Linux Ask! is a Q & A web site specific for Linux related questions. Questions are collected, answered and audited by experienced Linux users.
Put a profile in AppArmor complain mode
Answer:
Some applications, such as the MySQL server, if you changed the default datadir, you might not be able to startup MySQL.
To solve the problem, put the MySQL profile in AppArmor complain mode can solve the problem.
# sudo aa-complain /usr/sbin/mysqld
Then reload AppArmor
# sudo invoke-rc.d apparmor reload
How to check failed login attempt in Ubuntu
Answer:
Every login attempts are logged in the file /var/log/auth.log in Ubuntu.
To check failed login attempt(s),
E.g.
# grep 'Failed password' /var/log/auth.log
Jan 31 14:00:27 localhost sshd[16141]: Failed password...
Jan 31 14:00:46 localhost sshd[16141]: Failed password...
Jan 31 14:00:49 localhost sshd[16141]: Failed password...
Disable AppArmor in Ubuntu
Answer:
A lot of people don't like AppArmor and think it is too annoying, just like the SELinux, people sometimes want to disable it.
To do so:
# sudo invoke-rc.d apparmor stop
# sudo update-rc.d -f apparmor remove
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
