Security re FTP

The issue with standard FTP is that the data is not encrypted during transmission. (Of course, another issue is that the username and password for logging into the FTP server isn't encrypted either with normal FTP. But, that's a different problem.) So, the data can be "seen" by someone who can get on the network wire between your PC and the server you are communicating with, and who can capture the packets as they pass by with a packet sniffer or similar device.

Now some people will tell you every packet going everywhere is captured and scanned for valuable information, so you must encrypt everything you move, even the picture of your dog you are uploading to a family picture archive. In reality, you need to make a risk assessment of the data involved, the network you are transmitting over, and who you are worried about getting that data.

If you are using a public, un-encrypted wireless hot-spot, and you are FTPing your tax return in the clear, then we'll give that one a serious level of concern. If you are on a wired-only network, going a across a backbone that only the bankbone provider has access to, and the data is not the core of your personal identity or other highly private data, then your exposure is a lot less. But, there is still exposure. Most dialup and DSL fall into this category. On the other hand, some cable hook-ups provide a shared network wire between you and your neighbors, on which you can "sniff" your neighbors packets as easily as installing ethereal and turning it on. So, not only the employees at the ISP, but every neighbor could technically be watching.

FTP can still be used for some things, but, there are usually other tools available that provide more secure communications if you need it given your particular requirements.

 

It's a problem when someone who might be interested in your data has the ability to get a sniffer on to the network you are transmitting over. Every network has someone, somewhere, that can do monitoring. Every network provider has all kinds of monitoring equipment, even if only to monitor quality of service, with no intention of viewing your private data. But, they still have the ability to "sniff the wire" and capture any unencrypted data you transmit.

Depending upon what server you are ultimately communicating with, your data may pass from your ISP, to a third-party backbone provider, then to the provider that hosts the server, right down to the LAN that server is on. All along the way, the support staff that has direct access to the network could capture and monitor your data packets.

However, you have to consider the likelihood of that happening based upon what network you are using and who/where those people are. Think of the single tree in the massive forest thing here. If you use Monster ISP XYZ and have the type of connection that gives you isolation from the other customers of that ISP, (like many DSL connections provide), then your data is most likely not accessible by your neighbors, but could be monitored by the staff at the ISP. If from there it passes through an even more massive backbone provider and drops into a large Hosting company's network and down to a single server among dozens or hundreds, then it is probably unlikely any of them are watching your FTP packets looking for private data.

On the other hand, places where your data is at much greater risk are: unencrypted wireless networks (anyone person using that wireless access point could be collecting your packets), the LAN at work (co-workers, IT people, the boss possibly watching), your home LAN (family members watching), many shared cable broadband connections (neighbors watching)...

My home ADSL service can't be monitored by neighbors. The lines to each home only carry the traffic for that home. So, the only people who can watch my packets are some of the ISP's support staff. Depending upon what server I'm FTPing to, the staff at the interconnecting backbone provider and at the Hosting company might be monitoring, but that's pretty much it. In those circumstances, I'd use FTP without any concerns for many types of data. But, if I was at work, or on a more shared network connection anywhere, I wouldn't use FTP except for things that are available to others anyway.

As for usernames and passwords being exposed, the image below shows just a piece of an ethereal (packet sniffer software) capture of an FTP session - i.e. the authentication process. You can see that the username and password, along with the text messages of the login dialog, are all freely visible. That is what a person with a sniffer on the network can see.