I have server which IP address is whitelisted in some external system. And also, I have a few software developers with dynamic IPs which develop software and they need to connect to external system, but their IPs are not whitelisted, and cannot be whitelisted, because they are dynamic ones.
So, I have server with IP 1.2.3.4 which connects to external system and that system knows (by firewall rule, etc) that 1.2.3.4 is in white list and allow connection. But developers have dynamic IP (a few class B networks, no way to whitelist so many addresses).
Is there any software, TCP/IP port forwarding proxy, or whatever the correct name is, to allow developer connect to external system using server IP address? So instead of IP address of external system developer will connect to server and server will forward traffic to external system.
I do not want to force developers to install some proxy client or change system-wide settings other way.
Update:
I'm really really sorry. Server is Windows Server 2008 R2. I missed so important information 🙁
Best Answer
One of the options is setting up a VPN - a Virtual Private Network. One of such solutions is OpenVPN.
Though you don't want clients to install anything, thus you may need an alternative.
The alternative might be DNAT. Its configuration depends on OS that is installed on your intermediate server. In case you want your clients to authenticate somehow you may consider port knocking.
EDIT:
Since you said your server runs Windows Configuring Network Address Translation (NAT) in Windows Server 2008 article might help.