Setting up your internet connection for Linux
Setting up your i12 connection under Linux is fairly straightforward, simply follow the steps below to get your computer connected to the internet. It will be assumed that you have installed the essential networking software modules from your Linux distribution, and that you have set up which serial port that is to be used for the /dev/modem. The default configuration will usually only allow direct access to /dev/modem as user root.

Step one: setting up your i12 account
To connect to an i12 shell account directly, and to experiment with connection sequences, you may use the minicom program. It is pretty straight forward to use.

Configuration of the machine for use on the net should be done as user root. Before proceeding any further, ensure that the file /etc/hosts.deny contains the following line: ALL: ALL

You would normally want to allow yourself access, so add the following line to /etc/hosts.allow: ALL: LOCAL Or if you insist: ALL: 127.0.0.1

For the following, note that it is meant for those connected via PPP and with a dynamic IP address. If you have the benefit of a fixed connection (such as the forthcoming i12 ADSL service), there will be some differences.

It is nice to have a name connected to the machine, a name that the dynamic IP user really can select as he or she pleases. Put the name in /etc/HOSTNAME: i12

The next step is to set up the name server in /etc/resolv.conf: search .nameserver 212.1.130.33 <nidx>nameserver

Step two: configuring TCP/IP
The name server must be specified by a numeric IP address. If required, you can have up to three different servers, each on a separate line. They will be requested in the sequence in which they are listed.

If you want to be able to use names like somemachine as an abbreviation for somemachine.acme.xz , you must replace the first line with: search acme.xz

A certain minimum of configuration will also be required in /etc/hosts. Most users will be able to manage with: 127.0.0.1 localhost 0.0.0.0 i12

Those with a fixed IP-address will obviously replace 0.0.0.0 with that. Likewise, a minimum /etc/networks is: loopback 127.0.0.0 localnet 0.0.0.0

You should also set your external mail domain in /etc/mailname: acme.xz

The username and password at the ISP must be specified in /etc/ppp/pap-secrets dirk * PrettySecret

Step three: setup details
Finally, the fine detail regarding the connection procedure itself must be specified before PPP can be initiated. This is done in /etc/ppp/chatscript: TIMEOUT 5 "" ATZ

OK ATDT12345678 ABORT "NO CARRIER" ABORT BUSY ABORT "NO DIALTONE"
ABORT WAITING TIMEOUT 45 CONNECT "" TIMEOUT 5 "name:" ppp

Details here may have to be tuned somewhat. The phone number in the third line must of course be set as required. Some users may need to replace the ATZ modem initialisation string with something more tailored for the modem being used. The last line specifies that one is expecting a prompt that ends with name:, and that the response should be ppp when it arrives. Other systems may have other login procedures.

To actually initiate a call, the PPP protocol may be initiated by issuing the following command: exec pppd connect \ 'chat -v -f /etc/ppp/chatscript' \ -detach crtscts modem defaultroute \ user dirk \ /dev/modem 38400

We should now be on-line, and stay up until the program is closed by keying in a ctrl-C. Any messages concerning the connection will be appended to the system logs. To read them, try: tail /var/adm/messages or dmesg

As long as PPP is up, you will have direct access to the internet and may use programs like ftp, ncftp, rlogin, telnet, finger etc. All these programs should be part of the network package.

Further information concerning PPP is also available from:

/usr/lib/ppp/README.linux
/usr/lib/ppp/README.linux-chat

Step four: final details
Finally, an additional word about security The file /etc/inetd.conf lists all services that your machine will offer externally. With the /etc/hosts.deny file we have made, no external access will be allowed. For those who need it, access must be allowed explicitly in /etc/hosts.allow. Local traffic may be allowed by: ALL: LOCAL

See also man 5 hosts_access.

A final minor issue: A certain confusion exists regarding the names of the POP protocols. A definition in /etc/services compatible with just about everything is:

pop2 109/tcp pop-2 # PostOffice V.2

pop3 110/tcp pop-3 pop # PostOffice V.3

ALT: Instead of chatscript, one might use the much more flexible dip. But not in connection with dialled.

ALT: Those fortunate enough to have a permanent TCP/IP connection via e.g. an Ethernet may safely ignore anything about PPP and instead start concentrating about setting up their network card.

ALT: Others may not have the possibility of using PPP, but may be able to use SLIP instead, for which there is support in much the same manner as for PPP. Another possibility is UUCP Others again may have to rely on exchange of news and email be means of SOUP A description for the latter case may be found in:

Solving Linux internet connection problems
If you are getting the error message: 'could not determine remote address' when connecting with ppp, try putting in your /ppp/options file: :10.42.42.42 to replace either noipdefault or 0.0.0.0:0.0.0.0 or any other line which specifies the IP addresses for the ends of the ppp connection.

pppd seems to have a difficulty with the unnumbered interface at our end of the ppp connection, but you can surmount this by specifying an IP address for it. If you use an IP address beginning with '10.' then you can be sure this doesn't conflict with a 'real' IP address on the internet (IP addresses matching 10.x.x.x are reserved for private networks). All the 'x's there should be numbers between 1 and 254.

These files are from the /etc/ppp/ directory on a linux system with a working ppp connection, using kernel 2.1.125 and pppd 2.3.5. They should work with any pppd from 2.2.0 or greater. Using these files, pppd was launched with the command:

/usr/sbin/pppd -detach connect "/usr/sbin/chat -v -r /etc/ppp/report-chat -s -f /etc/ppp/ppp.chatscript"

Which is the sort of command line that belongs in a script somewhere...in fact it's the command installed to launch ppp by the ppp setup utility.

If you would like more information, then the PPP-HOWTO would be worth reading.