Ssh Server Admin

SSH Server Administration

A comprehensive skill for secure remote server management via SSH. Supports command execution, file transfers, port forwarding, and tunneling. Cross-platform compatible: Windows, macOS, and Linux.

Platform Detection

CRITICAL: Detect the operating system first to use the correct SSH approach.

Before executing SSH commands, check the platform:

• Windows: Use PowerShell or Windows OpenSSH (built into Windows 10+)
• macOS/Linux: Use standard bash SSH commands

Authentication Methods (In Order of Preference)

1. SSH Key Authentication (RECOMMENDED - Works Everywhere)

SSH keys are the most secure and reliable method. They work identically on all platforms.

Check for existing keys:

# Windows (PowerShell)
Get-ChildItem ~/.ssh/id_*.pub

# macOS/Linux
ls -la ~/.ssh/id_*.pub

If keys exist, use them:

# All platforms - key auth is automatic if keys are set up
ssh -o StrictHostKeyChecking=accept-new [username]@[host] "[command]"

If no keys exist, help user create them:

# All platforms (works in PowerShell, bash, zsh)
ssh-keygen -t ed25519 -C "user@example.com"

# Copy public key to server (if ssh-copy-id available)
ssh-copy-id -i ~/.ssh/id_ed25519.pub [username]@[host]

# Or manually append to server's authorized_keys
cat ~/.ssh/id_ed25519.pub | ssh [username]@[host] "mkdir -p ~/.ssh && cat >> ~/.ssh/authorized_keys"

2. Password Authentication

IMPORTANT: Password auth handling differs by platform.

Windows Approach

Windows OpenSSH doesn't support sshpass. Use one of these methods:

Option A: Use the included Python SSH helper (RECOMMENDED)

# Uses paramiko library for cross-platform SSH
python scripts/ssh_helper.py --host [host] --user [username] --password [password] --command "[command]"

Option B: Interactive SSH (user types password)

# This will prompt for password interactively
ssh -o StrictHostKeyChecking=accept-new [username]@[host] "[command]"

Option C: Use PuTTY's plink (if installed)

# plink can accept password via echo (less secure)
echo [password] | plink -ssh -pw [password] [username]@[host] "[command]"

macOS/Linux Approach

Option A: Use sshpass (if available)

# Check if sshpass is installed
which sshpass

# If installed, use it
sshpass -p '[password]' ssh -o StrictHostKeyChecking=accept-new [username]@[host] "[command]"

Option B: Use the Python SSH helper

python3 scripts/ssh_helper.py --host [host] --user [username] --password [password] --command "[command]"

Option C: Install sshpass

# Ubuntu/Debian
sudo apt-get install sshpass

# macOS (with Homebrew)
brew install hudochenkov/sshpass/sshpass

# Then use sshpass commands

Session Credential Management

CRITICAL: One-Time Credential Collection

When the user first requests an SSH operation, collect credentials ONCE:

I need SSH connection details. Please provide:

1. **Host/IP Address**: (e.g., 192.168.1.100 or server.example.com)
2. **Username**: (e.g., root, admin, ubuntu)
3. **Authentication Method**:
   - SSH Key (recommended) - just provide path if not default
   - Password
4. **Port** (optional): Default is 22

Example response:
- Host: 192.168.1.100
- Username: admin
- Auth: SSH Key (default location) OR Password: mypassword123
- Port: 22

After receiving credentials:

• Store them in working memory for the session
• Detect the operating system and choose appropriate SSH method
• Use credentials for ALL subsequent operations without re-prompting
• NEVER write credentials to files or logs

Cross-Platform Command Reference

Remote Command Execution

With SSH Keys (All Platforms):

ssh -o StrictHostKeyChecking=accept-new -o ConnectTimeout=30 [username]@[host] "[command]"

With Password (Platform-Specific):

# macOS/Linux with sshpass
sshpass -p '[password]' ssh -o StrictHostKeyChecking=accept-new [username]@[host] "[command]"

# All platforms with Python helper
python scripts/ssh_helper.py --host [host] --user [username] --password "[password]" --command "[command]"

File Transfer (SCP)

Upload file:

# With keys (all platforms)
scp -o StrictHostKeyChecking=accept-new [local_file] [username]@[host]:[remote_path]

# With password (macOS/Linux)
sshpass -p '[password]' scp -o StrictHostKeyChecking=accept-new [local_file] [username]@[host]:[remote_path]

# With Python helper (all platforms)
python scripts/ssh_helper.py --host [host] --user [username] --password "[password]" --upload [local_file] --remote-path [remote_path]

Download file:

# With keys (all platforms)
scp -o StrictHostKeyChecking=accept-new [username]@[host]:[remote_file] [local_path]

# With password (macOS/Linux)
sshpass -p '[password]' scp -o StrictHostKeyChecking=accept-new [username]@[host]:[remote_file] [local_path]

# With Python helper (all platforms)
python scripts/ssh_helper.py --host [host] --user [username] --password "[password]" --download [remote_file] --local-path [local_path]

Port Forwarding

Local Port Forwarding (-L):

# Access remote service on local port (all platforms with keys)
ssh -L [local_port]:localhost:[remote_port] [username]@[host]

# Example: Access remote MySQL (3306) on local port 3307
ssh -L 3307:localhost:3306 [username]@[host]

Remote Port Forwarding (-R):

# Expose local service to remote (all platforms with keys)
ssh -R [remote_port]:localhost:[local_port] [username]@[host]

Dynamic Port Forwarding (SOCKS Proxy):

ssh -D [local_port] [username]@[host]

Server Administration Tasks

System Information

# Check system info
ssh user@host "uname -a && cat /etc/os-release"

# Check disk space
ssh user@host "df -h"

# Check memory usage
ssh user@host "free -h"

# Check running processes
ssh user@host "ps aux --sort=-%mem | head -20"

# Check system load
ssh user@host "uptime && top -bn1 | head -15"

Service Management (systemd)

# Check service status
ssh user@host "systemctl status [service_name]"

# Start/stop/restart service
ssh user@host "sudo systemctl start|stop|restart [service_name]"

# View service logs
ssh user@host "journalctl -u [service_name] -n 50 --no-pager"

Log Analysis

# View recent system logs
ssh user@host "sudo tail -100 /var/log/syslog"

# Search logs for errors
ssh user@host "sudo grep -i error /var/log/syslog | tail -50"

# View auth logs
ssh user@host "sudo tail -50 /var/log/auth.log"

Network Diagnostics

# Check listening ports
ssh user@host "ss -tulpn"

# Check network connections
ssh user@host "netstat -an | grep ESTABLISHED"

# Test connectivity
ssh user@host "ping -c 3 [target] && traceroute [target]"

Instructions for Claude

1. Detect Platform First: Check if running on Windows, macOS, or Linux to choose the right SSH approach.

2. Prefer SSH Keys: Always check for and recommend SSH key authentication first.

3. First SSH Request: Prompt for credentials using the format above. Wait for response before proceeding.

4. Store Credentials: Remember credentials for the entire session. DO NOT ask again.

5. Choose Correct Method:

   • If SSH keys are available → Use standard SSH commands
   • If password auth on Windows → Use Python helper script or prompt user
   • If password auth on macOS/Linux → Try sshpass, fall back to Python helper

6. Handle Errors: If authentication fails, inform user and suggest alternatives:

   • Set up SSH keys
   • Install sshpass (macOS/Linux)
   • Use the Python helper script

7. Security First:

   • Never echo passwords in command output
   • Use -o StrictHostKeyChecking=accept-new for first connections
   • Recommend SSH keys over passwords

8. Custom Port: Add -p [port] to SSH/SFTP or -P [port] to SCP commands.

Configuration Options

Troubleshooting

When to Use This Skill

• "SSH into my server at 192.168.1.100"
• "Connect to my remote machine"
• "Run a command on the server"
• "Upload/download files to/from the server"
• "Set up port forwarding"
• "Create an SSH tunnel"
• "Check server status"
• "Restart a service on the server"
• "View server logs"

When NOT to Use This Skill

• Local file operations (no SSH needed)
• Cloud provider API operations (use their CLIs)
• Database client connections (use database tools)

Examples

Example 1: First Connection with Keys

User: "SSH into my server and check disk space"

Claude:

1. Prompts for connection details
2. User provides: Host: 10.0.0.5, Username: admin, Auth: SSH Key
3. Executes: ssh -o StrictHostKeyChecking=accept-new admin@10.0.0.5 "df -h"
4. Returns disk space information

Example 2: Windows with Password

User: "Connect to 192.168.1.100 with password and restart nginx"

Claude:

1. Detects Windows platform
2. Uses Python helper: python scripts/ssh_helper.py --host 192.168.1.100 --user admin --password "secret" --command "sudo systemctl restart nginx"
3. Returns result

Example 3: macOS/Linux with Password

User: "SSH to my server with password"

Claude:

1. Detects macOS/Linux
2. Checks for sshpass: which sshpass
3. If available: sshpass -p 'password' ssh admin@host "command"
4. If not: Uses Python helper or suggests installing sshpass

Python Helper Script

The scripts/ssh_helper.py provides cross-platform SSH with password authentication.

Install dependencies:

pip install paramiko

Usage:

# Run command
python scripts/ssh_helper.py --host 192.168.1.100 --user admin --password "secret" --command "df -h"

# Upload file
python scripts/ssh_helper.py --host 192.168.1.100 --user admin --password "secret" --upload ./local.txt --remote-path /tmp/remote.txt

# Download file
python scripts/ssh_helper.py --host 192.168.1.100 --user admin --password "secret" --download /var/log/syslog --local-path ./syslog.txt

See scripts/ssh_helper.py for full implementation.

Version History

• v2.0.0 (2025-12-17): Cross-platform rewrite - Windows, macOS, Linux support
• v1.0.0 (2025-12-17): Initial release