tftp config problem (ltsp)

[Paul Lussier]

sean <tech.junk at verizon.net> writes:

> 	Thanks for the response. You stated what I had discovered just after 
> sending the original message. TFTP is not running. When I started it 
> manually I found the following in the message log, attempted here again.
>
> Nov  4 15:30:30 tardis in.tftpd[10315]: cannot bind to local socket: 
> Address already in use
>
> Not sure what is blocking the socket.
> Would you know how can I check?
> I tried killing and starting a few things, but no luck.

Blindly killing/restarting things is not likely to help.  Rather, it's
more likely to cause problems.  Be deliberate and precise in what you
do, don't flail blindly, you'll knock something over or poke someone's
eye out.  And, as you know, it's all fun and games until someone loses
an eye!

To find what process is bound to a socket, use lsof.  I highly
recommend spending some time with the man page, but briefly, do
something like this:

  sudo lsof -i :www |grep -i listen

  -i [i]   This option selects the listing of files any of whose Internet
           address matches the address specified in i

   An Internet address is specified in the form:
      [protocol][@hostname|hostaddr][:service|port]

So, in the above example, I'm asking lsof to show me all processes
bound to port 80.  This will bring up a fascinating number of
connections if you have an open browser session running on your system :)

You need to be root to access low-numbered/reserved ports, hence the
sudo.  I use grep -i rather than grep LISTEN because it's easier to
type a -i and all lower-case than it is to type in all caps[1][2]

For your tftp problem you'd want something like:

  sudo lsof -i :tftp |grep -i listen
or
  sudo lsof -i :69 |grep -i listen

You could get more specific and specify a protocol or an address:

  sudo lsof -i udp at 127.0.0.1:69
or 
  sudo lsof -i udp:69

Hope that helps.
-- 
Seeya,
Paul

[1] proper key-boards don't have a caps-lock, rather 2 control keys.
[2] And, yeah, with bash, I could type 'listenM-bM-u', but really, why
   bother?