This process of decrypting the packet, checking its entire content, modifying it to point to the correct location and then sending it on is what slows everything down. You can see this simply by putting your cursor over any link on a web page that is being seen in a SSL VPN browse. That way if you click on one of those links within the SSL VPN browser window the new request will also go to the VPN concentrator. Every one of those HTML tags, as it passes through the concentrator back towards your browser, has to be modified to point to. For example, let's say your internal web server main index page that has a bunch of links pointing to otehr pages on this server. Any URL or location field within every HTML page also has to be modified so that it to points to the concentrator and not to straight to the internal server (which is inaccessible unless coming in over an SSL VPN). Just look in your browser's URL location when browsing to a web site behind the VPN concentrator, the browser is actually pointing at the VPN concentrator, right? The VPN concentrator grabs this HTML packet, decodes it and then forwards it onto the internal web server. Not only are the HTTPS packets decrypted, but the concentrator becomes basically a proxy server as well, having to inspect (and change) the data portion of the packet.

SSL VPN on the other hand is a whole different process. The same thing happens in the other direction.

It has not so much to do with the encryption as to the basic functions of how each type of VPN works.Ī standard IPSec client VPN is fairly simple, encrypted packets come into the concentrator, they're decrypted in hardware and the entire decrypted packet is simply forwarded on into the the internal network.

Why ssl vpn