VPNs are Virtual Private Networks. These are similar to LANs (Local Access Networks) except that they don’t use actual routers or cables. A VPN is created in a larger network by using virtual circuits or open connections. This allows administrators to segment certain systems of the network to manage them separately.
The Cisco VPN Client is a program that allows users to create VPNs for their organization. It is included in a Cisco’s 5500 Series of security appliances.
The Cisco VPN Error 412 is an error message generated by the Cisco VPN client-side software. The precise error message may vary based on the different versions of the Cisco VPN client. The error message usually reads: “Cisco – Reason 412: The remote peer is no longer responding”.
This means the VPN Client software has detected that the VPN server has deleted the connection and is not responding anymore.
Causes of the Error
- A firewall is blocking the VPN traffic;
- The user is behind a firewall blocking the ports ESP and/or the UDP 4500/500;
- There is poor Internet connection;
- The port 1000 is blocked. This is the default setting for VPN. If the client attempts to connect to TCP, a blocked port will not grant it with access;
- The responses from the server/concentrator aren’t reaching the client;
- Packets of information are not able to reach the VPN concentrator/server. As a result, the client thinks the server is no longer accessible;
- There is a general loss of package;
- Hardware malfunctions either in a network device or a network interface card;
- ACL (Access Control List) is being blocked, thus, requiring the following ports or protocols:
– For PPTP, the TCP port 1723 IP and the protocol 47 are required.
– For IPSec, the IP protocol 51 and the UDP port 500 are required.
- The VPN client is using a NAT (Network Address Translation), making it incompatible with the server. A client with a NAT device should be used with a NAT-T enabled server. The user will not be able to receive or send any traffic at all. VPN can attempt connection but the software will ultimately close it.
Solutions You Can Use
Here are some solutions that you can use to solve Error 412.
- If you are using a wireless connection, try using a cable;
- Turn off your firewall then test the connection to determine whether the problem is still occurring. If the problem is resolved, you can turn your firewall back on and add exceptions for the ports 4500 and 500, as well as for the ESP protocol;
- Switch on NAT-T/TCP in your profile and remember to unblock the port 10000; or
- Revise your profile with your editor and change ForceKeepAlive=0 to 1.