asr.tech.notes

Users often use the sum command to generate a checksum to verify the integrity of a file. However, it is possible for two distinct files to generate the same checksum. A cryptographic sum command, csum , has been implemented in AIX 5L Version 5.3 that offers a more reliable tool to verify file integrity. This command allows users to generate message digests using the AIX Cryptographic Library. The new, cryptographic, checksum is considered more secure than the old mechanism. While it is reasonably straightforward to construct data that will match the checksum generated by the sum command; it is computationally infeasible to construct data to generate a known cryptographic checksum, as provided by csum . csum allows users the option to select the algorithm that they prefer, including both MD5 and SHA-1, which are considered secure. It is estimated that the order of 2**64 operations would be required to derive two different files, which generate the same MD5 message digest. Also, t

Here is an easy way to list just the symmetrix disk (excluding internal or even other FC disks): #lsdev –CtMSYMM* Use –t to specify the type of the disk, and all symmetrix disks are of the same type starting with MSYMM* - comes from the EMC ODM fileset.