Linux-Misc Digest #961, Volume #23 Sun, 26 Mar 00 15:13:02 EST
Contents:
Linux Frequently Asked Questions with Answers (Part 4 of 6)
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Crossposted-To: news.answers,comp.answers
Subject: Linux Frequently Asked Questions with Answers (Part 4 of 6)
From: [EMAIL PROTECTED]
Reply-To: [EMAIL PROTECTED]
Date: Sun, 26 Mar 2000 20:02:50 GMT
http://www.cablemodeminfo.com/ has a section devoted to Linux.
6.18 Is there a ICQ program that runs under Linux?
Several ICQ clients are available on metlab.unc.edu. (See Where
can I get Linux material by FTP? .) ICQ itself does not have a Linux
client, but there is a Java client at
http://www.mirabilis.com/download/
contents
7. Solutions to common miscellaneous problems.
7.1 PPP connection dies when sending large files.
This is due, apparently, to some form of buffer overrun (Fall, 1999)
when uploading to Windows NT servers. Because MS Winmodems have parts
of their firmware in the operating system, the protocols used in NT
servers can be kept proprietary, even at the TCP/IP level. However,
there's no information at this time to confirm this.
In any case, users have been complaining more frequently about the
problem. It doesn't seem to occur when downloading files, only when
uploading longer files, past a certain, and not always determinable,
size. The problem occurs with newer and faster hardware. Also, there
have been reports that changing the mtu and mru to values much smaller
than the default of 1,500 solves the problem. If anyone has had this
kind of problem, and you have been able to solve it, please let the
FAQ maintainer know.
7.2 Free dumps core.
In Linux 1.3.57 and later, the format of /proc/meminfo was changed in
a way that the implementation of free doesn't understand.
Get the latest version, from metalab.unc.edu, in
/pub/Linux/system/Status/ps/procps-0.99.tgz.
7.3 How do I keep track of all my bookmarks in Netscape?
This probably applies to most other browsers, too. In the
Preferences/Navigator menu, set your home page to Netscape's
bookmarks.html file, which is located in the /.netscape (with a
leading period) subdirectory. For example, if your login name is
"smith," set the home page to:
file://home/smith/.netscape/bookmarks.html
Setting up your personal home page like this will present you with a
nicely formatted (albeit possibly long) page of bookmarks when
Netscape starts. And the file is automatically updated whenever you
add, delete, or visit a bookmarked site.
7.4 The computer has the wrong time.
There are two clocks in your computer. The hardware (CMOS) clock runs
even when the computer is turned off, and is used when the system
starts up and by DOS (if you use DOS). The ordinary system time, shown
and set by "date," is maintained by the kernel while Linux is
running.
You can display the CMOS clock time, or set either clock from the
other, with /sbin/clock (now called "hwclock" in many
distributions)--see "man 8 clock." or "man 8 hwclock."
There are various other programs that can correct either or both
clocks for system drift or transfer time across the network. Some of
them may already be installed on your system. Try looking for adjtimex
(corrects for drift), netdate, and getdate (get the time from the
network), or xntp (accurate, full-featured network time daemon).
7.5 Setuid scripts don't seem to work.
That's right. This feature has been disabled in the Linux kernel on
purpose, because setuid scripts are almost always a security hole.
Sudo and SuidPerl can provide more security that setuid scripts or
binaries, especially if execute permissions are limited to a certain
user ID or group ID.
If you want to know why setuid scripts are a security hole, read the
FAQ for comp.unix.questions.
7.6 Free memory as reported by free keeps shrinking.
The "free" figure printed by free doesn't include memory used as a
disk buffer cache--shown in the "buffers" column. If you want to
know how much memory is really free add the "buffers" amount to
"free"--newer versions of free print an extra line with this info.
The disk buffer cache tends to grow soon after starting Linux up. As
you load more programs and use more files, the contents get cached. It
will stabilize after a while.
7.7 When I add more memory, the system slows to a crawl.
This is a common symptom of a failure to cache the additional memory.
The exact problem depends on your motherboard.
Sometimes you have to enable caching of certain regions in your BIOS
setup. Look in the CMOS setup and see if there is an option to cache
the new memory area which is currently switched off. This is
apparently most common on a '486.
Sometimes the RAM has to be in certain sockets to be cached.
Sometimes you have to set jumpers to enable caching.
Some motherboards don't cache all of the RAM if you have more RAM per
amount of cache than the hardware expects. Usually a full 256K cache
will solve this problem.
If in doubt, check the manual. If you still can't fix it because the
documentation is inadequate, you might like to post a message to
comp.os.linux.hardware giving all of the details--make, model number,
date code, etc., so other Linux users can avoid it.
7.8 Some programs (e.g. xdm) won't let me log in.
You are probably using non-shadow password programs and are using
shadow passwords.
If so, you have to get or compile a shadow password version of the
programs in question. The shadow password suite can be found at
tsx-11.mit.edu:/pub/linux/sources/usr.bin/shadow/. This is the source
code. The binaries are probably in linux/binaries/usr.bin/.
7.9 Some programs let me log in with no password.
You probably have the same problem as in "Some programs (e.g.
xdm) won't let me log in. ", with an added wrinkle.
If you are using shadow passwords, you should put a letter `x' or an
asterisk in the password field of /etc/passwd for each account, so
that if a program doesn't know about the shadow passwords it won't
think it's a passwordless account and let anyone in.
7.10 My machine runs very slowly when I run GCC / X / ...
You may have too little real memory. If you have less RAM than all the
programs you're running at once, Linux will swap to your hard disk
instead and thrash horribly. The solution in this case is to not run
so many things at once or buy more memory. You can also reclaim some
memory by compiling and using a kernel with less options configured.
See "How do I upgrade/recompile my kernel? ".
You can tell how much memory and swap you're using with the free
command, or by typing:
cat /proc/meminfo
If your kernel is configured with a RAM disk, this is probably wasted
space and will cause things to go slowly. Use LILO or rdev to tell the
kernel not to allocate a RAM disk (see the LILO documentation or type
man rdev).
7.11 I can only log in as root.
You probably have some permission problems, or you have a file
/etc/nologin.
In the latter case, put rm -f /etc/nologin in your /etc/rc.local or
/etc/rc.d/* scripts.
Otherwise, check the permissions on your shell, and any file names
that appear in error messages, and also the directories that contain
these files, up to and including the root directory.
7.12 My screen is all full of weird characters instead of letters.
You probably sent some binary data to your screen by mistake. Type
echo '\033c' to fix it. Many Linux distributions have a command,
"reset," that does this.
If that doesn't help, try a direct screen escape command.
echo <Ctrl-V><Ctrl-O>
This resets the default font of a Linux console. Remember to hold down
the Control key and type the letter, instead of, for example,
`Ctrl-V'. The sequence
echo <Ctrl-V><Esc>c
causes a full screen reset. If there's data left on the shell command
line after typing a binary file, press Ctrl-C a few times to restore
the shell command line.
[Bernhard Gabler]
7.13 I have screwed up my system and can't log in to fix it.
Reboot from an emergency floppy or floppy pair. For example, the
Slackware boot and root disk pair in the install subdirectory of the
Slackware distribution.
There are also two, do-it-yourself rescue disk creation packages in
metalab.unc.edu/pub/Linux/system/Recovery. These are better
because they have your own kernel on them, so you don't run the risk
of missing devices and file systems.
Get to a shell prompt and mount your hard disk with something like
mount -t ext2 /dev/hda1 /mnt
Then your file system is available under the directory /mnt and you
can fix the problem. Remember to unmount your hard disk before
rebooting (cd somewhere else first, or it will say it's busy).
7.14 I've discovered a huge security hole in rm!
No you haven't. You are obviously new to unices and need to read a
good book to find out how things work. Clue: the ability to delete
files depends on permission to write in that directory.
7.15 lpr(1) and/or lpd(8) don't work.
First make sure that your /dev/lp* port is correctly configured. Its
IRQ (if any) and port address need to match the settings on the
printer card. You should be able to dump a file directly to the
printer.
cat the_file >/dev/lp1
If lpr gives you a message like "myname@host: host not found," it
may mean that the TCP/IP loopback interface, lo, isn't working
properly. Loopback support is compiled into most distribution kernels.
Check that the interface is configured with the ifconfig command. By
Internet convention, the network number is 127.0.0.0, and the local
host address is 127.0.0.1. If everything is configured correctly, you
should be able to telnet to your own machine and get a login prompt.
Make sure that /etc/hosts.lpd contains the machine's host name.
If your machine has a network-aware lpd, like the one that comes with
LPRng, make sure that /etc/lpd.perms is configured correctly.
Also look at the Printing-HOWTO "Where can I get the HOWTO's
and other documentation? ".
7.16 Timestamps on files on MS-DOS partitions are set incorrectly.
There is a bug in the program "clock" (often found in /sbin). It
miscounts a time zone offset, confusing seconds with minutes or
something like that. Get a recent version.
7.17 How do I get LILO to boot the kernel image?
>From kernel versions 1.1.80 on, the compressed kernel image, which is
what LILO needs to find, is in arch/i386/boot/zImage, or
arch/i386/boot/bzImage when it is built, and is normally stored in the
/boot/ directory. The /etc/lilo.conf file should refer to the vmlinuz
symbolic link, not the actual kernel image.
This was changed to make it easier to build kernel versions for
several different processors from one source tree.
7.18 I upgraded the kernel and now my PCMCIA card doesn't work.
The PCMCIA Card Services modules, which are located in
/lib/modules/<version>/pcmcia, where <version> is the version number
of the kernel, use configuration information that is specific to that
kernel image only. The PCMCIA modules on your system will not work
with a different kernel image. You need to upgrade the PCMCIA card
modules when you upgrade the kernel.
When upgrading from older kernels, make sure you have the most recent
version of the run-time libraries, the modutils package, and so on.
Refer to the file Documentation/Changes in the kernel source tree for
details.
Important: If you use the PCMCIA Card Services, do not enable the
"Network device support/Pocket and portable adapters" option of the
kernel configuration menu, as this conflicts with the modules in Card
Services.
Knowing the PCMCIA module dependencies of the old kernel is useful.
You need to keep track of them. For example, if your PCMCIA card
depends on the serial port character device being installed as a
module for the old kernel, then you need to ensure that the serial
module is available for the new kernel and PCMCIA modules as well.
The procedure described here is somewhat kludgy, but it is much easier
than re-calculating module dependencies from scratch, and making sure
the upgrade modules get loaded so that both the non-PCMCIA and PCMCIA
are happy. Recent kernel releases contain a myriad of module options,
too many to keep track of easily. These steps use the existing module
dependencies as much as possible, instead of requiring you to
calculate new ones.
However, this procedure does not take into account instances where
module dependencies are incompatible from one kernel version to
another. In these cases, you'll need to load the modules yourself with
insmod, or adjust the module dependencies in the /etc/conf.modules
file. The Documentation/modules.txt file in the kernel source tree
contains a good description of how to use the kernel loadable modules
and the module utilities like insmode, modprobe, and depmod.
Modules.txt also contains a recommended procedure for determining
which features to include in a resident kernel, and which to build as
modules.
Essentially, you need to follow these steps when you install a new
kernel.
* Before building the new kernel, make a record with the lsmod
command of the module dependencies that your system currently
uses. For example, part of lsmod's output might look like this:
memory_cs 2 0
ds 2 [memory_cs] 3
i82365 4 2
pcmcia_core 8 [memory_cs ds i82365] 3
sg 1 0
bsd_comp 1 0
ppp 5 [bsd_comp] 0
slhc 2 [ppp] 0
serial 8 0
psaux 1 0
lp 2 0
Module Pages Used by
This tells you for example that the memory_cs module needs the ds
and pcmcia_core modules loaded first. What it doesn't say is that,
in order to avoid recalculating the module dependencies, you may
also need to have the serial, lp, psaux, and other standard
modules available to prevent errors when insmod'ing the pcmcia
routines at boot time. A glance at the /etc/modules file will tell
you what modules the system currently loads, and in what order.
Save a copy of this file for future reference, until you have
successfully installed the new kernel's modules. Also save lsmod's
output to a file, for example, with the command:
lsmod >lsmod.old-kernel.output
* Build the new kernel, and install the boot image, either zImage or
bzImage, to a floppy diskette. To do this, change to the
arch/i386/boot directory (substitute the correct architecture
directory if you don't have an Intel machine), and, with a floppy
in the diskette drive, execute the command:
dd if=bzImage of=/dev/fd0 bs=512
If you built the kernel with the "make bzImage" command, and if
your floppy drive is /dev/fd0. This results in a bootable kernel
image being written to the floppy, and allows you to try out the
new kernel without replacing the existing one that LILO boots on
the hard drive.
* Boot the new kernel from the floppy to make sure that it works.
* With the system running the new kernel, compile and install a
current version of the PCMCIA Card Services package, available
from metalab.unc.edu as well as other Linux archives. Before
installing the Card Services utilities, change the names of
/sbin/cardmgr and /sbin/cardctl to /sbin/cardmgr.old and
/sbin/cardctl.old. The old versions of these utilities are not
compatible with the replacement utilities that Card Services
installs. In case something goes awry with the installation, the
old utilities won't be overwritten, and you can revert to the
older versions if necessary. When configuring Card Services with
the "make config" command, make sure that the build scripts know
where to locate the kernel configuration, either by using
information from the running kernel, or telling the build process
where the source tree of the new kernel is. The "make config" step
should complete without errors. Installing the modules from the
Card Services package places them in the directory
/lib/modules/<version>/pcmcia, where <version> is the version
number of the new kernel.
* Reboot the system, and note which, if any, of the PCMCIA devices
work. Also make sure that the non-PCMCIA hardware devices are
working. It's likely that some or all of them won't work. Use
lsmod to determine which modules the kernel loaded at boot time,
and compare it with the module listing that the old kernel loaded,
which you saved from the first step of the procedure. (If you
didn't save a listing of lsmod's output, go back and reboot the
old kernel, and make the listing now.)
* When all modules are properly loaded, you can replace the old
kernel image on the hard drive. This will most likely be the file
pointed to by the /vmlinuz symlink. Remember to update the boot
sector by running the lilo command after installing the new kernel
image on the hard drive.
Also look at the questions, How do I upgrade/recompile my kernel?
and Modprobe can't locate module, "XXX," and similar messages.
contents
8. How do I do this or find out that ... ?
8.1 How do I know if my notebook runs Linux?
There's no fixed answer to this question, because notebook hardware is
constantly updated, and getting the X display, sound, PCMCIA, modem,
and so forth, working, can take a good deal of effort.
Most notebooks currently on the market, for example, use
"Winmodems," which do not work with Linux because of the proprietary
nature of their hardware interfaces. Even notebooks that are certified
as "Linux compatible," may not be completely compatible.
The only notebook on the market at the time of this writing that has a
modem that works with Linux is the Sony Vaio. There is an IBM Thinkpad
that is certified as compatible with the Red Hat distribution, but
that apparently doesn't include the modem.
You can find the most current information, or ask other users about
their notebook experiences, on the linux-laptop mailing list, which is
hosted by the vger.rutgers.edu server. Refer to What mailing
lists are there?
A mailing list for Linux on IBM Thinkpads has its home page at
http://www.topica.com/lists/linux-thinkpad/.
Another Thinkpad mailing list is hosted by
http://www.bm-soft.com. Send E-mail with the word "help" in the
body of the message to [EMAIL PROTECTED]
The Linux Laptop home page is at
http://www.cs.utexas.edu/users/kharker/linux-laptop/.
There is a Web page devoted to Linux on IBM Thinkpads at
http://peipa.essex.ac.uk/tp-linux/.
For information about interfacing peripherals like Zip and CD-ROM
drives through parallel ports, refer to the Linux Parallel Port Home
Page, at http://www.torque.net/linux-pp.html.
If you need the latest version of the PCMCIA Card Services package, it
is (or was) located at ftp://cb-iris.stanford.edu/pub/pcmcia/,
but that host no longer seems to be available. Recent distributions
are on ftp://metalab.unc.edu/pub/Linux/kernel/pcmcia/. You will
also need to have the kernel source code installed as well. Be sure to
read the PCMCIA-HOWTO, which is included in the distribution.
8.2 How do I install Linux using FTP?
Installing a major distribution can be impractical because of the size
of the distribution and interdependence of many of the software
packages. Installing a basic Linux system that doesn't have a GUI or
the major applications, is possible with FTP, however. The main
non-commercial distribution in use is Debian GNU/Linux, and this
answer describes an installation of the basic Debian system, to which
you can add other Linux applications and commercial software as
necessary.
You will need a system with at least a 80386 processor, 8 Mb of
memory, and about 100 Mb of disk space. More memory and a larger disk
is necessary however, for practical everyday use.
* Connect using anonymous FTP to ftp.debian.org and cd to the
pub/debian/dists/stable/main/disks-i386/current/ subdirectory.
* Retrieve the rescue disk, and the drivers disk Depending on the
floppy drive installed on your machine, retrieve either the
diskette images with "1200" in the names if you have a 1.2 Mb,
5.25-in. floppy, or the disks with "1440" in the name if the
computer has a 3.25-in., 1.44 Mb floppy. Then retrieve the base
system diskettes. Note that there are 7 base system images in the
1.44-Mb set (which have a "14" in their names) , and 9 in the
1.2-Mb set of images (which have a "12" in their names). You will
use these to create the basic installation diskettes. If you have
a Linux machine, you can use dd to write the images to the
diskettes. If you are creating the installation diskettes on a
MS-DOS machine, also download the rawrite.exe MS-DOS utility,
which will copy the raw binary images to floppy disks. Also
download the install.en.txt document, which contains the detailed
installation instructions.
* Create the installation disk set on floppies using either the dd
program under Linux (e.g.: "dd if=resc1440.bin of=/dev/fd0"), or
the rawrite.exe utility under MS-DOS. Be sure to label each
installation diskette.
* Insert the rescue diskette into the floppy drive and reboot the
computer. If all goes well, the Linux kernel will boot, and you
will be able start the installation program by pressing [ENTER] at
the boot: prompt.
* Follow the on-screen instructions for partitioning the hard disk,
installing device drivers, the basic system software, and the
Linux kernel. If the machine is connected to a local network,
enter the network information when the system asks for it.
* To install additional software over the internet, be sure that you
have installed the ppp module during the installation process, and
run (as root) the /usr/sbin/pppconfig utility. You will need to
provide your user name with your ISP, your password, the ISP's
dial-up phone number, the address(es) of the ISP's Domain Name
Service, and the serial port that your modem is connected to,
/dev/ttyS0 - /dev/ttyS3. Be sure also to specify the
"defaultroute" option to the PPP system, so the computer knows to
use the PPP connection for remote Internet addresses.
* You may have to perform additional configuration on the PPP
scripts in the /etc/pppy subdirectory, and in particular, the
ISP-specific script in the /etc/ppp/peers subdirectory. There are
basic instructions in each script. For detailed information, refer
to the Debian/GNU Linux installation instructions that you
downloaded, the pppd manual page (type "man pppd"), and the PPP
HOWTO from the Linux Documentation project,
http://www.linuxdoc.org/.
* Once you have a PPP connection established with your ISP (it will
be displayed in the output of ifconfig), use the dselect program
to specify which additional software you want to install. Use the
"apt" [A]ccess option to retrieve packages via anonymous FTP,
and make sure to use the [U]pdate option to retrieve a current
list of packages from the FTP archive.
8.3 How can I get scrollback in text mode?
With the default US keymap, you can use Shift with the PageUp and
PageDown keys. (The gray ones, not the ones on the numeric keypad.)
With other keymaps, look in /usr/lib/keytables. You can remap the
ScrollUp and ScrollDown keys to be whatever you like. For example, to
remap them to the keys on an 84-key, AT keyboard.
The "screen" program,
http://vector.co.jp/vpack/browse/person/an010455.html provides a
searchable scrollback buffer and the ability to take "snapshots" of
text-mode screens.
You can't increase the amount of scrollback, because it is implemented
using the video memory to store the scrollback text. You may be able
to get more scrollback in each virtual console by reducing the total
number of VC's. See linux/tty.h.
8.4 How do I get E-mail to work?
For sending mail via SMTP (Simple Mail Transfer Protocol) and
receiving mail from an ISP's POP (Post Office Protocol) server, you
can use a desktop client like Netscape Communicator or KDE kmail. You
will need to enter the names of the SMTP and POP servers in the
preferences of the respective application, as well as your E-mail
address (username@isp's-domain-name), and your dial-up password. The
same applies to Usenet News. Enter the name of the NNTP (Network News
Transfer Protocol) server in your News client's preferences section.
You may also have to provide the IP addresses of the ISP's primary and
secondary name servers.
If you have a traditional MTA (Mail Transport Agent) like Sendmail,
Smail, or Exim, you'll need to follow the instructions in each
package. Basically, configuration entails determining which host
machine, either on your local LAN or via dial-up Internet, is the
"Smart Host," if you're using SMTP. If you're using the older UUCP
protocol, then you'll need to consult the directions for configuring
UUCP, and also make sure that your ISP's system is configured to relay
mail to you.
Information about Internet hosting, and News and E-mail in general, is
available on the Usenet News group news.announce.newusers.
8.5 How do I switch virtual consoles? How do I enable them?
In text mode, press Left Alt-F1 to Alt-F12 to select the consoles tty1
to tty12; Right Alt-F1 gives tty13 and so on. To switch out of X you
must press Ctrl-Alt-F1, etc; Alt-F5 or whatever will switch back.
If you want to use a VC for ordinary login, it must be listed in
/etc/inittab, which controls which terminals and virtual consoles have
login prompts. The X Window System needs at least one free VC in order
to start.
8.6 How do I set the time zone?
Change directory to /usr/lib/zoneinfo/. Get the time zone package if
you don't have this directory. The source is available in
metalab.unc.edu/pub/Linux/system/admin/time/.
Then make a symbolic link named localtime pointing to one of the files
in this directory (or a subdirectory), and one called posixrules
pointing to localtime. For example:
ln -sf US/Mountain localtime
ln -sf localtime posixrules
This change will take effect immediately--try date(1).
The manual page for tzset describes setting the time zone. Some
programs recognize the TZ environment variable, but this is not
POSIX-correct.
You should also make sure that your Linux kernel clock is set to the
correct GMT time--type date -u and check that the correct UTC time is
displayed. ("The computer has the wrong time. ")
8.7 How do I get dial-up PPP to work?
This information is mainly for people who do not have a wrapper
utility like kppp or pppconfig, or are not able to get those utilities
to work correctly. If you need to manually configure PPP to dial in to
your ISP, you will need the following information:
* The port that your modem is connected to: /dev/ttyS0-/dev/ttyS3,
which correspond to COM1-COM4 under MS-DOS.
* The phone number of your ISP's data connection.
* The user name and password that your ISP gave you.
* The IP addresses of the primary and possibly secondary Domain Name
Service that you will use when dialing in to the ISP. This assumes
that you will not be using a DNS that you installed on your
system.
When you have all of this information, make sure that the programs
pppd and chat, at the very minimum, are installed correctly. In most
current distributions, they are installed in the /usr/sbin directory,
and you will need to be logged in as root to use them. In addition,
you should also have the following programs installed: /sbin/ifconfig,
/sbin/route, /bin/ping, /usr/sbin/traceroute, because they are useful
for configuring network connections, determining network status, and
diagnosing problems.
These are the basic steps that you need to follow to configure PPP.
You must be logged in as root.
* Make sure that the serial port and modem are operating correctly.
Using a program like minicomm or kermit, you should be able to
send "AT" commands to the modem and recieve the "OK" string in
response from the modem.
* Enter the primary and possibly secondary Domain Name Server IP
addresses in the /etc/resolv.conf file, using dotted quad
notation, with the nameserver label. For example:
order hosts,bind
nameserver 199.182.101.103
nameserver 199.182.101.104
This tells your networking software, when it resolves network
domain addresses, to first look in the /etc/hosts file, and then
use the bind service; i.e., the DNS servers, which are specified
on the lines that begin with nameserver.
* Locate the chat script that PPP will use to dial the modem and
connect to your ISP. In many systems, this is either in the
/etc/chatscripts or /etc/ppp directory, and will be called
provider or something similar. You can store a chat script
anywhere, provided that you tell the pppd program to use it rather
than the default chat script. Refer to the chat and pppd manual
pages, and the information cbelow, for details.
Here is a sample chat script:
ABORT BUSY
ABORT "NO CARRIER"
ABORT VOICE
ABORT "NO DIALTONE"
"" ATDT<your_isp's_phone_number>
ogin <your_user_name>
word <your_password>
This is a chat program for a simple, script based login. The chat
program uses the pair of strings on each line as a match/response
pair. When it starts, it sends the string
ATDT"your_isp's_phone_number", where you have subsituted the
actual phone number of course. It then waits for the string
"ogin" (a substring of the word "login") and sends your user
name. Then it waits for "word" (part of "password") and sends
your password. If your ISP uses a different login and password
prompts, and any additional prompts, you will need to edit the
chat script accordingly. Again, refer to the chat manual page for
details.
If your ISP uses PAP or CHAP authentication, you will need to edit
the pap-secrets or chap-secrets files in /etc/ppp directory as
well. Refer to the manual pages for these files, as well as the
instruction in the files themselves.
* The configuration of pppd the program that maintains the actual
connection, is usually contained in two or three separate files.
The first is usually /etc/ppp/options, which contains options that
all of your system's pppd programs will use. (Yes, you can have
more than one; as many as your computer has serial ports,
generally.
Here is a sample /etc/ppp/options file:
# /etc/ppp/options
asyncmap 0
auth
crtscts
lock
noipx
# ---<End of File>---
The options may be given on one line or each on a separate line.
Many options files are much longer, and come with a description of
each option. Here, the options mean, in order, don't remap any
characters between the PPP client and server; always use password,
PAP, or CHAP authentication when making a connection; use the
modem's hardware handshake lines for flow control; lock the serial
port when in use so no other programs can access it; and do not
use the IPX network protocol.
* For connection set-up on each individual serial port or PPP host,
there will either be an /etc/ppp/options.ttyS1, for example,
options file for /etc/ttyS1, or a file for your ISP in the
/etc/ppp/peers directory. The default is often called
/etc/ppp/peers/provider. Here is a sample of the default provider
file.
noauth
connect "/usr/sbin/chat -v -f /etc/chatscripts/provider"
defaultroute
/dev/ttyS1
38400
persist
There might be an explanation of these and other options in the
/etc/ppp/peers/provider file itself. You can also refer to the
pppd manual page for details. Briefly, they mean: do not use PAP
authentication for this connection; use the chat program and the
/etc/chatscripts/provider script, which is described above, to
dial the phone and log in; set the network default route to the
PPP connection (so when your network software needs to resolve an
network address that is not on your local machine(s), it will use
the PPP connection to the Internet); use /dev/ttyS1 as the serial
port for the connection; set the modem speed to 38400; and keep
the pppd daemon running even if the connection fails.
* That is all of the configuration you need. To actually start and
stop PPP, there are often /usr/bin/pon and /usr/bin/poff scripts
(in Debian), or something similar, which are usually very simple,
and only contain the command:
/usr/sbin/pppd call ${1:-provider}
This will start pppd and use the "call" option to call the
server that you type on the command line, or the provider given in
the /etc/ppp/peers/provider file if you do not specify a remote
server. After making the call and logging in (about 30 seconds),
you should be able to use the /sbin/ifconfig program to determine
that the connection really did establish a PPP interface (the
first will be ppp0, the second will be ppp1, etc., depending on
how many simultaneous PPP connections you have. If something goes
wrong, you can look at the /var/log/ppp.log file to determine what
happened. You can also view the log as the connection is being
made, by "tailing" it in another window; that is, viewing it as
pppd logs the connection's status information. To do this, use the
command (again, as root):
tail -f /var/log/ppp.log
You should be also able to "ping" one of your ISP's domain names
(e.g., mail.isp.com) and receive a response.
These are the most basic steps for configuring a PPP connection. You
will also need to take into account what other network connections may
be present (for example, if there's an Ethernet connection that has
already been assigned the default route), as well as various security
measures at your ISP's end. If you're having trouble making the
--
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