brewtools:ssh

SSH Server Management

Manage remote Linux servers — connect, configure, deploy, administer with safety gates and persistent config.

<instructions>

Robustness Rules (MANDATORY — apply to ALL phases)

Fail-Fast

| Rule | Applies to | |------|-----------| | Every Bash call MUST end with && echo "OK ..." \|\| echo "FAILED ..." | ALL scripts | | On FAILED — stop current phase, report error to user, DO NOT retry same command blindly | ALL phases | | SSH commands MUST use -o ConnectTimeout=10 -o BatchMode=yes | ALL SSH calls | | Max 2 retries per failed operation. After 2nd failure — report and stop | ALL phases | | If a script exits non-zero — read its stderr, diagnose, fix root cause, then retry ONCE | Scripts |

Loop Protection

| Rule | Limit | |------|-------| | Phase 2 (Connection Setup) — max 3 key attempts, then ask user | 3 keys | | Phase 2 → Phase 5 round-trips — if sent back to Phase 2 more than once, stop and report | 1 re-entry | | Phase 5 (Execute) — max 5 SSH commands per invocation. If task needs more, delegate to ssh-admin agent via Task | 5 commands | | update-agent mode — max 3 servers per run. If more, process first 3 and report remaining | 3 servers | | AskUserQuestion — max 3 questions per phase. If skill needs more info, summarize what's missing in one combined question | 3 per phase |

Timeouts

| Operation | Timeout | Action on timeout | |-----------|---------|-------------------| | SSH connection test | 10s (ConnectTimeout=10) | Report "Server unreachable", stop | | server-discover.sh | 30s (timeout 30 bash ...) | Report partial results, continue | | Any single SSH command | 60s (timeout 60 ssh ...) | Kill, report "Command timed out", ask user | | Entire skill invocation | Do not exceed 15 SSH calls total | Stop, report progress, suggest continuing manually |

Fallback Strategy

If a script fails and cannot be fixed:

1. Report the exact error to user: script name, exit code, stderr
2. Attempt the same operation manually (inline Bash) — scripts are helpers, not gatekeepers
3. If manual fallback also fails — report both attempts and ask user what to do
4. NEVER silently swallow errors or continue with stale/missing data

Manual fallback examples:

| Failed script | Manual alternative | |---------------|--------------------| | detect-mode.sh | Parse $ARGUMENTS yourself — keyword matching is simple | | ssh-env-check.sh | Run ls ~/.ssh/id_* 2>/dev/null, ssh-add -l, cat ~/.ssh/config | | server-discover.sh | Run individual commands via SSH: uname -a, docker version, df -h | | claude-local-ops.sh | Read/write CLAUDE.local.md directly with Read/Edit tools |

Error Reporting (MANDATORY)

On ANY failure — before stopping or asking user — output:

SCRIPT_ERROR: <script-name>
EXIT_CODE: <code>
STDERR: <error message>
PHASE: <current phase>
ACTION: <what was attempted>
FALLBACK: <what will be tried next OR "asking user">

This is non-negotiable. Silent failures are bugs.

Phase 0: Mode Detection (MANDATORY FIRST STEP)

EXECUTE using Bash tool:

bash "${CLAUDE_SKILL_DIR}/scripts/detect-mode.sh" "$ARGUMENTS"

Output format:

ARGS: [arguments received]
MODE: [detected mode]

Use the MODE value and GOTO that mode section below.

Mode Reference

| Keyword in args | MODE | |-----------------|------| | setup, new server, add server | setup | | connect to, ssh to, login | connect | | configure, config, harden | configure | | update agent, refresh agent, refresh | update-agent | | (any other text) | execute | | (empty, no servers configured) | setup | | (empty, servers configured) | execute (prompt user) |

Phase 1: Environment & Config Check

Runs for ALL modes before branching.

EXECUTE using Bash tool:

bash "${CLAUDE_SKILL_DIR}/scripts/ssh-env-check.sh" && echo "OK env-check" || echo "FAILED env-check"

STOP if FAILED -- fix SSH environment before continuing.

Parse output key=value pairs. Note available keys and ssh-agent status.

Load Existing Server Config

EXECUTE using Bash tool:

bash "${CLAUDE_SKILL_DIR}/scripts/claude-local-ops.sh" list 2>/dev/null || echo "NO_SERVERS"

Branching logic:

| Condition | Action | |-----------|--------| | NO_SERVERS AND mode=setup | GOTO Phase 2: Connection Setup | | NO_SERVERS AND mode=execute/connect | GOTO Phase 2 (need server first) | | 1 server AND mode=connect/execute | Use as default, GOTO Phase 5 | | Multiple servers AND mode=connect/execute | AskUserQuestion: which server? Then GOTO Phase 5 | | mode=setup (servers exist) | GOTO Phase 2 (adding new server) | | mode=configure | AskUserQuestion: which server? Then GOTO Phase 5 | | mode=update-agent | GOTO Mode: update-agent |

Phase 2: Connection Setup

Step 1: Gather Connection Info

Use AskUserQuestion:

header: "SSH Server Setup"
question: "Provide connection details for the new server."

Collect via follow-up questions if not in $ARGUMENTS:

• Host (IP or hostname) -- REQUIRED
• User (default: deploy) -- REQUIRED
• Port (default: 22) -- optional
• Server name (short alias, e.g., vps-main) -- REQUIRED

Step 2: Key Discovery & Auth

EXECUTE using Bash tool -- try existing keys:

bash "${CLAUDE_SKILL_DIR}/scripts/ssh-env-check.sh" && echo "OK keys" || echo "FAILED keys"

Parse available keys from output. Try connection with each key (ed25519 first, then rsa, then ecdsa):

EXECUTE using Bash tool:

ssh-keyscan -p PORT HOST >> ~/.ssh/known_hosts 2>/dev/null && echo "OK keyscan" || echo "FAILED keyscan"

Replace PORT and HOST with actual values.

EXECUTE using Bash tool -- test key auth:

ssh -o BatchMode=yes -o ConnectTimeout=10 -p PORT USER@HOST echo "OK auth" 2>/dev/null || echo "FAILED auth"

Step 3: If Key Auth Fails

Use AskUserQuestion:

header: "SSH Authentication"
question: "Key authentication failed. Choose auth method:"
options:
  - label: "Password login (will set up key auth)"
    description: "Connect with password, then install SSH key"
  - label: "Specify key path"
    description: "Provide path to an existing private key"
  - label: "Cancel"
    description: "Abort server setup"

If password login:

1. Generate dedicated key:

EXECUTE using Bash tool:

ssh-keygen -t ed25519 -f ~/.ssh/id_ed25519_SERVERNAME -N "" -C "claude@SERVERNAME" && echo "OK keygen" || echo "FAILED keygen"

Replace SERVERNAME with the server name alias.

1. Instruct user to copy key manually:

Interactive command required. Run this in your terminal:

```

! ssh-copy-id -i ~/.ssh/id_ed25519_SERVERNAME.pub -p PORT USER@HOST

```

This requires password entry which Claude Code cannot do non-interactively.

1. After user confirms, verify:

EXECUTE using Bash tool:

ssh -o BatchMode=yes -o ConnectTimeout=10 -i ~/.ssh/id_ed25519_SERVERNAME -p PORT USER@HOST echo "OK key-auth" 2>/dev/null || echo "FAILED key-auth"

STOP if FAILED -- key auth must work before proceeding.

Step 4: SSH Config Entry

EXECUTE using Bash tool:

grep -q "^Host SERVERNAME$" ~/.ssh/config 2>/dev/null && echo "EXISTS" || echo "NEW"

If NEW, add config entry using Edit/Write to ~/.ssh/config:

Host SERVERNAME
    HostName HOST
    User USER
    Port PORT
    IdentityFile ~/.ssh/id_ed25519_SERVERNAME
    StrictHostKeyChecking accept-new

Step 5: Final Connection Test

EXECUTE using Bash tool:

ssh -o BatchMode=yes -o ConnectTimeout=10 SERVERNAME echo "OK connection" 2>/dev/null || echo "FAILED connection"

STOP if FAILED -- connection must work before discovery.

Phase 3: Server Discovery

EXECUTE using Bash tool:

bash "${CLAUDE_SKILL_DIR}/scripts/server-discover.sh" "USER@HOST" PORT && echo "OK discovery" || echo "FAILED discovery"

Replace USER@HOST and PORT with actu