System settings: time, locale, host name and kernel parameters
You set up a server's identity and core settings correctly: host name, time zone and time sync, language and keyboard, sysctl and persistent configuration.
Level 201 · 16 lessons · 15 practice labs
Lessons
Identity
- Host name: hostnamectl and /etc/hosts
- machine-id and the problem with cloned machines
- Login messages: motd and issue
- Short task: rename a server to the new naming standard
Time
- Time zones and timedatectl
- Time synchronisation with chrony
- The hardware clock and UTC
- Short task: fix a server running five minutes slow and verify sync
Language and environment
- Locales: locale, LANG and the Turkish I problem
- Console keyboard and font
- System-wide environment: /etc/environment and profile.d
- Short task: fix a script that breaks only under a Turkish locale
Kernel settings
- Runtime settings with sysctl
- Persistent settings and load order with sysctl.d
- User limits: limits.conf
- Capstone: bring a new server up to the company baseline settings
Practice labs
- Set the host name permanently: Change the server's name to follow the naming rule and verify it holds after a reboot.
- Fix an inconsistency in name resolution: Find and fix the mismatch between the hosts file and the host name that makes sudo slow.
- Separate the clashing identities of cloned servers: Regenerate the machine ID and SSH host keys that stayed identical on two servers cloned from one image.
- Correct the time zone: Correct the time zone of a server whose log times look wrong and verify the hardware clock is kept in UTC.
- Point time sync at the internal server: Configure chrony to use the organisation's time server and verify synchronisation from the sources status.
- Find why a server's clock drifts: Find from the tracking output why a clock is minutes off although sync looks enabled, and fix the firewall and step setting.
- Fix garbled characters with the locale: Find the locale of a session that shows Turkish characters garbled, generate the missing locale and make it permanent.
- Define an environment variable at the right scope: Define a proxy variable for all users and an app variable for one service only, and verify both scopes.
- Find a locale-dependent script bug: Find the locale difference that makes a script sort correctly interactively but wrongly when scheduled, and harden the script.
- Read a kernel setting and change it temporarily: Read the IP forwarding setting, change it temporarily and show it reverts after a reboot.
- Define a kernel setting persistently and tidily: Persist open-file and connection backlog settings in a separate file and show which file takes precedence.
- Audit kernel network settings against a hardening list: Compare a ten-item hardening list with the server's current values, apply what is missing and verify services are unaffected.
- Set the login message and legal notice: Set a pre-login legal notice and a post-login message showing the server role, and verify no version details leak.
- Write a baseline script for a new server: Write a script applying name, time zone, time sync and locale that changes nothing when run again.
- Diff the configuration of two servers and align them: Compare identity, time, locale and kernel settings of two servers meant to be identical and fix the deviations with reasons.
About this course
You set up a server's identity and core settings correctly: host name, time zone and time sync, language and keyboard, sysctl and persistent configuration.
What you will learn
- Identity
- Time
- Language and environment
- Kernel settings
Prerequisites
Finishing the level 101 courses of the same path, or knowing those topics, is enough.
Lab environment
Lessons run in your own Kali Linux terminal that opens in the browser. Nothing to install; the lab starts clean in every lesson.
Frequently asked questions
- Is this course right for my level?
- The course is at level 201; it assumes you know the topics of the lower-level courses.
- Is there anything to install?
- No. Every lesson runs in your own lab environment that opens in the browser.
- How do lessons work?
- Each lesson has 8 to 10 steps and a short quiz. Early steps show the command to type, later steps give less help; if two attempts fail, the solution opens.
- Can I try it for free?
- Yes. The first three lessons of every course are free.