Copying Files Across the Network with FTP

FTP (short for File Transfer Protocol) is a standard method of sending files between computers through a network. The primary difference between FTP and HTTP is that using FTP requires that you identify yourself with a user name (also known as a login) and a password. (Imagine if HTTP were like this. You would have to type in a user name and password every time you clicked a link!) In this part of the lab, you will use FTP to put your first file on the web, i.e., use FTP to make a file publicly available via HTTP. An FTP server is a lot like a bank for files, i.e., a computer on the network with lots of hard disk space that offers individual users access to private storage. Just like with a hard disk on your own computer, you can copy, delete and rename files on an FTP server, as well as maintain folders to keep your files organized. You use FTP client software to connect with an FTP server, just as you use a web browser (web client software) to connect with an HTTP server (web server).

We learned that web pages are stored and delivered from web servers, but how do web pages get to a web server in the first place? Sometimes, web authors create and edit them on the web server directly, but this is not the usual case. Typically, a web author edits a page on their own computer, makes sure the page looks right, then transfers a copy to the web server. As soon as a file is transferred to a web server, it generally becomes publicly available, so working on their own computer helps ensure that there are no mistakes in the pages that actually go on the web, or “go live,” as some people say, borrowing the expression from broadcast media. In this part of the lab, you will follow the same process to put your first file on the web. You will start by posting a plain text file in this lab.

1.  Use a text editor such as Notepad (Windows) or TextEdit (Mac) to create a new text file named bio.txt containing a single line that contains your name, today's date, and a short greeting such as "Welcome visitors."  Save the file on the Desktop.  In the lab, Notepad is located in
Start Menu > All Programs > Accessories > Notepad

2. Using Windows, start SSH Secure File Transfer, an FTP client program.
In the lab, the program can be found in
Start Menu > All Programs > SSH Secure Shell > Secure File Transfer Client
(On Mac, use CyberDuck or other FTP client).

3.  When the application appears, click "Quick Connect".  (Ignore an error message that appears).
Complete two fields for host name and user name.
Click Connect.
(You might see a dialog titled, “Host Identification.” Double-check that you have the hostname right, then click Yes.)
When prompted for your password enter your portal password.
"Add to profile" dialog will flash for a few seconds then disappear.

Note: Your user name and password are the same as your myCalpoly login.

4. The SSH FTP window looks a lot like Windows File Explorer, with the left pane showing a folder hierarchy
and right pane showing files in the currently selected folder. Unlike Explorer, however, the items in the right panel are folders and files on the ftp server, polylog1, not on the computer you are sitting at.

5. Your space on the ftp server is set up with a folder with a special name whose contents can be made accessible via the web.  This “web folder” is named public_html.  Select the web folder by double-clicking it in the right pane to open it.

6. The process of sending a copy of a file to a remote server is called uploading.  To start an upload, simply drag the bio.txt file from the left pane and drop it in the right pane.

When the transfer is complete, you should see the file in the right pane of the SSH ftp window.

7. Now you should verify that the file is available on the web. The URL for the file you just uploaded is shown below, except put your Cal Poly username in place of yourusername.

http://www.calpoly.edu/~yourusername/bio.txt

Leave SSH ftp open for now, and open a web browser window with the URL of your newly uploaded file. You should see the file’s contents in your browser window.

TROUBLESHOOTING:
If you are not able to access your text file using your web browser, do not panic. Start by identifying what kind of problem the server is having. Check the title bar of your browser window for an error code number and a brief description of the error. Here are some tips for dealing with the more common errors:
“404 Not Found” – Your URL specifies a file that does not exist on the server. Double-check all parts of the URL, especially the hostname, your user name, and the filename itself.
“Permission Denied” – The server has located the file, so your URL is correct, but the file’s properties on the server are set such that it is not publicly readable. See the next step for how to fix this.
“Cannot Find Server or DNS Error” – The hostname part of the URL is probably mistyped. Recall that DNS is the system by which hostnames are converted into IP addresses. If you request a host whose name is not registered with DNS, you will get this error.