Direct modem connection

From ArchWiki

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This article describes how one can connect directly to the Internet from an Arch Linux box using an internal modem or external modem in bridge mode.

Due to a lack of developers for dialup issues, connecting Arch to the Internet with a dialup line requires a lot of manual setup. If at all possible, set up a dedicated router which can be used as a default gateway on the Arch box.

Analog modem

To be able to use a Hayes-compatible, external, analog modem, you need to at least have the ppp package installed. Modify the file /etc/ppp/options to suit your needs, following instructions located in pppd(8). You will need to define a chat script to supply your username and password to the ISP after the initial connection has been established. The manpages for pppd and chat have examples in them that should suffice to get a connection up and running if you are up for it. With udev, your serial ports usually are /dev/tts/0 and /dev/tts/1.

Tip: Read #Dial-up without a dialer.

Instead of fighting a glorious battle with the plain pppd, you may opt to install wvdial or a similar tool to ease the setup process considerably. In case you are using a so-called WinModem, which is basically a PCI plugin card working as an internal analog modem, you should indulge in the vast information found on the LinModem homepage.

ISDN

Setting up ISDN is done in three steps:

  1. Install and configure hardware.
  2. Install and configure the ISDN utilities.
  3. Add settings for your ISP.

Install and configure hardware

The current Arch stock kernels include the necessary ISDN modules, meaning that you will not need to recompile your kernel unless you are about to use odd ISDN hardware. After physically installing your ISDN card in your machine or plugging in your USB ISDN-Box, you can try loading the kernel module. Nearly all passive ISDN PCI cards are handled by the hisax module, which needs two parameters: type and protocol. You must set protocol to:

  • '1' if your country uses the 1TR6 standard.
  • '2' if it uses EuroISDN (EDSS1).
  • '3' if you are hooked to a so-called leased-line without D-channel.
  • '4' for US NI1.

Details on all those settings and how to set them is included in the kernel documentation, more specifically in the isdn subdirectory, and available online. The type parameter depends on your card; a list of all possible types can be found in the README.HiSax kernel documentation. Choose your card and load the module with modprobe, using appropriate options like this: 

# modprobe hisax type=18 protocol=2

This will load the hisax module for my ELSA Quickstep 1000PCI, being used in Germany with the EDSS1 protocol. You should find helpful debugging output in your /var/log/everything.log file, in which you should see your card being prepared for action. Please note that you will probably need to load some USB modules before you can work with an external USB ISDN Adapter.

Once you have confirmed that your card works with certain settings, you can add the module to /etc/modprobe.d/ so it will be loaded at startup: 

/etc/modprobe.d/isdn.conf
alias ippp0 hisax
options hisax type=18 protocol=2

That being done, you should have working, supported hardware. Now you need the basic utilities to actually use it!

Install and configure the ISDN utilities

Install the isdn4k-utils[broken link: package not found] package, and read the manpage to isdnctrl, it will get you started. Further down in the manpage you will find explanations on how to create a configuration file that can be parsed by isdnctrl, as well as some helpful setup examples. Please note that you have to add your SPID to your MSN setting separated by a colon if you use US NI1.

After you have configured your ISDN card with the isdnctrl utility, you should be able to dial into the machine you specified with the PHONE_OUT parameter, but fail the username and password authentication. To make this work add your username and password to /etc/ppp/pap-secrets or /etc/ppp/chap-secrets as if you were configuring a normal analogous PPP link, depending on which protocol your ISP uses for authentication. If in doubt, put your data into both files.

If you set up everything correctly, you should now be able to establish a dial-up connection with: 

# isdnctrl dial ippp0

If you have any problems, remember to check the logfiles!

DSL (PPPoE)

These instructions are relevant to you only if your PC itself is supposed to manage the connection to your ISP. You do not need to do anything but define a correct default gateway if you are using a separate router of some sort to do the grunt work.

Before you can use your DSL online connection, you will have to physically install the network card that is supposed to be connected to the DSL-Modem into your computer. After loading the appropiate kernel module for your newly installed network card, you should install the rp-pppoe package and run the pppoe-setup script to configure your connection. After you have entered all the data, you can connect and disconnect your line by starting or stoping the adsl.service, respectively. The setup is usually easy and straightforward, but feel free to read the manpages for hints.

If you want to automatically 'dial in' at boot, issue command enable the adsl.service.

Dial-up without a dialer

This page tells you how you can execute pppd directly without using dialer software such as pon, poff, wvdial, kppp, etc. It stays connected throughout X server shutdowns and is extremely simple.

  • Back up /etc/ppp/options 
# mv /etc/ppp/options /etc/ppp/options.old
  • Create new /etc/ppp/options using this template:
lock
modem
debug
</dev/DEVICE>
115200
defaultroute
noipdefault
user <USERNAME>
connect 'chat -t60 \"\" ATZ OK ATX3 OK ATDT<NUMBER> CONNECT'

Replace /dev/DEVICE with your modem device. For comparison with another operating system device, see the following table:

Windows GNU/Linux
COM1 /dev/ttyS0
COM2 /dev/ttyS1
COM3 /dev/ttyS2

Edit to point device to your modem device, to use your dial-up account username, and to dial your ISP's number after the ATDT. You can disable call waiting using ATDT 70,15555555 (in North America, anyway). You may also wish to edit the dialer commands; search for information on how to do this. If your ISP uses CHAP, then the next file is chap-secrets. 

"USERNAME" * "PASSWORD"
  • Now you are ready to connect. Connect (as root) using pppd /dev/modem (or whatever device your modem is connected as). To disconnect, use pkill -3 pppd.

If you wish to connect as user, you can use sudo. Configure sudo to call the above commands for your user, and you can use the following aliases in your ~/.bashrc (or /etc/bash.bashrc for system-wide availability): 

alias dial='sudo pppd /dev/modem'
alias hang='sudo killall pppd'

Now you can connect by running dial from a terminal and disconnect with hang.