Intrusion detection systems
Basic configuration (debian way)
Install tripwire with apt-get (
apt-get install tripwire)
cd /etc/tripwire /usr/sbin/twadmin --create-polfile twpol.txt /usr/sbin/tripwire --init # Have patience, this will take a minute or so and # you'll get loads of "No such file" warnings...
Ok, we're fully installed now. So let's run our first check so we can tune the policy
/usr/sbin/tripwire --check > twout.txt # lots of warnings and patience gain...
Now use this perl script (fixpol.pl)
chmod u+x fixpol.pl ./fixpol.pl twout.txt twpol.txt | more # there's lots of output
fixpol prints what to do next near the end of its output in particular:
You should now run
diff twpol.txt twpol.txt.new | more
to make sure my changes aren't garbage. If it looks ok run
/usr/sbin/twadmin --create-polfile twpol.txt.new /usr/sbin/tripwire --init
to install the new policy in the database.
Now you're in a position to run
regularly in cron or whatever.
Comprehensive intrusion detection
- tiger - Report system security vulnerabilities
- tiger-otheros - Scripts to run Tiger in other operating systems
apt-get install tiger tiger-otheros
Either install the package that comes with your distribution (on Debian you would run)
apt-get install chkrootkit
or download the sources from www.chkrootkit.org and install manually:
wget --passive-ftp ftp://ftp.pangeia.com.br/pub/seg/pac/chkrootkit.tar.gz tar xvfz chkrootkit.tar.gz cd chkrootkit-<version>/ make sense
Afterwards, you can move the chkrootkit directory somewhere else, e.g.
cd .. mv chkrootkit-<version>/ /usr/local/chkrootkit
Now you can run chkrootkit manually:
cd /usr/local/chkrootkit ./chkrootkit
(if you installed a chkrootkit package coming with your distribution, your chkrootkit might be somewhere else).
You can even run chkrootkit by a cron job and get the results emailed to you: Run
to create a cron job like this:
0 3 * * * (cd /usr/local/chkrootkit-<version>; ./chkrootkit 2>&1 | mail -s "chkrootkit output my server" firstname.lastname@example.org)
That would run chkrootkit every night a 3.00h.
Download the latest rkhunter sources from www.rootkit.nl:
wget http://downloads.rootkit.nl/rkhunter-1.2.7.tar.gz tar xvfz rkhunter-1.2.7.tar.gz cd rkhunter/ ./installer.sh
This will install rkhunter to the directory
/usr/local/rkhunter. Now run
to download the latest chkrootkit/trojan/worm signatures (you should do this regularly). Now you can scan your system for malware by running
download from here
# wget http://www.rootkit.nl/files/lynis-1.1.8.tar.gz # tar xvfz lynis-1.1.8.tar.gz # ./lynis --check-update # ./lynis -c
MD5 sum checks
- debsums - Verify installed package files against MD5 checksums (Debian systems)
Generate a checksum for the partition you wish to image, run from shell
# md5sum /dev/hdc2 > /tmp/hdc2.md5
To make the copy of the disk(s), we'll use the dd command. From shell…
# dd if=/dev/hdc of=/tmp/hdc.img
You will need enough space in /tmp to hold a copy of the entire /dev/hdc drive. This means that /tmp shouldn't be a RAM disk and should not be stored on /dev/hdc. Write it to another hard disk !