Hello,

I realize that IPSec can be used with VPNs, but is it commonly used for anything else by default? Everything I've searched for thus far has described VPNs and the use of IPSec. Thanks for your help.

Many years ago there were PPTP and L2TP as well as other types of tunneling/VPN protocols. IPSec was envisioned to be a protection for those protocols, and is. But they also realized that IPSec could just be expanded and used to provide the VPN services from within itself. And for a couple of reasons, you could either encrypt the payload and leave the VPN headers alone, or encrypt all of the data and use IPSec packets to establish your VPN. I forget the pros and cons, they are real arguments, but to me it also boils down to choices as to what form of protection you'd prefer. In one form, people can sniff your traffic and know what two endpoints are talking, but not be able to easily view the payload due to encryption. In the other form, the identities of the endpoints are protected because it has been abstracted via the protocol. I believe that to be the difference. Either case the most common use has been for VPNs. I just don't think the concept caught on of using it point to point solely for encryption. The concept has mainly been for an outsider getting into the network and validating their credentials as being someone who does belong in that network. Otherwise if you're internally connected to the network, then you are already authenticated, so no need.

"IPSec" is the underlying technology of "VPNs" . . .

Thank you both for your responses.