Internet Support: Troubleshooting the 3 Most Common FTP Problems

24. November 2011 Internet Support 0

Welcome back to the last of my three Internet Diagnostic Blogs. Last month I covered Troubleshooting the 4 Most Common Email Errors and the month before it was IT Support for Internet Connection Problems. This month I cover diagnosing the three most common FTP connection problems – FTP Host, FTP Authentication and FTP Configuration. Before delving in, a quick description of FTP clients and servers:

The FTP client is the software you use to make the FTP connection from your computer. There are many clients to choose from, each one of them providing different levels of complexity for the novice and expert user. Most have similar features.

The FTP server is the software your FTP client connects to. The server software communicates with your FTP client and allows files to be uploaded or downloaded, keeping the file’s information on both sides synced so you can verify your files have been transferred properly.


A FTP host is merely the specific site you are connecting to on the FTP server. Some hosts use a static IP address which you direct your FTP client to and others use a domain name which resolves to a static, dynamic or shared IP address (e.g., ftp or

The benefit of using a static IP address is that you don’t have to rely on DNS to find your site. You just go there. The drawback to using a static IP is that some web hosting companies periodically change the IP assigned your domain, and if they don’t notify you quickly you will be unable to connect your FTP client to their FTP server. If you are using a static IP address that previously worked but are now unable to connect, contact your FTP provider and verify your IP address is unchanged and still valid.

Obviously, then, the benefit of using a name to connect to your FTP site is that if the static IP address ever changes it won’t matter because the name will, in theory, always point to the correct IP address (assuming no human errors – like typos – get in the way). However, using a name means you are relying on DNS. I’m not going to spend a lot of time on DNS right now — let me know if you would like me to blog about DNS in one of my future posts — but the main drawbacks to using DNS are:

1. DNS can sometimes break and leave you with no connectivity. This can be overcome by using the static IP assigned to the site as long as the IP address isn’t a shared IP. Sometimes shared IP addresses are not a problem either as long as the user’s authentication is assigned to the FTP site.

2. DNS changes are not fast moving. It can take DNS changes up to 24 hours (and sometimes longer), to propagate across the Internet. Again, the problem can be rectified by using a static IP for the host address.

If you cannot connect to your FTP site and are using a host name to connect, check with your provider to verify they haven’t made any recent DNS changes. If they have, see if they can provide you with a static IP address to use until the DNS changes propagate.


Authentication issues are typically the most common cause for FTP connectivity problems. Problems could be either user name or password related – though typically the latter. I’ve seen times here at Skyway West where we have had to change a FTP password because a customer’s FTP server was hacked and was spewing viruses to the world. We are vigilant about alerting clients to advise them that their password has been changed for security reasons (protect your passwords and avoid uploading infected files), but still there is the chance that they will try their old authentication details and fail to connect. Here are some tips about user settings:

USER NAME (Can also be called login name): This is provided by your ISP. Depending on how security conscious their server is, the name can be upper or lower case sensitive or have a specific minimum or maximum character limit. They may also not allow certain characters in the name.

PASSWORD: Passwords are most certainly case sensitive. Again, some characters may not be allowed and there may be size limitations to the length of your password. If you have issues connecting check with your provider to verify your credentials.

AUTHENTICATION SCHEME: This may sound daunting but it really only refers to the way your client passes your credentials on to the server. Typical options are anonymous, encrypted, password, Interactive or Account. If you are having difficulties connecting you might try verifying these settings with your provider.


If you have had your FTP client working prior to any problems, then configuration issues are probably not the problem. If however, you are making changes as set forth by your provider or are setting up for the first time it might be worthwhile reviewing your settings with your provider.

PROTOCOL: FTP connections require a certain connection protocol. The choices are FTP (File Transfer Protocol or SFTP (SSH File Transfer Protocol)). SFTP provides a more secure level of transfer.

ENCRYPTION: Encryption translates the data you are sending or receiving via FTP into “nonsense” garbage data and converts the data back at the other end. Anyone trying to decipher an encrypted FTP stream will have difficulties translating the code back into something usable. Options are typically No Encryption, Explicit FTP over TLS, or Implicit FTP over TLS.

PROXY: Your network may use a proxy to communicate to the outside world. If this is the case your FTP client must be configured to use it. Contact your IT support to determine and configure any proxy settings that may be required.

FTP PORTS: Think of a port as the passageway you would use to get on board an airplane. Go down the wrong one and you are flying to Japan instead of Toronto. You may also find yourself in a bit of trouble, but I digress. The default FTP port is 21. There are others and you will need to check with your provider to ensure you are using the correct one.

FILE TRANSFER: Files exist as different types. For example a text file is different than a photo file. FTP clients and servers handle them in different ways. Your best option here is to leave the setting at Auto. FTP clients and servers are usually smart enough to determine the file type and treat it properly as the files are transmitted.

FILE TRANSFER MODE: Your server will determine what mode it wants and your client needs to be set up to work with the server. The options are Active, Passive or auto/default. Stick with auto or default unless your provider says otherwise.

The above settings are necessary for connecting and transferring files across your connection. You may find configuring specific settings (as suggested by your provider), improves the speed and strength of your FTP connection. As always, check with your provider for the best options to maximize your FTP experience.

So there you have it: everything you need to know to set up, diagnose and maintain a FTP connection! I hope this and the earlier two segments have been of use to you. I am always looking for thoughts, questions and ideas for future blog posts. Feel free to contact me at with whatever is on your mind. I’ll always address your issues by return email if I don’t get the chance to post it here.