It will be assumed that we have installed the essential
networking software modules (e.g. essential parts of the
Slackware N-series), and that you have set up which serial port
that is to be used for the
The default configuration will usually only allow direct access
/dev/modem as user
To connect to ISP shell accounts directly, and to experiment with
connection sequences, you may use the
It is pretty straight forward to use.
Configuration of the machine for use on the net should be done as
root. Before proceeding any further, ensure that
/etc/hosts.deny contains the following line:
You would normally want to allow yourself, so add the following line to
Or if you insist:
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, 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
The next step is to set up the name server in
The name server must be specified by a numeric IP address, and will be different from ISP to ISP. 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.
search . nameserver 126.96.36.199
If you want to be able to use names like
an abbreviation for
somemachine.acme.net, you must
replace the first line with:
A certain minimum of configuration will also be required in
/etc/hosts. Most users will be able to manage with:
Those with a fixed IP-address will obviously replace 0.0.0.0 with this.
127.0.0.1 localhost 0.0.0.0 roderick
Likewise, a minimum
loopback 127.0.0.0 localnet 0.0.0.0
You should also set your external mail domain in
The username and password at the ISP must be specified in
dirk * PrettySecret
For those ISPs using CHAP instead of PAP, the filename is
Finally, the nitty gritty regarding the connection procedure
itself must be specified before PPP can be initiated. This is
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
TIMEOUT 5 "" ATZ OK ATDT12345678 ABORT "NO CARRIER" ABORT BUSY ABORT "NO DIALTONE" ABORT WAITING TIMEOUT 45 CONNECT "" TIMEOUT 5 "name:" ppp
ATZmodem initialization string with something more tailored for the modem being used. The last line specifies that one is expecting the prompt
name:, and that the response should be
pppwhen 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:
We should now be on-air, and stay up until the program is killed by typing a Ctrl-C. Any messages concerning the connection will be appended to the system logs. To read them, try:
exec pppd connect \ 'chat -v -f /etc/ppp/chatscript' \ -detach crtscts modem defaultroute \ user dirk \ /dev/modem 38400
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:
Finally, an additional word about safety. 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:
man 5 hosts_access.
A final small 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
ALT: Those fortunate enough to have a permanent TCP/IP connection via e.g. an Ethernet may safely ignore anything about PPP, and rather 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:
The TERM program is also an option. Refer to the Term-HOWTO.