Submit a ticketCall us

WebinarWebinar: A checklist for planning your Network Performance Monitor (NPM) upgrade

Are you ready for your next upgrade? To help you plan smoothly, join this webcast to learn more about, SolarWinds® Orion® Installer, SolarWinds Upgrade Advisor, Upgrades Guides, Training Videos, and other resources available. We’ll share key upgrade planning considerations, lessons learned from customers with practical advice from SolarWinds Product Experts. We’ll also give practical tips to identify the estimated time needed and resources, how to prepare the business and IT staff for changes, ways to plan for required system changes, and more.

Register now.

Home > Success Center > Serv-U Managed File Transfer & Serv-U FTP Server > Serv-U - Knowledgebase Articles > FTP Client and FTP Server display a different PASV response when using Windows Firewall

FTP Client and FTP Server display a different PASV response when using Windows Firewall

Updated May 5, 2017


There are cases where the Windows Firewall changes the outbound passive (PASV) mode response from Serv-U to an FTP client. The Serv-U log shows the proper PASV port specified under Server > Settings > Advanced. The client's log, however, indicates a different port. 

Use the following formula to calculate the PASV port:

Note: The port is specified in the last two numbers in a PASV response.

((The second to the last set of numbers x 256) + port number)


For example:

227 Entering Passive Mode (127,0,0,1,195,80).

((195 x 256) + 80) =50,000



All Serv-U versions


The issue is caused by the default FTP Server rule included in the firewall for port 21, which is designed for the Windows FTP service.


  1. Open the Windows Firewall configuration page through Control Panel > Windows Firewall.
  2. Click Advanced.
  3. Click Network Connection Settings > Settings.
  4. Highlight the appropriate network interface. If more than one shows in the list, select the network interface first.
  5. Clear the FTP Server option from the Services list.

The Windows Firewall should no longer modify Serv-U's PASV response. 




Last modified