When configuring SSH jump hosts on Windows 10, you might encounter this frustrating error during ProxyCommand execution. The root cause typically stems from either:

• Missing dependencies (netcat/nc not available)
• Path resolution issues in Windows OpenSSH implementation
• Command syntax differences between Unix and Windows environments

Here's a modified version that works reliably on Windows:

Host jumphost
  HostName jumphost.server.local
  User your_username

Host server*.server.local
  ProxyCommand C:\\Windows\\System32\\OpenSSH\\ssh.exe -W %h:%p jumphost
  ServerAliveInterval 60

If you specifically need netcat functionality, ensure it's properly installed:

# For Chocolatey users:
choco install netcat -y

# Then modify your config:
Host server*.server.local
  ProxyCommand ssh jumphost "C:\\path\\to\\nc.exe -w 120 %h %p"

When troubleshooting:

1. Verify each component works independently
2. Use absolute paths for all executables
3. Check Windows PATH environment variable
4. Test with simpler commands first

For more complex scenarios, consider PowerShell remoting:

Enter-PSSession -ComputerName jumphost -Credential (Get-Credential)
$session = New-PSSession -ComputerName targetserver -Credential (Get-Credential)
Invoke-Command -Session $session -ScriptBlock { your_commands }

If available, WSL often provides more reliable behavior:

# In WSL terminal:
sudo apt install netcat-openbsd
Host server*.server.local
  ProxyCommand ssh jumphost "nc -w 120 %h %p"

When configuring SSH jump hosts on Windows 10, the ProxyCommand directive is essential for routing connections through intermediate servers. The standard approach uses netcat (nc) as a tunnel:

Host jumphost
  HostName jumphost.example.com
  User admin

Host target*.example.com
  ProxyCommand ssh -W %h:%p jumphost
  # Alternative: ProxyCommand ssh jumphost netcat -w 120 %h %p

The error "posix_spawn: No such file or directory" typically occurs because:

• Windows OpenSSH lacks certain POSIX-compatible process spawning mechanisms
• The netcat binary isn't in the system PATH or not installed
• Command interpretation differs between Windows and Linux environments

Solution 1: Use Native Windows OpenSSH Features

Host target*.example.com
  ProxyCommand ssh -W %h:%p jumphost
  # No external dependencies required

Solution 2: Install Required Utilities

For systems requiring netcat functionality:

1. Install Nmap (includes ncat.exe)
2. Add to PATH: C:\Program Files (x86)\Nmap
3. Update config:

Host target*.example.com
  ProxyCommand ssh jumphost "ncat -w 120 %h %p"

Solution 3: Windows Subsystem for Linux (WSL)

For advanced scenarios using WSL's native SSH:

Host target*.example.com
  ProxyCommand wsl ssh jumphost "nc -w 120 %h %p"

When troubleshooting:

# Test basic connectivity:
ssh -v jumphost

# Verify netcat availability:
ssh jumphost which nc || echo "Netcat missing"

# Check PATH resolution:
ssh jumphost "echo \$PATH"

For enterprise environments consider:

• Windows-native port forwarding with netsh
• Persistent SSH tunnels with autossh
• Jump host alternatives like Teleport or Boundary