An equipment tries to download a file by TFTP through the router. This equipement sends a TFTP read request frame to the server. The server answers with a TFTP Option Acknowledgment (opcode 6) frame which is dropped by the inspect module. Reason : illegal TFTP code.
When disabling "inspect tftp", the transfer is OK.
The TFTP OACK is an option extention of the RFC1782.
It seems that this option is not supported by cisco ios fw tftp inspect.
Table of ContentsIntroductionVersion HistoryPossible Future
UpdatesDocuments PurposeNAT Operation in ASA 8.3+ SectionsRule Types
Network Object NATTwice NAT / Manual NATRule Types used per SectionNAT
Types used with Twice NAT / Manual NAT and Network Obje...
Table of Contents Introduction:This document describes details on how
NAT-T works. Background: ESP encrypts all critical information,
encapsulating the entire inner TCP/UDP datagram within an ESP header.
ESP is an IP protocol in the same sense that TCP an...