Understudy Host Hardening

Overview

Assess the host that runs Understudy, keep host controls separate from Understudy configuration, and require explicit approval before any change.

Core Rules

• Start with read-only checks.
• Require explicit approval before any state-changing action.
• Do not modify remote access settings until the current access path is confirmed.
• Prefer reversible changes with a rollback plan.
• Never claim Understudy itself changes the host firewall, SSH policy, or OS update settings.
• If identity or role is unclear, provide recommendations only.
• Present user choices as numbered lists.

Read-Only Workflow

1. Establish context:

• OS and version
• local console vs SSH/RDP/tunnel/tailnet access
• admin/root availability
• public exposure, reverse proxy, or private-only reachability
• backups, disk encryption, and automatic security updates

1. Run host checks:

• uname -a, sw_vers, cat /etc/os-release
• Linux: ss -ltnup, ufw status, firewall-cmd --state, nft list ruleset
• macOS: lsof -nP -iTCP -sTCP:LISTEN, /usr/libexec/ApplicationFirewall/socketfilterfw --getglobalstate, pfctl -s info
• macOS backups: tmutil status

1. Run Understudy checks:

• understudy security --audit
• understudy status --json
• understudy health --json
• understudy logs --tail 100
• understudy doctor --deep when broader local diagnostics are needed

Ask once for permission to run read-only checks. If granted, infer as much as possible from commands before asking follow-up questions.

Risk Profiles

Offer one of these numbered defaults after the host context is known:

1. Home / workstation balanced
2. Remote / headless hardened
3. Developer convenience with explicit exposure warnings
4. Custom constraints supplied by the user

Remediation Plan

Always present the plan before making changes. Include:

• target profile
• current posture summary
• gaps vs target
• exact commands to run
• rollback or access-preservation notes
• credential and file-permission hygiene notes

Execution Rules

For each state-changing step:

• show the exact command first
• explain impact and rollback
• confirm remote access will remain available
• stop on unexpected output

Require explicit approval for:

• firewall changes
• opening or closing ports
• SSH or RDP configuration changes
• package installation or removal
• enabling or disabling services
• user or group changes
• scheduled jobs or persistence
• access to sensitive files or credentials

Verification

After any change, re-check:

• firewall status
• listening ports
• remote access still works
• understudy security --audit

Deliver a final posture summary and note any deferred items.

Periodic Checks

Use Understudy's canonical scheduling surfaces:

• In agent/runtime workflows: use the schedule tool with actions status, create, list, update, remove, run, runs
• For explicit manual CLI instructions: use the real understudy schedule command with supported flags such as --status, --list, --add, --update, --remove, --run, and --runs
• Prefer stable job names:
• healthcheck:security-audit
• healthcheck:status-snapshot
• Before creating or updating, inspect existing jobs with schedule action "list" or understudy schedule --list.
• Example recurring commands:
• weekly understudy security --audit
• daily understudy status --json

Do not create recurring jobs without explicit approval.

Command Accuracy

Use only commands that exist in this repo:

• understudy security --audit
• understudy status --json
• understudy health --json
• understudy logs --tail 100
• understudy doctor --deep

Do not invent understudy update status, understudy cron ..., unsupported schedule subcommands, or flags that are not in this repo.

Recordkeeping

If the user wants an audit trail, record:

• plan ID and timestamp
• approved steps and exact commands
• exit codes and files modified (best effort)
• redacted findings only

Never log tokens or full credential contents.

Memory Writes (Conditional)

Only write to memory files when the user explicitly opts in and the session is private or local. If memory is requested:

• append dated notes to memory/YYYY-MM-DD.md
• update MEMORY.md only for durable preferences such as risk posture or allowed ports
• redact hostnames, IPs, usernames, serials, service names, and secrets

If the session cannot write to the workspace, provide a redacted summary the user can store manually.