Ask Klaus!

Network Connections

Question:

I wrote last year about connecting to Optus from Linux. I have since bought a wifi router to use with the ADSL modem. The first instruction in the router setup was to set the modem mode to nat or napt, as Optus has modems modified to use something called optus-bridge, which seems to restrict the user to one computer. Changing my Seimens modem to napt mode allowed most Live CDs to work out on boot up with any DHCP program. This may help others with similar problems.

Note that if you are using a fixed address, each new distro needs a different fixed address; I don't know why.

Answer:

Setting up the DSL modem to Router/DHCP mode with NAT (network address translation) is surely the easiest setting from the client side. All provider-specific information is stored inside the modem that had been set up previously, and on the computer side, all you have to do is select automatic ip configuration via DHCP. Note that in this setting, the IP address acquired by the computer is not the one that is being seen from the Internet side because NAT maps every internal IP address to the external one. A security advantage of this is that no connection can be initiated originating from the Internet to the home network, unless your computer has initiated that connection first.

It should well be possible to connect multiple clients with different client IP addresses over the same router. With static IP addresses, each real or virtul machine needs a different IP address, which is what the DHCP server takes care of when clients use DHCP for configuration. Running a different OS from the same machine, however, should not require a different IP address, as long as the old address is not still in use.

Live USB Creator

Question:

I read this InformationWeek article today (http://www.informationweek.com/story/showArticle.jhtml?articleID=207800392) and was disappointed not to see a word about Knoppix! I am a long time Knoppix user, over 5 years, and would like to see a script developed that has the simplicity of that which is offered by Fedora (ugh), but their script is elegant in its simplicity! See: https://fedorahosted.org/liveusb-creator.

I know that the Knoppix community can match this and not make building a USB Flash bootable Knoppix such a headache as it currently is.

How about it Mr. Knopper? I would like to be able to download the most current Japanese Knoppix and build a flash so that it can easily travel with me and as a side benefit I can listen to music CDs or watch a DVD under Knoppix on my laptop.

Answer:

It's already done, the command is called mkbootdev on your Knoppix DVD.

Basically, what it does is copy the Live CD/DVD content to a FAT16/FAT32 filesystem, moving the boot files from boot/isolinux/* to the root directory of the flash disk, renaming isolinux.cfg to syslinux.cfg, and executing syslinux /dev/sda1 (in this example, /dev/sda is the flash disk). Depending on previous installations, it might be necessary to also create a master boot record by ms-sys -s /dev/sda and marking the first partition bootable with sfdisk -A1 /dev/sda.

CD Format

Question:

I have a Windows XP home computer with CD burner, but I have been experimenting with Linux Live CDs for a while.

All the various Linux mags seem to give out discs with a DVD format I cannot handle.

Is there a way for me to convert a Linux DVD to a CD-R on my friend's computer that has both DVD and CD drives?

I think it is possible by ripping the DVD, but I do not know how to do that.

Answer:

Windows should be capable of reading the standard ISO 9660 filesystem that is used for both CDs and DVDs. Linux prefers the Rock Ridge extension (mkisofs option -R), Windows prefers Joliet (mkisofs option -J) for long and mixed-case file names. Combining -R/-r and -J when creating a CD filesystem with the mkisofs command adds both extensions, so neither Windows nor Linux should run into problems. For example,

mkisofs -D -r -J -o /tmp/mycd.iso source_directory

will create the ISO image /tmp/mycd.iso that is compatible with Linux as well as Windows CD filesystems.

For DVDs, UDF is sometimes used to support single files inside the filesystem structure that are larger than 4GB, as well as other extensions that are found on Video DVDs. Normally, you should not need this mkisofs -udf option.

Converting DVD videos to SVCD videos, thus decreasing size and quality, is a different topic. For this task, you can use dvdbackup and ffmpeg.

Some commercial DVDs have a country code and CSS as "copy protection." In most countries, it is not legal to play or even read these on ANY operating system ifyou have not paid for a valid license key for the software or hardware player, even if it is technically possible.

Specifically, for videos, the DVD drive can refuse to play if its country code does not match that from the DVD, unless you change the drive's country code.

CD and DVD images made by mkisofs or growisofs with the -r and -J option, however, should always be readable on a large variety of operating systems without problems.