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>]

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