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Overview

This document explains how to use the active or passive mode to connect to a File Transfer Protocol (FTP) server.

Important:

In cPanel & WHM version 60 and later, the system enables passive ports 49152 through 65534 for Pure-FTPd servers and ProFTPd servers by default. If you use the CSF firewall plugin, the system also adds passive port ranges to your server's firewall by default.

Active and passive mode sessions

FTP uses a data port and a command port to transfer information between a client and a server. During a typical active mode session, the command port uses port 21 and the data port uses port 20. When you use a passive mode session, however, the data port does not always use port 20.

Active

In active mode, the FTP server responds to the connection attempt and returns a connection request from a different port to the FTP client. Network Address Translation (NAT) configurations block this connection request.

ACTIVE FTP

ACTIVE FTP (With Firewall)

The firewall blocks the server's attempt to communicate with the client because the server uses a different port than the first connection.

Passive

In passive mode, the FTP client initiates both connection attempts. NAT configurations do not block this connection request.

PASSIVE FTP (With Firewall)

The firewall does not block the server's attempt to communicate with the client because the client initiated the communication both times.

Note:

If FTP users exist on the private network side of a NAT configuration, you must enable FTP's passive mode, and open the passive port range in your FTP server's configuration file. You may also need to open the passive port range on your firewall.

Configure FTP servers

To configure your FTP server, select the tab that corresponds to your cPanel & WHM version:


The sections below explain how to edit the default configurations for a Pure-FTPd server and a ProFTPd server.

Notes:

  • A local file contains your desired settings which overwrite any default settings from the main file.
  • The system enables passive ports 49152 through 65534 for Pure-FTPd servers and ProFTPd servers by default.

Pure-FTPd servers

To edit the FTP configuration for a PureFTP server, perform the following steps:

  1. Log in to the server as the root user via SSH.
  2. Open the /var/cpanel/conf/pureftpd/local file, if it already exists, with a text editor. If it does not already exist, create the /var/cpanel/conf/pureftpd/local file.
  3. Add the desired changes to the file. If your FTP server exists behind a NAT configuration, set the ForcePassiveIP option to the FTP server's public IP address, as in the following example:

    ForcePassiveIP: 203.0.113.0

    If your server does not exist in a NAT configuration, set the ForcePassiveIP option to the following entry:

    ForcePassiveIP: ~

    Important:

    Only one ForcePassiveIP entry can exist in a configuration file.

  4. If you want to change your server's default passive port range, run the following commands:

    echo "PassivePortRange: 49152 65534" >> /var/cpanel/conf/pureftpd/local
    /usr/local/cpanel/scripts/setupftpserver pure-ftpd --force
  5. Configure your server to allow the passive port range to pass through the firewall. To do this, follow the directions in the Configure the firewall section below.

  6. Restart the PureFTP service with the following command:

    /usr/local/cpanel/scripts/setupftpserver pure-ftpd --force

ProFTPd servers

To edit the FTP configuration for a ProFTPd server, perform the following steps:

  1. Log in to the server as the root user via SSH.

  2. Open the /var/cpanel/conf/proftpd/local file, if it already exists, with a text editor. If it does not already exist, create the /var/cpanel/conf/proftpd/local file.

  3. Add the desired changes to the file. If your FTP server exists behind a NAT configuration, set the MasqueradeAddress option to the FTP server's public IP address, as in the following example:

    MasqueradeAddress: 203.0.113.0

    If your server does not exist in a NAT configuration, set the MasqueradeAddress option to the following entry:

    MasqueradeAddress: ~

    Important:

    Only one MasqueradeAddress entry can exist in a configuration file. 

  4. If you want to change your server's default passive port range, run the following commands:

    echo "PassivePorts: 49152 65534" >> /var/cpanel/conf/proftpd/local
    /usr/local/cpanel/scripts/setupftpserver proftpd --force
  5. Configure your server to allow the passive port range to pass through the firewall. To do this, follow the directions in the Configure the firewall section below.

  6. Restart the ProFTP service with the following command:

    /usr/local/cpanel/scripts/setupftpserver proftpd --force

Configure the firewall

Note:

The system enables passive ports 49152 through 65534 for Pure-FTPd servers and ProFTPd servers by default.

You may need to add your FTP server's passive port range to the firewall manually.

CSF

If you use the CSF plugin to manage your server's firewall, open the /etc/csf/csf.conf file, and confirm that the passive port range exists at the end of the TCP_IN line. The system adds your FTP server's passive port range to the firewall by default. For more information about how to install and use CSF, visit the CSF website.

IPTABLES

If you use the IPTABLES application for your FTP server's firewall, perform the following steps to add the passive port range to your server's firewall:

  1. Open the /etc/sysconfig/iptables file with a text editor.

  2. After you add an IPTABLES entry to the /etc/sysconfig/iptables file, run the following commands:

    iptables -I INPUT -p tcp --dport 49152:65534 -j ACCEPT
    service iptables save

firewalld

If you use the firewalld application for your CentOS 7, CloudLinux™ 7, or Red Hat® Enterprise Linux (RHEL) 7 server, run the following commands to add the passive port range to your server's firewall:

firewall-cmd --permanent --zone=public --add-service=ftp
firewall-cmd --permanent --add-port=49152-65534/tcp
firewall-cmd --reload

Warning:

This section contains information for End of Life versions of cPanel & WHM. We no longer update the information in this section. For assistance, update your version of cPanel & WHM to a supported version. For more information, read our cPanel Long Term Support documentation.

Enable the passive port range for Pure-FTPd

To enable the passive port range on a server that uses Pure-FTPd, perform the following steps as the root user in the command line:

  1. Open the /etc/pure-ftpd.conf configuration file with a text editor.
  2. Remove the comment (#) from the beginning of the line that contains the PassivePortRange option.

  3. Set the PassivePortRange option to a port range that is greater than or equal to 1024.

    In the following example, 49152 65534 represents the PassivePortRange option:

    PassivePortRange 49152 65534

    If your server does not exist in a NAT configuration, comment out the ForcePassiveIP option, as in the following following:

    #ForcePassiveIP 203.0.113.0

    Important:

    We strongly recommend that you configure a large port range so the server can process many simultaneous passive connections. For example, the Internet Assigned Numbers Authority (IANA) recommends the 49152:65534 port range.

  4. Save your changes to the configuration file.

  5. If your FTP server exists behind a NAT configuration, open the /var/cpanel/conf/pureftpd/main file with a text editor set the ForcePassiveIP option to the FTP server's public IP address.

    Warning:

    • We strongly recommend that you only perform this action if your server exists behind a NAT configuration. This option prevents connections to other IP addresses on the server and connections via domains that resolve to other IP addresses. If you set an IP address for the ForcePassiveIP option, you can only connect to the FTP server via that IP address.
    • Only one ForcePassiveIP entry can exist in a configuration file.
  6. Run the following commands to allow connections through the passive port range of your server's firewall:

    iptables -I INPUT 2 -p tcp --dport 49152:65534 -j ACCEPT
    service iptables save

    Important:

    If your FTP server exists on a CentOS 7, CloudLinux™ 7, or Red Hat® Enterprise Linux (RHEL) 7 server, run the following commands to allow connections through the passive port range that you set:

    firewall-cmd --permanent --zone=public --add-service=ftp
    firewall-cmd --permanent --add-port=49152-65534/tcp
    firewall-cmd --reload
  7. Run the /usr/local/cpanel/scripts/restartsrv_ftpserver command to restart the FTP server.

  8. To make these changes permanent, you must append the passive ports to the configuration file. To do this, run the following commands as the root user:

    echo "PassivePortRange: 49152 65534" >> /var/cpanel/conf/pureftpd/main
    /usr/local/cpanel/scripts/setupftpserver pure-ftpd --force

For more information about how to edit your Pure-FTPd configuration, read our FTP FAQ documentation.

Enable the passive port range for ProFTPd

To enable the passive port range on a server that uses ProFTPd, perform the following steps via the command line as the root user:

  1. Open the /etc/proftpd.conf configuration file with a text editor.
  2. Add the following line to the first section of the configuration file, where 49152 65534 represents the PassivePorts option:

    PassivePorts 49152 65534
  3. If your FTP server exists behind a NAT configuration, add the hostname and FTP server's public IP address to the proftpd.conf configuration file, as in the following example:

    MasqueradeAddress: example.com
    MasqueradeAddress: 203.0.113.0

    Note:

    The MasqueradeAddress lines specify the FTP server's public IP address.

    If your server does not exist behind a NAT configuration, set the MasqueradeAddress option to the following:

    MasqueradeAddress: ~
  4. Save the changes to the configuration file.
  5. Run the following commands to allow connections through the passive port range of your server's firewall:

    iptables -I INPUT 2 -p tcp --dport 49152:65534 -j ACCEPT
    service iptables save

    Important:

    If your FTP server exists on a CentOS 7, CloudLinux 7, or RHEL 7 server, run the following commands to allow connections through the passive port range that you set:

    firewall-cmd --permanent --zone=public --add-service=ftp
    firewall-cmd --permanent --add-port=49152-65534/tcp
    firewall-cmd --reload
  6. Run the /usr/local/cpanel/scripts/restartsrv_ftpserver command to restart the FTP server.

  7. System updates may overwrite these configuration changes. To make these changes permanent, you must append the passive ports to the configuration file. To do this, run the following commands as the root user:

    echo "PassivePorts: 49152 65534" >> /var/cpanel/conf/proftpd/main
    /usr/local/cpanel/scripts/setupftpserver proftpd --force

For more information about how to edit your Pro-FTPd configuration, read our How to Enable FTP Passive Mode documentation.

SolusVM and Xen

If you use SolusVM and Xen on a CloudLinux™ server, you may experience problems with passive FTP. These problems may resemble a firewall or other connection issue, even when no firewall exists.

To resolve these issues, perform the following steps:

  1. Replace the IPTABLES_MODULES=ip_conntrack_netbios_ns line in the /etc/sysconfig/iptables-config file on the VPS node with the following line:

    IPTABLES_MODULES=ipt_REJECT ipt_tos ipt_TOS ipt_LOG ip_conntrack ipt_limit ipt_multiport iptable_filter iptable_mangle ipt_TCPMSS ipt_tcpmss ipt_ttl ipt_length ipt_state iptable_nat ip_nat_ftp ipt_owner ipt_REDIRECT
  2. Run the service iptables restart command to restart the iptables service.

Troubleshoot FTP passive mode

If your NAT-configured server cannot execute Passive FTP connections to other IP addresses on the server, perform either of the following actions:

  • In cPanel & WHM version 66 and later, set the ForcePassiveIP option with a tilde (~) character. The system interprets this character as an undefined directive and prevents automatic changes to the /etc/pure-ftpd.conf or /etc/proftpd.conf files.
  • In cPanel & WHM version 64 and earlier, follow the directions in our Passive FTP and NAT Configuration Temporary Workaround documentation.

Additional documentation