No authentication popup received when accessing an FTP site while using FTP over HTTP in Explicit

Products

• Advanced Secure Gateway Software - ASG
• ProxySG Software - SGOS

Issue/Introduction

The purpose of this article is to provide an explanation to the behavior that the browsers have when trying to log into an FTP server using FTP over HTTP and going through the ProxySG.

 

Cause

Every browser treats FTP over HTTP connections differently, and some of them require some extra considerations that should be taken into account to prevent issues related to this area.

Resolution

There are some workarounds that can be applied depending on the browser in use.

Mozilla Firefox:
FTP over HTTP prompts the clients for username and password after passing the username via de URL such as ftp://user@domain

Internet Explorer:
Popup isn't supported. IE requires the username and password to be sent in the request like this: ftp://user:password@domain

Google Chrome:
Even if credentials are sent in the URL (such as in IE), the browser will send an "anonymous" user upstream, and if this user is not supported by the server, it will just reset the connection. This means non-anonymous FTP over HTTP access is not possible in Chrome.

We strongly recommend using an FTP client such as Filezilla or WinSCP for this purpose, as browsers are implementing more and more security measures to prevent these kinds of connections. See articles TECH247427 and TECH247429 find out more about the required configuration using those two clients.