Open a TCP port in Ubuntu's ufw firewall
Answer:
To open a TCP port, e.g. 8080 in the Ubuntu's UFW firewall (Uncomplicated firewall)
# sudo ufw allow 8080/tcp
# sudo ufw reload
How to generate random password?
Answer:
Install the "makepasswd" package, for example, in Ubuntu, type
sudo apt-get install makepasswd
Then execute command
# makepasswd
ShdDHNt7z
Or you can use another tool called pwgen
sudo apt-get install pwgen
and execute
# pwgen 8 10
It will generate 10 passwords with length equal to 8
Jan 012010
Turn off PHP error messages?
Answer:
In a production server, you should always turn off PHP error messages to be displayed for public, to do so, edit the php.ini
E.g.
vi /etc/php.ini
And turn off display_errors
display_errors = Off
How to perform checksum on a file?
Answer:
You can use the md5sum or shasum commands.
Example
#md5sum test.txt
f1d41356dcabb8d8acefed069b22b0da test.txt
#shasum test.txt
809970aec0109c5464dd36a3a9a5a9e79f838313 test.txt
md5sum is faster if you perform the command on a very large file, but shasum is more secure since the chance of two different files have the same checksum is smaller.
References:
How to avoid SQL injection in PHP?
Answer:
The easiest method is to use the mysql_real_escape_string function
Example:
$query = sprintf("SELECT * FROM users WHERE user='%s' AND password='%s'",
mysql_real_escape_string($user),
mysql_real_escape_string($password));
Reference: http://php.net/manual/en/function.mysql-real-escape-string.php
