tftp times out on localhost

Question

On the same server, I can't connect to my in.tftp over localhost name:

$ tftp localhost -c put test.file && echo Sent\!
Transfer timed out.

$ tftp 127.0.0.1 -c put test.file && echo Sent\!
Sent!

Does the tftp centos client ignore the hosts file? Other things seem to work as expected:

$ echo quit|nc localhost 25
220 my.ser.ver ESMTP Postfix
221 2.0.0 Bye

Strace of the time out also indicates the proper IP conversion takes place: http://snipt.org/Giho1/#expand — AXE Labs, Feb 19 '14 at 03:29

score 1 · Answer 1 · answered Feb 19 '14 at 03:42

1

Looking at the strace of the failing command, it turns out that 'localhost' was resolving to '::1' which was a secondary IPv6 entry in the hosts file. My xinet.d/tftp definition had a flag for IPv4 only.

The solution is to either remove the IPv6 hosts entry or remove the IPv4 from the tftp server. This now works:

$ tftp localhost -c put test.file && echo Sent\!
Sent!

answered Feb 19 '14 at 03:42

AXE Labs

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Or have the TFTP server listening on both IPv4 and IPv6. Or IPv6 only. It's a very bad idea to remove the entry from the hosts file. – Michael Hampton Feb 19 '14 at 03:44
Yep. That's what I suspected. – Evan Anderson Feb 19 '14 at 04:06
This just happened to me or Oracle Linux 7. Commented out the IPv6 localhost entry in `/etc/hosts` and it works fine now. – Chad Skeeters Mar 21 '17 at 14:47

tftp times out on localhost

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