Fix "EAI_NONAME FTP Error" – Firewall Blocking FTP Connections

Table of Contents: Understanding the Error Check If Firewall Is Blocking FTP Allow FTP in Windows Firewall Allow FTP in Linux Firewalls Check Router Settings & Port Forwarding Use Passive Mode in FileZilla

The "EAI_NONAME - Neither nodename nor servname provided, or not known" FTP error often indicates DNS resolution issues, but if your firewall is blocking FTP traffic, you may experience connection timeouts or refused connections alongside this error. This guide focuses specifically on configuring firewalls on Windows, Linux (UFW/Firewalld/Iptables), and routers to allow FTP access.

Understanding the Error

The EAI_NONAME error combined with FTP connection failures typically means:

1. The FTP client successfully resolves the hostname to an IP address (DNS works)
2. But the firewall blocks the actual FTP connection attempt (TCP ports 21, 20, or 990)
3. Or the firewall blocks DNS queries before the connection even attempts

Firewalls can block FTP at multiple levels:

• Local software firewall: Windows Defender, third-party antivirus
• Operating system firewall: UFW, Firewalld, iptables on Linux
• Network firewall: Router/access point security settings
• Corporate/ISP firewall: Network-level blocking of FTP ports

Check If the Firewall Is Blocking FTP

Before modifying firewall settings, verify that FTP ports are actually being blocked.

Test FTP Port Connectivity

Using Netcat (Cross-Platform):

Using Telnet:

Using PowerShell (Windows):

Interpretation of Results:

Allow FTP in Windows Firewall

Allow FTP in Linux Firewalls

Check Router Settings & Port Forwarding

If you're connecting to an FTP server behind a home/office router, configure port forwarding.

1. Log into your router: Typically http://192.168.1.1, http://192.168.0.1, or check the router label
2. Find Port Forwarding/Virtual Server: Usually under Advanced Settings, Security, or NAT
3. Add forwarding rules:

   Service Name	Protocol	External Port	Internal Port	Internal IP
   FTP Control	TCP	21	21	[FTP server's local IP]
   FTP Data (Active)	TCP	20	20	[FTP server's local IP]
   FTPS	TCP	990	990	[FTP server's local IP]
   FTP Passive Range	TCP	30000-50000	30000-50000	[FTP server's local IP]

4. Save settings and restart router if necessary

Use Passive Mode in FileZilla

Passive mode (PASV) is often more firewall-friendly because all connections are initiated by the client.

1. Open FileZilla
2. Go to Edit > Settings (Windows) or FileZilla > Settings (Mac)
3. Navigate to Connection > FTP
4. Select Passive (recommended) under Transfer mode
5. Optional: Check "Fall back to active mode"
6. For specific networks, you may need to configure:
   • Use the server's external IP address instead (if behind NAT)
   • Limit local ports to a specific range for easier firewall rules
7. Click OK and try connecting

Summary of Firewall Fixes for "EAI_NONAME FTP Error"