I have a couple FTP servers setup which I am unable to access using a particular client machine. The client is a Windows 2012 server in my company's network over which I do not have admin rights. The client has WinSCP installed as its FTP client, and is unable to use either of the FTP servers I have setup. Other machines have no problem connecting to the FTP servers, so my problem is isolated to my Windows 2012 client.
The specific protocol I am using on the WinSCP client is FTP with either (1) no encryption, or (2) TLS explicit encryption. One of the FTP servers does not have any certificates installed, so to connect to that one requires no encryption (we will call this FTP server A). The other FTP server does have a certificate installed, so TLS Explicit encryption is required to connect to it (we will call this FTP server B).
When attempting to connect with the FTP client, the specific WinSCP error message just says "Access denied". I know that the client machine from which I am having issues establishing a FTP connection has a firewall configured, but I was told from my system admin that ports 20, 21, and 990 had been opened for allowing connections.
- Are ports 20, 21, and 990 the ports required for utilizing FTP with either no encryption or TLS explicit encryption?
- Is there a way that I can check these ports as a user to see whether or not they actually are open? I have heard that the TRACERT command might be useful, but I do not know how to use it to diagnose this particular problem.
I have admin rights to the FTP servers themselves, so perhaps I can monitor or reconfigure anything on that end to diagnose the problem. However, I think that would generally be a step in the wrong direction, since no other FTP clients are experiencing issues with either FTP server.
The FTP servers are both Windows 2008 R2 boxes with Filezilla as their FTP server software.