telnetshell

A security-testing skill for connecting to network-accessible IoT device shells through Telnet, a remote command-line protocol.

In plain words
What is it for?
Enumerating IoT devices, testing credentials, finding vulnerabilities, and carrying out authorized post-exploitation work over Telnet.
Why use it?
It provides a structured way to inspect devices and test weak or missing login protection while recording the session.

Skill for Claude CodeCodex

Install

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.

agentmods
npx agentmods add skills/brownfinesecurity/iothackbot/telnetshell
Any agent
npx skills add BrownFineSecurity/iothackbot --skill telnetshell
Clone the repo
git clone --depth 1 https://github.com/BrownFineSecurity/iothackbot

Made for: Claude Code, Codex.

Per session 56 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,344 The whole file, excluding the scripts and references it only reads on demand.
Security scan F 4 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5 $0.00056 $0.04344
Opus 5 $0.00028 $0.02172
Sonnet 5 $0.00011 $0.00869
Haiku 4.5 $0.00006 $0.00434

Measured 2d ago against content hash 5f9d819e8558, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade F, and why

telnetshell scanned grade F with 4 findings 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 2d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (telnet_helper.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

Enumerates the file system for secretshighData exfiltration

Searching home directories for .env, .ssh, .aws or credential files is reconnaissance for credential theft.

find / -name "*.pem" 2>/dev/null

Asks for rootmediumPrivilege escalation

A mod that escalates privileges can change anything on the machine, not only the project.

- Python 3 with pexpect library (`pip install pexpect` or `sudo pacman -S python-pexpect`)

Reaches for credential fileshighPrivilege escalation

SSH keys, cloud credentials, git-credentials, .npmrc, /etc/shadow: reading these is how a config file becomes a credential leak.

echo "your_ssh_public_key" >> /root/.ssh/authorized_keys

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

- Networking tools are often present (telnet, wget, nc/netcat, ftpget)
skills/telnetshell/SKILL.md · 541 lines

How it starts

The opening of the file, as written. The whole thing — 541 lines — stays where its author put it; the contents beside it link to each section on GitHub.

IoT Telnet Shell (telnetshell)

This skill enables interaction with IoT device shells accessible via telnet for security testing and penetration testing operations. It supports unauthenticated shells, weak authentication testing, device enumeration, and post-exploitation activities.

Prerequisites

  • Python 3 with pexpect library (pip install pexpect or sudo pacman -S python-pexpect)
  • telnet client installed on the system (sudo pacman -S inetutils on Arch)
  • Network access to the target device's telnet port

IMPORTANT: This skill includes a Python helper script (telnet_helper.py) that provides a clean, reliable interface for telnet communication. This is the RECOMMENDED method for interacting with IoT devices.

Default Session Logging

ALL commands run by Claude will be logged to /tmp/telnet_session.log by default.

To observe what Claude is doing in real-time:

# In a separate terminal, run:
tail -f /tmp/telnet_session.log

This allows you to watch all telnet I/O as it happens without interfering with the connection.

Why Use the Telnet Helper?

The helper script solves many problems with direct telnet usage:

  • Clean output: Automatically removes command echoes, prompts, and ANSI codes
  • Prompt detection: Automatically detects and waits for device prompts
  • Timeout handling: Proper timeout management with no arbitrary sleeps
  • Easy scripting: Simple command-line interface for single commands or batch operations
  • Session logging: All I/O logged to /tmp/telnet_session.log for observation
  • Reliable: No issues with TTY requirements or background processes
  • JSON output: For programmatic parsing and tool chaining

Quick Start with Telnet Helper

Single Command:

python3 .claude/skills/telnetshell/telnet_helper.py --host 192.168.1.100 --command "uname -a"

Custom Port:

python3 .claude/skills/telnetshell/telnet_helper.py --host 192.168.1.100 --port 2222 --command "ls /"

Read the full file on GitHub · 541 lines

Files

What ships with it

7 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.

Changes

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.

  1. 2d ago First seen · 541 lines · 56 tokens per session scan F 5f9d819e8558

Subscribe to this mod's changes

telnetshell is a skill published in the GitHub repository BrownFineSecurity/iothackbot (819 stars, last pushed 3mo ago), licensed MIT. It adds 56 tokens to every session and 4,344 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it F with 4 findings (enumerates the file system for secrets, asks for root, reaches for credential files). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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