Fixing “500 Illegal PORT Command” Error in Ubuntu FTP Transfers to EC2 AMI

When trying to download Drupal modules via FTP from ftp.drupal.org to an Ubuntu-based EC2 instance, many developers encounter the frustrating "500 Illegal PORT command" error. This occurs even during basic operations like ls or get commands, effectively blocking file transfers.

The error stems from FTP's passive/active mode mismatch and EC2's network configuration. Traditional FTP uses PORT command to specify where the server should connect back, but this fails when:

EC2 instances sit behind NAT
Security groups block the ephemeral ports
The client's IP appears different from server's perspective

Option 1: Force Passive Mode

Add this to your ~/.netrc file:

machine ftp.drupal.org
login anonymous
password your@email.com
macdef init
passive on

Option 2: Use wget Instead

wget --ftp-user=anonymous --ftp-password=your@email.com \\
     ftp://ftp.drupal.org/path/to/module.tar.gz

Option 3: Configure vsftpd on EC2

If you control the server, edit /etc/vsftpd.conf:

pasv_enable=YES
pasv_min_port=60000
pasv_max_port=61000
pasv_address=your.elastic.ip

Always run FTP with -v flag for troubleshooting:

ftp -v ftp.drupal.org

This reveals the actual PORT command being rejected and helps identify network path issues.

For EC2 transfers, consider using SCP instead:

scp -i your-key.pem user@ec2-instance:/remote/path /local/path

or rsync for better reliability:

rsync -avz -e "ssh -i your-key.pem" \\
      user@ec2-instance:/remote/path /local/path

When trying to download Drupal modules via FTP from ftp.drupal.org on an EC2 AMI running Ubuntu, many developers encounter the frustrating "500 Illegal PORT command" error. This typically occurs when attempting basic commands like ls or get after establishing the initial connection.

The root cause stems from how FTP handles data connections. Traditional FTP uses separate control and data channels, with the PORT command specifying where the server should connect back to send data. In cloud environments like EC2 with complex networking (NAT, firewalls, security groups), these connections often fail.

$ ftp ftp.drupal.org
Connected to ftp.drupal.org.
220---------- Welcome to Pure-FTPd [privsep] [TLS] ----------
Name (ftp.drupal.org:ubuntu): anonymous
331 Anonymous login ok, send your complete email address as your password
Password:
230- Welcome to drupal.org's FTP site
230 Anonymous user logged in
ftp> ls
500 Illegal PORT command

Option 1: Force Passive Mode

Passive mode (PASV) reverses the data connection direction, which typically works better in restricted network environments:

ftp> passive
Passive mode on.
ftp> ls
227 Entering Passive Mode (192,0,78,25,195,149)
150 Accepted data connection

Option 2: Use cURL Instead

For simple downloads, cURL often works better:

curl -O ftp://ftp.drupal.org/path/to/module.tar.gz

Option 3: Configure FTP Client Settings

Create or modify ~/.netrc for automated connections:

machine ftp.drupal.org
login anonymous
password user@example.com

Then use it with:

ftp -v ftp.drupal.org

For Drupal modules, consider these alternatives to FTP:

# Using drush (Drupal shell)
drush dl module_name

# Using wget
wget https://ftp.drupal.org/files/projects/module_name-8.x-1.0.tar.gz

If problems persist, check your EC2 security groups and network ACLs. FTP requires:

Port 21 (control channel)
Port range 49152-65535 (passive mode data channels)

Verify connectivity with:

telnet ftp.drupal.org 21
nc -zv ftp.drupal.org 21