Opening custom port for a Passive mode FTP Server

09/30/2022 322 People found this article helpful 486,656 Views

Description

File Transfer Protocol (FTP) operates on TCP ports 20 and 21 where port 21 is the Control Port and 20 is Data Port. However, when using non-standard ports (eg. 2020, 2121), SonicWall drops the packet as it is not able to identify it as FTP traffic. A new option has been introduced to set custom control port for FTP traffic called "Enable FTP Transformations for TCP port(s) in Service Object". Enabling this option would help SonicWall identify traffic to and from the custom port as FTP traffic.

This article describes the method to set a custom control port for FTP.

Resolution

Resolution for SonicOS 7.X

This release includes significant user interface changes and many new features that are different from the SonicOS 6.5 and earlier firmware. The below resolution is for customers using SonicOS 7.X firmware.

In this scenario we have an FTP server behind the SonicWall listening on port 2121 configured in Passive Mode. The configuration would be the same if the server is configured in Active Mode also.

Click OBJECT in the top navigation menu
Navigate to the Match Objects| Addresses page.
Click on Add
Create an Address Object for the private IP address of the FTP server.
Click on Save
Click OBJECT in the top navigation menu
Navigate to the Match Objects| Services page.
Click on Add
Create an Service Object for the private IP address of the FTP server.
Click on Save
Create the following Access Rule and NAT Policy.
Click Policy in the top navigation menu
Click on Add
Create the access rule as below
Click on ADD
Click Manage in the top navigation menu
Navigate to Rules and Policies | NAT Rules
Click on Add
Create the NAT Policy as below
Click on ADD
Select the address object for the custom service under Enable FTP Transformations for TCP port(s) in Service Object on the Network | Firewalll Settings | Advanced page.

Resolution for SonicOS 6.5

This release includes significant user interface changes and many new features that are different from the SonicOS 6.2 and earlier firmware. The below resolution is for customers using SonicOS 6.5 firmware.

In this scenario we have an FTP server behind the SonicWall listening on port 2121 configured in Passive Mode. The configuration would be the same if the server is configured in Active Mode also.

Click Manage in the top navigation menu
Navigate to the Objects| Address Objects page.
Click on Add
Create an Address Object for the private IP address of the FTP server.
Click on ADD

Click Manage in the top navigation menu
Navigate to the Objects | Services page
Click on Add
Create the custom Service for the FTP Server.
Click on ADD

Create the following Access Rule and NAT Policy.

Click Manage in the top navigation menu
Navigate to Rules | Access Rules
Click on Add
Create the access rule as below
Click on ADD

Click Manage in the top navigation menu
Navigate to Rules | NAT Policies
Click on Add
Create the NAT Policy as below
Click on ADD

Select the address object for the custom service under Enable FTP Transformations for TCP port(s) in Service Object on the Firewalll Settings | Advanced page.

Resolution for SonicOS 6.2 and Below

The below resolution is for customers using SonicOS 6.2 and earlier firmware. For firewalls that are generation 6 and newer we suggest to upgrade to the latest general release of SonicOS 6.5 firmware.

In this scenario we have an FTP server behind the SonicWall listening on port 2121 configured in Passive Mode. The configuration would be the same if the server is configured in Active Mode also.

Navigate to the Network | Address Objects page.
Create an Address Object for the private IP address of the FTP server.

Navigate to the Network | Services page
Create the custom Service for the FTP Server.

Create the following Access Rule and NAT Policy
Access Rule under Firewall | Access Rule
NAT Policy under Network | NAT Policies

Select the address object for the custom service under Enable FTP Transformations for TCP port(s) in Service Object on the Firewalll Settings | Advanced page.

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Opening custom port for a Passive mode FTP Server

Description

Resolution

Resolution for SonicOS 7.X

Resolution for SonicOS 6.5

Resolution for SonicOS 6.2 and Below

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