You can modify it for your specific requirements or grab some code for another use.

#!/usr/bin/perl -w
use strict;
use warnings;

use IPC::Open3;

# example
my $filename  = $ARGV[0];
my %videoInfo = videoInfo($filename);
print "duration: " . $videoInfo{'duration'} . "\n";
print "durationsecs: " . $videoInfo{'durationsecs'} . "\n";
print "bitrate: " . $videoInfo{'bitrate'} . "\n";
print "vcodec: " . $videoInfo{'vcodec'} . "\n";
print "vformat: " . $videoInfo{'vformat'} . "\n";
print "acodec: " . $videoInfo{'acodec'} . "\n";
print "asamplerate: " . $videoInfo{'asamplerate'} . "\n";
print "achannels: " . $videoInfo{'achannels'} . "\n";

#
# returns media information in a hash
sub videoInfo {
	# ffmpeg command
	my $ffmpeg = '/usr/local/bin/ffmpeg';

	my %finfo = (
				  'duration'     => "00:00:00.00",
				  'durationsecs' => "0",
				  'bitrate'      => "0",
				  'vcodec'       => "",
				  'vformat'      => "",
				  'acodec'       => "",
				  'asamplerate'   => "0",
				  'achannels'       => "0",
	);

	my $file = shift;

	# escaping characters
	$file =~ s/(\W)/\\$1/g;

	open3( "</dev/null", ">/dev/null", \*ERPH, "$ffmpeg -i $file" ) or die "can't run $ffmpeg\n";
	my @res = <ERPH>;

	# parse ffmpeg output
	foreach (@res) {
        print;

		# duration
		if (m!Duration: ([0-9][0-9]:[0-9][0-9]:[0-9][0-9].[0-9][0-9])!) {
			$finfo{'duration'} = $1;
		}

		# bitrate
		if (m!bitrate: (\d*) kb/s!) {
			$finfo{'bitrate'} = $1;
		}

		# vcodec and vformat
		if (/Video: (\w*), (\w*),/) {
			$finfo{'vcodec'}  = $1;
			$finfo{'vformat'} = $2;
		}

        # Stream #0.1(und): Audio: aac, 48000 Hz, 1 channels, s16, 64 kb/s

		# acodec, samplerate, stereo and audiorate
		if (m!Audio: (\w*), (\d*) Hz, (\d*)!) {
			$finfo{'acodec'}     = $1;
			$finfo{'asamplerate'} = $2;
			$finfo{'achannels'}     = $3;
		}
	}

	my $tenths  = substr( $finfo{'duration'}, 9, 2 );
	my $seconds = substr( $finfo{'duration'}, 6, 2 );
	my $minutes = substr( $finfo{'duration'}, 3, 2 );
	my $hours   = substr( $finfo{'duration'}, 0, 2 );
	$finfo{'durationsecs'} = ( $tenths * .01 ) + $seconds + ( $minutes * 60 ) + ( $hours * 360 );

	return %finfo;
}

This has been tested on Ubuntu Lucid and Jaunty. This procedure will create a system with:

• Install a separate Dropbox client (daemon) for individual users
• Each user has a separate Dropbox account
• All the daemons will be managed together with normal daemon controls

This allows individuals to have their own Dropbox accounts, each with a separate process syncing their individual ~/Dropbox directory. With one command an admin can start or stop all the daemons at once.

Install Prerequisites

Later, we’ll need to read a sqlite3 database record, so install sqlite3.

sudo aptitude -y install sqlite3

Install Dropbox client for an individual user

This step is repeated for each user that wants a Dropbox client. Start by setting up your own account, then repeat for each user. This is run with a user’s own account. The changes made all take place in their home directory.

First, determine whether you have 32-bit or 64-bit Ubuntu Server. You must install the correct version, either 32 or 64 bit or it will not work. The following command will tell you which is installed:

uname -a | grep '_64' >/dev/null && echo 'A 64-bit OS is installed'; uname -a | grep '_64' >/dev/null || echo 'A 32-bit OS is installed'

Run the correct installation, based on whether a 32-bit or 64-bit OS is installed.

32-bit installation:

cd ~
wget -O dropbox.tar.gz http://www.dropbox.com/download/?plat=lnx.x86
tar -zxof dropbox.tar.gz

or

64-bit installation:

cd ~
wget -O dropbox.tar.gz http://www.dropbox.com/download/?plat=lnx.x86_64
tar -zxof dropbox.tar.gz

Link user’s Dropbox client to their Dropbox account:

wget http://dl.dropbox.com/u/6995/dbmakefakelib.py
python dbmakefakelib.py

The above will run for a little while without printing anything, then print “dropboxd ran for 15 seconds without quitting – success?”. When it does so, press control-c twice. Yes, it is unusual. What this does is populate a sqlite3 database with an ID from the Dropbox server. Next, we’ll extract that code and use it to link your Dropbox user account with this CLI Dropbox client instance.

Get the URL with:

echo https://www.dropbox.com/cli_link?host_id=`echo '.dump config' | sqlite3 ~/.dropbox/dropbox.db | grep host_id | cut -d \' -f 4 | python -c 'print raw_input().decode("base64")' | grep '^V' | cut -b 2-`

Copy the URL that the above printed and paste it into a web browser. When you do so, Dropbox will register your client on the server with your Dropbox account.

At this point, Dropbox will not be quite working yet. The next steps will take care of that.

Create Dropbox daemon control

The next task is to create a system to start and stop the dropbox daemon for each user on the system that has Dropbox installed for his/her user account. The following daemon init script was lifted from: http://wiki.dropbox.com/TipsAndTricks/TextBasedLinuxInstall.

Of course, this is for the use of the system admin. This creates a normal daemon init start/stop script and installs it so the Dropbox daemons are started when the system boots. The admin can also use this to control the Dropbox daemons manually.

sudo vi /etc/init.d/dropbox

Paste in the following code. Then, modify line 3, replacing “user1 user2″ with your username. For future reference, additional user’s Dropbox daemons can be controlled with this one script – add additional username separated with spaces.

# dropbox service
# separate usernames in the following line with spaces.
DROPBOX_USERS="user1 user2"

DAEMON=.dropbox-dist/dropbox

start() {
    echo "Starting dropbox..."
    for dbuser in $DROPBOX_USERS; do
        HOMEDIR=`getent passwd $dbuser | cut -d: -f6`
        if [ -x $HOMEDIR/$DAEMON ]; then
            HOME="$HOMEDIR" start-stop-daemon -b -o -c $dbuser -S -u $dbuser -x $HOMEDIR/$DAEMON
        fi
    done
}

stop() {
    echo "Stopping dropbox..."
    for dbuser in $DROPBOX_USERS; do
        HOMEDIR=`getent passwd $dbuser | cut -d: -f6`
        if [ -x $HOMEDIR/$DAEMON ]; then
            start-stop-daemon -o -c $dbuser -K -u $dbuser -x $HOMEDIR/$DAEMON
        fi
    done
}

status() {
    for dbuser in $DROPBOX_USERS; do
        dbpid=`pgrep -u $dbuser dropbox`
        if [ -z $dbpid ] ; then
            echo "dropboxd for USER $dbuser: not running."
        else
            echo "dropboxd for USER $dbuser: running (pid $dbpid)"
        fi
    done
}

case "$1" in
  start)
    start
    ;;

  stop)
    stop
    ;;

  restart|reload|force-reload)
    stop
    start
    ;;

  status)
    status
    ;;

  *)
    echo "Usage: /etc/init.d/dropbox {start|stop|reload|force-reload|restart|status}"
    exit 1

esac

exit 0

Make the init script executable and restart the daemon:

sudo chmod +x /etc/init.d/dropbox
sudo /etc/init.d/dropbox restart

When you restart the daemon, it will be running correctly linked to your Dropbox account. It will create a Dropbox directory in your home directory and will start to populate it with files you have on Dropbox.

Have the daemon(s) run automatically at boot time:

sudo update-rc.d dropbox defaults

The above correctly copies links as needed so the daemon(s) start when the server boots.

Managing the Daemons

A separate daemon will be run for each user that has the Dropbox client installed – with only one command. This makes it easy for individual users to have separate Dropbox accounts, each syncing to ~/Dropbox for their user account. Here are the commands to manage these daemons:

Start Dropbox services for all users:

sudo /etc/init.d/dropbox start

Stop Dropbox services for all users:

sudo /etc/init.d/dropbox stop

Restart Dropbox services for all users:

sudo /etc/init.d/dropbox restart

Get service status for each user Dropbox service:

sudo /etc/init.d/dropbox status

#! /bin/bash

CODE="upc"
OWNER="myusername"
GROUP="mygroupname"
KOHANA_URL="http://dev.kohanaframework.org/attachments/download/1355/kohana-v2.3.4.zip"
KOHANA_ZIP="kohana-v2.3.4.zip"
SITESROOT="/usr/local/var/www"
URL="www.mysite.com"
# database.php parameters
DBUSER="mydbuser"
DBPWD="mydbpasswd"
DBHOST="localhost"
DBDATABASE="mydbname"

#
# make sure this is run as root
#
if [[ $UID -ne 0 ]]; then
    echo "Not running as root"
    exit
fi

if [ ! -d $SITESROOT ]; then
	echo "$SITESROOT directory does not exist"
	exit
fi

#
# change to the siteroot directory
#
cd $SITESROOT

if [ -d $URL ]; then
	echo "$SITESROOT/$URL directory already exists"
	exit
fi 

mkdir $URL
chown $OWNER:$GROUP $URL
cd $URL

#
# create kohana directory
#
echo creating kohana directory
mkdir kohana
chown $OWNER:$GROUP kohana
chmod g+ws kohana
wget "$KOHANA_URL"
unzip "$KOHANA_ZIP"
rm "$KOHANA_ZIP"
chown -R $OWNER:$GROUP kohana
chmod -R g+w kohana
chown $OWNER:www-data kohana/application/logs
rm kohana/example.htaccess
rm kohana/install.php
rm kohana/Kohana\ License.html
rm kohana/kohana.png

#
# create public directory
#
echo creating public directory
mkdir public
chown $OWNER:$GROUP public
chmod g+ws public
mv kohana/index.php public/
sed -i "s\\kohana_application =.*$\\kohana_application = '../kohana/application';\\" public/index.php
sed -i "s\\kohana_modules =.*$\\kohana_modules = '../kohana/modules';\\" public/index.php
sed -i "s\\kohana_system =.*$\\kohana_system = '../kohana/system';\\" public/index.php
echo "# turn on URL rewriting
RewriteEngine On
RewriteBase /
" > public/.htaccess

#
# create Apache logs directory
#
echo creating logs directory
mkdir logs
chown $OWNER:www-data logs
chmod g+ws logs
touch logs/error.log
touch logs/combined.log

#
# create utilties directory
#
echo creating utilties directory
mkdir utilities
chown $OWNER:$GROUP utilities
chmod g+ws utilities

#
# modify kohana/application/config/config.php
#
echo modifying kohana/application/config/config.php
sed -i "s\\'/kohana/'\\'$URL/'\\" kohana/application/config/config.php

#
# create kohana/application/config/database.php
#
echo creating kohana/application/config/database.php
cp kohana/system/config/database.php kohana/application/config/database.php
chown $OWNER:$GROUP kohana/application/config/database.php
chmod g+w kohana/application/config/database.php
sed -i "s\\'user'.*$\\'user'     => '$DBUSER',\\" kohana/application/config/database.php
sed -i "s\\'pass'.*$\\'pass'     => '$DBPWD',\\" kohana/application/config/database.php
sed -i "s\\'host'.*$\\'host'     => '$DBHOST',\\" kohana/application/config/database.php
sed -i "s\\'database'.*$\\'database' => '$DBDATABASE',\\" kohana/application/config/database.php

#
# create kohana/application/config/routes.php
#
echo creating kohana/application/config/routes.php
cp kohana/system/config/routes.php kohana/application/config/routes.php
chown $OWNER:$GROUP kohana/application/config/routes.php
chmod g+w kohana/application/config/routes.php
sed -i "s\\'welcome'\\'/index'\\" kohana/application/config/routes.php

#
# copy kohana/application/config/profiler.php
#
echo creating kohana/application/config/profiler.php
cp kohana/system/config/profiler.php kohana/application/config/profiler.php
chown $OWNER:$GROUP kohana/application/config/profiler.php
chmod g+w kohana/application/config/profiler.php

#
# create Apache virtual site
#
echo creating Apache virtual site file in /etc/apache2/sites-available
echo "<VirtualHost *:80>
	ServerName $URL
	DocumentRoot $SITESROOT/$URL/public
	DirectoryIndex index.php
	LogLevel warn
	ErrorLog $SITESROOT/$URL/logs/error.log
	CustomLog $SITESROOT/$URL/logs/combined.log combined
</VirtualHost>
" > /etc/apache2/sites-available/$URL

#
# finish up
#
echo "enable site with: sudo a2ensite $URL"
echo "restart Apache with: sudo /etc/init.d/apache2 restart"

• Wait for video files to be dropped via FTP and then process them
• Check for a recurring problem and report it to admin
• Monitor system load and report to the admin at a certain threshold

In this post we’ll take a look at how to create a Perl daemon script and how to get it to run as a daemon whenever the system is started. For the Perl script, a template will be created and for control of the daemon process, standard Debian facilities will be used.

What will be covered:

• Create the start/stop script in /etc/init.d
• Create the Perl daemon script in /usr/bin/
• Create the log file in /var/log/
• Get the daemon to start automatically when the system boots
• How to manage your daemon

The start/stop script starts and stops the daemon. It is also used by the system to start your daemon when the system starts.

The Perl daemon script contains your custom Perl code to run in the background. It executes your code every x number of seconds.

Create the Start/stop Script

Happily, Debian and therefore Ubuntu, supplies a template that uses the Debian start-stop-daemon command to start and stop daemons. It is only necessary to copy this template to a new file of the correct name and modify it for the purpose.

These scripts reside in the /etc/init.d/ directory. The script you create will have the exact same filename as the Perl daemon script you will create and the name cannot have a file extension – just the bare name.

Substitute your daemon’s name for “mydaemon” in the examples.

sudo cp /etc/init.d/skeleton /etc/init.d/mydaemon
sudo chmod +x /etc/init.d/mydaemon

sudo vi /etc/init.d/mydaemon

Make changes to your start/stop script. Locate the header in the script:

PATH=/sbin:/usr/sbin:/bin:/usr/bin
DESC="Description of the service"
NAME=daemonexecutablename
DAEMON=/usr/sbin/$NAME
DAEMON_ARGS="--options args"
PIDFILE=/var/run/$NAME.pid
SCRIPTNAME=/etc/init.d/$NAME

Create the Perl Daemon Script

Use the Perl Daemon Script Template located at the end of this post. In the following, the script template is copied to /usr/bin/where executables specific to this system are located. Actually, you would copy the template to your home directory, make the changes and then copy the daemon script to /usr/bin/.

sudo cp daemon_template.pl /usr/bin/mydaemon
sudo vi /usr/bin/mydaemon
sudo chmod +x /usr/bin/mydaemon

The script template is commented with the changes that are needed. In particular, change the value of $daemonName to the exact name of your new daemon. Ten, add your custom code where # do something appears.

Prerequisites

The script uses File::Pid and POSIX from CPAN, so you’ll need to install that module:

sudo aptitude install cpan
sudo cpan POSIX
sudo cpan File::Pid

Create the Log File

We’ll create the log file so it has the correct ownership and permissions. The log fie has the daemon name appended with “.log”. It is located in the /var/log/ directory.

sudo touch /var/log/mydaemon.log
sudo chmod 640 /var/log/mydaemon.log
sudo chown root:adm /var/log/mydaemon.log

The permissions and ownership change allow adm group members to read the log, per convention. Add yourself to adm group to view logs.

Run your Daemon

As you have created a standard start/stop script for your daemon, you can start it the standard way:

sudo /etc/init.d/mydaemon start

Stop your Daemon

Similarly, your daemon is easy to stop and restart:

sudo /etc/init.d/mydaemon stop

sudo /etc/init.d/mydaemon restart

Automatically Start your Daemon

This command tells your system to start your daemon automatically when the system starts:

update-rc.d mydaemon defaults 99

To keep your daemon from starting, if needed:

update-rc.d -f mydaemon remove

Managing Daemons

List running daemons

Well-behaved daemons generally create a PID file in /var/run/. List that directory and your have a fair list of running daemons.

sudo ls /var/run/

Get PID for a particular daemon

If you know the name of a daemon and want to see if it is running and get its PID, use pgrep.

pgrep mydaemon

Also useful is the ps command, which list processes.

ps aux

The aux switch limits output to processes not associated with a terminal.

Show programs running as daemons

This line attempts to show programs that are running as daemons.

which `ps aux | cut -c 66- | cut -d\  -f 1` | sort | uniq

The Perl Daemon Script Template

#!/usr/bin/perl -w
#
# mydaemon.pl by Andrew Ault, www.andrewault.net
#
# Free software. Use this as you wish.
#
# Throughout this template "mydaemon" is used where the name of your daemon should
# be, replace occurrences of "mydaemon" with the name of your daemon.
#
# This name will also be the exact name to give this file (WITHOUT a ".pl" extension).
#
# It is also the exact name to give the start-stop script that will go into the
# /etc/init.d/ directory.
#
# It is also the name of the log file in the /var/log/ directory WITH a ".log"
# file extension.
#
# Replace "# do something" with your super useful code.
#
# Use "# logEntry("log something");" to log whatever your need to see in the log.
#
use strict;
use warnings;
use POSIX;
use File::Pid;

# make "mydaemon.log" file in /var/log/ with "chown root:adm mydaemon"

# TODO: change "mydaemon" to the exact name of your daemon.
my $daemonName    = "mydaemon";
#
my $dieNow        = 0;                                     # used for "infinte loop" construct - allows daemon mode to gracefully exit
my $sleepMainLoop = 120;                                    # number of seconds to wait between "do something" execution after queue is clear
my $logging       = 1;                                     # 1= logging is on
my $logFilePath   = "/var/log/";                           # log file path
my $logFile       = $logFilePath . $daemonName . ".log";
my $pidFilePath   = "/var/run/";                           # PID file path
my $pidFile       = $pidFilePath . $daemonName . ".pid";

# daemonize
use POSIX qw(setsid);
chdir '/';
umask 0;
open STDIN,  '/dev/null'   or die "Can't read /dev/null: $!";
open STDOUT, '>>/dev/null' or die "Can't write to /dev/null: $!";
open STDERR, '>>/dev/null' or die "Can't write to /dev/null: $!";
defined( my $pid = fork ) or die "Can't fork: $!";
exit if $pid;

# dissociate this process from the controlling terminal that started it and stop being part
# of whatever process group this process was a part of.
POSIX::setsid() or die "Can't start a new session.";

# callback signal handler for signals.
$SIG{INT} = $SIG{TERM} = $SIG{HUP} = \&signalHandler;
$SIG{PIPE} = 'ignore';

# create pid file in /var/run/
my $pidfile = File::Pid->new( { file => $pidFile, } );

$pidfile->write or die "Can't write PID file, /dev/null: $!";

# turn on logging
if ($logging) {
	open LOG, ">>$logFile";
	select((select(LOG), $|=1)[0]); # make the log file "hot" - turn off buffering
}

# "infinite" loop where some useful process happens
until ($dieNow) {
	sleep($sleepMainLoop);

	# TODO: put your custom code here!
	# do something

	# logEntry("log something"); # use this to log whatever you need to
}

# add a line to the log file
sub logEntry {
	my ($logText) = @_;
	my ( $sec, $min, $hour, $mday, $mon, $year, $wday, $yday, $isdst ) = localtime(time);
	my $dateTime = sprintf "%4d-%02d-%02d %02d:%02d:%02d", $year + 1900, $mon + 1, $mday, $hour, $min, $sec;
	if ($logging) {
		print LOG "$dateTime $logText\n";
	}
}

# catch signals and end the program if one is caught.
sub signalHandler {
	$dieNow = 1;    # this will cause the "infinite loop" to exit
}

# do this stuff when exit() is called.
END {
	if ($logging) { close LOG }
	$pidfile->remove if defined $pidfile;
}

Open a Terminal and type in the following commands:

sudo aptitude remove google-chrome-beta
sudo aptitude install google-chrome-stable

Your settings will be preserved.

I’ve tested what is presented here in Ubuntu Server 10.04 (Lucid). If you want to harden your new Ubuntu server, this is a good start.

Ubuntu server is well designed, regularly updated and relatively secure. The Ubuntu Security Team manifests an onging effort to keep Ubuntu secure. Regular security updates are available and easy to implement.

• No open ports
• Role-based administration
• No X server
• Security updates
• Kernel and compiler hardening

In this post, we are going to meet the security challenge in with multi-pronged effort that will include: system analysis, changing settings for additional hardening against attack, installing a firewall maintenance system, scanning for rootkits, and offering a regular maintenance regimen.

• Change settings for increased security
• Implement UFW, the uncomplicated firewall
• Use denyhosts to automatically blacklist attackers
• Scan the system for vulnerabilities with Tiger
• Detect attempted intrusions with psad
• Install nmap and scan the system for open ports
• Check the system for rootkits with chkrootkit
• Monitor logs

Change settings for increased security

see also: https://help.ubuntu.com/community/StricterDefaults

Secure shared memory

/dev/shm can be used in an attack against a running service, such as httpd. Modify /etc/fstab to make it more secure.

sudo vi /etc/fstab

Add this line:

tmpfs     /dev/shm     tmpfs     defaults,noexec,nosuid     0     0

Disable root SSH login

The root account is disabled by default in Ubuntu. If you installed Ubuntu on Slicehost or Linode, root is enabled. In any case, it is a good idea to disable root SSH access. Edit /etc/ssh/sshd_config and set PermitRootLogin to no.

sudo vi /etc/ssh/sshd_config

Change PermitRootLogin to no:

PermitRootLogin no

Of course, if you access your server via SSH, you should make sure you have sudo working for your user before disabling SSH root access.

Only allow admin users to use su

This helps prevent privilege escalation.

By default, Ubuntu does not have an admin group. Create an admin group:

sudo groupadd admin

Add yourself to the admin group:

sudo usermod -a -G admin andrew

Restrict access to /bin/su to admin group members:

sudo dpkg-statoverride --update --add root admin 4750 /bin/su

Check permissions for /bin/su with:

ls -lh /bin/su

…and see the following:

-rwsr-x--- 1 root admin 31K 2010-01-26 17:09 /bin/su

Do not permit source routing of incoming packets

see also: http://www.cromwell-intl.com/security/security-stack-hardening.html

sudo sysctl -w net.ipv4.conf.all.accept_source_route=0
sudo sysctl ­-w net.ipv4.conf.default.accept_source_route=0

Don’t allow system users to access an FTP server

This is only needed is ftpd is installed and running. Only if you’ve installed ftpd. However, it is Ok to do this anyway and it will remove a FAIL from the tiger report.

SFTP is probably better than FTP, if it is usable for your files transfer needs.

see ftpusers manual: http://manpages.ubuntu.com/manpages/lucid/man5/ftpusers.5.html

Edit /etc/ftpusers:

sudo vi /etc/ftpusers

Add system users to deny use of ftpd:

backup
bin
daemon
games
gnats
irc
libuuid
list
lp
mail
man
mysql
news
ntp
postfix
proxy
sshd
sync
sys
syslog
uucp
www-data

UFW: basic firewall

previous post: Ubuntu UFW Uncomplicated Firewall Examples

community documentation: https://help.ubuntu.com/community/UFW

server guide: https://help.ubuntu.com/10.04/serverguide/C/firewall.html

ufw manual: http://manpages.ubuntu.com/manpages/lucid/en/man8/ufw.8.html

project wiki: https://wiki.ubuntu.com/UncomplicatedFirewall

nice article: http://savvyadmin.com/ubuntus-ufw/

UFW (Uncomplicated Firewall) provides an easy to understand interface to control iptables (iptables conteol Netfilter, which is built into the kernel). Will just a few commands, your server can control access. Checking status is also easy.

UFW (uncomplicated firewall) is a simple interface used to configure iptables.

Install and enable Uncomplicated Firewall:

sudo aptitude install -y ufw
sudo ufw enable

Display available UFW commands:

sudo ufw show

Display UFW configuration:

sudo ufw status

Allow SSH and HTTP access to the Apache server:

sudo ufw allow ssh
sudo ufw allow http

In the above example, ports for OpenSSH and Apache were opened by service name (“ssh” and “http”). You can use a port number instead of the service name (like “80″ instead of “http”).

See services running and which names to use:

The practice here is to open only ports that you use – ports that use a service that have a service running. To see a list of services that you have running for which you might want to open ports for:

sudo ufw app list

To see a list of services that UFW uses (like in the “sudo ufw allow ssh” example, above):

less /etc/services

Denyhosts: avoid SSH attacks

project: http://denyhosts.sourceforge.net/

Looking at /var/log/auth.log on servers that I manage shows a steady streams of attacks on SSH. I am countering these attacks in a number of ways, starting with denyhosts.

Denyhosts periodically scans /var/log/auth.log for repeated failures to access the system via SSH. It then adds these offenders to /etc/hosts.deny. See the project page for details.

sudo aptitude -y install denyhosts

That does it – the rest is automatic. You can see the IP addresses added to /etc/hosts.deny with:

sudo less /etc/hosts.deny

Tiger: security system scanner

project: http://www.nongnu.org/tiger/

Tiger creates an automated security audit by analyzing files and settings on the system and creating a report listing what has been analyzed and listing warning, alerts and failures.

The tiger command creates a report of potential security problems in /var/log/tiger. The use the tigexp command to look up the resulting codes generated for a detailed explanation and what to do to make the system more secure. The problems tiger considers most serious are marked with FAIL.

Install tiger:

sudo aptitude -y install tiger

Run tiger to create a report of security issues.

sudo tiger

Use less to view the most recent tiger report:

sudo -i
less /var/log/tiger/`ls -t1 /var/log/tiger | head -1`
exit

Use tigexp to list explanations for FAIL codes:

tigexp dev002f

Google is also helpful, naturally.

Ignore these:

--FAIL-- [dev002f] /dev/fuse has world permissions
--FAIL-- [logf005f] Log file /var/log/btmp permission should be 660

Changing permissions for these could cause problems.

Detect attempted intrusions with psad

project: http://www.cipherdyne.org/psad/

Psad is a collection of lightweight daemons that log attempted intrusions, in particular monitoring iptables.

Installation:

sudo aptitude -y install psad

The daemons will run automatically.

To check current status:

sudo psad -S

You can modify psad settings to e-mail the admin in the event of intrusion detection.

Nmap: port scanning

project: http://nmap.org/

This allows you to see which ports are open, verifying that UFW/iptables is working correctly.

Installing nmap:

sudo aptitude install -y nmap

Port scanning:

nmap -v -sT localhost

SYN Scanning:

sudo nmap -v -sS localhost

scan type explanations: http://nmap.org/book/man-port-scanning-techniques.html

Chkrootkit: check for rootkit presence

project: http://www.chkrootkit.org/

Chkrootkit scans the system for evidence that a rootkit has been installed.

This is a confidence test to be used to test whether your system has been compromised. In a perfect world you would not need this…but in this world, it is good to run periodically.

Installing chkrootkit:

sudo aptitude install -y chkrootkit

Running chkrootkit:

sudo chkrootkit

LogWatch

Ubuntu community documentation: https://help.ubuntu.com/community/Logwatch

The most detailed and informative logs in the world are useless if no one looks at them. Logwatch winnows the deluge to a succinct report…which you will look at. Even so, familiarize yourself with your system’s logs and review them on a regular basis. A daily logwatch habit would be a good start.

Installation:

sudo aptitude -y install logwatch

Usage:

sudo logwatch | less

Ongoing maintenance

Your server is now more secure. Once a week, perform on-going maintenance.

Updating software:

sudo aptitude update
sudo aptitude safe-upgrade

The safe-upgrade action is preferred by me because it does not upgrade packages that rely on dependencies that have not been upgraded to required levels.

see: http://wiki.debian.org/Aptitude

Or, you could set-up automatic security updates, if you cannot do the weekly maintenance. This is not a perfect solution because an administrator is not monitoring what is being updated and testing after updates. see: https://help.ubuntu.com/10.04/serverguide/C/automatic-updates.html

Check for attempted instrusions:

sudo psad -S

UPDATED: Analyze system with tiger. Because the tiger reports in /var/log/tiger/are owned by root, run these commands one at a time. (This solves a problem some people were having with permissions.)

sudo -i
tiger
grep FAIL /var/log/tiger/`ls -t1 /var/log/tiger | head -1`
exit

In the above, FAILs are pulled from the newest report file with grep. The ls clause in backticks gives grep the newest file in the directory. The sudo -i command allows you to run multiple commands as root, ending with exit.

Use tigexp to list explanations for FAIL codes:

tigexp dev002f

Scan ports with nmap:

sudo nmap -v -sS localhost

Check for rootkits

sudo chkrootkit

Look at logs:

sudo logwatch | less

Keep up with trends

visit: http://www.linuxsecurity.com/

Elsewhere

http://www.itsecurity.com/features/ubuntu-secure-install-resource/

http://www.cyberciti.biz/tips/linux-security.html