Securely exposing an internal server to the internet
I have an internal web server that I need to expose to a large range of external addresses on port 80 only, and we may or may not be able to find out all of these addresses (although we may be able to verify that these address are correct via a reverse DNS lookup), hence for all intents and purposes we will need to expose the server to the Net.
Ordinarily I would place this server in a DMZ etc, pretty straightforward, however in this instance a DMZ will be tricky.
The server is on a large server Vlan that terminates on the collapsed core, the core then routes traffic to the ASA. Now I could create a DMZ and NAT the server to the Net through the DMZ however if this server were compromised it would be able to bounce around its own Vlan (and it does need acces to other servers within its own Vlan), and possibly other Vlans within the wider network via the core.
Locking down this servers in and out traffic to the core will be tricky as constant changes will need to be made to accomodate the changing access requirements of this server.
Is there any method by which this server can be exposed to the net without leaving it wide open, can for instance an ASA act as a reverse proxy?
You may also want to put your server into a PVLAN to prevent it talking to other devices in the subnet in the event of a compromise. You could then further constrain it by using an ACL on the subnets SVI.
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...