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+-+ TTYLINUX USER GUIDE | ttylinux 2.2 (c) 2001,2002 Pascal Schmidt <pharao90@tzi.de> | Last update: Wed Jun 5 17:00:22 CEST 2002 A vertical bar at the left margin indicates changes since the last version. +-+ Contents 1. Introduction 1.1 What is ttylinux? 1.2 What is ttylinux not? 1.3 Who is ttylinux aimed at? 1.4 License 2. Installation guide 2.1 Requirements | 2.2 Download 2.3 Customization 2.4 Installation 3. System guide 3.1 Features 3.2 Bootup and shutdown (initscripts) 3.3 Using PPP 3.4 Using thttpd 3.5 Setting up network devices 3.6 Using the firewall 3.7 Shell environment 3.8 pkg script 4. Contact Appendices A. How to make a bootable ttylinux CD +-+ 1. Introduction This section gives an overview on ttylinux. What is it, who can use it, why it is there. +-+ 1.1 What is ttylinux? ttylinux is a minimalistic Linux distribution. In fact, it is so minimalistic that it can't even run standalone without the help of another Linux system, even if this system is only really needed for installation. ttylinux aims to put as much as possible into as little space as possible. It provides multi-tasking, multi-user, and networking capabilities within less than 4 megabytes of operating system size. The main use that ttylinux comes prepared for is dialing into an Internet provider by modem or ISDN and then browse the world wide web. There is also a WWW server present for serving content to other people. ttylinux can be installed on hard disk, CD-ROM, or any other media you can boot from and has at least 2.88 megabytes of room. The preferred way to run ttylinux is to install its image files somewhere on the hard disk (needs at most 2.88 megabytes of space) and then run the system itself from ramdisk. This makes the system immune to crashes and user errors and takes less space than a normal install on hard disk, which would take at least 4 megabytes of space. +-+ 1.2 What is ttylinux not? ttylinux is not a standalone distribution, you need another working Linux system to get it up and running. +-+ 1.3 Who is ttylinux aimed at? As ttylinux can be used on machines which are considered obsolete by now, such as 386SX class PCs, it is aimed at people who want to have a minimalistic Linux distribution to run when little space is available. ttylinux is aimed at people who already have some Linux experience. There is no big user manual describing how to use the system, so a bit of Unix or Linux experience is very useful when trying to use ttylinux. Most of the programs present are smaller versions of common Unix utilities, documentation on those can be found in various places on the Internet. ttylinux fits into an eltorito image useful for bootable CD-ROMs. It could be used for installation CDs or rescue systems on CD. ttylinux provides a working Linux environment from the boot image, and then some script could mount the rest of the CD to provide a full system. Note: ttylinux is really not aimed at Linux beginners. Knowledge about how to compile a kernel and find your way around a Linux system in general is assumed. +-+ 1.4 License All of the software that is used on ttylinux is under the GNU Public License. A copy is included in the file COPYING. There are a few scripts on the system which I wrote to keep it all together. I place them and the system as a whole under the GPL, too. +-+ 2. Installation guide This section describes the requirements of ttylinux, where to down- load it, and how to customize and install it. +-+ 2.1 Requirements This installation guide describes how to setup ttylinux to run from a ramdisk image. You will need at least a 386SX processor and 10 megabytes of RAM to use this approach. Installation on hard disk is only described in brief but should work on systems with as low as 6 megabytes of RAM. You will also need a Linux kernel suitable for your system, but with some addition requirements for ttylinux. The kernel used for running ttylinux needs to have ramdisk support, initial ramdisk support, and a default ramdisk size of at least 4096. Note that the stock kernel configuration will use a ramdisk size of 4096, which is enough. If you want to use the basic firewall script of ttylinux, your kernel also needs ipchains support. If you want to use the telnet server in ttylinux, your kernel will need to have Unix98 pty support and support for the devpts file- system. The Linux kernel on the system that is used to install ttylinux needs to have support for the ext2 filesystem and loopback device. If there is no loopback support, you cannot customize ttylinux for your system. No problem if the defaults suit you, but this is rather unlikely for anybody outside Germany. For the default installation process describes below, it is also required that the system used to install ttylinux is based on glibc, aka libc6. The installation process needs to run a program from ttylinux at one point that is linked against glibc. This may all sound like a lot of requirements for the preparation system, but almost any half-recent Linux distribution with its default kernel will do. +-+ 2.2 Download You can download ttylinux from the official homepage, which at the moment is at: http://www.informatik.uni-bremen.de/~pharao90/ttylinux/ | There you will find an archive named "ttylinux-2.2.tar.gz". Grab this. Inside the archive you will find this user guide and a file called "rootfs.gz", which is the compressed filesystem image for ttylinux itself. +-+ 2.3 Customization Before you can run ttylinux, you need to change a few settings inside the image file to fit your own system. This is done by uncompressing and mounting the image and then making the appropriate changes. If the image is in the current working directory, do the following as root: gunzip rootfs.gz mkdir mnt mount -o loop rootfs mnt Now the ttylinux filesystem is mounted on the directory "mnt". Take a look at it if you wish. If you want to install ttylinux to a hard disk, you can now create an installation archive for that purpose as follows: cd mnt tar cvzf ../ttylinux-hd.tar.gz . cd .. After this, you have a file called "ttylinux-hd.tar.gz" that can be unpacked onto any filesystem you like. The things you will probably want to customize on ttylinux are the keyboard map and timezone in use and the Internet provider settings. You can copy over the keyboard and timezone setting from your working system as follows: mnt/bin/dumpkmap > mnt/etc/i18n/keymap.dat cp /etc/localtime mnt/etc/localtime To set up the dial information for an Internet provider, you need to know the following: - the device your modem is connected to, i.e. /dev/ttyS1 - the init string for your modem, i.e. ATZ - the speed your modem can talk to the computer, i.e. 115200 - the phone number of your ISP, i.e. 1-800-LETMEIN - your user name at the ISP, i.e. joeuser - your password at the ISP, i.e. joepass The above is for dialup using a modem. If you have ISDN, you need to know the following: - the phone number of your ISP, i.e. 1-800-12345678 - your user name at the ISP, i.e. joeuser - your password at the ISP, i.e. joepass - the phone number you want to use for dialing out (one of your MSNs [multiple subscriber number]) - whether you want to use automatic or manual dialing Edit the file "mnt/etc/isp.conf" and change the settings there to your liking. Note that ttylinux only knows about providers that launch a PPP session immediately after dialup, so if some special procedure is needed to log you in, your Internet connection will not work with ttylinux. The ttylinux approach will work with almost all providers in Germany, but I don't know about other countries. NOTE: If you have ISDN, please also change mnt/etc/firewall.conf so that the line defining the external interface has "ippp0" instead of the default "ppp0" setting. NOTE: For ttylinux to use ISDN, you need to have USE_ISDN=yes in /etc/isp.conf, the default is not to use ISDN. Obviously, you also need a kernel with ISDN support and hardware support for your ISDN hardware. If you need some module(s) to run your ISDN hardware, you will also need to add those and a suitable /etc/modules.conf to the ttylinux filesystem. Once you are finished making changes, unmount the filesystem and run gzip to compress it again: umount mnt gzip -9 rootfs You are now ready for the real installation. Note that this section has only covered the minimum customization needed to run ttylinux. There is more to tune, have a look at the system guide section below for information. If you aim at the default approach of running ttylinux from ramdisk, you must configure everything for your needs before you continue the installation, so it may be a wise idea to read the system guide section before you countinue. If you install to a hard disk, you can always configure things later. +-+ 2.4 Installation I am assuming that you use LILO as your boot loader. You can also use others like loadlin, but you will obviously need some LILO experience to convert the LILO example given here to some other boot manager. Put the "rootfs.gz" image and the Linux kernel you want to use to run ttylinux into the directory that holds your other boot files, most likely this will be "/boot". Let's say your kernel image file is called "bzImage-ttylinux". You now need to add the following section to "/etc/lilo.conf": image=/boot/bzImage-ttylinux label=ttylinux initrd=/boot/rootfs.gz root=/dev/ram0 read-only Now rerun LILO by saying "/sbin/lilo". On your next boot, you can just say "ttylinux" on the LILO boot prompt to boot ttylinux. That is all, you are now ready to try ttylinux. If you want to install onto hard disk, you need to have a partition of at least 4 megabytes size available. Assuming this partition is "/dev/hda8", do the following, using the file "ttylinux-hd.tar.gz" obtained above: mke2fs /dev/hda8 mount -t ext2 /dev/hda8 mnt cd mnt tar xvzf ../ttylinux-hd.tar.gz cd .. Now do the customization as outlines above. You will also need to change the root device configured in "mnt/etc/fstab". Once you are done, you just need to unmount the partition: umount mnt Now you can setup LILO as explained above, only change the line for the root filesystem to "root=/dev/hda8". Ready to go. +-+ 3. System guide This section gives a short overview over the system and some of the installed programs. +-+ 3.1 Features On bootup, ttylinux provides 6 text consoles for login. The default setup has two users: root with password "root" and guest with pass- word "guest". Syslog and klog daemons are running and log kernel and system messages to "/var/log/messages". If you need a text editor, "e3" is installed. Simply invoke it by typing "e3 /path/to/filename". A help screen is available, simply press "Alt-h". e3 unstands a lot of the old WordStar commands, so it feels a bit like WordStar or the common Linux editor "joe". For manipulation of users, groups and passwords, the tools "passwd", "adduser", "addgroup", "deluser", and "delgroup" are present. If you have not changed the timezone and keyboard settings as out- lined above, ttylinux will use its default settings. The default timezone is Europe/Berlin and the default keyboard mapping is for a 102-key German keyboard. These setting should work in Germany. The inetd super-server is running by default. A telnet server will be forked by inetd when a telnet connection comes in. ttylinux includes a basic packet filtering firewall. +-+ 3.2 Bootup and shutdown (initscripts) On system bootup, init runs the script "/etc/rc.d/rc.sysinit" to get the system up. The script will do the usual business of checking and remounting the root filesystem and will start up basic networking. After all is done, "rc.sysinit" will run all executables from the directory "/etc/rc.d/rc.start". It does not matter whether these are scripts or compiled programs. All executables will be passed the parameter "start". For example, if there is a script called "runme", "rc.sysinit" will execute "runme start". The default initscripts that come with ttylinux are stored in the directory "/etc/rc.d/init.d". Those that need to be run at bootup are symlinked to the "rc.start" directory. If you want to write your own initscripts, place them in the "init.d" directory and place a symlink in the "rc.start" and perhaps also in the "rc.stop" directory. If you don't want to write your own script, you can also add commands to the file /etc/rc.d/rc.local - this script will be run at the very end of the boot process, after all others scripts have run. On shutdown, the script "/etc/rc.d/rc.reboot" gets run. This will run all the programs from the "/etc/rc.d/rc.stop" directory, each program will be passed a "stop" parameter. Our example script called "runme" would be executed as "runme stop". Both scripts from "rc.start" and "rc.stop" will be run in ASCII order. If you need them to run in a specific order, you could for example use names like "01.first" and "02.second". This is how the scripts that come with ttylinux are named. Everything in "rc.start" and "rc.stop" should be a symlink, so you can simply remove that link if you want to disable a specific script. Initscripts can also be called manually in case you want to start or stop something while the system is running. For example, /etc/rc.d/init.d/inetd stop will stop the inetd server daemon. All scripts (except pppconf, which understands no options) know about the options "start", "stop", and "restart" that do the obvious things. Some scripts also know about "status" and "reload" for displaying status information and for re- loading service configuration files. +-+ 3.3 Using PPP What to put into "/etc/isp.conf" to configure the dailup information is outlined above in the customization subsection. What you will find here is an overview of how to actually use the PPP system. Assuming "/etc/isp.conf" was setup correctly before boot, you only need one command to start up the Internet connection: ppp-up NOTE: If you use ISDN with autodialing enabled (ISDN_MODE=auto set), you do not need to run ppp-up. ppp-up triggers the ppp daemon, which will dial the provider and try to login. ppp-up can be run by any user in the ppp group. In the default ttylinux configuration, the ppp group has no members, so only root can start and stop the internet connection. You can watch "/var/log/messages" (using tail -f) to see when the connection is up and running. After that, you can browse the web by using the "links" browser. Type in something like: links http://www.slashdot.org/ Inside links, press ESC (escape) to active the menu. You can use the cursor and return keys to navigate links' menu. Outside the menu, use cursor up and down to jump from link to link. Press cursor right to follow a link and cursor left to go back to the previous page. Now you can browse the Internet for a while. If you decide that you want to cut the link, just issue: ppp-down This will take the connection down. Once again, this can be done by root or any user from the ppp group that started the connection. NOTE: If you change any of the settings in /etc/isp.conf, you need to reboot for the changes to take effect or do one of the following. For modem users, just run: pppconf ISDN users will have to do more: /etc/rc.d/init.d/isdn stop pppconf /etc/rc.d/init.d/isdn start After that, you can again use ppp-up and ppp-down. Note that both of these methods only work for root, not ordinary users. SECURITY NOTE: Users in the ppp group will be able to read the file /etc/isp.conf which contains your session password. This may or may not be a good idea, depending on how much you trust your users. If you only wish to use ISDN, you can remove the group read permission with chmod g-r /etc/isp.conf +-+ 3.4 Using thttpd thttpd is a small but fast web server. It will be started on system bootup and will by default serve the contents of "/home/web" to the world. The default web page is a congratulation message with a link to the ttylinux homepage. You can change some of the settings of thttpd in "/etc/httpd.conf". The default settings will also allow CGI scripts to run if they are in the directory "/home/web/cgi-bin" or their name ends in ".cgi". +-+ 3.5 Setting up network devices To set up a network device, go to the directory "/etc/network.d" and copy the file "sample" found there to a file named "interface.dev". For example, if you want to setup the device "eth0", name the file "interface.eth0": cp sample interface.eth0 Now edit the new file to adjust the settings for the device. You can either let the system use the DHCP protocol to obtain the settings from a DHCP server or you can set the IP address and other parameters manually within the file. +-+ 3.6 Using the firewall The default settings of the ttylinux firewall script assume that the network interface to the rest of the world is called "ppp0", which is only true for modem PPP connections to the Internet. By default, the firewall will allow the world to access the HTTP server, but will deny access to the telnet server. Access to any other server running on a port below 1024 is denied, and the outside world is not allowed to ping the ttylinux machine. You can change the settings of the firewall in "/etc/firewall.conf". Note that this firewall script is very simple and assumes that local users are always trusted. There is no protection against users running server daemons on ports above 1024. If you don't trust your users, this firewall script is not enough for you! +-+ 3.7 Shell environment The default shell used by ttylinux is bash. You can change the startup environment (variables, aliases, etc) in /etc/profile. You can also put files into the directory /etc/profile.d - all readable files in this directory will be sourced by bash when you login on the ttylinux machine. Using /etc/profile.d is a good choice for your own personal changes. You may want to update to a new version of ttylinux sometime later, and then you could end up loosing all your changes to /etc/profile if you forget to make a backup. In /etc/profile.d, your changes are safe. +-+ 3.8 pkg script There is a script called pkg that can give some information about programs and packages that are part of ttylinux. The script is built to mimic some of RPM's query options. You can list all packages, find out to which package a file belongs, and list the files that belong to a specific package. To get a list of all packages, run pkg -qa To find out which package /bin/login belongs to, use pkg -qf /bin/login To list all files from the bash package, run pkg -ql bash +-+ 4. Contact If you have bug reports, suggestions, or anything else about ttylinux that you think is important, feel free to contact me. You can reach me by email at: Pascal Schmidt <pharao90@tzi.de> Or by FidoNet netmail to: Pascal Schmidt @ 2:241/215.72 See the file AUTHORS in the ttylinux distribution for a list of people who contributed ideas, bug reports, or code so far. +-+ A. How to make a bootable ttylinux CD To follow these instructions, you need the following programs on your working system: mkisofs, mkdosfs, and syslinux. mkdosfs is usually found inside a package called "dosfstools", syslinux can be found on the Internet and on Red Hat installer CDs. You will need the ttylinux filesystem image rootfs.gz and a linux kernel image (the result of a "make zImage" or "make bzImage"). I assume you have these files in your current working directory and the kernel image file is called "vmlinuz". The following instructions will only work for root, not normal users. First, go through the rest of this user guide and do all the customization you want to do. Once ttylinux is burned onto the CD, you don't get any further chances to change anything. Now we start preparing the CD image. mkdir mnt mkdir -p iso/boot dd if=/dev/zero of=image bs=10k count=288 mkdosfs image syslinux image mount -o loop image mnt cp vmlinuz mnt/linux rdev mnt/linux /dev/ram0 cp rootfs.gz mnt At this point, we have created an image file resembling a 2.88 mega- byte floppy disk, syslinux has put a bootloader onto this image, we have mounted the image on the "mnt" directory and copied our kernel image and filesystem image files onto the disk image. We also told the kernel to expect the root filesystem on /dev/ram0 when booting. Now we need to create a syslinux config file on the disk image. vi mnt/syslinux.cfg In this file, place the line append initrd=rootfs.gz If you need to pass kernel parameters to your kernel, do this on the same append line. For example, if you need to pass, say "idebus=33", your line should be append initrd=rootfs.gz idebus=33 Now we are finished creating the disk image we need for making a bootable CD. Let's start putting together the iso image. umount mnt cp image iso/boot/boot.img The boot image itself is only 2.88 megabytes, so you will have extra space available. You can mount the CD after booting to get access to all the files you put on the iso image in addition to the boot.img file. Simply put anything you want into the "iso" directory now. Once you are done with that: cd iso mkisofs -r -b boot/boot.img -c boot/boot.cat -o ../bootcd.iso . cd .. Congratulations, you finished the job of creating a bootable iso image with ttylinux on it. All you need to do now is use some CD burning program to put the "bootcd.iso" image on a real CD. +-+