I've been doing this with content filters and trying to add/remove headers as necessary.
We have an internal group that generates automated emails to clients. The problem is they are less than confident in the solution on their end, so they want the IP to do checking incase their solution barfs.
So, they want to allow attachments of (pdf|doc|docx) but that's it. A .txt or any other attachment should get blocked.
All works well when there is one attachment, but if there is a .eafsdf and a .pdf, the pdf causes it to pass. Doing a not (!) in front of the file types and setting the header value doesn't seem to work either (reminds me of the wireshark filters). I'm a little confused how to match a true on one file and a false on the other since I don't see how particularly the content filters are handling it.
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...