I know ipfire is made from scratch, but when i need use commands in terminal, which linux (debian, ubuntu, red hat or what another) are similar to learn. Or somewhere is manpages for all possible terminal commands for ipfire?
In my opinion the console approach to IPFire requires first to understand where things are (Init scripts, configuration scripts and files, logs etc.) which is superficially similar to the major distributions but also quite different at a more granular level. For example, the Init process of any modern distro using systemd will be different from IPFire. Using a different distro for this will be more confusing than helpful.
The only way to learn is in gradual steps, using mostly IPFire official documentation and asking on this forum specific questions. For instance, you could install IPFire in a cheap machine or in a virtual machine in a testing/learning environment, follow the principles highlighted in this blog post, where you block everything first and then you learn how to open and give permission to the machines and services you need in your network.
If you want to go next step, focus on understanding how IPTables works (any distro will do, as well as IPFire own internal documentation) as it is basically the heart of IPFire. Next, learn enough shell programming to read IPFire configuration scripts. Next, learn enough Perl to read the scripts behind the web interface. Again, this is pretty much distribution agnostic.
Finally, research the individual programs IPFIre uses (i.e. IPSec, OpenVPN, Squid, hostapd ecc…) and how they work, directly from their documentation, as the way they are packaged in IPFire doesn’t change their inner working.
Having said that, do not try to learn in abstract, focus your attention to a specific aspect that interest you, starting from installing IPFire and configuring it in the most basic way and go from there.
actually, it is made from Linux from scratch., which is a learning tool on its self, if you are willing to invest few years of your life to learn the inner working of a Linux distribution to an insane level of granularity.
Linux from Scratch is way to setup an own Linux system. BTW the main distribution do the same.
The Linux from Scratch has the advantage, that developpers of a LfS based distribution do not have to watch all parts of the Linux system. The community works together in doing this.
IPFire is constructed from commonly known parts of Linux. So for each part you can read the documentation. The usage of these parts is documented in our wiki also.
The ‘glue’ of the operating system IPFire is really a bunch of scripts, mainly in written in Perl and part of the apache server. This may be a bit different to the other distributions, which present a fully graphical user interface. But all sources of the IPFire web user interface are open, either as scripts directly in the system or as C files in Git.
Most configuration is done in the WebUI.