Allow SSH for specific IP without using IPTABLES.

With using below steps you can block and Allow specific IPs to take SSH without using iptables and Firewall.

Open below file,

cat /etc/hosts.allow

sshd: 192.168.0.13 : allow
sshd: ALL : deny

This will allow SSH for 192.168.0.13 IP only.

Preserve bash history

 # Maximum number of history lines in memory

export HISTSIZE=50000

# Maximum number of history lines on disk

export HISTFILESIZE=50000

 
# Ignore duplicate lines

export HISTCONTROL=ignoredups:erasedups

# When the shell exits, append to the history file instead of overwriting it

shopt -s histappend

# After each command, append to the history file and reread it

export PROMPT_COMMAND="${PROMPT_COMMAND:+$PROMPT_COMMAND$'n'}history -a; history -c; history -r"

 

 

# Linux command history with date and time.

echo 'export HISTTIMEFORMAT="%d/%m/%y %T "' >> ~/.bash_profile

source ~/.bash_profile

Or set it permenant, add below entry into .bashrc

export HISTTIMEFORMAT="%d/%m/%y %T "

Execute custom script as command.

Create bash script, 

Create file: script.sh

#!/bin/bash 

date echo "testing" 

 

 Apply executable permission.

# chmod 0777 script.sh

 

Move script to /usr/local/bin/

# mv script.sh /usr/local/bin/

 

Now you can execute script from anywhere.

# cd /home/
# script.sh 

output:

Thu Nov 18 11:05:41 IST 2021
testing

record delete restriction trigger

DELIMITER $$
CREATE TRIGGER trigger_name
BEFORE DELETE
ON table_name
FOR EACH ROW
BEGIN
    if SUBSTRING_INDEX(USER(),'@',1) NOT IN ('root') THEN
        CALL cannot_delete_error;
    END if;
END
$$