LOSETUPSection: MAINTENANCE COMMANDS (8)
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NAMElosetup - set up and control loop devices
SYNOPSISlosetup [ [-e|-E] encryption ] [ -o offset ] [ -p pfd ] loop_device file
losetup [ -d ] loop_device
DESCRIPTIONlosetup is used to associate loop devices with regular files or block devices, to detach loop devices and to query the status of a loop device. If only the loop_device argument is given, the status of the corresponding loop device is shown.
EncryptionIt is possible to specify transfer functions (for encryption/decryption or other purposes) using one of the -E and -e options. There are two mechanisms to specify the desired encryption: by number and by name. If an encryption is specified by number then one has to make sure that the Linux kernel knows about the encryption with that number, probably by patching the kernel. Standard numbers that are always present are 0 (no encryption) and 1 (XOR encryption). When the cryptoloop module is loaded (or compiled in), it uses number 18. This cryptoloop module wil take the name of an arbitrary encryption type and finds the module that knows how to perform that encryption. (Thus, either one uses a number different from 18 with the -E option, or one uses a name with the -e option.)
RETURN VALUElosetup returns 0 on success, nonzero on failure. When losetup displays the status of a loop device, it returns 1 if the device is not configured and 2 if an error occurred which prevented losetup from determining the status of the device.
/dev/loop0, /dev/loop1, ... loop devices (major=7)
EXAMPLEIf you are using the loadable module you must have the module loaded first with the command
Maybe also encryption modules are needed.
The following commands can be used as an example of using the loop device.
If you are using the loadable module you may remove the module with the command
RESTRICTIONDES encryption is painfully slow. On the other hand, XOR is terribly weak. Both are insecure nowadays. Some ciphers may require a licence for you to be allowed to use them.
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Time: 00:16:00 GMT, March 05, 2024