Split tunneling is a feature that you can use in order to define the traffic for the subnets or hosts that must be encrypted. Client can use the Internet (browser) and VPN connection in parallel. This involves the configuration of an Access Control List (ACL) that will be associated with this feature. The traffic for the subnets or hosts that are defined on this ACL will be encrypted over the tunnel from the client-end, and the routes for these subnets are installed on the PC routing table.
Complete these steps in order to move from the Tunnel-all (default) configuration to the Split-tunnel configuration:
Navigate to Configuration > Remote Access VPN > Group Policies:
Click Edit, and use the navigation tree in order to navigate to Advanced > Split Tunneling. Uncheck the Inherit checkbox in the Policy section, and select Tunnel Network List Below from the drop-down menu:
Uncheck the Inherit checkbox in the Network List section, and click Manage in order to select the ACL that specifies the LAN network(s) to which the client needs access:
Click Standard ACL, Add, Add ACL, and then ACL name:
Click Add ACE in order to add the rule:
Once connected, the routes for the subnets or hosts on the split ACL are added to the routing table of the client machine. On Microsoft Windows machines, this can be viewed in the output of the route print command. The next hop for these routes will be an IP address from the client IP pool subnet (usually the first IP address of the subnet):
C:\Users\admin>route print IPv4 Route Table ====================================================================== Active Routes: Network Destination Netmask Gateway Interface Metric 0.0.0.0 0.0.0.0 10.106.44.1 10.106.44.243 261 10.10.10.0 255.255.255.0 10.10.11.2 10.10.11.1 2 !! This is the split tunnel route.
On MAC OS machines, enter the netstat -r command in order to view the PC routing table:
$ netstat -r Routing tables Internet: Destination Gateway Flags Refs Use Netif Expire default hsrp-64-103-236-1. UGSc 34 0 en1 10.10.10/24 10.10.11.2 UGSc 0 44 utun1 !! This is the split tunnel route.