Why Snapshots Could Break Your Virtual ISE Deployment

-

In this article I would like to focus on virtual machines, in particular Cisco ISE virtual machines running on VMware. I will explain why virtual ISE deployments DO NOT support snapshots as well as the potential issues that you could face if snapshots are enabled.


So what is a snapshot?


A snapshot is a copy of a virtual machines disk file (.VMDK) at a particular point in time. VMware allows you to take manual snapshots of a virtual machine or even automatically take snapshots of devices at a specific time. Snapshots are useful in situations where an operational device is rendered useless for whatever reason and you would like to restore that device back to a working state.

So why doesn't Cisco ISE support snapshots?


Cisco ISE comes with its own backup and restore utilities and not only that, Cisco ISE doesn't support backups because the data within the nodes is constantly changing and is being synchronised with the database.

What happens if snapshots are taken of ISE nodes?


If snapshots are taken of ISE nodes, the nodes will freeze and cause services to stop. To resume services, a reboot of the affected ISE node will be required.

Snapshots can seriously affect the deployment to a point where the ISE database becomes corrupted and a complete new install is required of that node again. I've also seen behaviour where the ISE node becomes corrupted but even after an application reset, it still doesn't work as it should.

I don't have access to the VMware environment so how would I know that snapshots may be affecting my ISE deployment?


If the VMware infrastructure is managed by a third party, more often than not you may not have access to the back-end environment. When trying to troubleshoot issues with virtual ISE instances, this can sometimes prove challenging, especially if you need to see whether snapshots are the root cause of issues within your ISE deployment.

Nevertheless, we can often diagnose the issue from ISE. So if you find that you are troubleshooting a potential snapshot issue, take a look at the following points that have been observed on virtual ISE deployments when snapshots are enabled.

  • The ISE node is still reachable via ping however you cannot login via SSH
  • AAA requests to ISE PSN's is failing
  • When I try to access the GUI of the ISE node, it times out
  • I can access the primary PAN but some of the nodes are shown as offline when I check the deployment status

How can I maintain backups ensuring snapshots don't affect my ISE deployment?


  • Ensure automatic snapshots are disabled
  • Ensure the relevant teams are aware that snapshots shouldn't be taken of ISE nodes
  • Configure scheduled backups within ISE
Kelvin Charles - Network and Cyber Security Professional.

Popular Posts

Capturing EAPOL and RADIUS Using Wireshark

-
Image
In this article we are going to take a look at how to capture Extensible Authentication Protocol Over LAN (EAPOL) and Remote Authentication Dial-In User Service (RADIUS) packets using Wireshark. This article can be useful for troubleshooting 802.1x within your environment and can also be used for learning purposes. The following topology has been used to gather the required output for this article. Note: This article will only cover the switch configurations that are required to gather EAPOL and RADIUS configuration. Overview of the Topology The supplicant is configured to perform 802.1x using EAP-TLS as the authentication method The user certificate on the supplicant will be used for authentication The supplicant has Wireshark installed Cisco ISE is used for authentication and authorisation The supplicant is assigned to VLAN 10 upon authentication and all other endpoint ports are assigned to VLAN 99 Sniffer device is running Wireshark in order to capture RADIUS flows via SPAN 802.1x
Read more

Configuring Cisco Smart License Software

-
In this article, I would like to demonstrate how to configure Cisco Smart Licensing on the virtual Cisco Adaptive Security Appliance (ASAv). This post assumes that readers already have access to there own Smart Account and would like to know the process of applying licenses. Step 1: Generate ID Token Sign into your Cisco Software Portal: software.cisco.com and navigate to “Smart Software Licensing” You will now need to create an ID token for your device, this is required for communication between the device and the licensing authority. Follow the steps below to create a new token. Click Inventory >>> General >>> New Token and select your preferred options and enter a description for your token. Once you are happy with your token settings click Create Token . You should now have a token created which can be copied over to the device you wish to license. All commands and output from this point will be related to the ASA so please seek out further advice if you wish
Read more

Cisco :: FXOS Authentication Using TACACS

-
In this article, I will describe how to enable authentication and authorization for Firepower eXtensible Operating System (FXOS) devices. The use case presented in this document illustrates how Cisco Identity Services Engine (ISE) can be utilised with attribute-value pairs (AV-Pairs) to authenticate and authorize users accessing the Firepower Chassis Manager (FCM) or FXOS platforms via TACACS+. At the time of writing this post, I found that limited documentation existed and of that documentation that did exist, the examples given weren’t as straightforward. In an effort to make this process easier for my colleagues and customers to understand I have put together the following instructions based on a previous use case given to me. Extracts of this document have been taken from a wider document I am currently creating. I will update this article with the complete document when it has been finalized. Requirements A ‘Device Administration’ license is required in order to use TACACS+ with
Read more

Configuring Remote Access VPN on Firepower

-
Image
In this article we are going to take a look at how to configure remote access VPN's on Firepower devices. This demonstration is based on the following lab environment: Cisco Virtual Firepower Management Center Cisco Virtual Firepower Threat Defense Cisco ISE 2.6 Windows host with AnyConnect VPN Windows Server 2019 (CA Server) All Firepower devices are running version 6.5 Note: ISE is used for authentication and authorization in the following lab however the configuration elements of ISE are out of scope for this demonstration. Generate a CSR for Remote Access VPN's Those accessing your network remotely need to trust the service you're running. Without the correct trust users could face issues connecting via VPN. With access to the FMC navigate to Objects > Object Management > PKI > Cert Enrollment Assuming you are opting for manual enrollment, select 'Manual' in Enrollment Type and copy the CA Certificate BASE-64 into the field. Now select the 'Certifi
Read more

Kali Linux :: CAM Table Overflow Attack Demonstration

-
Image
As part of my on-going studying for the CCNA Security 210 – 260 certification I have been exploring different types of network attacks, one of which is CAM table overflow attacks. In this article I would like to share what I have learnt and provide a demonstration of the attack carried out in a lab environment. To understand my demonstration, you first need to understand how a CAM table overflow attack works and what happens as a result of the attack.   Switches build Content Addressable Memory (CAM) tables based on mac-addresses and port numbers. When a switch receives a frame it checks the table to see if the source mac-address is already known, if the source mac-address is unknown the switch will add the mac-address to the table along with the port number. The switch then checks the destination layer two frame and if no entry exists the switch broadcasts the frame out of all ports except the port in which the frame was received. Presuming the destination mac-address wants to respond
Read more