Troubleshooting IPsec Tunnels with NSX-T Edge CLI

When building a cloud with VMware vCloud Director or using NSX-T, you may encounter issues with IPsec tunnels. These tunnels are crucial for secure communication between your environment and other networks, but their negotiation process can be complex and prone to misconfiguration. Unfortunately, the NSX-T UI often provides generic error codes, making it challenging to diagnose the problem. However, the NSX Edge CLI offers more detailed logging options to help you troubleshoot these issues. In this blog post, we will explore how to use the Edge CLI to investigate and resolve IPsec tunnel issues.

Connecting to the Edge

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To start, you need to connect to the Edge via SSH. The easiest way to find the Edge hosting the Service Router of the session you want to troubleshoot is by searching for the session in the NSX-T GUI. Once you have identified the corresponding Tier-1 Gateway, click on the HA mode to view the currently active Edges. Connect as the NSXCLI-User (admin is the default).

Checking the IPsec VPN Service

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Before diving into logging, you should first ensure that the ipsecvpn service is running without any errors. You can check this by using the following command:

“`

show ipsecvpn

“`

This command will display information about all IPsec VPN services on the Edge. If there are any issues, you will see an error message indicating the problem.

Enabling Logging for Specific Sessions

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To troubleshoot specific sessions, you need to enable logging for those sessions. You can do this by using the following command:

“`

set session-logging enable follow

“`

Replace “ with the ID of the session you want to log. The `follow` key tells the Edge to display the log output directly in the console until you press CTRL+C.

Viewing IKE Negotiation Logs

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To view the IKE negotiation logs, you can use the following command:

“`

show ike-negotiation follow

“`

Replace “ with the ID of the session you want to log. This command will display the IKE negotiation logs for the specified session in real-time.

Filtering Log Entries

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To filter log entries based on specific criteria, you can use the `find` command with the pipe operator (`|`). For example, to view only IKE SA established logs, you can use the following command:

“`

show ike-negotiation follow | find “IKE SA Established”

“`

You can filter by multiple criteria by using multiple `find` commands.

Stopping Logging

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To stop logging for a specific session, you can use the following command:

“`

set session-logging disable

“`

Replace “ with the ID of the session you want to stop logging for.

Scraping Metrics with NSX Application Platform

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If you have installed the NSX Application Platform, you can use its REST API to scrape metrics such as CPU utilization, memory usage, and network traffic. This can help you identify potential issues before they become critical.

Outdated Versions

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Please note that this walkthrough is based on an outdated version of NSX-T. For the latest updates, please see the updated version of this post.

Conclusion

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Troubleshooting IPsec tunnels with NSX-T Edge CLI can be a complex process, but it provides valuable insights into the negotiation process. By enabling logging for specific sessions and filtering log entries based on criteria, you can identify and resolve issues more efficiently. Additionally, scraping metrics with the NSX Application Platform can help you proactively address potential problems before they impact your environment.