Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add BagelHole/DevOps-Security-Agent-Skills --skill firewall-configgit clone --depth 1 https://github.com/BagelHole/DevOps-Security-Agent-SkillsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/bagelhole/devops-security-agent-skills/firewall-config)<a href="https://agentmods.dev/skills/bagelhole/devops-security-agent-skills/firewall-config"><img src="https://agentmods.dev/badge/skills/bagelhole/devops-security-agent-skills/firewall-config/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/bagelhole/devops-security-agent-skills/firewall-config"><img src="https://agentmods.dev/badge/skills/bagelhole/devops-security-agent-skills/firewall-config.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 1 finding, up to medium
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- medium Privilege Escalation · line 26 Commands invoke sudo or root privileges. Verify this elevated access is necessary and justified.Fix: Avoid sudo/root unless strictly required. Prefer least-privilege patterns. If elevation is needed, document the justification and scope.
What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00034 | $0.03335 |
| Opus 5 | $0.00017 | $0.01667 |
| Sonnet 5 | $0.00007 | $0.00667 |
| Haiku 4.5 | $0.00003 | $0.00333 |
Grade A, and why
firewall-config scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 9d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Asks for rootlowPrivilege escalation
A mod that escalates privileges can change anything on the machine, not only the project.
- Root or sudo access on Linux hosts Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.
How it starts
The opening of the file, as written. The whole thing — 454 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Firewall Configuration
Configure host-based and cloud firewalls for network security.
When to Use This Skill
Use this skill when:
- Setting up a new server and need to restrict network access
- Implementing network segmentation between application tiers
- Configuring cloud security groups for AWS, GCP, or Azure resources
- Migrating from iptables to nftables
- Auditing existing firewall rules for compliance
- Responding to a security incident requiring emergency network blocks
Prerequisites
- Root or sudo access on Linux hosts
- AWS CLI configured for cloud security groups
- Understanding of TCP/IP, ports, and protocols
- Network diagram showing required traffic flows
iptables
Basic Setup with Default Deny
# Flush existing rules
iptables -F
iptables -X
iptables -t nat -F
iptables -t mangle -F
# Default policies - deny all inbound, allow outbound
iptables -P INPUT DROP
iptables -P FORWARD DROP
iptables -P OUTPUT ACCEPT
# Allow established connections
iptables -A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT
# Allow loopback
iptables -A INPUT -i lo -j ACCEPT
# Drop invalid packets
iptables -A INPUT -m conntrack --ctstate INVALID -j DROP
# Allow SSH (restrict to management subnet)
iptables -A INPUT -p tcp --dport 22 -s 10.0.100.0/24 -j ACCEPT
# Allow HTTP/HTTPS from anywhere
iptables -A INPUT -p tcp -m multiport --dports 80,443 -j ACCEPT
# Allow ICMP (ping) with rate limiting
iptables -A INPUT -p icmp --icmp-type echo-request -m limit --limit 1/s --limit-burst 4 -j ACCEPT
# Log dropped packets (rate limited to avoid log flooding)
iptables -A INPUT -m limit --limit 5/min -j LOG --log-prefix "IPTABLES-DROP: " --log-level 4
# Save rules (Debian/Ubuntu)
iptables-save > /etc/iptables/rules.v4
ip6tables-save > /etc/iptables/rules.v6
Anti-DDoS Rules
# SYN flood protection
iptables -A INPUT -p tcp --syn -m limit --limit 25/s --limit-burst 50 -j ACCEPT
iptables -A INPUT -p tcp --syn -j DROP
# Limit new connections per source IP
iptables -A INPUT -p tcp --dport 80 -m connlimit --connlimit-above 50 -j REJECT
# Block port scanning (detect TCP flags abuse)
iptables -A INPUT -p tcp --tcp-flags ALL NONE -j DROP
iptables -A INPUT -p tcp --tcp-flags ALL ALL -j DROP
iptables -A INPUT -p tcp --tcp-flags ALL FIN,URG,PSH -j DROP
iptables -A INPUT -p tcp --tcp-flags SYN,RST SYN,RST -j DROP
iptables -A INPUT -p tcp --tcp-flags SYN,FIN SYN,FIN -j DROP
What ships with it
4 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 9d ago First seen · 454 lines · 34 tokens per session scan A 707aedfc1967
firewall-config is a skill published in the GitHub repository BagelHole/DevOps-Security-Agent-Skills (1,084 stars, last pushed 3mo ago), licensed MIT. It adds 34 tokens to every session and 3,335 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 1 finding (asks for root). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.
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