What is the easiest way to log what private IP used a Natted public IP at specific window of time. We recently were informed that address 188.8.131.52 (within the scope of our public addresses) was scanning ports on a network.
You could enable logging at the firewall (and forwarding the logs to a syslog server if you have one.) If you set the logging level to informational that will generate alerts as the example below which has both the inside private and public addresses used.
ASA-6-302013: Built outbound TCP connection 94225810 for outside:184.108.40.206/80 (220.127.116.11/80) to inside:10.160.42.68/4057 (18.104.22.168/43498)
To set the logging at this level and to forward to a syslog server enter the following in config mode.
logging trap informational
logging host inside x.x.x.x (inside being the interface associate with the NW where the logging server is and x.x.x.x being the ip address of the logging server.
Please note: this could generate an awful lot of logging information.
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...