A consultant will be installing an agent in some of our internal servers so they can monitor them from the outside. This agent needs to talk to an specific IP as well as Port on the outside interface and the communication is bidirectional. I don't have enough outside IPs to do a one to one translation so I am reaching out to you to see what is the best way to accomplish this.
This is what I would do:
1. Create an object group with all the servers
2. Create an access list with the above object group to allow the agent access to the specified IP and port #
3. Deny statement to block the rest of the traffic
If you have a group of servers that needs to be mapped on the outside interface of the ASA, then that migth be a problem, because although you can do port forwarding on the outside interface of the ASA, that is also a one-to-one nat, so if one server uses the port 443 on the outside interface then the other servers would not be able to use it.
After gathering more information, I found out that the agent only needs access to the outside so there is no need for a one-to-one translation. What I did was, I created an object group that contains all the servers in question and create an ACL allowing IP traffic from the object group to the destination on port XXXX and added another statement to deny any other traffic.
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...