microsoft · Mereta (mereta) · Aug 27, 2026
@@ -45,7 +45,7 @@ Apply to both Agent and Operator.
 ## Agent Configuration
 
 * `logLevel`: Define the level of logs to store.
-* `enabledPlugin_linux`: List of enabled plugins.
+* `enabledPlugin_linux`: List of enabled plugins. See the [plugin list](../03-Metrics/plugins/readme.md) for valid names and operating-system availability.
 * `metricsInterval`: Interval for gathering metrics (in seconds). (@deprecated, use `metricsIntervalDuration` instead)
 * `metricsIntervalDuration`: Interval for gathering metrics (in `time.Duration`).
 * `enablePodLevel`: Enables gathering of advanced pod-level metrics, attaching pods' metadata to Retina's metrics.

@@ -40,8 +40,13 @@ The table below outlines the different metrics generated.
 | **networkobservability_dns_request_count**     | Total DNS request count | | ✅ | ❌ |
 | **networkobservability_dns_response_count**    | Total DNS response count | | ✅ | ❌ |
 | **networkobservability_windows_hns_stats**     | Windows HNS statistics (packets sent/received) | `direction` | ❌ | ✅ |
-| **networkobservability_node_connectivity_status** | Connectivity status between nodes (1=connected, 0=not) | `source_node_name`, `target_node_name` | ✅ | ✅ |
-| **networkobservability_node_connectivity_latency_seconds** | Latency in seconds between nodes | `source_node_name`, `target_node_name` | ✅ | ✅ |
+| **networkobservability_node_connectivity_status** | Deprecated; registered but not populated | `source_node_name`, `target_node_name` | ❌ | ❌ |
+| **networkobservability_node_connectivity_latency_seconds** | Deprecated; registered but not populated | `source_node_name`, `target_node_name` | ❌ | ❌ |
+
+> **Note:** Linux `interface_stats` may expose no samples because it includes
+> only non-zero `ethtool -S` counters containing `err` or `drop`.
+> The deprecated node-connectivity collectors remain registered for
+> compatibility but expose no metric series.
 
 ### Pod-Level Metrics (Hubble Metrics)
 

@@ -158,6 +158,10 @@ Metrics enabled when `tcpretrans` plugin is enabled (see [Metrics Configuration]
 | ---------------------- | -------------------------------------------------------- | -------------- |
 | `adv_tcpretrans_count` | ***Advanced/Pod-Level***: TCP retransmitted packet count | context labels |
 
+> **Note:** This differs from
+> node-wide `linuxutil` counters such as
+> `tcp_connection_stats{statistic_name="TCPLostRetransmit"}`.
+
 #### Label Values
 
 See [Context Labels](#context-labels).
@@ -93,10 +93,14 @@ Possible values for TCP `state`:
 Possible values for `statistic_name` (for metric `tcp_connection_stats`):
 
 - `TCPTimeouts`
-- `TCPTSReorder`
-- `ResetCount`
+- `TCPLossProbes`
+- `TCPLostRetransmit`
 - and many others (full list [here](../plugins/Linux/linuxutil.md#label-values-for-tcp_connection_stats))
 
+> **Note:** Linux emits only non-zero values from the current `linuxutil`
+> allowlist. For example, `TCPTSReorder` may exist in `/proc/net/netstat`, but
+> it is not currently emitted.
+
 Possible values for `statistic_name` (for metric `ip_connection_stats`):
 
 - `InNoECTPkts`
@@ -120,6 +124,12 @@ Possible values for `statistic_name` (for metric `interface_stats`):
 - `tx_send_full`
 - and many others (as seen by running `ethtool -S <interface_name>` on the Node)
 
+> **Note:** For `interface_stats` only, Retina exports an `ethtool -S` counter
+> when its value is greater than zero and its name contains `err` or `drop`.
+> Retina adds matching values from all supported interfaces together and sets
+> `interface_name="all_interfaces"`. If no counter matches both conditions,
+> the metric has no series.
+
 ### Plugin: `dns` (Linux)
 
 Metrics enabled when `dns` plugin is enabled (see [Metrics Configuration](../configuration.md)).
@@ -141,14 +151,15 @@ Metrics enabled when `conntrack` plugin is enabled and `enableConntrackMetrics`
 | `conntrack_bytes_rx`         | Total bytes received tracked by conntrack        |              |
 | `conntrack_total_connections`| Total number of tracked connections              |              |
 
-### Node Connectivity Metrics (Linux/Windows)
+### Node Connectivity Metrics (Deprecated)
 
-These metrics are available when node connectivity monitoring is enabled.
+| Metric Name                         | Description                                   | Extra Labels                           |
+| ----------------------------------- | --------------------------------------------- | -------------------------------------- |
+| `node_connectivity_status`          | Deprecated connectivity status between nodes | `source_node_name`, `target_node_name` |
+| `node_connectivity_latency_seconds` | Deprecated latency in seconds between nodes   | `source_node_name`, `target_node_name` |
 
-| Metric Name                          | Description                                           | Extra Labels                         |
-| ------------------------------------ | ----------------------------------------------------- | ------------------------------------ |
-| `node_connectivity_status`           | Connectivity status between nodes (1=connected, 0=not)| `source_node_name`, `target_node_name` |
-| `node_connectivity_latency_seconds`  | Latency in seconds between nodes                      | `source_node_name`, `target_node_name` |
+> **Note:** These collectors remain registered for compatibility, but the
+> current agent does not populate them, so they expose no metric series.
 
 ### Plugin: `hnsstats` (Windows)
 
@@ -187,6 +198,12 @@ Possible values for `statistic_name` (for metric `tcp_connection_stats`):
 - `TimedOutCount`
 - `TimeWaitExpiredCount`
 
+> **Note:** `ResetCount` appears as
+> `networkobservability_tcp_connection_stats{statistic_name="ResetCount"}`.
+> These connection statistics are inbound node-level gauges without a
+> `direction` label. `tcp_flag_gauges` is separate and includes both ingress
+> and egress VFP packet counters.
+
 Possible values for TCP `flag`:
 
 - `SYN`

@@ -54,6 +54,10 @@ type NetstatOpts struct {
 
 These are initialized in the linuxutil.go file.
 
+> **Note:** The current runtime sets `errOrDropKeysOnly: true` and
+> `addZeroVal: false`. Therefore, `interface_stats` includes only non-zero
+> counters containing `err` or `drop`, aggregated as `all_interfaces`.
+
 ## Label Values for `tcp_connection_stats`
 
 Below is a running list of all statistics for the metric `tcp_connection_stats`, captured from the `netstats` utility:
@@ -108,3 +112,8 @@ Below is a running list of all statistics for the metric `tcp_connection_stats`,
 - `TWRecycled`
 - `TcpDuplicateDataRehash`
 - `TcpTimeoutRehash`
+
+> **Note:** This is a source-level list, not the current emitted allowlist.
+> Production Linux emits only non-zero names in `netstatCuratedKeys`; for
+> example, `TCPTSReorder` is currently filtered out. `ResetCount` is a Windows
+> `hnsstats` statistic.
@@ -13,6 +13,10 @@ The plugin uses a native eBPF tracepoint (`tracepoint/tcp/tcp_retransmit_skb`) t
 The plugin does not generate Basic metrics.
 In Advanced mode (see [Metric Modes](../../modes/modes.md)), the plugin turns an eBPF result into an enriched `Flow` (adding Pod information based on IP), then sends the `Flow` to an external channel so that a tcpretrans module can create Pod-Level metrics.
 
+> **Note:** This plugin must be present in `enabledPlugin` and Pod-Level metrics
+> must be enabled. It emits `networkobservability_adv_tcpretrans_count` and is
+> separate from node-wide retransmission-related statistics from `linuxutil`.
+
 ### Code locations
 
 - Plugin and eBPF code: *pkg/plugin/tcpretrans/*

@@ -4,6 +4,10 @@ Each metric is associated with a Plugin.
 Associated metrics are linked below.
 See [Metrics Configuration](../configuration.md) for info on configuration.
 
+The names in the table are the exact values accepted in the agent's
+`enabledPlugin` configuration. Availability depends on the agent operating
+system.
+
 To run Retina without any plugins, the `CAP_BPF` capability (since Linux 5.8) is required for memory locking and for loading/using BPF programs. This capability is mandatory. If you're using any plugins, ensure that the necessary capabilities for those plugins are also added. If a plugin requires `CAP_SYS_ADMIN`, you can substitute it for `CAP_BPF`.
 
 | Name                    | Description                                                                                                                  | Metrics in Basic Mode                                  | Metrics in Advanced Mode                                  | Development Guide               |
@@ -12,6 +16,8 @@ To run Retina without any plugins, the `CAP_BPF` capability (since Linux 5.8) is
 | `dropreason` (Linux)    | Counts number of packets/bytes dropped on a Node, along with the direction and reason for drop.                              | [Basic Mode](../modes/basic.md#plugin-dropreason-linux)      | [Advanced Mode](../modes/advanced.md#plugin-dropreason-linux)   | [Dev Guide](./Linux/dropreason.md)    |
 | `linuxutil` (Linux)     | Gathers TCP/UDP statistics and network interface statistics from the `netstats` and `ethtool` Node utilities (respectively). | [Basic Mode](../modes/basic.md#plugin-linuxutil-linux)       | Same metrics as Basic mode                                | [Dev Guide](./Linux/linuxutil.md)     |
 | `dns` (Linux)           | Counts DNS requests/responses by query, including error codes, response IPs, and other metadata.                             | [Basic Mode](../modes/basic.md#plugin-dns-linux)             | [Advanced Mode](../modes/advanced.md#plugin-dns-linux)          | [Dev Guide](./Linux/dns.md)           |
-| `hnstats` (Windows)     | Gathers TCP statistics and counts number of packets/bytes forwarded or dropped in HNS and VFP.                               | [Basic Mode](../modes/basic.md#plugin-hnsstats-windows)      | Same metrics as Basic mode                                | [Dev Guide](./Windows/hnsstats.md)      |
+| `hnsstats` (Windows)    | Gathers TCP statistics and counts number of packets/bytes forwarded or dropped in HNS and VFP.                               | [Basic Mode](../modes/basic.md#plugin-hnsstats-windows)      | Same metrics as Basic mode                                | [Dev Guide](./Windows/hnsstats.md)      |
 | `packetparser` (Linux)  | Captures TCP and UDP packets traveling to and from pods and nodes.                | No basic metrics                                       | [Advanced Mode](../modes/advanced.md#plugin-packetparser-linux) | [Dev Guide](./Linux/packetparser.md)  |
-| `cilium` (Linux) | Collect agent and perf events from cilium via monitor1_2 socket and process flows in our hubble observer | [Metrics](./Linux/ciliumeventobserver.md#metrics) | Same metrics as Basic mode | [Dev Guide](./Linux/ciliumeventobserver.md) |
+| `ciliumeventobserver` (Linux) | Collects agent and perf events from Cilium via the `monitor1_2` socket and processes flows in the Hubble observer. | [Metrics](./Linux/ciliumeventobserver.md#metrics) | Same metrics as Basic mode | [Dev Guide](./Linux/ciliumeventobserver.md) |
+| `infiniband` (Linux)    | Gathers NVIDIA InfiniBand port counters and interface status parameters.                                             | InfiniBand node metrics                                 | Same metrics as Basic mode                                | [Dev Guide](./Linux/infiniband.md)     |
+| `tcpretrans` (Linux)    | Captures TCP retransmissions from the kernel tracepoint for Pod-Level metrics.                                       | No basic metrics                                        | [Advanced Mode](../modes/advanced.md#plugin-tcpretrans-linux)   | [Dev Guide](./Linux/tcpretrans.md)     |