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SSH Remote Projects Setup Guide

This guide covers how to use Emdash's SSH feature to work with remote projects on remote servers via SSH/SFTP.

Overview

Emdash supports remote development by connecting to servers via SSH. This allows you to:

  • Run coding agents on remote machines
  • Access and edit files on remote servers through SFTP
  • Execute Git operations on remote repositories
  • Use worktrees for parallel development on remote hosts

How It Works

When you add a remote project:

  1. Emdash establishes an SSH connection to your server
  2. Files are accessed via SFTP for browsing and editing
  3. Git operations run over SSH commands
  4. Coding agents execute in remote worktrees
  5. All connections use your system's SSH agent or configured keys

Adding a Remote Project

Step 1: Configure SSH Connection

  1. Open Settings → SSH Connections
  2. Click "Add Connection"
  3. Enter connection details:
Name:           My Server
Host:           server.example.com
Port:           22
Username:       your-username
Auth Type:      [Select method]

Step 2: Test Connection

Before saving, click "Test Connection" to verify:

  • Network connectivity
  • Authentication credentials
  • Host key verification

Step 3: Add Remote Project

  1. Go to Projects → Add Project
  2. Select "Remote Project" tab
  3. Choose your configured SSH connection
  4. Enter the remote path to your project:
Connection:     My Server
Project Path:   /home/user/projects/my-app
  1. Emdash will validate the path and detect Git configuration

Connection Configuration Options

Basic Settings

Option Description Default
Name Display name for this connection Required
Host Server hostname or IP address Required
Port SSH port (usually 22) 22
Username SSH username Required

Connection Timeouts

Emdash uses sensible defaults for connection reliability:

  • Ready Timeout: 20 seconds (connection establishment)
  • Keepalive Interval: 60 seconds (connection health check)
  • Keepalive Count Max: 3 retries before disconnect

These settings ensure stable long-running agent sessions.

Authentication Methods

Emdash supports three authentication methods, listed from most to least secure:

1. SSH Agent (Recommended)

Uses your system's SSH agent for key-based authentication without storing private keys in Emdash.

Requirements:

  • SSH agent running (ssh-agent)
  • Key added to agent (ssh-add ~/.ssh/id_ed25519)
  • SSH_AUTH_SOCK environment variable set

Setup:

# Start SSH agent (if not already running)
eval "$(ssh-agent -s)"

# Add your key
ssh-add ~/.ssh/id_ed25519

# Verify
ssh-add -l

macOS Note: macOS automatically manages the SSH agent via Keychain. Your keys are typically available after first use.

2. Private Key

Specify a private key file directly. Emdash reads the key file but stores passphrases securely in your system keychain.

Supported Key Formats:

  • OpenSSH format (id_rsa, id_ed25519, id_ecdsa)
  • PEM format
  • Keys with or without passphrases

Configuration:

Auth Type:        Private Key
Private Key Path: /Users/you/.ssh/id_ed25519
Passphrase:       [if key is encrypted]

Security: Passphrases are stored in your OS keychain (macOS Keychain, Linux Secret Service), not in Emdash's database.

3. Password

Direct password authentication. Stored securely in your system keychain.

When to use:

  • Servers without key-based auth configured
  • Temporary/testing connections
  • Legacy systems

Security Note: Password authentication is less secure than key-based methods. Consider setting up SSH keys for production use.

Host Key Verification

Emdash verifies server identity using SSH host keys to prevent man-in-the-middle attacks.

First Connection

When connecting to a new server, you'll see a host key fingerprint:

Host Key Verification
Server: server.example.com:22
Fingerprint: SHA256:ABC123xyz...
Algorithm: ssh-ed25519

[Trust Host] [Cancel]

Verify the fingerprint matches your server's actual key before trusting.

Managing Known Hosts

Emdash uses your system's ~/.ssh/known_hosts file for host key storage. This means:

  • Host keys trusted in Emdash are also trusted by your CLI SSH
  • Host keys verified via CLI SSH are trusted in Emdash
  • No separate host key management needed

Host Key Changed Warning

If a server's host key changes (e.g., after rebuild), you'll see:

WARNING: Host key has changed!
This could indicate a man-in-the-middle attack.

Previous: SHA256:ABC123...
Current:  SHA256:XYZ789...

[View Details] [Accept New Key] [Cancel]

Only accept the new key if you know why the host key changed (e.g., server was rebuilt).

Troubleshooting Common Issues

Connection Timeout

Symptoms: "Connection timed out" or long delays

Solutions:

  1. Verify host and port are correct
  2. Check firewall rules (port 22 open)
  3. Test with CLI: ssh -v user@host
  4. Check if VPN is required

Authentication Failed

Symptoms: "Authentication failed" or "Permission denied"

For Password Auth:

  • Verify username and password
  • Check if account is locked or expired

For Key Auth:

  • Verify key file exists and is readable
  • Check key permissions (should be 600)
  • Ensure public key is in server's ~/.ssh/authorized_keys

For Agent Auth:

  • Verify SSH_AUTH_SOCK is set: echo $SSH_AUTH_SOCK
  • Check key is loaded: ssh-add -l
  • Reload key if needed: ssh-add ~/.ssh/id_ed25519

Host Key Verification Failed

Symptoms: "Host key verification failed"

Solutions:

  1. Check if server was recently rebuilt
  2. Verify fingerprint with server admin
  3. Remove old entry: ssh-keygen -R hostname
  4. Reconnect and accept new key

SFTP Operations Fail

Symptoms: Can connect but file operations fail

Solutions:

  1. Verify SFTP is enabled on server (Subsystem sftp in sshd_config)
  2. Check disk space on remote server
  3. Verify permissions on project directory
  4. Try manual SFTP: sftp user@host

Git Operations Fail on Remote

Symptoms: Git commands return errors

Solutions:

  1. Ensure Git is installed on remote server: ssh user@host git --version
  2. Check repository permissions
  3. Verify Git config (user.name, user.email) on remote
  4. For private repos, ensure SSH agent forwarding or deploy keys

Slow File Operations

Symptoms: File browsing or editing is slow

Solutions:

  1. Check network latency: ping server
  2. Consider connection multiplexing in ~/.ssh/config:
Host server
    ControlMaster auto
    ControlPath ~/.ssh/sockets/%r@%h-%p
    ControlPersist 600

Security Best Practices

1. Use SSH Keys, Not Passwords

Keys are more secure and convenient:

# Generate Ed25519 key (recommended)
ssh-keygen -t ed25519 -C "emdash@workstation"

# Copy to server
ssh-copy-id user@server

2. Protect Private Keys

  • Never commit private keys to Git
  • Use strong passphrases for keys
  • Store keys in ~/.ssh/ with 600 permissions
  • Use hardware security keys (YubiKey) for high-security environments

3. Verify Host Keys

Always verify host key fingerprints on first connection. For known servers, distribute fingerprints securely:

# Get server fingerprint
ssh-keyscan -t ed25519 server.example.com

4. Use SSH Config for Advanced Options

Create ~/.ssh/config for server-specific settings:

Host prod-server
    HostName prod.example.com
    User deploy
    IdentityFile ~/.ssh/prod_ed25519
    StrictHostKeyChecking accept-new
    ServerAliveInterval 60

Host dev-server
    HostName 192.168.1.100
    User developer
    ForwardAgent yes

5. Limit Agent Forwarding

Only enable agent forwarding when needed:

Host trusted-server
    ForwardAgent yes

6. Regular Key Rotation

Rotate SSH keys periodically:

  • Generate new keys every 6-12 months
  • Remove old keys from authorized_keys
  • Update Emdash connections with new key paths

7. Audit Connections

Review your ~/.ssh/known_hosts periodically:

# List known hosts
ssh-keygen -l -f ~/.ssh/known_hosts

# Remove stale entries
ssh-keygen -R old-server.example.com

Quick Reference

SSH Config File Location

  • macOS/Linux: ~/.ssh/config
  • Known hosts: ~/.ssh/known_hosts

Common SSH Commands

# Test connection
ssh -v user@host

# Check loaded keys
ssh-add -l

# Add key to agent
ssh-add ~/.ssh/id_ed25519

# Remove key from agent
ssh-add -d ~/.ssh/id_ed25519

# Remove host from known_hosts
ssh-keygen -R hostname

# Get server fingerprint
ssh-keyscan -t ed25519 hostname

Emdash SSH Storage Locations

  • Connection configs: Local SQLite database
  • Passwords/Passphrases: System keychain (via keytar)
  • Host keys: ~/.ssh/known_hosts (shared with system SSH)
  • Private keys: Never stored by Emdash (only paths are stored)

For technical details on SSH implementation, see SSH Architecture.