I recently ran a Knoppix 6.4 LiveCD and set up my printer for some online printing. I then shut down and removed the CD. About a week later I again booted the LiveCD and when I installed my printer I noticed Knoppix remembered my printer. I installed using localhost:631 to access CUPS and my printer was listed. In order for Knoppix to remember my printer something has to be writing to my hard drive. The CD is a CD-R, I thought with a LiveCD this was not supposed to happen? Jim
Normally, the operating environment in the CD (WinPE, Linux), executes from memory or from memory and CD, and doesn´t write anything to the hard disk. But any other program that is run can write to the hard disk.
Just to understand this fully... Let's say that a Live CD has a plain text editor. I have a text file on the hard disk. I can view it, edit it, and save it to the hard disk using the text editor on the Live CD.
AFAIK, yes. Another example: some WinPE disks can modify the boot information in the hard disk to solve boot problems.
Just so we are all on the same page about Live CDs here, a Live CD is typically created as a Read Only medium with an iso9660 files system which is written once to the CD-ROM. Therefore, a LiveCD does not have persistent memory and cannnot remember anything from one boot to the next reboot, unlike a persisten USB flash drive holding the same contents as the LiveCD, but implemented to remember some things in its persistent memory on the USB flash drive - i.e. not in the .iso file system recorded on it. Hard drives can be mount in any Live CD session to save files onto a hard drive by simply becoming root (required to issue the mount command). It is likely Puppy Linux on a Live CD has no memory of what was saved in a previous - i.e. by definition a Live CD has no persistent memory, whereas a hard drive does. Unless a new .iso filesystem was generated with the information from the previous Live CD session, and then used in the next Live CD reboot, nothing will be remembered by the Live CD. -- Tom
Ture, I have never tried it, but Puppy Linux is the exception - not the usual Live CD due to its very small size, clever though, and in fact it is all about a Live DVD approach rather than a Live CD. Cheers, -- Tom
I began using a LiveCD for online banking thinking it did not read, nor write, to the hard drive, and that it would be more secure than a hard drive based Windows or Linux system. Apparently I also didn't adequately research this topic. So, if a LiveCD can read and write to the hard drive then is a LiveCD safe for online banking? If my printer data can be stored and remembered why can't my Bank log-in data also be stored and then accessed? Jim
Hi JConLine, A LiveCD is a read-only CDROM and the hard drives are not mounted when it boots up. I typically turn my router off at night, and in the morning when I bring up my Live CD the router is not yet turned on. After I setup the Linux environment the way I want it which includes running iptables to setup rules for netfilter (i.e. initialize the computer's firewall), the drives during the setup are mounted to be able to do the setup, and then unmounted prior to turning on the router to start a connection and get on the Internet with a browser. During my Linux session, with one click, I can disable the network connection temporarity if I have downloaded anything I want to save to hard drive, and then unmount the hard drive again before I re-enable the network connection. While I am connected to the browser to the Internet, I am using the browser from a standard user account - i.e. not with the root/sysadmin account. No drives are mounted and there are no root account processes running except for the standard ones to be able to run (in memory) from the Live CD system. You can opt to create a persistent USB flash drive (version of your Live CD) which could save your Bank log-in data in persistent storage - but, if you do so, you should encrypt it, so that if your stored Bank log-in data is accessed by anyone but you with the decryption password, then they won't be able to compromise your data. -- Tom
Hi Tom, Thanks for the excellent info. I'll have to read your response a couple of time to absorb what you're saying. I have been just booting with the CD-R thinking I was protected, that is until I saw my printer was remembered. Jim
Hi JConLine, I am not sure what you mean when you say "I saw my printer was remembered". During boot up of a Live CD, the Live CD system is enabled in RAM, including a full file system, and it boots after it is unrolled into RAM and detects all of the hardware attached to your computer including your printer. (without accessing any installed OS on a hard drive). None the less, I have to do a short and sweet setup to change my printer's default options every time I boot with my Live CD system, i.e. for media size to set it from A4 to Letter 8.5x11 inch, and Normal Color to Normal Grayscale. Check your printer's options to assure that they are setup properly before you try to print something because when your say the Live CD remembered your printer, if it did, then the printer's default settings would not have to be changed on every boot - which should be the case. In Linux, when the Live CD system is mounted, it is mounted on /cdrom. When I run the following commands, it assures me that my Live CD system is read-only: $ ls -ldt /cdrom dr-xr-xr-x 11 root root 4096 2010-10-07 12:24 /cdrom $ mount /dev/sr1 on /cdrom type iso9660 (ro,noatime) Today, I am running via a non-persistent USB Flash drive with the Ubuntu 10.10 Maverick Meerkat i386 desktop .iso, and it reports via the mount command: $mount /dev/sde on /cdrom type iso9660 (ro,noatime) Note: I have 4GB (3 of which are useable) which amounts to about 1.85GB when I run my Live CD system, although I currently have 8GB, but need to recobble my Live CD system to exchange the regular linux-headers, linux-generic and linix-image packages for their latest PAE versions to be able to access up to 36-bit memory for my upgraded montherboard over and above the 4GB limit without the PAE packages for the Live CD system OS. -- Tom
Hi Tom, Again, thanks for all the good information. About remembering my printer. I used a Knoppix 6.4 LiveCD and installed my printer using CUPS, ie localhost:631. I have an old HP5 LaserJet, that just keeps going, connected to a JetDirect print server which is connected to a switch which is connected to a Linksys router. I use my laptop for online banking and connect to the router using a wireless connection. As I said when installing the printer (the first time) using the Knoppix LiveCD my printer was not listed until I began the install process. However, the second time I used the Knoppix LiveCD when I installed my printer, my HP5 was already listed in the CUPS setup. Also, the Knoppix LiveCD, by default, mounts my hard drive partitions. I have since began using an Ubuntu 10.10 32 bit LiveCD which does not remember my printer and which does not mount my hard drive partitions unless asked. Thanks, Jim
I recommend Lightweight Portable Security for online banking, because it doesn't write to internal hard disks.
You can never really know what software is doing. I'm a hands-on kind of guy, so my solution has been to install an on/off toggle switch on the power leads of every hard drive in my case. I can switch any or all of them off as needed, so the drives won't even spin up, then I can boot to any Linux CD and be absolutely certain that nothing is being written to hard disk. However, for the "electronically challenged" an easier solution would be to use removable caddys, as these almost always include a mechanical on/off switch.
