Linux Tools for Sysadmins
Tools for day-to-day Linux administration: look up a command and its common options, build and check a cron schedule before it goes into crontab, and turn sar -A output into charts to spot CPU, memory, load and network bottlenecks.
3 free linux tools
Guides: Linux & Sysadmin
- The Linux OOM Killer, ExplainedHow the kernel decides to kill a process under memory pressure, the oom_score and oom_score_adj, reading the OOM dmesg dump, overcommit settings, cgroup OOM, and prevention.
- kdump and Kernel Crash AnalysisHow kdump captures a vmcore on a kernel panic using a reserved memory region and a second kernel, configuring it, triggering a test crash, and a first pass at reading the dump with crash.
- fail2ban in PracticeHow fail2ban watches logs and bans IPs, jail.local configuration, filters and failregex, ban actions (nftables/firewalld/iptables), recidive, allowlists, and testing a filter.
- sysctl Network Tuning for ServersThe network sysctls worth changing on a busy server — backlog, buffers, TIME_WAIT reuse, ephemeral ports, SYN cookies, keepalives — what each does, and how to measure before and after.
- LUKS Full-Disk EncryptionHow LUKS/dm-crypt works, LUKS1 vs LUKS2, key slots and passphrases, unlocking at boot with a keyfile or TPM (clevis), adding/rotating keys, and recovering with the header backup.
- Linux Software RAID with mdadmRAID levels and when to use each, creating and growing an array, the mdadm.conf and initramfs requirement, monitoring and email alerts, replacing a failed disk, and the write-hole.
Checking a whole domain? The Super Scanner runs every DNS, email, website and security check at once and gives one score.