All servers KDM are located behind the so-called firewall, which guarantees the basic level of system security.
To ensure an additional level of security, login to the user's shell accounts is only possible with SSH, copying files is only possible with SCP.
Access to files and directories are determined on the basis of 3 factors: reading (r), writing (w) and executing (x). Permission for files and directories are different. The table below show the differences between permissions for files and directories.
| Permission | File | direcroty |
|---|---|---|
| Read (r) | View file content | List files in directory |
| Write (w) | Modify/rename/delete file | Delete/move/rename directory and files in directory |
| Execute (x) | Execute scripts and program | Change directory |
Permissions to files and directories can be set for the owner, group (member of the group of the owner) and all other.
The command chmod is used to change permissions for files and directories.
You may limit other access to your data by setting the access rights to your home directory (/home/$USER) and temporary (e.g.: /dev/shm/$USER.) respectively.
By default, other users have the right to read and browse the directories of a given user without the right to write.
The following example shows how to set permissions so nobody except the owner of the directory does not have access to it.
user1@ui ~> ls -ld /home/user1
drwxr-xr-x 39 user1 kdm 4096 cze 7 07:35
user1@ui ~> chmod go-rwx /home/user1
user1@ui ~> ls -ld /home/user1
drwx------ 39 user1 kdm 4096 cze 7 07:35
Allow members of the groups to edit the file results.txt
user1@ui ~> ls -l results.txt
-rw-r--r-- 1 user1 kdm 7792 maj 31 13:14 results.txt
user1@ui ~> chmod g+w results.txt
user1@ui ~> ls -l results.txt
-rw-rw-r-- 1 user1 kdm 7792 maj 31 13:14 results.txt
More details on this topic can be found in the manuals available in the system: man chmod.