Linux Hardening

What it does

When your agent uses it

• Tasks that involve Linux administration

Example prompts

• “/linux-hardening”

Requirements

• Compatibility (from SKILL.md): Requires the relevant security tooling (scanners, vault CLIs) and an authorized scope for any active assessment. Docs-only; helper scripts and templates not bundled.

What it can do on your machine

Read from SKILL.md and the folder at commit ec02547. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  Shell commands in SKILL.md call:

  • apt

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  Links to these hosts (documentation or services it may open):

  • github.com

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

• Compatibility

  Requires the relevant security tooling (scanners, vault CLIs) and an authorized scope for any active assessment. Docs-only; helper scripts and templates not bundled.

  From compatibility in the SKILL.md frontmatter.

Context cost

Linux Hardening loads about 875 tokens when it runs. Until then it costs about 16 tokens; SKILL.md has 125 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~16

When it runs · the whole SKILL.md, loaded when a task matches

~875

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

• NoteRuns commands with sudoSKILL.md:50

  sudo apt install libpam-pwquality

• NoteRuns commands with sudoSKILL.md:61

  # Audit sudo usage

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from sickn33/agentic-awesome-skills at commit ec02547, republished under its MIT licence (© sickn33). 125 words, ~875 tokens.

name

linux-hardening

description

Apply CIS benchmarks and secure Linux servers.

compatibility

Requires the relevant security tooling (scanners, vault CLIs) and an authorized scope for any active assessment. Docs-only; helper scripts and templates not bundled.

category

security

risk

critical

source

https://github.com/BagelHole/DevOps-Security-Agent-Skills

source_repo

BagelHole/DevOps-Security-Agent-Skills

source_type

community

date_added

2026-09-20

license

MIT

license_source

https://github.com/BagelHole/DevOps-Security-Agent-Skills/blob/main/LICENSE

metadata.author

devops-skills

metadata.version

1.0

# /etc/ssh/sshd_config
PermitRootLogin no
PasswordAuthentication no
PubkeyAuthentication yes
MaxAuthTries 3
ClientAliveInterval 300
ClientAliveCountMax 2
AllowUsers deploy admin
Protocol 2

# Password policy
sudo apt install libpam-pwquality
# /etc/security/pwquality.conf
minlen = 14
dcredit = -1
ucredit = -1
ocredit = -1
lcredit = -1

# Lock inactive accounts
useradd -D -f 30

# Audit sudo usage
echo "Defaults logfile=/var/log/sudo.log" >> /etc/sudoers

# UFW setup
ufw default deny incoming
ufw default allow outgoing
ufw allow ssh
ufw allow 443/tcp
ufw enable

# Or iptables
iptables -P INPUT DROP
iptables -P FORWARD DROP
iptables -A INPUT -i lo -j ACCEPT
iptables -A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT
iptables -A INPUT -p tcp --dport 22 -j ACCEPT

# /etc/sysctl.d/99-security.conf
net.ipv4.conf.all.send_redirects = 0
net.ipv4.conf.all.accept_redirects = 0
net.ipv4.conf.all.accept_source_route = 0
net.ipv4.icmp_echo_ignore_broadcasts = 1
kernel.randomize_va_space = 2
fs.suid_dumpable = 0

# Apply
sysctl -p

# Critical files
chmod 600 /etc/shadow
chmod 644 /etc/passwd
chmod 700 /root
chmod 600 /etc/ssh/sshd_config

# Find world-writable files
find / -type f -perm -0002 -ls

# Find SUID files
find / -perm -4000 -type f -ls

# Install auditd
apt install auditd

# /etc/audit/rules.d/audit.rules
-w /etc/passwd -p wa -k identity
-w /etc/shadow -p wa -k identity
-w /etc/sudoers -p wa -k actions
-a always,exit -F arch=b64 -S execve -k exec

# Read-only first: inventory before any active step.
which <tool> && <tool> --help | head -n 20

© sickn33, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in skills/linux-hardening of sickn33/agentic-awesome-skills.

Open the folder on GitHubat commit ec02547

Used in 1 other repository

We found 5 copies of this SKILL.md (exact, near-identical or edited) in other folders, from 1 other GitHub owner. This page covers the copy in sickn33/agentic-awesome-skills, which our catalogue first saw on October 7, 2026.

• lingxling/awesome-skills-cnantigravity-awesome-skills/skills/linux-hardeningantigravity-awesome-skills/plugins/agentic-awesome-skills/skills/linux-hardening+1 more