring to triage NM problems in Ubuntu, about 50% of the problems relate to a failure to understand how to use the configuration icon. In particular the mistakes that are made are:

1. Right clicking and using manual configuration when it is unnecessary.
2. Failing to appreciate that it is necessary to left-click on the icon to configure wireless. This is a particular problem with users coming from a Windows environment.
3. Not knowing the network passphrase, or only having a hex passphrase when a string is required (some BT Homehub users).
4. Setting it up, changing the hub configuration and failing to make a note of the default keyring password and being unable to change the configuration.

On the topic of kernel versions, it's not enough just to rely on the kernel version for the 3G modems, because the udev rules have to be right as well.

As a rule it's best to avoid upgrading. The best strategy seems to be to have multiple partitions, maybe with a shared /home partition and do a clean install into the least used partition. You might then decide to migrate to the latest (greatest?!) version, or alternatively just give it a miss this time around.