How to Disconnect AnyConnect VPN without Losing Whole Internet Connection (No Reboot Required)

In this article, we will discuss how to disconnect from a Cisco Secure Client using AnyConnect VPN without losing your entire internet connection. This will ensure that you can seamlessly switch between VPN and local network without any interruptions or the need to reboot your system.

Understanding the Problem

When using a VPN, your system has two network interfaces: the local network and the VPN network. While connected to the VPN, all your traffic is routed through the VPN, and once disconnected, your system switches back to the local network. However, sometimes when disconnecting from the VPN, you may experience a brief period where your entire internet connection drops, rendering you offline for a few moments.

Key Concepts

To prevent this issue, it is essential to understand the following concepts:

• Routing: The process of forwarding data packets between networks based on their IP addresses.
• DNS: The Domain Name System translates domain names (such as google.com) into IP addresses (such as 172.217.16.174).
• Default Gateway: The network node that forwards data packets to other networks when the destination IP address is not on the local network.

Preventing Internet Connection Loss

To disconnect from AnyConnect VPN without losing your internet connection, follow these steps:

1. Step 1: Check your current routing table
   To view your system's routing table, open the Command Prompt (cmd.exe) or Terminal and execute the following command:
   route print
2. Step 2: Identify the VPN adapter and associated routes
   Look for the adapter name and related routes associated with your VPN connection. Note down the destination network, mask, and gateway for further reference.

   AnyConnect VPN Adapter
    Destination Gateway Genmask Flags Metric Ref Use Iface
    10.0.0.0 10.0.0.1 255.255.255.0 UG 20 0 0 tun0
    

3. Step 3: Modify your system's routing table
   Before disconnecting from the VPN, you need to modify your routing table so that the default gateway remains unchanged. This ensures that your system continues using the local network for internet connectivity.

   Execute the following command:

   route CHANGE 0.0.0.0 0.0.0.0 192.168.1.1 1 Replace 192.168.1.1 with your local default gateway IP address.

4. Step 4: Disconnect from VPN
   Now, you can safely disconnect from your VPN using the Cisco Secure Client or AnyConnect client.

   cisco anyconnect disconnect

5. Step 5: Restore original routing table (Optional)
   If you wish to restore the routing table to its original state, execute the following command:
   route CHANGE 0.0.0.0 0.0.0.0 192.168.1.1 20

• Understanding key networking concepts such as routing, DNS, and default gateway helps you avoid losing internet connectivity when disconnecting from a VPN.
• Before disconnecting from the VPN, modify your routing table to keep the default gateway unchanged.
• After disconnecting from the VPN, restore the original routing table (optional).

References

• Cisco AnyConnect Frequently Asked Questions
• route Command
• Default Gateway