SSH Microagent
This microagent provides capabilities for establishing and managing SSH connections to remote machines.
Capabilities
- Establish SSH connections using password or key-based authentication
- Generate and manage SSH key pairs
- Configure SSH for easier connections
- Execute commands on remote machines
- Transfer files between local and remote machines
- Manage SSH configurations and known hosts
Authentication Methods
Password Authentication
ssh username@hostname
When prompted, you should ask the user for their password or a private key.
Key-Based Authentication
Generate a new SSH key pair:
ssh-keygen -t ed25519 -f ~/.ssh/key_name -C "comment" -N ""
Copy the public key to the remote server:
ssh-copy-id -i ~/.ssh/key_name.pub username@hostname
Connect using the private key:
ssh -i ~/.ssh/key_name username@hostname
SSH Configuration
Create or edit the SSH config file for easier connections:
mkdir -p ~/.ssh
cat > ~/.ssh/config << 'EOF'
Host alias
HostName hostname_or_ip
User username
IdentityFile ~/.ssh/key_name
Port 22
ServerAliveInterval 60
EOF
chmod 600 ~/.ssh/config
Then connect using the alias:
ssh alias
Common SSH Options
-p PORT: Connect to a specific port-X: Enable X11 forwarding-L local_port:remote_host:remote_port: Set up local port forwarding-R remote_port:local_host:local_port: Set up remote port forwarding-N: Do not execute a remote command (useful for port forwarding)-f: Run in background-v: Verbose mode (add more v's for increased verbosity)
File Transfer with SCP
Copy a file to the remote server:
scp /path/to/local/file username@hostname:/path/to/remote/directory/
Copy a file from the remote server:
scp username@hostname:/path/to/remote/file /path/to/local/directory/
Copy a directory recursively:
scp -r /path/to/local/directory username@hostname:/path/to/remote/directory/
SSH Agent
Start the SSH agent:
eval "$(ssh-agent -s)"
Add a key to the agent:
ssh-add ~/.ssh/key_name
Troubleshooting
- Check SSH service status on remote:
systemctl status sshd
- Verify SSH port is open:
nc -zv hostname 22
- Debug connection issues:
ssh -vvv username@hostname
- Check permissions: SSH private keys should have 600 permissions (
chmod 600 ~/.ssh/key_name)
- Verify known_hosts: If host key changed, remove the old entry with
ssh-keygen -R hostname
Secure SSH Key Management
Local Storage with Proper Permissions
The most basic approach is to ensure proper file permissions:
# Set correct permissions for private keys
chmod 600 ~/.ssh/id_ed25519
# Set correct permissions for public keys
chmod 644 ~/.ssh/id_ed25519.pub
# Set correct permissions for SSH directory
chmod 700 ~/.ssh