Site for admins about operating systems and security
Is there any known distro to have a failsafe or transactional model in its core?
NixOS (https://nixos.org), among other features, gives the possibility to always rollback in a transactional way to a previous system state without using any external software backup or snapshots like in VMware.
Is there any VPN solution based on IPSEC + IKE in Linux?
See project Openswan (https://www.openswan.org/).
How to create a password which can be used to grant access to some areas in your server?
With the Apache utility htpasswd like in the example below
htpasswd -c /usr/local/apache/passwd/passwords rbowen
Note that the password file must be outside the DocumentRoot FOlder and therefore outside from Internet reach, for obvious reasons.
How can I display local listening ports (and services) with nmap?
nmap -sT localhost
How do you find the X server version?
$ X -version
How do I list the content of a Debian package?
$ dpkg –contents <package>
or
$ dpkg -c <package>
Can I clone the Ubuntu public repository?
Yes, with the tool apt-mirror.
Can I develop in Prolog in Linux?
Sure, using the free Prolog environment SWI-Prolog (http://www.swi-prolog.org/).
Any Linux distro recommended for NAS or other storage solutions?
How can avoid that a process is killed when the controlling (shell) terminal exits?
$ man nohup