Wednesday May 20, 2009

Bizarre ftp Behaviour

After spending couple of hours editing a webpage, I lost all that effort when copying the file to my webserver. And of course before the automatic backup had been made. :-(

As always, there is a lesson to be learned.

Try this yourself:

$ ftp webserver

ftp> prompt
Interactive mode off.

ftp> mput *
local: img_2.gif remote: img_2.gif
227 Entering Passive Mode (192,168,32,72,126,33)
150 Opening BINARY mode data connection for img_2.gif.
226 Transfer complete.
12980 bytes sent in 4.2e-05 seconds (3e+05 Kbytes/s)
local: img_3.jpg remote: img_3.jpg
227 Entering Passive Mode (192,168,32,72,126,33)
150 Opening BINARY mode data connection for img_3.jpg.
226 Transfer complete.
28488 bytes sent in 0.017 seconds (1.6e+03 Kbytes/s)
local: webpage.html remote: webpage.html
227 Entering Passive Mode (192,168,32,72,164,239)
150 Opening BINARY mode data connection for webpage.html.
226 Transfer complete.
12498 bytes sent in 4.5e-05 seconds (2.7e+05 Kbytes/s)

ftp> ls *
227 Entering Passive Mode (192,168,32,72,219,226)
150 Opening ASCII mode data connection for /bin/ls.
total 268
-rw-r--r--    1 wwwillem wwwillem    12980 May 20 09:08 img_2.gif
-rw-r--r--    1 wwwillem wwwillem    28488 May 20 09:08 img_3.jpg
-rw-r--r--    1 wwwillem wwwillem    12498 May 20 09:08 webpage.html
226 Transfer complete.

ftp> ls -l
227 Entering Passive Mode (192,168,32,72,207,63)
150 Opening ASCII mode data connection for /bin/ls.
total 268
-rw-r--r--    1 wwwillem wwwillem    12980 May 20 09:08 img_2.gif
-rw-r--r--    1 wwwillem wwwillem    28488 May 20 09:08 img_3.jpg
-rw-r--r--    1 wwwillem wwwillem    12498 May 20 09:08 webpage.html
226 Transfer complete.

So far all has gone well. Notice the file-size of webpage.html, 12 kB.

Now comes the problem:

ftp> ls -l *html
227 Entering Passive Mode (192,168,32,72,142,146)
150 Opening ASCII mode data connection for /bin/ls.
226 Transfer complete.

ftp> quit
221-Thank you for using the FTP service on webserver.
221 Goodbye.

$ ls -l webpage.html
total 62
-rw-r--r-- 1 willem willem   209 May 20 09:07 webpage.html

Notice how the file has shrunk from 12 kB to only couple of hundred bytes? Let's have a look at the (new) content.

$ cat webpage.html
total 123
-rw-r--r-- 1 willem willem 12980 May 20 09:01 img_2.gif
-rw-r--r-- 1 willem willem 28488 May 20 09:01 img_3.jpg
-rw-r--r-- 1 willem willem   209 May 20 09:07 webpage.html

What happened here? The 'ls *' ftp command was ok, same for 'ls -l'. However when we did 'ls -l *html', the result of the 'ls -l' command was written to the local html file, in this case webpage.html. That's definitely not what I would have expected to happen. Very weird behaviour!!

Finally, the client was ftp on CentOS 5 and the server was an ancient RedHat 6.2 server. And no, 6.2 is not the successor of EL5. :-)