Re: bin/49868: tftpd(8) doesn't play well with clients that return acknowledgements to the broadcast address

[John Nemeth <jnemeth%cue.bc.ca@localhost>]

The following reply was made to PR bin/49868; it has been noted by GNATS.

From: John Nemeth <jnemeth%cue.bc.ca@localhost>
To: gnats-bugs%NetBSD.org@localhost, gnats-admin%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost
Cc: 
Subject: Re: bin/49868: tftpd(8) doesn't play well with clients that return acknowledgements to the broadcast address
Date: Thu, 30 Apr 2015 10:52:55 -0700

 On Apr 30,  5:10pm, buhrow%nfbcal.org@localhost wrote:
 }
 } >Number:         49868
 } >Category:       bin
 } >Synopsis:       Clients that return acks to the brodcast address can't talk to our tftpd(8) server
 } >Responsible:    bin-bug-people
 } >State:          open
 } >Class:          sw-bug
 } >Arrival-Date:   Thu Apr 30 17:10:00 +0000 2015
 } >Originator:     Brian Buhrow
 } >Release:        NetBSd-current and all prior releases
 } >Environment:
 } 	
 } System: NetBSD lothlorien.nfbcal.org 5.2_STABLE NetBSD 5.2_STABLE (RBL) #0: Thu Mar 27 10:15:56 PDT 2014 buhrow%lothlorien.nfbcal.org@localhost:/usr/src/sys/arch/i386/compile/RBL i386
 } Architecture: i386
 } Machine: i386
 } >Description:
 } 
 } Some Cisco equipment have firmware recovery software in them that includes
 } a tftp client which can be used to reflash the device with fresh firmware
 } in the event that the original firmware became unusable.
 } This tftp client is broken in the sense that when it returns
 } acknowledgements to the tftp server as its receiving data, rather than
 } sending those acks to the unicast address representing the server's IP
 } address, it sends them to the broadcast address.  To illustrate, here is a
 } tcpdump showing the problem in action.
 
      I would say the bug is that tftpd responds to broadcast at
 all.  What happens if you have more then one tftpd on a network
 segment?
 
 }-- End of excerpt from buhrow%nfbcal.org@localhost