Anton Titov’s blog

Few days ago, a server of mine had all of it’s 4 disk crashed. The problem was that one of the disks was overheating and that seemed to help other harddrives to crash (don’t buy Maxtor).

So, if you have a case like mine - some partitions with reiserfs on hard drive with bad blocks this guide may help you.

Firts try to mount you partition and copy as mouch data as you can. But the chances are, that if you are searching the net for a solution that you cannot mount your partiton and reiserfsck dies, saying you have bad blocks.

First download and install dd_rescue (if you plan to boot from LiveCD while restoring, you can try this statically linked binary dd_rescue binary), as dd conv=noerror will not help - it will not write something instead of unreadable zones which changes drive size and most of the data, that is after the bad blocks will not be restored /or you will have the files, but with garbage in them/. dd_rescue also shows you how much of the disk cannot be copied, which may give you some hope to restore you files, as most of the time you will have just few megabytes or less in bad blocks.

You will need another hard disk with enough free space to copy the whole partition (not only for used space). Now boot from a good hard drive or from LiveCD (Gentoo, Knoppix, Ubuntu, should not matter). Mount the good hard drive with free space somewhere.

Now if your failed partiton is /dev/sda1, and /mnt/disk2 is a place with enough free space run

dd_rescue /dev/sda1 /mnt/disk2/sda1-img
or
/path/to/just/downloaded/from/above/link/dd_rescue /dev/sda1 /mnt/disk2/sda1-img

now find some work to do as this will be slow.

When dd_rescue finishes you may want to make another copy of just copied image if you have enough free space, this most probably will be faster:

dd_rescue /mnt/disk2/sda1-img /mnt/disk2/sda1-img2

Now run

reiserfsck –rebuild-tree /mnt/disk2/sda1-img

if after you type Yes program dies silently try:
reiserfsck –rebuild-sb /mnt/disk2/sda1-img

first.

Now you should be able to mount your partition as:
mkdir /mnt/sda1fixed
mount -o loop /mnt/disk2/sda1-img /mnt/sda1fixed

now go to /mnt/sda1fixed and see what you have.

If you are unlucky most of your files will be in /lost+found with strange names. The good news is if you find a directory there, it’s contents will have good names. So you may want to try:
cd /mnt/sda1fixed/lost+foud
find -name some_file_with_not_common_name_that_should_be_in_directory_that_is_important_for_you

with

find -name shadow

you should be able to find your /etc directory.

After trying this, if you-re still missing important data, you can try the above procedure, but with adding -S to reiserfsck parameters:
reiserfsck –rebuild-sb -S /mnt/disk2/sda1-img

but first read reiserfsck man page.

Hope this helped you.

And a piece of advice: backup you data regularly.

There are many forms on the web, that use PHP mail() function to send mail, most of the time to the site owner. The problem with this is that many of them do not verify submitted data and can be used to trick the script to send mail to any recipient with changed body of the mail. The trick is that most of the form give the user ability to write a mail subject and/or his mail, that will be used as “From: ” for sending the mail. The only thing a spammer should do to send spam through such a form is to inject a text, similar to this to the subject field:

Some subject here
Bcc: john@domain1.com, jack@domain2.com

Here goes the spam body, take into account the fact that value that should be submitted as subject should contain one new line character between subject and bcc: and two newline characters between bcc and body.

So the only thing spammer should do is to try to insert text with new line characters to some (or all) of the form fields and your server will start sending spam.

The problem is the spammers know this and currently widely use it. Few days ago I was receiving few hundred mails a day from AOL that mail which originated from my network is marked as spam from user (you can register for free to this service here: http://postmaster.aol.com/tools/fbl.html). Trying to force hundreds users whose forms was abused to validate input data was not an option, so I’ve developed a patch for PHP’s mail() function that checks if subject or to fields have new line characters or if additional headers parameter have two subsequent new line characters and in this case trows a warning and do not send the mail. You can download it here:

http://www.titov.net/php-nospam.patch

It is developed for PHP 4.4.1 and it works for me. For few days already no user (from thousands) reported any negative consequences of this patch so give it a try.

If you’re a PHP developer, feel free to include the code or the idea into the PHP source. I’ll appreciate a credit in the ChangeLog if you do that.