NewDisk

Adding a new disk

Before doing this in production, make sure you practice this on a non-production system!

There are at least 3 different ways to do this:

Method 1: LVM (Logical Volume Management)

As of Security Onion 14.04, the Ubuntu installer supports LVM. If you chose the LVM option in the Ubuntu installer, then this should be the easiest way of adding disk space: https://wiki.ubuntu.com/Lvm

Method 2: Mount a separate drive to /nsm

This can be done in the Ubuntu installer, or after installation is complete. If doing this after running Setup, then you'll need to copy the existing data in /nsm to the new drive using something like this:

1. Comment out the cron job in /etc/cron.d/nsm-watchdog
2. Restart cron
   sudo service cron restart
3. Stop all services
   sudo service nsm stop
sudo service syslog-ng stop
sudo service apache2 stop
sudo service mysql stop
4. Check for any ELSA perl processes which may need to be killed manually
   ps aux |grep perl
5. Determine your new drive's path
   sudo fdisk -l
6. Partition the new drive using fdisk or parted
7. Format the new partition using mkfs
8. Mount the new drive to a temporary location in the filesystem
   sudo mount /dev/sdb2 /mnt
9. Copy the existing data from /nsm to the temporary location
   sudo cp -av /nsm/* /mnt/
10. Unmount the new drive from the temporary location
    sudo umount /mnt
11. Rename the existing /nsm
sudo mv /nsm /nsm-backup
12. Update /etc/fstab to mount the new drive to /nsm
sudo vi /etc/fstab (You can use blkid to find your drive's UUID to write in /etc/fstab)
    sudo blkid /dev/sdb2
13. Mount the new /nsm
sudo mount /nsm
14. Start all services
    sudo service mysql start
sudo service apache2 start
sudo service syslog-ng start
sudo service nsm start
15. Uncomment the cron job in /etc/cron.d/nsm-watchdog
16. Restart cron
    sudo service cron restart

Method 3: Make /nsm a symlink to the new logging location

If you do this, you'll need to do something like the following to avoid AppArmor issues:

Stop all services

sudo service nsm stop

Copy existing data from /nsm to new mount point

sudo cp -av /nsm/* /mnt/nsm

Rename existing /nsm

sudo mv /nsm /nsm-backup

Make /nsm a symlink to the new logging location

sudo ln -s /mnt/nsm /nsm

Go to /etc/apparmor.d/local/

cd /etc/apparmor.d/local/

Edit usr.sbin.mysqld, copy the /nsm line(s), and change /nsm to the new location

sudo vi usr.sbin.mysqld

Edit usr.sbin.tcpdump, copy the /nsm line(s), and change /nsm to the new location

sudo vi usr.sbin.tcpdump

Restart apparmor

sudo service apparmor restart

Start all services

sudo service nsm start

#### Moving the MySQL Databases ####

Synopsis:

In this article I’m going to show how you can move the MySQL databases containing all of your important alert and event data to another place. I will be moving the databases to a large external drive I have mounted as /nsm, though, any other location will do.

Procedure:

The MySQL databases are stored under /var/lib/mysql. We will need to move this folder and its sub-contents to the destination location. First, we must stop all processes that may be writing or using the databases.

sudo service nsm stop
sudo service mysql stop
sudo service sphinxsearch stop

Now, we need to make sure all other nsm-related processes are stopped. To double-check, run lsof on the nsm mount point to list any processes that have open file descriptors. Kill everything, or nearly everything, that comes up in the list.

lsof /nsm

Next, let’s copy the data over to the new location leaving the original intact. You can use cp or rsync or another similar tool but be sure to preserve permissions ( -p ) and copy recursively ( -r ). Both examples are listed below, choose one:

sudo cp -rp /var/lib/mysql /nsm
sudo rsync -avpr var/lib/mysql /nsm

Once that’s finished, rename or backup the original just in case something goes wrong.

sudo mv /var/lib/mysql /var/lib/mysql.bak

Next, create a symbolic link from /var/lib/mysql to the new location:

sudo ln -s /nsm/mysql /var/lib/mysql

Ubuntu uses AppArmor to add an additional layer of security to running applications. We must tell apparmor about the new mysql database locations otherwise it will prevent the system from using it.

sudo service apparmor stop

Edit /etc/apparmor.d/usr.sbin.mysqld to reflect the following patch which adds the new location:

sudo vim /etc/apparmor.d/usr.sbin.mysqld

--- a/apparmor.d/usr.sbin.mysqld
+++ b/apparmor.d/usr.sbin.mysqld
@@ -19,8 +19,8 @@

/etc/hosts.allow r,
/etc/hosts.deny r,

+  /nsm/mysql/ r,
+  /nsm/mysql/** rwk,
+  /nsm/elsa/data/mysql/ r,
+  /nsm/elsa/data/mysql/** rwk,
/etc/mysql/*.pem r,
/etc/mysql/conf.d/ r,
/etc/mysql/conf.d/* r,

Finally, start all the processes back up.

sudo service apparmor start
sudo service mysql start
sudo service sphinxsearch start
sudo service nsm start