ITEM: J2572L

tftp permissions: Error 0: permission denied

QUESTION:
Attempting tftp between two systems.  From one, I can put and get
with no problem.  From the other, can only get. When attempting put,
receive error code 0, permission denied.  I own both directories
and write permission set to 'world write'.  I have no TFTP access
control file....  What am I missing?

A:  After some testing, it appears that there are two conditions
    which could result in an 'Error code 0: Permission denied' message.

    Either:

    1)  The tftpd daemon on the remote machine has been started
        without the "-n" flag which would prevent remote users from
        creating files on the remote host (i.e. rs01-01 in your case),
        or

    2)  The file you are attempting to transfer from the source
        system (i.e. test1 on rs02-02) does not have read permission for
        the user attempting to transfer the file.

    Foregoing the later, check the /etc/inetd.conf file on the target
    system (i.e. rs01-01.tgsc-trng.trs.com) for an uncommented
    tftp entry as follows:

       tftp    dgram    udp    wait    nobody  /etc/tftpd   tftpd -n

    The following entry in must be in the /etc/services file:

       tftp    69/udp

    If you have to modify either of the above, you will need to
    refresh the "inetd" daemon to read the changes.  Perform the
    following:

       \# inetimp
       \# refresh -s inetd

    Then restart the tftp subserver with the following command:
       stopsrc -t tftp
       startsrc -t tftp

    Note: The tftpd will not show up as an active process (i.e. in
    the "ps -ef" output) until it is invoked by a remote user performing
    a tftp to the RISC System/6000.  Thus, to verify that the tftpd
    daemon has been activated, issue the folowing:

       lssrc -t tftp

    The above was extracted from the InfoExplorer article on the "tftpd
    daemon".  This article can be referenced through the Commands
    section or via the command line with "man tftpd".

    Permissions required for the PUT subcommand

    The tftp command uses the nobody account as defined in the /etc/inetd.conf 
    file. The nobody account uses 'other' permissions by default when referencing
    files. Therefore the permissions on the directory that you want
    to transfer a file to must have permissions of 777.  

d rwx rwx rwx
   |   |   |--------other
   |   |
   |   |------------group
   |
   |----------------owner

Actually all you need is the write bit activated for 'group' or 
'owner'.  'Other' must have all its bits activated, plus owner and
group must all be activated as well.  That is why the permissions
for a nobody user using 'other' must be 777.
If you want to restrict permissions, you can change the nobody's 
user group to a certain 'primary group', where only those who belong 
to that group can transfer files to the directory on the remote machine.
The nobody's user group must be changed on the remote machine, where
we are doing the putting a file.

smit user
Change / Show Characteristics of a User
Enter in 'nobody' for user name.
Change the 'PRIMARY Group' to a specified group: system, staff, etc.

If you want to have a file transferred to the same directory on the
remote machine and have the same filename, just do the following:

tftp> put /etc/motd

Notice that there is not a destination path and filename.
This statment will transfer 'motd' to the 'etc' directory on the
remote machine.



Support Line: tftp permissions: Error 0: permission denied ITEM: J2572L

Dated: September 1994 Category: N/A

This HTML file was generated 99/06/24~13:30:43

Comments or suggestions?
Contact us