cilium/tetragon

Cilium’s new Tetragon component enables powerful realtime, eBPF-based Security Observability and Runtime Enforcement.

Tetragon detects and is able to react to security-significant events, such as

• Process execution events
• System call activity
• I/O activity including network & file access

When used in a Kubernetes environment, Tetragon is Kubernetes-aware - that is, it understands Kubernetes identities such as namespaces, pods and so-on - so that security event detection can be configured in relation to individual workloads.

Functionality Overview

eBPF Real-Time

Tetragon is a runtime security enforcement and observability tool. What this means is Tetragon applies policy and filtering directly in eBPF in the kernel. It performs the filtering, blocking, and reacting to events directly in the kernel instead of sending events to a user space agent.

For an observability use case, applying filters directly in the kernel drastically reduces observation overhead. By avoiding expensive context switching and wake-ups, especially for high frequency events, such as send, read, or write operations, eBPF reduces required resources. Instead, Tetragon provides rich filters (file, socket, binary names, namespace/capabilities, etc.) in eBPF, which allows users to specify the important and relevant events in their specific context, and pass only those to the user-space agent.

eBPF Flexibility

Tetragon can hook into any function in the Linux kernel and filter on its arguments, return value, associated metadata that Tetragon collects about processes (e.g., executable names), files, and other properties. By writing tracing policies users can solve various security and observability use cases. We provide a number of examples for these in the repository and highlight some below in the 'Getting Started Guide', but users are encouraged to create new policies that match their use cases. The examples are just that, jumping off points that users can then use to create new and specific policy deployments even potentially tracing kernel functions we did not consider. None of the specifics about which functions are traced and what filters are applied are hard-coded in the engine itself.

Critically, Tetragon allows hooking deep in the kernel where data structures can not be manipulated by user space applications avoiding common issues with syscall tracing where data is incorrectly read, maliciously altered by attackers, or missing due to page faults and other user/kernel boundary errors.

Many of the Tetragon developers are also kernel developers. By leveraging this knowledge base Tetragon has created a set of tracing policies that can solve many common observability and security use cases.

eBPF Kernel Aware

Tetragon, through eBPF, has access to the Linux kernel state. Tetragon can then join this kernel state with Kubernetes awareness or user policy to create rules enforced by the kernel in real time. This allows annotating and enforcing process namespace and capabilities, sockets to processes, process file descriptor to filenames and so on. For example, when an application changes its privileges we can create a policy to trigger an alert or even kill the process before it has a chance to complete the syscall and potentially run additional syscalls.

Table Of Content

• Local Development
• Docker Deployment
• Kubernetes Quickstart Guide
  • Requirements
  • Create a cluster
    • Kind
    • GKE
  • Deploy Tetragon
  • Deploy Demo Application
  • Explore Security Observability Events
    • Raw JSON events
    • tetra CLI
• Tetragon Events
  • Process execution
    • Use case 1: Monitoring Process Execution
    • Use case 2: Privileged Execution
  • Generic tracing
    • Use case 1: File Access
    • Use case 2: Network Observability
• BTF Requirement
• FAQ
• Additional Resources
• Conference Talks
  • Book
  • Blog posts
  • Hands-on lab
• Community
  • Slack

Local Development

For getting started with local development, you can refer to the Contribution Guide.

Docker Deployment

For getting started without having to deploy on a Kubernetes cluster, please refer to the Docker deployment guide

Package deployment

For deploying Tetragon as a systemd service, please refer to the Package deployment guide

Kubernetes Quickstart Guide

This Quickstart guide uses a Kind cluster and a helm-based installation to provide a simple way to get a hands on experience with Tetragon and the generated events. These events include monitoring process execution, network sockets, and file access to see what binaries are executing and making network connections or writing to sensitive files.

In this scenario, we are going to install a demo application,

• observe all process execution happening inside a Kubernetes workload
• detect file access and writes
• observe network connections that a Kubernetes workload is making
• detect privileged processes inside a Kubernetes workload

While, we use a Kubernetes Kind cluster in this guide, users can also apply the same concepts in other Kubernetes platforms, bare-metal, or VM environments.

Requirements

The base kernel should support BTF or the BTF file should be placed where Tetragon can read it.

For reference, the examples below use this Vagrantfile and we created our Kind cluster using the defaults options.

Create a cluster

Create a Kubernetes cluster using Kind or GKE.

Kind

Run the following command to create the Kubernetes cluster:

kind create cluster

GKE

Run the following command to create a GKE cluster:

export NAME="$(whoami)-$RANDOM"
gcloud container clusters create "${NAME}" \
  --zone us-west2-a \
  --num-nodes 1

Deploy Tetragon

To install and deploy Tetragon, run the following commands:

helm repo add cilium https://helm.cilium.io
helm repo update
helm install tetragon cilium/tetragon -n kube-system
kubectl rollout status -n kube-system ds/tetragon -w

By default, kube-system pods are filtered. For the examples below, we use the demo deployment from Cilium to generate events.

Deploy Demo Application

Once Tetragon is installed, you can use our Demo Application to explore the Security Observability Events:

kubectl create -f https://raw.githubusercontent.com/cilium/cilium/v1.11/examples/minikube/http-sw-app.yaml

Before going forward, verify that all pods are up and running - it might take several seconds for some pods until they satisfy all the dependencies:

kubectl get pods
NAME                         READY   STATUS    RESTARTS   AGE
deathstar-6c94dcc57b-7pr8c   1/1     Running   0          10s
deathstar-6c94dcc57b-px2vw   1/1     Running   0          10s
tiefighter                   1/1     Running   0          10s
xwing                        1/1     Running   0          10s

Explore Security Observability Events

After Tetragon and the Demo Application is up and running you can examine the security and observability events produced by Tetragon in different ways.

Raw JSON events

The first way is to observe the raw json output from the stdout container log:

kubectl logs -n kube-system -l app.kubernetes.io/name=tetragon -c export-stdout -f

The raw JSON events provide Kubernetes API, identity metadata, and OS level process visibility about the executed binary, its parent and the execution time.

tetra CLI

A second way is to pretty print the events using the tetra CLI. The tool also allows filtering by process, pod, and other fields.

If you are using homebrew, you can install the latest release with:

brew install tetra

Or you can download and install the latest release with the following commands:

GOOS=$(go env GOOS)
GOARCH=$(go env GOARCH)
curl -L --remote-name-all https://github.com/cilium/tetragon/releases/latest/download/tetra-${GOOS}-${GOARCH}.tar.gz{,.sha256sum}
sha256sum --check tetra-${GOOS}-${GOARCH}.tar.gz.sha256sum
sudo tar -C /usr/local/bin -xzvf tetra-${GOOS}-${GOARCH}.tar.gz
rm tetra-${GOOS}-${GOARCH}.tar.gz{,.sha256sum}

(see https://github.com/cilium/tetragon/releases/latest for supported GOOS/GOARCH binary releases)

To start printing events run:

kubectl logs -n kube-system -l app.kubernetes.io/name=tetragon -c export-stdout -f | tetra getevents -o compact

The tetra CLI is also available inside tetragon container.

kubectl exec -it -n kube-system ds/tetragon -c tetragon -- tetra getevents -o compact

Tetragon Events

Tetragon is able to observe critical hooks in the kernel through its sensors and generates enriched events from them. In the next sections we detail the available sensors and the events they produce:

1. Process execution: generating process_exec and process_exit events.
2. Generic tracing: generating process_kprobes and process_tracepoint events.

Along, we present use cases on how they can be used as a starting point.

Process execution

Tetragon observes process creation and termination with default configuration and generates process_exec and process_exit events:

• The process_exec events include useful information about the execution of binaries and related process information. This includes the binary image that was executed, command-line arguments, the UID context the process was executed with, the process parent information, the capabilities that a process had while executed, the process start time, the Kubernetes Pod, labels and more.
• The process_exit events, as the process_exec event shows how and when a process started, indicate how and when a process is removed. The information in the event includes the binary image that was executed, command-line arguments, the UID context the process was executed with, process parent information, process start time, the status codes and signals on process exit. Understanding why a process exited and with what status code helps understand the specifics of that exit.

Both these events include Linux-level metadata (UID, parents, capabilities, start time, etc.) but also Kubernetes-level metadata (Kubernetes namespace, labels, name, etc.). This data make the connection between node-level concepts, the processes, and Kubernetes or container environments.

These events enable a full lifecycle view into a process that can aid an incident investigation, for example, we can determine if a suspicious process is still running in a particular environment. For concrete examples of such events, see the next use case on process execution.

Use case 1: Monitoring Process Execution

This first use case is monitoring process execution, which can be observed with the Tetragon process_exec and process_exit JSON events. These events contain the full lifecycle of processes, from fork/exec to exit, including metadata such as:

• Binary name: Defines the name of an executable file
• Parent process: Helps to identify process execution anomalies (e.g., if a nodejs app forks a shell, this is suspicious)
• Command-line argument: Defines the program runtime behavior
• Current working directory: Helps to identify hidden malware execution from a temporary folder, which is a common pattern used in malwares
• Kubernetes metadata: Contains pods, labels, and Kubernetes namespaces, which are critical to identify service owners, particularly in a multitenant environments
• exec_id: A unique process identifier that correlates all recorded activity of a process

As a first step, let's start monitoring the events from the xwing pod:

kubectl logs -n kube-system -l app.kubernetes.io/name=tetragon -c export-stdout -f | tetra getevents -o compact --namespace default --pod xwing

Then in another terminal, let's kubectl exec into the xwing pod and execute some example commands:

kubectl exec -it xwing -- /bin/bash
whoami

If you observe, the output in the first terminal should be:

🚀 process default/xwing /bin/bash
🚀 process default/xwing /usr/bin/whoami
💥 exit    default/xwing /usr/bin/whoami 0

Here you can see the binary names along with its arguments, the pod info, and return codes in a compact one-line view of the events.

For more details use the raw JSON events to get detailed information, you can stop the Tetragon CLI by Crl-C and parse the tetragon.log file by executing:

kubectl logs -n kube-system -l app.kubernetes.io/name=tetragon -c export-stdout -f | jq 'select(.process_exec.process.pod.name=="xwing" or .process_exit.process.pod.name=="xwing")'

Example process_exec and process_exit events can be:

{
  "process_exec": {
    "process": {
      "exec_id": "a2luZC1jb250cm9sLXBsYW5lOjExNDI4NjE1NjM2OTAxOjUxNTgz",
      "pid": 51583,
      "uid": 0,
      "cwd": "/",
      "binary": "/usr/bin/whoami",
      "arguments": "--version",
      "flags": "execve rootcwd clone",
      "start_time": "2022-05-11T12:54:45.615Z",
      "auid": 4294967295,
      "pod": {
        "namespace": "default",
        "name": "xwing",
        "container": {
          "id": "containerd://1fb931d2f6e5e4cfdbaf30fdb8e2fdd81320bdb3047ded50120a4f82838209ce",
          "name": "spaceship",
          "image": {
            "id": "docker.io/tgraf/netperf@sha256:8e86f744bfea165fd4ce68caa05abc96500f40130b857773186401926af7e9e6",
            "name": "docker.io/tgraf/netperf:latest"
          },
          "start_time": "2022-05-11T10:07:33Z",
          "pid": 50
        }
      },
      "docker": "1fb931d2f6e5e4cfdbaf30fdb8e2fdd",
      "parent_exec_id": "a2luZC1jb250cm9sLXBsYW5lOjkwNzkyMjU2MjMyNjk6NDM4NzI=",
      "refcnt": 1
    },
    "parent": {
      "exec_id": "a2luZC1jb250cm9sLXBsYW5lOjkwNzkyMjU2MjMyNjk6NDM4NzI=",
      "pid": 43872,
      "uid": 0,
      "cwd": "/",
      "binary": "/bin/bash",
      "flags": "execve rootcwd clone",
      "start_time": "2022-05-11T12:15:36.225Z",
      "auid": 4294967295,
      "pod": {
        "namespace": "default",
        "name": "xwing",
        "container": {
          "id": "containerd://1fb931d2f6e5e4cfdbaf30fdb8e2fdd81320bdb3047ded50120a4f82838209ce",
          "name": "spaceship",
          "image": {
            "id": "docker.io/tgraf/netperf@sha256:8e86f744bfea165fd4ce68caa05abc96500f40130b857773186401926af7e9e6",
            "name": "docker.io/tgraf/netperf:latest"
          },
          "start_time": "2022-05-11T10:07:33Z",
          "pid": 43
        }
      },
      "docker": "1fb931d2f6e5e4cfdbaf30fdb8e2fdd",
      "parent_exec_id": "a2luZC1jb250cm9sLXBsYW5lOjkwNzkxODU5NTMzOTk6NDM4NjE=",
      "refcnt": 1
    }
  },
  "node_name": "kind-control-plane",
  "time": "2022-05-11T12:54:45.615Z"
}

{
  "process_exit": {
    "process": {
      "exec_id": "a2luZC1jb250cm9sLXBsYW5lOjExNDI4NjE1NjM2OTAxOjUxNTgz",
      "pid": 51583,
      "uid": 0,
      "cwd": "/",
      "binary": "/usr/bin/whoami",
      "arguments": "--version",
      "flags": "execve rootcwd clone",
      "start_time": "2022-05-11T12:54:45.615Z",
      "auid": 4294967295,
      "pod": {
        "namespace": "default",
        "name": "xwing",
        "container": {
          "id": "containerd://1fb931d2f6e5e4cfdbaf30fdb8e2fdd81320bdb3047ded50120a4f82838209ce",
          "name": "spaceship",
          "image": {
            "id": "docker.io/tgraf/netperf@sha256:8e86f744bfea165fd4ce68caa05abc96500f40130b857773186401926af7e9e6",
            "name": "docker.io/tgraf/netperf:latest"
          },
          "start_time": "2022-05-11T10:07:33Z",
          "pid": 50
        }
      },
      "docker": "1fb931d2f6e5e4cfdbaf30fdb8e2fdd",
      "parent_exec_id": "a2luZC1jb250cm9sLXBsYW5lOjkwNzkyMjU2MjMyNjk6NDM4NzI="
    },
    "parent": {
      "exec_id": "a2luZC1jb250cm9sLXBsYW5lOjkwNzkyMjU2MjMyNjk6NDM4NzI=",
      "pid": 43872,
      "uid": 0,
      "cwd": "/",
      "binary": "/bin/bash",
      "flags": "execve rootcwd clone",
      "start_time": "2022-05-11T12:15:36.225Z",
      "auid": 4294967295,
      "pod": {
        "namespace": "default",
        "name": "xwing",
        "container": {
          "id": "containerd://1fb931d2f6e5e4cfdbaf30fdb8e2fdd81320bdb3047ded50120a4f82838209ce",
          "name": "spaceship",
          "image": {
            "id": "docker.io/tgraf/netperf@sha256:8e86f744bfea165fd4ce68caa05abc96500f40130b857773186401926af7e9e6",
            "name": "docker.io/tgraf/netperf:latest"
          },
          "start_time": "2022-05-11T10:07:33Z",
          "pid": 43
        }
      },
      "docker": "1fb931d2f6e5e4cfdbaf30fdb8e2fdd",
      "parent_exec_id": "a2luZC1jb250cm9sLXBsYW5lOjkwNzkxODU5NTMzOTk6NDM4NjE="
    }
  },
  "node_name": "kind-control-plane",
  "time": "2022-05-11T12:54:45.616Z"
}

Use case 2: Privileged Execution

Tetragon also provides the ability to check process capabilities and kernel namespaces access.

This information would help us determine which process or Kubernetes pod has started or gained access to privileges or host namespaces that it should not have. This would help us answer questions like:

Which Kubernetes pods are running with CAP_SYS_ADMIN in my cluster?

Which Kubernetes pods have host network or pid namespace access in my cluster?

As a first step let's enable visibility to capability and namespace changes via the configmap by setting enable-process-cred and enable-process-ns from false to true:

kubectl edit cm -n kube-system tetragon-config
# change "enable-process-cred" from "false" to "true"
# change "enable-process-ns" from "false" to "true"
# then save and exit

Restart the Tetragon daemonset:

kubectl rollout restart -n kube-system ds/tetragon

As a second step, let's start monitoring the Security Observability events from the privileged test-pod workload:

kubectl logs -n kube-system -l app.kubernetes.io/name=tetragon -c export-stdout -f | tetra getevents --namespace default --pod test-pod

In another terminal let's apply the privileged PodSpec:

kubectl apply -f https://raw.githubusercontent.com/cilium/tetragon/main/testdata/specs/testpod.yaml

If you observe the output in the first terminal, you can see the container start with CAP_SYS_ADMIN:

🚀 process default/test-pod /bin/sleep 365d                🛑 CAP_SYS_ADMIN
🚀 process default/test-pod /usr/bin/jq -r .bundle         🛑 CAP_SYS_ADMIN
🚀 process default/test-pod /usr/bin/cp /kind/product_name /kind/product_uuid /run/containerd/io.containerd.runtime.v2.task/k8s.io/7c7e513cd4d506417bc9d97dd9af670d94d9e84161c8c8 fdc9fa3a678289a59/rootfs/ 🛑 CAP_SYS_ADMIN

Generic tracing

For more advanced use cases, Tetragon can observe tracepoints and arbitrary kernel calls via kprobes. For that, Tetragon must be extended and configured with custom resources objects named TracingPolicy. It can then generates process_tracepoint and process_kprobes events.

TracingPolicy is a user-configurable Kubernetes custom resource that allows users to trace arbitrary events in the kernel and optionally define actions to take on a match. For example, a Sigkill signal can be sent to the process or the return value of a system call can be overridden. For bare metal or VM use cases without Kubernetes, the same YAML configuration can be passed via a flag to the Tetragon binary or via the tetra CLI to load the policies via gRPC.

For more information on TracingPolicy and how to write them, see the TracingPolicy Guide.

Use case 1: File Access

The first use case is file access, which can be observed with the Tetragon process_kprobe JSON events. By using kprobe hook points, these events are able to observe arbitrary kernel calls and file descriptors in the Linux kernel, giving you the ability to monitor every file a process opens, reads, writes, and closes throughout its lifecycle.

In this example, we can monitor if a process inside a Kubernetes workload performs an open, close, read or write in the /etc/ directory. The policy may further specify additional directories or specific files if needed.

As a first step, let's apply the following TracingPolicy:

kubectl apply -f https://raw.githubusercontent.com/cilium/tetragon/main/examples/tracingpolicy/sys_write_follow_fd_prefix.yaml

As a second step, let's start monitoring the events from the xwing pod:

kubectl logs -n kube-system -l app.kubernetes.io/name=tetragon -c export-stdout -f | tetra getevents -o compact --namespace default --pod xwing

In another terminal, kubectl exec into the xwing pod:

kubectl exec -it xwing -- /bin/bash

and edit the /etc/passwd file:

vi /etc/passwd

If you observe, the output in the first terminal should be:

🚀 process default/xwing /usr/bin/vi /etc/passwd
📬 open    default/xwing /usr/bin/vi /etc/passwd
📚 read    default/xwing /usr/bin/vi /etc/passwd 1269 bytes
📪 close   default/xwing /usr/bin/vi /etc/passwd
📬 open    default/xwing /usr/bin/vi /etc/passwd
📝 write   default/xwing /usr/bin/vi /etc/passwd 1277 bytes
💥 exit    default/xwing /usr/bin/vi /etc/passwd 0

Note, that open and close are only generated for /etc/ files because of eBPF in kernel filtering. The default CRD additionally filters events associated with the pod init process to filter init noise from pod start.

Similarly to the previous example, reviewing the JSON events provides additional data. An example process_kprobe event observing a write can be:

{
   "process_kprobe":{
      "process":{
         "exec_id":"a2luZC1jb250cm9sLXBsYW5lOjE1MDA0MzM3MDE1MDI6MTkxNjM=",
         "pid":19163,
         "uid":0,
         "cwd":"/",
         "binary":"/usr/bin/vi",
         "arguments":"/etc/passwd",
         "flags":"execve rootcwd clone",
         "start_time":"2022-05-26T22:05:13.894Z",
         "auid":4294967295,
         "pod":{
            "namespace":"default",
            "name":"xwing",
            "container":{
               "id":"containerd://4b0df5a137260a6b95cbf6443bb2f4b0c9309e6ccb3d8afdbc3da8fff40c0778",
               "name":"spaceship",
               "image":{
                  "id":"docker.io/tgraf/netperf@sha256:8e86f744bfea165fd4ce68caa05abc96500f40130b857773186401926af7e9e6",
                  "name":"docker.io/tgraf/netperf:latest"
               },
               "start_time":"2022-05-26T21:58:11Z",
               "pid":25
            }
         },
         "docker":"4b0df5a137260a6b95cbf6443bb2f4b",
         "parent_exec_id":"a2luZC1jb250cm9sLXBsYW5lOjEyMDQ1NTIzMTUwNjY6MTc1NDI=",
         "refcnt":1
      },
      "parent":{

      },
      "function_name":"__x64_sys_write",
      "args":[
         {
            "file_arg":{
               "path":"/etc/passwd"
            }
         },
         {
            "bytes_arg":"cm9vdDp4OjA6MDpyb290Oi9yb290Oi9iaW4vYXNoCm5hdGFsaWEKYmluOng6MToxOmJpbjovYmluOi9zYmluL25vbG9naW4KZGFlbW9uOng6MjoyOmRhZW1vbjovc2Jpbjovc2Jpbi9ub2xvZ2luCmFkbTp4OjM6NDphZG06L3Zhci9hZG06L3NiaW4vbm9sb2dpbgpscDp4OjQ6NzpscDovdmFyL3Nwb29sL2xwZDovc2Jpbi9ub2xvZ2luCnN5bmM6eDo1OjA6c3luYzovc2JpbjovYmluL3N5bmMKc2h1dGRvd246eDo2OjA6c2h1dGRvd246L3NiaW46L3NiaW4vc2h1dGRvd24KaGFsdDp4Ojc6MDpoYWx0Oi9zYmluOi9zYmluL2hhbHQKbWFpbDp4Ojg6MTI6bWFpbDovdmFyL3Nwb29sL21haWw6L3NiaW4vbm9sb2dpbgpuZXdzOng6OToxMzpuZXdzOi91c3IvbGliL25ld3M6L3NiaW4vbm9sb2dpbgp1dWNwOng6MTA6MTQ6dXVjcDovdmFyL3Nwb29sL3V1Y3BwdWJsaWM6L3NiaW4vbm9sb2dpbgpvcGVyYXRvcjp4OjExOjA6b3BlcmF0b3I6L3Jvb3Q6L2Jpbi9zaAptYW46eDoxMzoxNTptYW46L3Vzci9tYW46L3NiaW4vbm9sb2dpbgpwb3N0bWFzdGVyOng6MTQ6MTI6cG9zdG1hc3RlcjovdmFyL3Nwb29sL21haWw6L3NiaW4vbm9sb2dpbgpjcm9uOng6MTY6MTY6Y3JvbjovdmFyL3Nwb29sL2Nyb246L3NiaW4vbm9sb2dpbgpmdHA6eDoyMToyMTo6L3Zhci9saWIvZnRwOi9zYmluL25vbG9naW4Kc3NoZDp4OjIyOjIyOnNzaGQ6L2Rldi9udWxsOi9zYmluL25vbG9naW4KYXQ6eDoyNToyNTphdDovdmFyL3Nwb29sL2Nyb24vYXRqb2JzOi9zYmluL25vbG9naW4Kc3F1aWQ6eDozMTozMTpTcXVpZDovdmFyL2NhY2hlL3NxdWlkOi9zYmluL25vbG9naW4KeGZzOng6MzM6MzM6WCBGb250IFNlcnZlcjovZXRjL1gxMS9mczovc2Jpbi9ub2xvZ2luCmdhbWVzOng6MzU6MzU6Z2FtZXM6L3Vzci9nYW1lczovc2Jpbi9ub2xvZ2luCnBvc3RncmVzOng6NzA6NzA6Oi92YXIvbGliL3Bvc3RncmVzcWw6L2Jpbi9zaApudXQ6eDo4NDo4NDpudXQ6L3Zhci9zdGF0ZS9udXQ6L3NiaW4vbm9sb2dpbgpjeXJ1czp4Ojg1OjEyOjovdXNyL2N5cnVzOi9zYmluL25vbG9naW4KdnBvcG1haWw6eDo4OTo4OTo6L3Zhci92cG9wbWFpbDovc2Jpbi9ub2xvZ2luCm50cDp4OjEyMzoxMjM6TlRQOi92YXIvZW1wdHk6L3NiaW4vbm9sb2dpbgpzbW1zcDp4OjIwOToyMDk6c21tc3A6L3Zhci9zcG9vbC9tcXVldWU6L3NiaW4vbm9sb2dpbgpndWVzdDp4OjQwNToxMDA6Z3Vlc3Q6L2Rldi9udWxsOi9zYmluL25vbG9naW4Kbm9ib2R5Ong6NjU1MzQ6NjU1MzQ6bm9ib2R5Oi86L3NiaW4vbm9sb2dpbgo="
         },
         {
            "size_arg":"1277"
         }
      ],
      "action":"KPROBE_ACTION_POST"
   },
   "node_name":"kind-control-plane",
   "time":"2022-05-26T22:05:25.962Z"
}

In addition to the Kubernetes Identity and process metadata from exec events, process_kprobe events contain the arguments of the observed system call. In the above case they are

• path: the observed file path
• bytes_arg: content of the observed file encoded in base64
• size_arg: size of the observed file in bytes

To disable the TracingPolicy run:

kubectl delete -f https://raw.githubusercontent.com/cilium/tetragon/main/examples/tracingpolicy/sys_write_follow_fd_prefix.yaml

Use case 2: Network Observability

To view TCP connect events, apply the example TCP connect TracingPolicy:

kubectl apply -f https://raw.githubusercontent.com/cilium/tetragon/main/examples/tracingpolicy/tcp-connect.yaml

To start monitoring events in the xwing pod run the Tetragon CLI:

kubectl logs -n kube-system -l app.kubernetes.io/name=tetragon -c export-stdout -f | tetra getevents -o compact --namespace default --pod xwing

In another terminal, start generate a TCP connection. Here we use curl.

kubectl exec -it xwing -- curl http://cilium.io

The output in the first terminal will capture the new connect and write,

🚀 process default/xwing /usr/bin/curl http://cilium.io
🔌 connect default/xwing /usr/bin/curl tcp 10.244.0.6:34965 -> 104.198.14.52:80
📤 sendmsg default/xwing /usr/bin/curl tcp 10.244.0.6:34965 -> 104.198.14.52:80 bytes 73
🧹 close   default/xwing /usr/bin/curl tcp 10.244.0.6:34965 -> 104.198.14.52:80
💥 exit    default/xwing /usr/bin/curl http://cilium.io 0

To disable the TracingPolicy run:

kubectl delete -f https://raw.githubusercontent.com/cilium/tetragon/main/examples/tracingpolicy/tcp-connect.yaml

BTF Requirement

Many common Linux distributions now ship with BTF enabled and do not require any extra work. To check if BTF is enabled on your Linux system, the standard location is:

$ ls /sys/kernel/btf/

Otherwise Tetragon repository provides a Vagrantfile that can be used to install a vagrant box for running Tetragon with BTF requirement. Other VM solutions work as well.

To run with vagrant:

 $ vagrant up
 $ vagrant ssh

This should be sufficient to create a Kind cluster and run Tetragon. For more information on the vagrant builds, see the Development Guide.

Verify Tetragon Image Signatures

Prerequisites

You will need to install cosign.

Verify Signed Container Images

Since version 0.8.4, all Tetragon container images are signed using cosign.

Let's verify a Tetragon image's signature using the cosign verify command:

$ COSIGN_EXPERIMENTAL=1 cosign verify --certificate-github-workflow-repository cilium/tetragon --certificate-oidc-issuer https://token.actions.githubusercontent.com <Image URL> | jq

Note

COSIGN_EXPERIMENTAL=1 is used to allow verification of images signed in KEYLESS mode. To learn more about keyless signing, please refer to Keyless Signatures.

Software Bill of Materials

A Software Bill of Materials (SBOM) is a complete, formally structured list of components that are required to build a given piece of software. SBOM provides insight into the software supply chain and any potential concerns related to license compliance and security that might exist.

Starting with version 0.8.4, all Tetragon images include an SBOM. The SBOM is generated in SPDX format using the bom tool. If you are new to the concept of SBOM, see what an SBOM can do for you.

Download SBOM

The SBOM can be downloaded from the supplied Tetragon image using the cosign download sbom command.

$ cosign download sbom --output-file sbom.spdx <Image URL>

Verify SBOM Image Signature

To ensure the SBOM is tamper-proof, its signature can be verified using the cosign verify command.

$ COSIGN_EXPERIMENTAL=1 cosign verify --certificate-github-workflow-repository cilium/tetragon --certificate-oidc-issuer https://token.actions.githubusercontent.com --attachment sbom <Image URL> | jq

It can be validated that the SBOM image was signed using Github Actions in the Cilium repository from the Issuer and Subject fields of the output.

FAQ

Q: Can I install and use Tetragon in standalone mode (outside of k8s)?

A: Yes! You can run make to generate standalone binaries and run them directly. Make sure to take a look at the Development Setup guide for the build requirements. Then use sudo ./tetragon --bpf-lib bpf/objs to run Tetragon.

Q: CI is complaining about Go module vendoring, what do I do?

A: You can run make vendor then add and commit your changes.

Q: CI is complaining about a missing "signed-off-by" line. What do I do?

A: You need to add a signed-off-by line to your commit messages. The easiest way to do this is with git fetch origin/main && git rebase --signoff origin/main. Then push your changes.

Additional Resources

Conference Talks

Uncovering a Sophisticated Kubernetes Attack in Real-Time - Jed Salazar & Natália Réka Ivánkó, KubeCon EU, 2020

Uncovering a Sophisticated Kubernetes Attack in Real Time Part II. - Jed Salazar & Natália Réka Ivánkó, O'Reilly Superstream Series, Infrastructure & Ops, 2021

Keeping your cluster safe from attacks with eBPF - Jed Salazar & Natália Réka Ivánkó, eBPF Summit, 2021

You and Your Security Profiles; Generating Security Policies with the Help of eBPF - John Fastabend & Natália Réka Ivánkó, eBPF Day North America, 2022

Container Security and Runtime Enforcement with Tetragon - Djalal Harouni, eBPF Summit, 2022

Securing the Superpowers: Who Loaded That eBPF Program? - John Fastabend & Natália Réka Ivánkó, CloudNative SecurityCon NA, 2023

Book

Security Observability with eBPF - Jed Salazar & Natália Réka Ivánkó, OReilly, 2022

Blog posts

Detecting a Container Escape with Cilium and eBPF - Natália Réka Ivánkó, 2021

Detecting and Blocking log4shell with Isovalent Cilium Enterprise - Jed Salazar, 2021

Hands-on lab

Security Observability with eBPF and Tetragon - Natália Réka Ivánkó, Roland Wolters, Raphaël Pinson

Community

Slack

Join the Tetragon Slack channel to chat with developers, maintainers, and other users. This is a good first stop to ask questions and share your experiences.