v3.2 README2: A LINUX-TO-DEMON-INTERNET CONFIGURATION GUIDE 10/05/96

BASE: CONFIGURING SLACKWARE LINUX FOR INTERNET ACCESS AND E-MAIL
================================================================

Copyright 1994-6 John A. Phillips. john@linux.demon.co.uk

This README has been tested on Slackware 3.0, 2.3, 2.2 and 2.1. There
are earlier versions for Slackware 2.0 and 1.2. It describes basic,
static IP, serial-line networking with Demon Internet, using dip for the
dialler, SLIP/CSLIP or PPP as the serial line protocol, with e-mail
using sendmail, deliver and elm. It does not cover PoP.

Files you may need are contained in the package. See the list at the
end of this README. Configuration should be done as user root.

You will occasionally find references such as [12.1] in the text. These
are section numbers in the NET-2-HOWTO in /usr/doc/faq/howto if you
installed disk set F. You will find relevant additional detail there.


2A Requirements and installation notes
--------------------------------------
I assume you have installed at least disk sets A and N. I recommend
installing disk sets AP and F. They contain the manual pages, various
editors, GNU diffutils, which is (IMHO) indispensable, and the FAQs.

Disk set D is recommended for the compilers and other development tools,
Under Slackware 3.0 you *must* install the libaout package from disk set
D for some key applications to work, such as sendmail and dip.

From amongst the optional packages of disk set N, several are required
for the basic network set-up:

elm Required as your mail user agent (NOTE 1)
tcpip Required for networking
deliver Required as the local mail delivery agent for sendmail
sendmail Required as the mail transport agent for network mail
dip Required as the dialler for (C)SLIP and PPP access
ppp Required if you want to use PPP

NOTE 1: You don't have to install elm if you install pine or another
mail reader instead. However only elm is described in this guide.

NOTE 2: Other optional packages from disk set N are needed in other
parts in this guide (e.g. if you want to install usenet news). Please
see the READMEs in the other packages.

The kernel must have SLIP, CSLIP and/or PPP installed in order to use
the relevant protocol. Some Slackware kernels have these already set
up, but you may be unlucky and have to install the Linux kernel source,
recompile and reinstall it (see [8], and /usr/src/linux/README if you
have the kernel source installed).

You should not ask the Slackware installer to configure networking for
you unless this is for a separate Ethernet. If you do anyway, it will
probably block your serial-line access. See section 2C about fixing the
rc.inet1 file if you have run Slackware's netconfig.

* Please create an unpriveleged (i.e. non-root) user if you don't
already have one. This package assumes you have at least one. It is
not a good idea to regularly use ftp, mail, news, etc. from the root
account. It should just be used for configuration and other things that
can only be done as the superuser. You can run "adduser" which will do
the job for you if you follow the prompts. BTW, do not use capital
letters in user names (just when setting them up) as this can confuse
some applications.

Also, make sure you set a password for root and for all other users you
have. Remember that whilst connected, your computer is on the Internet
and should be protected as well as possible.

* The default Unix editor is vi with which you should become familiar
before starting. Elm, for example, uses it for composing mail messages.
If you don't like vi, it is often possible to make programs use another
editor by adding these lines to one of your shell start-up files. If
you use bash as your shell the files are /etc/profile (for everybody) or
~/.bash_profile (for an individual):

EDITOR=/usr/bin/joe
export EDITOR
VISUAL=/usr/bin/joe
export VISUAL

In many applications this will cause /usr/bin/joe to be used instead of
the default editor. This is just an example and some applications have
special config files you can (or must) edit instead. I'm told joe looks
like WordStar, but you can use any other editor that suits you instead.


2B Set up the clock
-------------------
You must decide whether to keep your PC's CMOS clock set to local time,
or set permanently to GMT (also known as UTC). GMT is the normal way to
get automatic winter/summer time corrections in Unix. If you want DOS
to have the correct time when you run it with a GMT clock, install
clk360rs.zip from a SIMTEL archive. Alternatively, use local time and
change the CMOS clock twice a year.

* If you are operating your CMOS clock on GMT, edit /etc/rc.d/rc.S to
change the "/sbin/clock -s" line to read:

/sbin/clock -u -s

If you keep your CMOS clock on local time, /etc/rc.d/rc.S is correct,
but you must edit certain configuration files to reflect this. I'll
remind you to do this in the section(s) where the files are set up.


2C Set up networking
--------------------
This section assumes you have only one network connection, through your
serial interface and modem using (C)SLIP or PPP.

* Set up /etc/hosts [11.4.1]. You only need two entries: (i) the
loopback address; and (ii) your own host name and IP address. Change
"AAA.BBB.CCC.DDD" to your IP address, and use your own (single-word)
host name in place of "<YOUR_HOST_NAME>" here, throughout this README,
and in the example files.

127.0.0.1 localhost
AAA.BBB.CCC.DDD <YOUR_HOST_NAME>.demon.co.uk <YOUR_HOST_NAME>

You can add other machines to this file as well, but I do not recommend
it. It will save a little on network traffic in looking up IP
addresses, but you must maintain the list properly, and any changes of
IP address are not automatically followed.

* Set up /etc/hosts.deny to deny everybody access your machine. This is
a good security measure for a machine on the Internet unlil you are sure
of what you are doing. Add this line to the file:

ALL: ALL

Then set up /etc/hosts.allow to allow just local users to access your
machine's networking. Add this line and configure the name:

ALL: 127.0.0.1 <YOUR_HOST_NAME>.demon.co.uk

See "man 5 hosts_access" for more details of changing these files.

* Check /etc/networks [11.4.3]. It should have only the following line
(apart from comments):

loopback 127.0.0.0

NOTE: lines for "default" and "localnet" are recommended in the
NET-2-HOWTO. They are not needed in this serial-line set-up.

* Check the file /etc/host.conf [11.4.4]. It should read as follows:

order hosts, bind
multi on

This orders the name resolver to look first in /etc/hosts to find IP
addresses for a host name, before asking the name server(s) listed in
/etc/resolv.conf. It also allows multiple IP addresses per host name.

* In /etc/resolv.conf [11.4.5] you should specify Demon's name servers
by IP address. This file is in the package. It should read:

search . demon.co.uk
nameserver 158.152.1.58
nameserver 158.152.1.43

* Set up the /etc/HOSTNAME file [11.4.6] to contain a single line with
your fully-qualified domain name (FQDN), like this:

<YOUR_HOST_NAME>.demon.co.uk

* Edit the fall back FQDN in /etc/rc.d/rc.M. This isn't really needed,
since you've already set up /etc/HOSTNAME, but it tidies up a loose end.

...
# If there's no /etc/HOSTNAME, fall back on this default:
if [ ! -r /etc/HOSTNAME ]; then
echo "<YOUR_HOST_NAME>.demon.co.uk" > /etc/HOSTNAME
fi
...

* Check /etc/rc.d/rc.inet1 [9.3, 9.3.1]. It only needs to configure the
local loopback interface [9.4] with these lines:

/sbin/ifconfig lo 127.0.0.1
/sbin/route add -net 127.0.0.0

If you used the Slackware network configuration option and the Ethernet
parts of this file have been set up, this may cause non-fatal errors at
boot time (assuming you actually have no Ethernet card), and may block
your serial line access.

If you don't have an Ethernet, all parts of rc.inet1 after the two lines
above should be commented out. If you do have an Ethernet, then this is
where to set it up, but don't include the "route add default" line since
this will divert traffic away from the serial line to the Ethernet.

If you want to refer to your machine by its host name when you are not
connected (rather than just calling it localhost), then you should
arrange for the dummy interface to be compiled into the kernel [8] (if
it is not already) and place these commands in /etc/rc.d/rc.inet1.

/sbin/ifconfig dummy <YOUR_HOST_NAME>.demon.co.uk
/sbin/route add -host <YOUR_HOST_NAME>.demon.co.uk

The dummy interface can get you over occasional problems associated with
a networked machine that is only sometimes connected to the Internet.

* Check out /etc/rc.d/rc.inet2 [9.3, 9.3.2, 11.1, 11.2]. It is normally
correct but you can check that it starts certain daemons in the correct
order. These should be:

syslogd
klogd
inetd

Leave rc.inet2 as it is if the essential bits above are in place.

Other daemons, such as the line printer daemon (lpd), name server
(named), SUN RPC portmapper, etc. may also be started here. You can
leave them as they are for now and decide later whether you want to run
them or not. They are not essential for a basic network service.

NOTE: Do not start up routed in rc.inet2 unless you know what you are
doing, as it can block your serial line IP connection.


2D Set up sendmail
------------------
There are other Mail Transport Agents (MTAs) such as Smail. This
section assumes you are setting up sendmail.

* Install /etc/sendmail.cf, the configuration file for sendmail. The
file installed by the Slackware 2.* setup (the SMTP+BIND option) is
close but not 100% OK. The sendmail.cf file contained in this package
needs no editing and should be installed instead.

The file linux.demon.mc, which I used to generate this sendmail.cf, is
included as well. If you ever want to create a sendmail.cf, ensure the
Slackware m4 and smailcfg packages are installed, put linux.demon.mc in
/usr/src/sendmail/cf/cf, and run "m4 linux.demon.mc" in that directory.

* In /etc/rc.d/rc.M, remove the "-q 15m" from the line that runs
sendmail (and from the "echo" line above it). If you leave the option
there, sendmail will try to deliver queued mail to the network every 15
minutes. If you are not on-line and there is mail in the queue, it will
leave an error message in one of the logfiles every time. The mail
queue is explicitly processed whenever you connect, by scripts that are
installed later, so it is not normally necessary to ask the sendmail
daemon to try delivery on its own.

* Install /etc/aliases, the global mail aliases list. You should alias
mail for at least root, postmaster, MAILER-DAEMON, usenet and news to
real users. Use your own non-root user(s) substituted for <USERNAME>:

usenet:news
news:<USERNAME>
postmaster:<USERNAME>
root:<USERNAME>
MAILER-DAEMON:<USERNAME>

All hosts connected to the Internet *must* have a postmaster address.
Sendmail employs the pseudo-user MAILER-DAEMON, so it is a good idea to
make sure someone receives any mail for this user (e.g. error reports
that can't be delivered). The users news and usenet may receive error
messages from C News or INN - someone should see these. Finally, for
safety reasons, the root account should not normally be used for mail.

This file is in the package and may be copied into place then
configured. You can add other aliases here later if you wish (after
which you need to install the new aliases as described below).

* Re-boot now (with "shutdown -t3 -r now" or just Control-Alt-Del) to
get the system name right after the previous edits and run sendmail with
the correct configuration file. Then log in as root and run the
following command to install the aliases:

/usr/sbin/sendmail -bi

This creates /etc/aliases.dir and /etc/aliases.pag (database files
containing your aliases in dbm format). Running the command
"newaliases" is equivalent.


2E Set up basic network access
------------------------------
* Install the following files from the package:

/usr/local/sbin/start.dip
/usr/local/sbin/stop.dip
/usr/local/sbin/querypost
/usr/local/sbin/querystatus
/usr/local/sbin/setclock

No configuration is required for the first four. If you decided in
section 2B to run your CMOS clock on local time rather than GMT, edit
the first executable line of setclock, changing the default zone from
"GMT" to "local", otherwise leave this one alone too.


2F Set up (C)SLIP
-----------------
* Install /usr/local/etc/demon_slip.dip, the (C)SLIP dialler script from
the package. Make sure it is owned by root and cannot be read by anyone
else (since it will contain your login name and password).

You must edit this to set your own hostname (twice), password, your
gateway (PoP) telephone number, the modem port, the DTE speed (how fast
your computer talks to the modem), and the modem set-up commands.

See Demon's "Modem.txt" and the instructions for your modem for details
of the correct modem set-up requirements. Depending on your modem, it
is possible you may have to make significant changes to this script, to
deal, for example, with busy tones or other failures.

You may also wish to edit the script to set idle=0 in the protocol line
at login if you wish Demon's machine to keep the connection up even if
no traffic is being sent or received. The example script asks (with
idle=240) for the link to be dropped after four minutes of idling.

Note that this script asks for SLIP (with "mode SLIP"), not compressed
SLIP (CSLIP). The Ascend terminal servers at Demon do not at the time
of writing support CSLIP. They may do so at some time in the future.


2G Set up PPP
-------------
* Install /usr/local/etc/demon_ppp.dip, the PPP dialler script from the
package. Make sure it is owned by root and cannot be read by anyone
else (since it will contain your login name and password).

You must configure this file. It is just like setting up demon_slip.dip
(section 2F), except that you only have to set your own hostname once.

* Copy into /etc/ppp the files in ./ppp from this package. No editing
is needed. The installed files are:

/etc/ppp/ip-up
/etc/ppp/ip-down
/etc/ppp/options

* For Slackware 2.1 and 2.2 only, to run PPP you must update your
version of dip and its manpage. Copy dip-3.3.7n from this package into
/sbin. Then make static links to it from /sbin/dip and /sbin/diplogin
using the following commands:

cd /sbin
ln -sf dip-3.3.7n dip
ln -sf dip-3.3.7n diplogin

Then copy the new manpage, dip.8, from the package into /usr/man/man8
and remove the old page (/usr/man/preformat/cat8/dip.8.gz).

NOTE: dip-3.3.7i (Slackware 2.1) and dip-3.3.7l (Slackware 2.2) will
not work with PPP, although they will work with (C)SLIP.

* For Slackware 2.3 only, the dip-3.3.7n executable knows how to use PPP
so you don't have to update it, but it thinks pppd is in directory
/usr/sbin. Fix this with the following commands:

cd /usr/sbin
ln -s ../lib/ppp/pppd pppd


2H Set up elm
-------------
There are other Mail User Agents (MUAs) such as pine. This section
assumes you are setting up elm.

* Edit /var/lib/elm/elm.rc to tell elm about your machine and its names.
You need to set up the following lines:

hostname = <YOUR_HOST_NAME>
hostdomain = .demon.co.uk
hostfullname = <YOUR_HOST_NAME>.demon.co.uk

* Install /var/lib/elm/aliases.text to specify the global elm aliases.
These are used on mail from local elm users. They should normally
duplicate the aliases for sendmail (which are used for mail arriving
from the network). This file is in the package and may be copied into
place and configured with your own non-root user(s) substituted for
<USERNAME>:

usenet = Local Usenet Administrator = news
news = Local Usenet Administrator = <USERNAME>
postmaster = Local Postmaster = <USERNAME>
root = Local System Administrator = <USERNAME>
MAILER-DAEMON = Local Sendmail MAILER-DAEMON = <USERNAME>

* After setting this up, install the aliases with

newalias -g

This creates the files aliases, aliases.dir and aliases.pag. After
adding more aliases in the future you must run "newalias -g" again to
install them.

* If you want to run elm whenever you type "mail" (as well as "elm"),
you should make sure your users have the command mail aliased to elm, so
elm becomes their foreground mailer. A line in /etc/profile such as:

alias mail=elm

will do this for all bash users. For individuals, the same line in the
file ~/.bash_profile (in the user's home directory) will also work.

* In Slackware 2.1 only, elm mistakenly thinks BST is GMT+2 hours. To
fix this, you can use the environmental variable TZ. Put "export
TZ=GMT0BST,M3.5.0/01:00:00,M10.5.0/02:00:00" in /etc/profile. The
manpages for "newctime" and "newtzset" explain more about TZ.

* The text in the file .signature in your home directory will be added
to the end of your e-mail if you add the line "signature = ~/.signature"
to ~/.elm/elmrc. Run elm first to create the ~/.elm directory and set
up a default elmrc file if it's not there already.

* If you want to keep a copy of mail you send, add the line "copy = on"
to the ~/.elm/.elmrc file. Mail will be copied to the file ~/Mail/sent
and may be reviewed later in elm by changing to the "=sent" folder.

* For Slackware 2.2 only, fix a bug that stops elm from working, with:

chmod 771 /var/spool/mail

E-mail should now work. Mail to users on your site should be delivered
immediately. Off-site mail should go into the mail queue (see it with
"mailq"). You can force local mail to go via Demon by addressing it to
either "@post.demon.co.uk:<USERNAME>@<YOUR_HOST_NAME>.demon.co.uk", or
"<USERNAME>%<YOUR_HOST_NAME>.demon.co.uk@post.demon.co.uk".

Please test mail, if you wish to, as a non-root user. Using root to
receive and send mail is often considered a security risk.


2I Check access to Demon Internet Services
------------------------------------------
I assume here that your Demon account is already set up and working, and
that you don't need to do anything special to log on. If you do have a
brand new unused account, you will probably have to log on using a
standard comms program to set up your account and set your password. At
a pinch "dip -t" can do this if you set up the modem port, go into term
mode, execute the account set-up manually, exit to dip's command mode
and then quit, but other programs may be better.

At this point, you should be able to send and receive mail, and ftp,
telnet etc. will work. If you wish to prevent incoming mail from
arriving whilst you test other networking services, find the PID of the
sendmail daemon with "ps -aux", and kill the process with "kill <PID>".
To start receiving mail again, either re-boot or re-start sendmail with
"/usr/sbin/sendmail -bd".

* To connect, run this command:

/usr/local/sbin/start.dip slip

Just "start.dip" on its own is equivalent, since I have made slip the
default. DIP should execute the script in demon_slip.dip and the system
should log in automatically with (C)SLIP. The network connection should
be active when the command prompt comes back. If you need to interrupt
start.dip, it may be necessary to press Control-C twice.

If you want to use PPP, use "start.dip ppp" instead. Alternatively,
edit the first executable line of start.dip and change "slip" to "ppp"
if you wish start.dip to use PPP by default instead of (C)SLIP.

* To do a test ftp transfer on a couple of files, log in to your
machine, as an ordinary user, on another virtual terminal (e.g. press
Alt-F2 for VT2, or Ctrl-Alt-F2 to get there from X-windows), and
execute:

$ cd /tmp
$ ftp ftp.demon.co.uk
... Name: anonymous
... Password: <USERNAME>@<YOUR_HOST_NAME>.demon.co.uk
ftp> cd /pub/test
ftp> bin
ftp> hash
ftp> get fullfile
ftp> get regularfile
ftp> quit
$

Other commands like "telnet", "traceroute", "whois", "finger", etc.
should also work. Please see the manual pages for further details.

* To close down the connection, go back to the root terminal (press
Alt-F1 if you logged root onto VT1), and run this command:

/usr/local/sbin/stop.dip

Wait a few seconds and then check that the phone line has been put back
on hook. If DIP fails to cause the modem to hang up, turn off the power
to your modem for a few seconds, or pull out the plug. You should be
able to set up the modem via the initialization commands in
demon_slip.dip and demon_ppp.dip to hang up when DIP hangs up. DIP
negates (drops) the DTR line when it hangs up; your modem's
documentation should show you how to hang up the line when DTR is
negated. The command &D2 is common but not universal. See Demon's
Modem.txt and your modem's documentation for help.

If you have a V.32bis/V.42bis modem (14400 bits/second with
compression), and things are not very busy at the Demon end, you should
have received fullfile (102400 bytes) in about 64 seconds (about 1.6
kbytes/second), and regularfile (102400 bytes) in about 37 seconds
(about 2.7 kbytes/second). If your modem's V.42bis compression has
better than minimum performance, regularfile may arrive more quickly, at
up to 3.8 kbytes/second. This assumes a DTE rate of 38,400 bps or more.
At a DTE rate of 19,200 bps, regularfile may only arrive at about 1.9
kbytes/second.

If you have a V.34 modem and can drive the serial port at 57,600 bps or
preferably greater, you may get about twice the download speeds above.


2J Trouble?
-----------
For de-bugging purposes, I suggest you try, in this order:

ping -c5 127.0.0.1
ping -c5 localhost
ftp localhost
ping -c5 158.152.1.222
ping -c5 demon-du.demon.co.uk
ftp ftp.demon.co.uk

These commands try out increasing levels of networking service. Those
which work and those which don't, and especially the error messages from
the failures, may give clues as to what is wrong. The first three
should work properly off-line, and trying the next two off-line provides
useful data from the error messages. Make sure you try the last three
on line as well.

If ping works to external machines, but other things, such as ftp and
telnet do not, it is possible that the gateway machine you are using
understands SLIP but not CSLIP. In this case change the "mode CSLIP"
line in demon_slip.dip to "mode SLIP". Alternatively try PPP which
avoids this problem.

If the modem appears locked, but in fact it is not, this could be
because dip is sometimes bad at removing its lock file
/var/spool/uucp/LCK..ttyS1 (or LCK..cua1, LCK..modem etc.). This lock
file may have been left behind by a previous dip session. Remove this
file by hand if pppd complains when the modem is actually available.

If you get "network unreachable" with "DIP: tty: set_disc(1): Invalid
argument" when DIP is run, it means you don't have SLIP and/or CSLIP
compiled into your kernel. You will need to re-compile and re-install
the kernel using the instructions in /usr/src/linux/README [8].

A "network unreachable" error on its own suggests some other
configuration fault. There are, unfortunately, too many possible causes
of this for specific advice here to be useful. The commands "ping",
"route", "netstat", "ifconfig", "cat /proc/net/dev" etc. are useful for
de-bugging. Please see the manual pages for further information.


2K Summary and notes
--------------------
At this point, your basic set-up is complete. You go on-line with the
command /usr/local/sbin/start.dip (or just start.dip). You can use
either "ppp" or "slip" as a parameter to start.dip to explicitly select
the serial line protocol, rather than just using the default. You go
off-line with /usr/local/sbin/stop.dip. These commands must be executed
by user root, or perhaps through the sudo package by normal users (which
I haven't tried myself).

When you go on-line, your CMOS clock is updated from a network time
server (and you can run the "setclock" script separately if you wish -
but this may only be done by root). Also your mail is checked and a
list is printed on the screen (root can run "querypost" separately).
Finally, Demon's status messages are fetched and printed (using the
"querystatus" script, which can also be run separately by root).

You will get incoming mail delivered whenever you go on-line, and mail
will also be delivered to you periodically whilst you remain on-line.
Mail that has arrived on your machine should be readable with the
command "elm" (or "mail" if you log in after setting up an alias).

Outgoing mail will be put into the mail queue if you send it whilst you
are off-line (revealed by running "mailq"). When you go on-line,
start.dip will automatically send any queued mail to the network.
Whilst on-line, sendmail will immediately pass to the network any mail
you send. To force sendmail to try delivering queued mail, run
"/usr/sbin/sendmail -q" when on-line.

To check if any network connections are still active, you can run
"netstat -t", or "netstat -nt". When connections reach the TIME_WAIT
state, they have completed, and will not be interrupted by a shut down.


2L Files in this package
------------------------

File name (Slackware) Location in this package
===================== ========================
/var/lib/elm/aliases.text base/aliases.text
/etc/aliases base/aliases
/usr/local/etc/demon_ppp.dip base/demon_ppp.dip
/usr/local/etc/demon_slip.dip base/demon_slip.dip
/usr/src/sendmail/cf/cf/linux.demon.mc base/linux.demon.mc
/etc/resolv.conf base/resolv.conf
/etc/sendmail.cf base/sendmail.cf
/usr/man/man8/dip.8 base/dip.8
/etc/ppp/ip-down base/ip-down
/etc/ppp/ip-up base/ip-up
/etc/ppp/options base/options
/sbin/dip-3.3.7n base/dip-3.3.7n
/usr/local/sbin/querypost base/querypost
/usr/local/sbin/querystatus base/querystatus
/usr/local/sbin/setclock base/setclock
/usr/local/sbin/start.dip base/start.dip
/usr/local/sbin/stop.dip base/stop.dip

END OF README2