Managing physical and virtual partitions with eMount

Mount Up

By Falko Benthin

Dennis Cox, 123RF

If you don't often work with encrypted partitions, you might find it hard to cope with the cryptic commands you are expected to type. eMount [1] is a tool that will help you manage your encrypted partitions.

The eMount utility, developed in C++, gives users a graphical tool and a convenient interface for creating and managing encrypted partitions. According to the project website, eMount will help you:

• create plain and encrypted disk images with ext2, ext3, ext4, FAT16, FAT32, HFS, HFS+, NTFS, ReiserFS, and XFS;

• Create encrypted volumes from physical disks;

• mount system partitions and virtual disks;

• enlarge disk images (ext2, ext3, ext4, ReiserFS, and XFS);

• copy and clone devices such as disk images; and

• support all ciphers and hash algorithms provided by the operating system.

With built-in support for LUKS (Linux Unified Key Setup), Cryptsetup allows users to encrypt partitions with just a few clicks.

The first official version of eMount, version 0.7.0, was released in early March, and ever since then, developer Raimondo Del Gaudio has incremented the counter every couple of weeks. The current version is 0.10.0.

Using eMount

When you launch eMount, it comes up with a window sporting File, Modules, View, and Help menu items at the top. Select File | Mount or press Ctrl+M to mount the existing media partitions (see Figure 1).

Figure 1: To mount a virtual partition, you need to specify the file name, the filesystem type, and the mount point.

You can create a new disk image either via the File | New Disk Image menu or with the Ctrl+N keyboard shortcut. eMount then displays a dialog and asks you for important information, such as the file name, label, size, filesystem, and possible encryption of the filesystem image (Figure 2).

Figure 2: eMount offers a simple input window for creating new virtual partitions.

Creating an image is burdensome for the CPU. On our lab machine, with a 1600MHz Pentium M CPU, the load went up to more than 90 percent at times. The system took around two minutes to create an image with a size of around 300MB with the use of an ext4 filesystem.

The reason for the many cycles is that the kernel generates random byte sequences and writes them to the new image until the required size is reached. Interestingly, eMount will let you create ext4 images even if the system doesn't actually have the necessary requirements. Unfortunately, you will experience problems when you try to mount the image later on.

eMount offers an equally simple approach to encrypting partitions (File | New Encrypted Volume). After selecting the device, the filesystem, and required options, such as the encryption method, the key length, and the password, eMount creates a Cryptsetup LUKS-encrypted partition at the press of a button. Optionally, you can tell eMount to store a key in a file instead of using a password.

The two menu items below Modules let you load the kernel modules required for the filesystem, encryption, and digest algorithms. The View menu lets you organize the media you manage in eMount. The program shows you all the storage media it has mounted in an overview, listing the label names and the occupied and available storage space (Figure 3).

Figure 3: After creating or mounting a device, eMount will list it in a table. The drop-down menu on the right of the name provides more options.

Each list entry has a small drop-down menu labeled Options on the right that gives the user a selection of activities. You can use this drop-down menu to copy and initialize partitions you have added to eMount or to remove them from the list. In addition, the menu takes you to functions for, say, resizing virtual filesystems. When you select the Initialize entry, eMount will write out any changes and then reinitialize the image or partition, which will delete any existing data.

eMount at the Command Line

In addition to providing a GUI, eMount also offers rudimentary command-line-based controls. For example, the emount -l command lists all the images and devices; -m mounts them, and -e unmounts them. The eMount -p or -s option lets you query the status. Because eMount only identifies the label names of the disk images or partitions, this command is not available until you have used the GUI to mount.

Conclusions

eMount is a practical tool for users with little command-line experience. More experienced users will not benefit greatly from it. Despite the graphical interface, the program still demands that the user have a fair amount of system know-how; for example, you need to discover how to address the individual media and disk images, find the mountpoints, and discover the filesystem. After discovering all the partitions, the program does manage them neatly in a table, and it lets the user perform many tasks by simply clicking.

One of eMount's major strengths is that it helps newcomers who have never worked with Cryptsetup to create crypto containers or copies of selected partitions in a simple way.

The application lets you work with filesystems that the kernel doesn't actually support, which is a blot on the developer's copybook. However, because most modern distributions support a large selection of filesystems, and thus include the matching kernel modules out of the box, and because eMount loads them at the press of a button, complications are actually unlikely in the real world.