Clone a remote repository with GitPython

Example code:

{% highlight python %} import git

remote = '' local = '/home/marios/Tests/gitpython'

git.Repo.clone_from(remote, local) {% endhighlight %}


mysqlhotcopy is a Perl script for backing up MySQL tables stored in either the MyISAM or ARCHIVE engines. It works very fast because it doesn't dump the contents of the tables. Instead it takes advantage of the fact that MyISAM tables are contained in separate files, and simply locks the tables and copies the flat files.

Example Setup

  1. Create a user in MySQL for running mysqlhotcopy. The user will need to be granted the SELECT, RELOAD and LOCK TABLES privileges on the databases that will be backed up. In this example, I want all databases to be backed up:

    mysql> CREATE USER `mysqlhotcopy`;
    mysql> GRANT SELECT, RELOAD, LOCK TABLES ON *.* TO `mysqlhotcopy`@`localhost`;
  2. Create a daily cron job to backup every database, except for information_schema, which is a dynamic schema created my the MySQL server itself and does not exist as files on the filesystem. An example script is:

    for database in $(mysql --user mysqlhotcopy           \
                            --batch                       \
                            --skip-column-names           \
                            --execute 'SHOW DATABASES;' | \
                      grep -v '^information_schema$')
        mysqlhotcopy $database /root/mysql-dumps/ --allowold --keepold --user=mysqlhotcopy

    This script maintains one previous copy of the databases, by renaming the directory, appending the suffix _old to the name.

See also



This is the nicest guide for streaming replication that I've found: Zero to PostgreSQL streaming replication in 10 mins. It is written for Ubuntu, but it only needs a couple of steps done differently on CentOS, which I have noted in the comments of that article. This guide is not as clear (for my preference), but it includes some commands to verify that the replication is running: How To Setup PostgreSQL Replication On CentOS.


Random tips for BackupPC:

  1. On your client systems (those that will be backed up by BackupPC), rotate your logs (whether compressed or not) with dates in the filenames, instead of appending prefixes such as .1, .2, .3, etc. The benefit from this is that BackupPC will ignore old logs on new runs, since they will have the same name and the same checksum. If you rotate logs with numbered names, BackupPC will transfer them again, since the name will have changed. This configuration is achieved with the dateext parameter set in logrotate configuration file, which on CentOS 6 is at /etc/logrotate.conf, by default.

  2. If mlocate is installed on the BackupPC system, you should exclude the backup directory from being indexed by the nightly run of updatedb, otherwise /var/lib/mlocate/mlocate.db will become enormous. To exclude the backup directory, edit /etc/updatedb.conf and append the directory path to the end of the line for the PRUNEPATHS variable.

See Also

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Raspberry Pi Security Bootstrap

These are my notes on the first steps of improving security on a new Raspberry Pi. The default configuration that an RPi comes with might be suitable for a development environment in a private or isolated network, but if you intend on exposing your RPi to the world then you need to tweak that configuration to be more robust. The commands mentioned here have been tested on a Raspberry Pi B+, running a fresh installation of Raspbian.


Security is fluid and open-ended. The following are mere suggestions. Taking these steps will hopefully reduce your exposure, but does not guarantee complete safety. Nothing does.

User configuration

  1. This goes without saying: Change the default user's password. By default, the RPi user is pi and her password is raspberry. Change that as soon as you get your operating system runnning, either by running passwd as the pi user, or by running sudo raspi-config and selecting the option for password change.

  2. Change the default user's sudo configuration. By default, the pi user can execute anything with sudo, without providing a password. As the pi user, do:

    sudo visudo

    ...and the change the line:


    pi ALL=(ALL) ALL
  3. Additionally, you might want to disable the default pi user altogether, and create another user that you will use on your RPi. As the user pi, do:

    sudo adduser myuser

    ...and answer the questions. Only the password question is important, the rest can be left blank. Then, to make the new user a sudoer, do:

    sudo visudo

    ...and add this line in the end of the file:

    myuser ALL=(ALL) ALL

    Additionally, since login will be disabled for pi, you might as well comment out the line in /etc/sudoers that refers to that user. Finally, to disable login for the default pi user, logout from pi and login as the new user that you created, and do:

    sudo usermod --lock pi
    sudo usermod --shell /sbin/nologin pi

SSH Configuration

  1. Forbid SSH login for user root. If your RPi is exposed to the world, it will get attacked with SSH attempts for common usernames and passwords, which is yet another reason to disable the default pi username. Another username that your RPi will be hammered with is root. Now, you can't disable the root account, but you can disallow logins for it. To do that, edit the file /etc/ssh/sshd_config, and change the line:

    PermitRootLogin yes


    PermitRootLogin no

    ...and then restart the SSH daemon:

    sudo service ssh restart
  2. Restrict Incoming IPs for SSH, using entries in /etc/hosts.allow and /etc/hosts.deny. For example, I allow SSH on my RPi from my internal LAN subnets (192.168.x.x), and from one public IP only ( in this example). To achieve that, put in /etc/hosts.allow:

    sshd: 192.168.

    ...and in /etc/hosts.deny:

    sshd: ALL

    Attempting to login to the RPi from a restricted host will return an error to the client:

    [email protected] ~ $ ssh [email protected]
    ssh_exchange_identification: Connection closed by remote host

    ...and will also create a log in /var/log/auth.log:

    Dec 13 11:40:48 rpi sshd[3456]: refused connect from (

Firewall Configuration with iptables

On my RPi running a freshly installed Raspbian OS, iptables was already installed, and it was running with an empty rule set, i.e. all traffic was allowed in all directions. Furthermore, Raspbian does not include a SysV script for the iptables service, but this functionality is offered by the iptables-persistent package.

  1. Install iptables-persistent, to help make the iptables rules survive a reboot:

    sudo apt-get install iptables-persistent

    If you accept the defaults during the installation, the currently running empty rule set of iptables will be saved in /etc/iptables/rules.v4. After the installation, you can manage your firewall with:

    service iptables-persistent {start|restart|reload|force-reload|save|flush}

    Here are the contents of that file, with the default configuration of the firewall:

    # Generated by iptables-save v1.4.14 on Sat Dec 13 14:23:03 2014
    :INPUT ACCEPT [1291:113154]
    :OUTPUT ACCEPT [828:105910]
    # Completed on Sat Dec 13 14:23:03 2014
  2. Next, you will need to add some rules to the iptables configuration, to start blocking some traffic. There are two methods that you can apply:

    A. Replace the line :INPUT ACCEPT that defines a default policy to accept all incoming traffic), with :INPUT DROP, and then define rules that will only allow selected traffic through the firewall.

    B. Keep the default :INPUT ACCEPT policy for incoming traffic, but have one last rule that rejects all incoming traffic.

    I'm going with the second option, simply because of the convenience of copying rules from one of my CentOS machines :) Here it is then, my rules file, implementing only the restriction to SSH port to the same IPs that I mentioned earlier:

    :INPUT ACCEPT [0:0]
    :OUTPUT ACCEPT [0:0]
    -A INPUT -p icmp -j ACCEPT
    -A INPUT -i lo -j ACCEPT
    -A INPUT -m state --state NEW -m tcp -p tcp --source --dport 22 -j ACCEPT
    -A INPUT -m state --state NEW -m tcp -p tcp --source     --dport 22 -j ACCEPT
    -A INPUT -j REJECT --reject-with icmp-host-prohibited
    -A FORWARD -j REJECT --reject-with icmp-host-prohibited


With these measures taken to improve the security of my Raspberry Pi, I am now more confident that I can assign it a public IP and expose it the the world, without it being a very easy target.


Hello, I'm Marios Zindilis and this is my website. Opinions are my own. You also find me on LinkedIn and GitHub.

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