Modify the/etc/motd file to prevent intruders.

The/etc/motd is messageoftoday. The content of the/etc/motd file is displayed on the user's terminal each time the user logs on. The system administrator can edit system activity messages in files. For example, the Administrator notifies the user of the system when to upgrade the software or hardware and when to perform system maintenance. If shell supports Chinese, you can also use Chinese, which makes it easier to understand.
The disadvantage of/etc/motd is that if the user logs on to the system as a graphical interface, the information will not be displayed.

The usage of the/etc/issue file is not much different from that of the/etc/motd file. The main difference is that when a network user logs on to the system through a serial port, the/etc/issue file content is displayed before the login prompt, while the/etc/motd content is displayed after the user successfully logs on to the system.

Meaning of codes in issue
Date of the local end time;
/L displays the terminal interfaces;
/M Displays the hardware level (i386/i38/ i586/i686 ...);
/N displays the Network Name of the host;
/O display domain name;
/R operating system version (equivalent to uname-r)
/T display the Time of the local end time;
/S operating system name;
/V operating system version.
 
PC: After many linux Hosts are infiltrated, several files collected by attackers include/etc/issue, which includes your version release number. For the sake of security, we should try to modify the following files.

1) delete/etc/redhat_release. We recommend that you modify the name. If you rush to install some software, you may not be able to install it.
Mv/etc/redhat_release/etc/new name
2) edit/etc/issue # It is recommended that you modify the keyword
3.) write the/etc/motd # bulletin board. If an unauthorized user breaks into the bulletin board, a text warning can be given. If a foreign user goes into court for this reason, the prompt "Welcome" will be prompted. Haha
List the following examples:
(1)
* ** Wrrning ***
Without the owner's prior written consent,
No decompiling or reverse-engineering shall be allowed
* Notice:
This is a private communication system.
Unauthorized access or use may lead to prosecution.
 
(2)
* ** Wrrning ***
Authorised access only
This system is the property of www.pcxxoo.com
Disconnect IMMEDIATELY if you are not an authorized user!
Your IP has been IDS records Don't damage any files!