AWS VPC VPN Test

Amazon VPC (Virtual Private Cloud) lets you provision a logically isolated section of the Amazon Web Services (AWS) cloud where you can launch AWS resources in a virtual network that you define. You have complete control over your virtual networking environment, including selection of your own IP address ranges, creation of subnets, and configuration of route tables and network gateways.

By default, instances that you launch into a virtual private cloud (VPC) cannot communicate with your own network. You can enable access to your network from your VPC by attaching a virtual private gateway to the VPC, creating a custom route table, updating your security group rules, and creating an AWS managed VPN connection. A VPN connection refers to the connection between your VPC and your own network. Each VPN connection has two tunnels, with each tunnel using a unique virtual private gateway public IP address. It is important to configure both tunnels for redundancy. When one tunnel becomes unavailable (for example, down for maintenance), network traffic is automatically routed to the available tunnel for that specific VPN connection.

To ensure continuous communication between the VPC and the network therefore, administrators should track the status (up/down) of both tunnels and make sure that at least one tunnel is up and running at all times. Since a VPN tunnel comes up only when traffic is generated from the customer-side of the VPN connection, administrators must keep an eye on the incoming and outgoing traffic on each tunnel to determine whether the absence of traffic is what caused a tunnel to go down. To quickly detect that a tunnel is down and to rapidly diagnose its root-cause, administrators can use the AWS VPC VPN Test.

For each VPN tunnel configured for the AWS VPC, this test reports the status of that tunnel and the amount of traffic flowing in the tunnel. This way, the test alerts administrators when a tunnel goes down or is idle.

Target of the test: Amazon EC2 Cloud

Agent deploying the test : A remote agent

Outputs of the test : One set of results for each VPN tunnel.

Configurable parameters for the test
Parameter Description

Test Period

How often should the test be executed.

Host

The host for which the test is to be configured.

AWS Access Key, AWS Secret Key, Confirm AWS Access Key, Confirm AWS Secret Key

To monitor an Amazon EC2 instance, the eG agent has to be configured with the access key and secret key of a user with a valid AWS account. For this purpose, we recommend that you create a special user on the AWS cloud, obtain the access and secret keys of this user, and configure this test with these keys. The procedure for this has been detailed in the Obtaining an Access key and Secret key topic. Make sure you reconfirm the access and secret keys you provide here by retyping it in the corresponding Confirm text boxes.

Proxy Host and Proxy Port

In some environments, all communication with the AWS EC2 cloud and its regions could be routed through a proxy server. In such environments, you should make sure that the eG agent connects to the cloud via the proxy server and collects metrics. To enable metrics collection via a proxy, specify the IP address of the proxy server and the port at which the server listens against the Proxy Host and Proxy Port parameters. By default, these parameters are set to none , indicating that the eG agent is not configured to communicate via a proxy, by default.

Proxy User Name, Proxy Password, and Confirm Password

If the proxy server requires authentication, then, specify a valid proxy user name and password in the Proxy User Name and Proxy Password parameters, respectively. Then, confirm the password by retyping it in the Confirm Password text box. By default, these parameters are set to none, indicating that the proxy sever does not require authentication by default.

Proxy Domain and Proxy Workstation

If a Windows NTLM proxy is to be configured for use, then additionally, you will have to configure the Windows domain name and the Windows workstation name required for the same against the Proxy Domain and Proxy Workstation parameters. If the environment does not support a Windows NTLM proxy, set these parameters to none.

Exclude Region

Here, you can provide a comma-separated list of region names or patterns of region names that you do not want to monitor. For instance, to exclude regions with names that contain 'east' and 'west' from monitoring, your specification should be: *east*,*west*

VPN Filter Name

By default, this parameter is set to Vpn Id. In this case, the test will report metrics for each VPN. If required, you can override this default setting by picking the Tunnel Ip Address option from this drop-down. In this case, the test will report metrics for each tunnel in each VPN.

Measurements made by the test
Measurement Description Measurement Unit Interpretation

Tunnel state

By default, this test reports the current state of the tunnels in this VPN.

If the VPN Filter Name is set to Tunnel Ip Address, then this measure will report the state of this tunnel.

The values that this measure reports and their corresponding numeric values are listed in the table below:

Measure Value Numeric Value

Up

1

Down

0

If both the tunnels in a VPN are down, then this measure will report the value Down for that VPN. If both the tunnels in a VPN are up and running, or if only one of the tunnels is up, then this measure will report the value Up for that VPN. In this case, you can configure the VPN Filter Name parameter of the test to Tunnel Ip Address and determine which tunnel in the VPN is down.

Typically, a VPN tunnel comes up when traffic is generated from your side of the VPN connection. The virtual private gateway is not the initiator; your customer gateway must initiate the tunnels. If your VPN connection experiences a period of idle time (usually 10 seconds, depending on your configuration), the tunnel may go down. To prevent this, you can use a network monitoring tool to generate keepalive pings; for example, by using IP SLA.

Note:

By default, this test uses the Measure Values listed in the table above to indicate the state of a tunnel. In the graph of this measure however, the same is indicated using the numeric equivalents only.

Tunnel incoming data

By default, this test indicates the total amount of data received through both the VPN tunnels in this VPN.

If the VPN Filter Name is set to Tunnel Ip Address, then this measure will report the amount of data received through this tunnel.

KB

This metric counts the data after decryption.

If a VPN tunnel goes down very often, you may want to check if the value of the 'Tunnel incoming data' and 'Tunnel outgoing data' measures is consistently 0 for that tunnel. Lack of traffic on the tunnels is a common reason for VPN tunnels to fail. There is a vendor-specific VPN idle time for policy based VPN connections. If there is no traffic through the VPN tunnel for that duration, the IPsec session can be torn down.

For tunnels going down due to idle timeout, be sure there is constant bidirectional traffic between your local network and VPC. Consider setting up a host that sends one ICMP requests every 5 seconds to an instance in the VPC that responds to ICMP. This allows the tunnel to stay up as it continues to respond to the ICMP requests, and makes sure that there are packets being encrypted and decrypted across the tunnel.

Tunnel outgoing data

By default, this test indicates the total amount of data sent through both the VPN tunnels in this VPN.

If the VPN Filter Name is set to Tunnel Ip Address, then this measure will report the amount of data sent through this tunnel.

KB

This metric counts the data after encryption.

If a VPN tunnel goes down very often, you may want to check if the value of the 'Tunnel incoming data' and 'Tunnel outgoing data' measures is consistently 0 for that tunnel. Lack of traffic on the tunnels is a common reason for VPN tunnels to fail. There is a vendor-specific VPN idle time for policy based VPN connections. If there is no traffic through the VPN tunnel for that duration, the IPsec session can be torn down.

For tunnels going down due to idle timeout, be sure there is constant bidirectional traffic between your local network and VPC. Consider setting up a host that sends one ICMP requests every 5 seconds to an instance in the VPC that responds to ICMP. This allows the tunnel to stay up as it continues to respond to the ICMP requests, and makes sure that there are packets being encrypted and decrypted across the tunnel.