What does an SSL VPN protect you from vs an IPSec VPN and what are the pros and cons to each?
Pro IPsec VPN:
you can create site-to-site VPNs, allowing multiple hosts to access a remote network at the same time
in this scenario, hosts don't need any additional software to participate in the VPN, allowing for arbitrary operating systems as long as they are able to network
supports client-to-network as well, using a client software
encrypted traffic between VPN gateways cannot (at this time) be
decrypted by third party, without the receiving end noticing
Contra IPsec VPN:
5. requires dedicated hardware in each participating network, usually embedded in a router or gateway firewall.
uses a standard protocol (HTTPS) which is very rarely blocked in public spaces (hotels, free Wifi etc.); IPsec needs ESP, AH protocols, or standard UDP on uncommon high ports (500, 4500).
for limited, predefined access to remote applications, a user only needs a browser and no additional software client. This requires on the SSLVPN gateway a proxy for each application offered.
to support arbitrary applications, hosts need to use a software client for SSLVPN tunnel mode
hosts can only be part of the VPN if there is a browser or a VPN client software available for their OS (figure: printers, measurement probes,...) encryption places an additional CPU load on the host (vs. on the VPN gateway for IPsec)
can be decrypted when intercepted, scanned and re-encrypted (although this will trigger a certificate warning at the client's end).