Posts Tagged applications

Safe rm – stops you accidentally wipeing the system!

Posted by on Monday, 21 September, 2009

I found this the today , and having had the odd accident im most definitely going to be installing this on my own server!

What is safe-rm?

Safe-rm is a safety tool intended to prevent the accidental deletion of important files by replacing /bin/rm with a wrapper, which checks the given arguments against a configurable blacklist of files and directories that should never be removed.

Users who attempt to delete one of these protected files or directories will not be able to do so and will be shown a warning message instead:

    $ rm -rf /usr
    Skipping /usr

(Protected paths can be set both at the site and user levels.)

Recovering important files you deleted by mistake can be quite hard.

So, why not install this on your server and save yourself some hassles in case you accidentally have that shell script gone wrong problem. Now if somebody could do the same to fdisk I would be totally happy, there was this time when i accidentally repartitioned my own server HDD after puting a new one in, and got the wrong drive :/

For manual install its as simple as

wget the file

tar zvxf safe-rm-0.6.tar.gz

cd safe-rm-0.6

mv /bin/rm /bin/old-rm

mv safe-rm /bin/rm

For those running debian variants you can

apt-get install safe-rm

Points to note in the README:

Once you have installed safe-rm on your system (see INSTALL), you will need to
fill the system-wide or user-specific blacklists with the paths that you’d like
to protect against accidental deletion.

The system-wide blacklist lives in /etc/safe-rm.conf and you should probably add
paths like these:


The user-specific blacklist lives in ~/.safe-rm and could include things like:


Here are two projects which allow you to recover recently deleted files by trapping
all unlink(), rename() and open() system calls through the LD_PRELOAD facility:

delsafe (link in the readme is dead but i googled and updated it here)


There are also projects which implement the trashcan spec. For example:


Linux Backups for Servers and Desktops

Posted by on Thursday, 18 June, 2009

Everyone wants to back up right? Well you will once you have totally lost the last years worth of work on a website and somebody breaks things severely!

Heres a quick and nasty backup HOWTO.

Database Dumps

mysqldump -u root -p mydatabase > mydatabase.sql

This dumps a database into a file, you can modify this to dump it offsite using ssh with this command.

su postgres -c "pg_dumpall" > pgdatabase.psql

If you use postgres you can change this to something like this

mysqldump -u root -p mydatabase > mydatabase.sql | ssh “dd of=mydatabase.sql”

If you want to dump the entire database you can use

mysqldump -A -u root -p >entiredatabase.sql

This may take some time. To put this in a shell script and dump multiple copies and keep track of things you can use something similar to this

date=`date +%m-%h-%Y`

mysqldump -A -u root -p >${date}-fulldatabase.sql

This will expand to dump it into something like


File Backup


To run a regular interactive FTP session:

lftp -u 'username,password'

To backup one or more files:

lftp -u 'username,password' -e "set ftp:ssl-protect-data true; mput /local/dir/files* /remotedir; exit"

You need to set ftp:ssl-protect-data else you will not be able to store the file. If you want to make this a default option, add it to the lftp.conf file. e.g. :

grep -qai "set ftp:ssl-protect-data true" /etc/lftp.conf || echo "set ftp:ssl-protect-data true" >> /etc/lftp.conf

To restore a file from the FTP server to your Machine:

lftp -u 'username,password' -e "set ftp:ssl-protect-data true;mget /remotedir/files* -O /localdir; exit" .

The -O option is not required it you wish to store to the current local directory.

To mirror a whole directory to the FTP server:

lftp -u 'username,password' -e "set ftp:ssl-protect-data true;mirror --reverse /local/dir/name remotedirname; exit" .

--reverse means that the ‘mirroring’ is going in the reverse direction than ‘normal’. i.e. from your server to the backup server. If you run man lftp there are a few other options to choose from. e.g. --delete to delete files on the backup server that do not exist locally. Or --continue to continue a mirror job. Or --exclude files to exclude certain files from the transfer.

To restore a whole directory from the FTP server to your machine:

lftp -u 'username,password' -e "set ftp:ssl-protect-data true;mirror remotedirname /local/dir/name;exit"

To create a nightly cronjob that uploads a directory to the backup FTP server, create a /etc/crond.daily/ftpbackup file like this:

lftp -u 'username,password' -e "set ftp:ssl-protect-data true;mirror --reverse /local/dir/name remotedirname;exit" > /dev/null


chmod +x /etc/cron.daily/ftpbackup .

Then check the files have been mirrored as you expect the next day.


Rsync is a better option in some ways as it checks the MD5 of files and updates them if they are out of date, rather than re-copying the entire lot. Short but easy shell script to copy things over

EXCLUDE=” –exclude *.tmp \
–exclude *.temp”

rsync –archive -vv –rsh=ssh $EXCLUDE $USER@$HOST:/etc/ $BACKUPPATH/$HOST/etc


This is better again than rsync as it does versioning control and only backs up the difference in files.

To backup files

rdiff-backup /some/local-dir

To restore

rdiff-backup --restore-as-of now local-dir/file
rdiff-backup -r now local-dir/file

The -r command is the same as –restore-as-of

The main advantage of rdiff-backup is that it keeps version history. This command restores as it was 10 days ago into a new location /tmp/file .

rdiff-backup -r 10D /tmp/file

Other acceptable time strings include 5m4s (5 minutes and 4 seconds) and 2002-03-05 (March 5th, 2002). For more information, see the TIME FORMATS section of the manual page.

More examples can be found at

This tutorial was compiled from several others, and props go out to and

Postgrey HOWTO for Centos and Debian based Linux – Postfix Greylisting

Posted by on Wednesday, 6 May, 2009

Greylisting is a great invention to minimize a huge pile of spam. Any SMTP server thats incorrectly configured or mail sent from infected desktop machines just tries the first time, gets bounced, and never tries again.

Legitimate email comes through fine, however the downside is it can take a few minutes more than the usual. Considering how much Spam greylisting prevents its worth it for a lot of people.

The quick and dirty of the install is.

For debian based distros (Ubuntu etc included)

apt-get install postgrey

For Redhat/Centos based distros you will need to add the DAG/rpmforge repos into your lists and then

yum install postgrey

Next you need to enable it to listen on a port. In debian edit the file /etc/defaults/postgrey and add-in/edit the line

POSTGREY_OPTS="--inet= --delay=60"

For Redhat based releases you need to CREATE /etc/sysconfig/postgrey and add in the following line

OPTIONS="--inet= --delay=60"

Now restart the postgrey daemon with

/etc/init.d/postgrey restart

If you do a netstat you can see its now listening on localhost port 60000 (unless you buggered something up of course)

Now you need to edit the /etc/postfix/
search for the line that has smtpd_recipient_restrictions and add to it

check_policy_service inet:

And average config will look something like this

smtpd_recipient_restrictions =
check_policy_service inet:

Now reload the postfix with /etc/init.d/postfix reload
Now all you need to do is check the logs with tail -f /var/log/maillog and hope you got it all going right.