Suppose that you need second full functional Postfix instance on the same machine. You can edit ‘‘ file of course but this solution does not provide necessary¬†separation level. This tutorial describes how to start second Postfix instance with separate ‘/var/spool/postfix‘ directory (queues, sockets, pids etc.).

In first step you need to create separate working directory for another server instance. Let’s copy:

/var/spool/postfix directory to /var/spool/postfix2,

/etc/postfix directory to /etc/postfix2.

Next create a copy of /usr/lib/systemd/system/postfix.service (with new name ‘postfix2.service’) and change following lines in ‘[Service]‘ section. Continue Reading

Rsync is a very powerful¬† backup tool. It can significantly speed up backup process and minimize amount of data transferred during synchronization. In most cases rsync is used to make incremental backups, but it also has another interesting option which gives you ability to keeping old versions of files on backup server. Mentioned option is ‘–backup’ or simply ‘-b’. Continue Reading

This short article describe how to reset lost root password on Linux system. IMPORTANT: This method require physical access to the machine.

On GRUB screen select normal boot option:

1Press ‘e’ to edit selected option. You will see short GRUB code.


Search for the line starting with “linux /boot/vmlinuz…” or similar depending of Linux distribution. This is the place where kernel and rootfs is selected. Change ‘ro’ option to ‘rw’ and add: Continue Reading

Sometimes happens that establishing of SSH (or other service) connection takes a really long time. This is often caused by failed reverse DNS lookups.

That situation can occur because of network problems or can be intentional action performed by system administrator.

How can you handle with it? Simply add this line to your sshd_config file.

UseDNS no

Now SSH connection should be established significantly faster.