Linux-Misc Digest #281, Volume #25 Sun, 30 Jul 00 09:13:02 EDT
Contents:
Linux Frequently Asked Questions with Answers (Part 4 of 6)
([EMAIL PROTECTED])
----------------------------------------------------------------------------
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: 30 Jul 2000 09:02:28 -0400
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 than 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 ftp:/
/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, then 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
ftp://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 Forgot the root Password.
Note: Incorrectly editing any of the files in the /etc/ directory can
severely screw up a system. Please keep a spare copy of any files in
case you make a mistake.
If your Linux distribution permits, try booting into single-user mode
by typing "single" at the LILO: prompt. More recent distributions
still require a password. In that case, boot from the installation or
rescue floppy, and switch to another virtual console with Alt-F1--
Alt-F8, and then mount the root file system on /mnt. Then proceed
with the steps below to determine if your system has standard or
shadow passwords, and how to remove the password.
Using your favorite text editor, edit the root entry of the /etc/
passwd file to remove the password, which is located between the
first and second colons. Do this only if the password field does not
contain an "x," in which case see below.
root:Yhgew13xs:0:0: ...
Change that to:
root::0:0: ...
If the password field contains an "x," then you must remove the
password from the /etc/shadow file, which roughly the same format.
=====================================================================
7.15. 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.
=====================================================================
7.16. lpr and/or lpd 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? ".
=====================================================================
7.17. 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.
=====================================================================
7.18. 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.
=====================================================================
7.19. 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 that 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 kludgey, 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 insmod, 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 the lsmod output might look like this:
Module Pages Used by
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
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 installing the
pcmcia routines at boot time with insmod. 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 the lsmod 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 the lsmod 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.
=====================================================================
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 often do not work with Linux because of their proprietary
hardware interfaces. Even notebooks which are certified as "Linux
compatible," may not be completely compatible.
Information about installing Winmodems in general is contained in the
Winmodems-and-Linux HOWTO. (Refer to "Where Can I Get the HOWTO's and
Other Documentation?")
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
mailto:[EMAIL PROTECTED].
There is a Web page about Linux on IBM Thinkpads at http://
peipa.essex.ac.uk/tp-linux/.
The Linux Laptop home page is at http://www.cs.utexas.edu/users/
kharker/linux-laptop/.
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/ppp 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 do I resume an interrupted FTP transfer?
Use the "reget" command of the ftp program.
=====================================================================
8.4. How Can I Get Scrollback in Text Mode?
With the default US keymap, you can use Shift with the PgUp and PgDn
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.
=====================================================================
8.5. 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, and
those FAQ's are also archived at ftp://rtfm.mit.edu/pub/usenet/.
=====================================================================
8.6. How do I prevent Sendmail from pausing for up to a minute at
each command?
Make sure that Sendmail can resolve your hostname to a valid (i.e.,
parsable) domain address. If you are not connected to the Internet,
or have a dial-up connection with dynamic IP addressing, add the
fully qualified domain name to the /etc/hosts file, in addition to
the base host name; e.g., if the host name is "bilbo" and the domain
is "bag-end.com:"
192.168.0.1 bilbo.bag-end.com bilbo
And make sure that either the /etc/host.conf or /etc/resolv.conf file
contains the line:
order hosts,bind
Caution: Do not change the "localhost" entry in /etc/host, because
many programs depend on it for internal message-passing.
=====================================================================
8.7. How Do I Switch Virtual Consoles? How Do I Enable Them?
In text mode, press the 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.
=====================================================================
8.8. 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 ftp://
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.
If the system uses Red Hat-style configuration files, the respective
time zone info files are /usr/share/zoneinfo and /etc/localtime.
The manual pages for tzset or tzselect describe 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.")
=====================================================================
8.9. 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, the following programs are also useful for configuring
network connections, determining network status, and diagnosing
problems: /sbin/ifconfig, /sbin/route, /bin/ping, /usr/sbin/
traceroute.
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 receive 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 pppd to use it rather than the default script.
Refer to the chat and pppd manual pages, and the information
below, 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
"ATDTyour_isp's_phone_number," where you have substituted the
actual phone number of course. It then waits for the string ogin
(a substring of the word login) and sends your user name. It then
waits for word (a substring 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 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 PPP connections will use. (Yes, you can
have more than one; as many as your computer has serial ports,
--
<a href="coffee://localhost/cream/">stop</a> http://www.mainmatter.com/
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