Would you please help me on these messages? Cause I keep getting those every day, I am wondering there is something happen, but I am not sure how. The source ip is our DNS server and destination ip from outside.
This is a false positive. The DNS server is responding to a client that is using port 69 (the TFTP port). Because the traffic is UDP, the sensor is confusing the DNS traffic as TFTP activity. Something the DNS response matchs the regex for this signatures. Applying a filter for this alarm with the DNS server as a source will eliminate this problem.
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...