Re: FTP Permissions question

[Scott Klement <midrange-l@xxxxxxxxxxxxxxxx>]

> What does this directory listing from Windows command line FTP mean?
> -rwx------ 1 GATES 0 85476 Nov 03 01:35 file.edi

When an FTP client requests a directory listing, it sends the command to 
the server, and the server responds with a directory listing. There's 
absolutely nothing in the FTP standard that specifies what this directory 
listing should look like.  It's human readable, so as long as a human can 
figure it out, it's "following the standard".

In this case, it appears that the directory server is trying to make the 
file list look like the Unix "ls" command. But, remember, it doesn't HAVE 
to do this. Any FTP server can send the data in any format it likes, and 
that data may or may not include permission information.

If you assume that this really is a Unix directory, and the LS command has 
been called, then the first bunch of characters lists the permissions for 
3 different groups:

  -rwx------  = the permissions line

it breaks into:  1 char for object type
                 3 chars for owner's permissions
                 3 chars for group permissions
                 3 chars for everyone else's permissions

In this case, the object type is left off (by specifying a "-") which 
means that this is a normal file.

The owner's permissions are "rwx".

The group's permissions are "---" which means no permission (files on Unix 
systems have two owners, a user profile that's an owner, and a group 
profile that's an owner.  You can set the permissions separately for 
each.)

Everyone who's not the owner, or a member of the group, falls into the 
third category, which is also "---" and it also means "no permission".

The next two fields in the display are "GATES 0".  That specifies the 
owner (GATES) and the group profile (0).  In this case, zero means that 
there's no group assigned.

Then comes the file's size, last modification date, and filename.

> Does GATES have full rwx authority?

Maybe.  If this is a Unix system, he does.  If this is a Windows system or 
something else that doesn't actually use Unix-style permissions, then all 
bets are off.

If it's a non-Unix system, they often emulate the way the Unix 
directory listings look to help certain FTP clients that assume that 
they'll be in this particular format.  (Which technically goes against the 
standards, but people do it anyway.)

Since those systems don't have the unix permissions system, they may just 
"fudge" the permissions on the left-hand side in order to make it as 
compatible as possible.  In this case, I don't know that I'd trust the 
permissions.

> I'm logged on as BILL. How can I tell my authority from that display?

If you assume that this is a real Unix LS command, then BILL has no 
authority to the file because he's not the owner, and only the owner is 
listed as having any permissions.

Again, if this isn't a real Unix system with real Unix permissions, all 
bets are off.