Month: November 2011

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Graphing SSH dictionary attacks with HighCharts

After my 10-year-old basement Linux server died this week from a power outage, I took the sad step of giving up on it. It’s died before and I’ve patched it back together with a new power supply here or an addon PCI SATA card there, but I finally decided to throw in the towel since I had a newer old computer that had been idle for several years. The one that died was an Athlon K7 750 MHz with 512 MB ram. The new one is an Athlon 2 GHz (3200+) with 1 gig. For my uses, specs don’t really matter that much, but it’s nice to have more power for free.

I put CentOS 6 on it and configured Samba and copied all the data off the old machine and was back up and running within a few hours. Since I forward ports through my FiOS router to this box I did my standard lockdown procedure, including adding myself to the AllowUsers in sshd_config. Afterwards I took a look in /var/log/secure and saw the typical flood of dictionary attacks trying to get in as root or bob or tfeldman or jweisz. I have iptables configured to rate-limit SSH connections to 2 per 5 seconds per IP so the box doesn’t get DoSed out of existence, but some stuff does make it through to sshd.

Looking through /var/log/secure, I got to thinking it would be interesting if there was some way to visualize the attacks in a handy graph. Then I remembered, oh, wait, I can do that.

I wrote a perl script to parse out the attacks from /var/log/secure and insert them into a Postgres DB. This turned out to be pretty easy. Then I thought it would be more interesting to tie the IP of each attack to its originating country. I’ve used MaxMind’s GeoIP DB pretty extensively before, but I was looking something free. That’s when I remembered that MaxMind has a free GeoIP DB: GeoLiteCity. I grabbed it and yum-installed the Perl lib and added the geo data to the attack DB. Rather than worry about normalizing the schema I just shoved the info into the same table. Life is easier this way, and it’s just a for-fun project.

So I got that all working and parsed it against the existing /var/log/secures via

[root@lunix2011 ~]# zcat /var/log/secure-20111117.gz | perl parse-secure.pl

I wrote ssh.php to see what’s in the table:

ssh.php list of hacking attempts
ssh.php list of hacking attempts

So now that the data was all in place, time to move on to the graphs, which is what I really wanted to do. Last time I wanted to graph data programmatically I used JPGraph, which does everything in PHP and is super versatile. But I wanted something… cooler. Maybe something interactive. A little Googling turned up Highcharts which is absolutely awesome, and does everything in JavaScript. I basically modified some of their example charts and pumped my data into them and got the charts below.

Pie chart of attacks grouped by country for the past 30 days:

Pie chart by country
Pie chart by country

Bar graph of attacks per day:

Bar graph of daily attacks
Bar graph of daily attacks

So, that’s that. Code is in github if anyone wants to play around with it. I’ve cronned parse-secure.pl to run every 5 minutes so the data gets updated automatically.

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Installing Sun (Oracle) JDK 1.5 on an EC2 instance

I’m currently working on moving a Tomcat-based application into EC2. The code was written for Java 5.0. While Java 6 would probably work, I’d like to keep everything as “same” as possible, since EC2 presents its own challenges. I spun up a couple of t1.micro instances and copied everything over, including the Java 5 JDK, jdk-1_5_0_22-linux-amd64.rpm. Installing from RPM was easy, but the EC2 instance defaults to using OpenJDK 1.6:

[root@ec2 ~]# java -version
java version "1.6.0_20"
OpenJDK Runtime Environment (IcedTea6 1.9.10) (amazon-52.1.9.10.40.amzn1-x86_64)
OpenJDK 64-Bit Server VM (build 19.0-b09, mixed mode)

There were a couple of things I had to do to get the system to accept the Sun JDK as its “real” java.

Alternatives

Red Hat’s “alternatives” system is designed to allow a system to have multiple versions of a program installed and make it easy to choose which one you want to run. Unfortunately I’ve found the syntax a bit strange and always have to Google it, so I figured I’d document it here for posterity.

So here’s the default:

[root@ec2 ~]# alternatives --config java

There is 1 program that provides 'java'.

  Selection    Command
-----------------------------------------------
*+ 1           /usr/lib/jvm/jre-1.6.0-openjdk.x86_64/bin/java

Enter to keep the current selection[+], or type selection number:

Here’s how to add Sun java, assuming the java binary is in /usr/java/jdk1.5.0_22/jre/bin/java (where the RPM puts it).

[root@ec2 ~]# alternatives --install /usr/bin/java java /usr/java/jdk1.5.0_22/jre/bin/java 1
[root@ec2 ~]# alternatives --config java
There are 2 programs which provide 'java'.

  Selection    Command
-----------------------------------------------
*+ 1           /usr/lib/jvm/jre-1.6.0-openjdk.x86_64/bin/java
   2           /usr/java/jdk1.5.0_22/jre/bin/java

Enter to keep the current selection[+], or type selection number: 2
[root@ec2 ~]# java -version
java version "1.5.0_22"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_22-b03)
Java HotSpot(TM) 64-Bit Server VM (build 1.5.0_22-b03, mixed mode)

Yay! Unfortunately this doesn’t help with the other problem I had with Tomcat, which was that EC2 instances set the JAVA_HOME var to OpenJDK as well (/usr/lib/jvm/jre). Fortunately this is an easy fix as well.

Setting JAVA_HOME

The JAVA_HOME var is set in /etc/profile.d/aws-apitools-common.sh. Comment out this line:

export JAVA_HOME=/usr/lib/jvm/jre

Create a new file, /etc/profile.d/sun-java.sh, and put this in it:

export JAVA_HOME=/usr/java/jdk1.5.0_22/jre

Also in that file I added the following to instruct the JVM to process all dates in America/New_York, since that’s the timezone all of our other servers use, and it makes reading log files easier when all dates are in the same tz:

export TZ=America/New_York

(I found I had to do this even after pointing /etc/localtime to the correct zoneinfo – Java was stuck on UTC even after the rest of the system was using America/New_York.)