Huawei E173s
This page describes how to set up Huawei E173s 3G USB modem on Arch Linux. It involves switching the USB stick from CD-ROM mode to modem mode using usb_modeswitch, making a connection to the network with sakis3g and setting it up to run at system startup.
Activating the SIM
Before using a brand new SIM (or a USB stick with SIM included) for the first time in Linux it may need to be activated first by using the Windows-only software on the stick, otherwise it will not connect no matter how many times you try (was true in my case).
Checking modem
Plug in the modem and run lsusb:
$ lsusb | grep Huawei
The output should be something like this:
Bus 003 Device 003: ID 12d1:1c0b Huawei Technologies Co., Ltd.
The ID 12d1:1c0b refers to vendor id and product id. If you get different values, it means your modem is not Huawei E173s (of course, you can always open the USB stick to double check).
Set up usb_modeswitch
At this point, if you remove your modem and re-insert it udev should switch to modem mode automatically but sometimes it just does not work (on my system for example) so you have to do it manually as root:
# usb_modeswitch -c /usr/share/usb_modeswitch/12d1\:1c0b -v 12d1 -p 1c0b
Check if the modem is switched
$ lsusb | grep Huawei
The output should be something like this:
Bus 003 Device 003: ID 12d1:1c05 Huawei Technologies Co., Ltd.
Note that the product ID has changed from 1c0b to 1c05. It means that the USB stick can now be used as a modem. Also note that it can take some time (probably not more than 15 seconds) for the modem to switch if you removed and re-inserted it instead of running usb_modeswitch manually.
Connecting
One way to connect is with sakis3g. This script has an interactive mode which tries to guide, and lead the user by hand.
Install sakis3gAUR[broken link: package not found]. Then run sakis3g:
$ sakis3g --interactive
You will have to provide your APN, username and password, assuming everything goes right you should be connected by now. Note while sakis3g should detect your modem, sometimes it just does not (it is the case on my system). If that's the case you have to specify CUSTOM_TTY, for example /dev/ttyUSB0.
Connecting at system startup
Creating a configuration file
Create /etc/sakis3g.conf.
Add the following lines (CUSTOM_APN, APN_USER and APN_PASS refer to your APN, username and password respectively, you may have to adjust them):
OTHER=CUSTOM_TTY CUSTOM_TTY="/dev/ttyUSB0" APN=CUSTOM_APN CUSTOM_APN="general.t-mobile.uk" APN_USER="t-mobile" APN_PASS="tm"
This configuration file works very well on my system but you may have to adjust CUSTOM_TTY as well if you have more than one USB modem. Note that it is also modem-independent - if you start using a different modem you should not have to change anything.
Running sakis3g at system startup
What you need to do is to run sakis3g connect at system startup. With SysVinit, one can add these lines to /etc/rc.local (it does not always work, I do not know why):
sakis3g connect --console sleep 3
The second line gives you time to examine the output of sakis3g at system startup to see if everything is working as it should. If it is, you can just remove it later. If using X with an xinit#xinitrc, and without a display manager like GDM, one can add
sudo sakis3g connect &
to .xinitrc.
Although if you are using GNOME, you should add it in gnome-session-properties instead:
Name: sakis3g Command: sudo sakis3g connect
For both of these to work you need the root user privileges. Or a substitute. With the sudo substitution, add the following line to sudo#Configuration:
username ALL=(ALL) NOPASSWD:/usr/bin/sakis3g