NHC, SNR and FAR

[Nihar Ranjan Mishra]

Hello, Please see this 
https://docs.redhat.com/en/documentation/openshift_container_platform/4.18/html-single/installing_on_any_platform/index#installation-network-connectivity-user-infra_installing-platform-agnostic

I want to know if ICMP message type 13,14 and 5 by any chance is apart of NHC.SNR,FAR operator 

for example  

in case of the health check here -
https://www.medik8s.io/remediation/self-node-remediation/how-it-works/#a-node-with-api-server-access. Tx.

Nihaar

[Or Raz]

Hi Nihar,

Thanks for the question. The OpenShift installation page you linked lists ICMP generically as required for "Network reachability tests" between nodes, so it doesn't break down by specific ICMP message types.
Assuming we are speaking of the ICMP type messages 13 (Timestamp), 14 (Timestamp Reply), and 5 (Redirect), then NHC, SNR, or FAR are not using these kinds of ICMP messages.

Regarding the 3 Medik8s operators:

1. Node Healthcheck Operator (NHC) - Does no network probing at all. It works entirely through the Kubernetes API, watching node.Status.Conditions and comparing them against configured thresholds. No ICMP of any kind.
2. Fence Agents Remediation (FAR) - Delegates to external fence agent binaries (e.g., fence_ipmilan, fence_aws). No ICMP of any kind.
3. Self Node Remediation (SNR)- Operator uses three health-check mechanisms:
1. API server check — HTTP GET to the API server's /readyz endpoint.
2. Peer health check — gRPC over TLS between SNR agent pods.
3. Endpoint health check (optional, control-plane only) — when endpointHealthCheckUrl is configured, SNR pings that endpoint using standard ICMP Echo (Type 8/0).

Is there a reason why you are asking about ICMP message types 13, 14, and 5 concerning Medik8s operators?

Best regards,

Or Raz

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