I currently have two IIS websites with windows authentication turned on. Internally on my network when you connect to them you're authenticated seamlessly and logged on. Externally you are prompted to login. This is all fine and expected.
However the two sites reference assets on each other, so going to site A causes not only a prompt to login for site A but also a prompt to login for site B as well.
Is there any kind of server that I can stick in front of the two websites so that the user will only have to authenticate once against that server and then all subsequent authentication is handled by it?