trace_sni

The trace_sni gadget tracks Server Name Indication (SNI) from TLS requests.

Getting started

Running the gadget:

kubectl gadget

$ kubectl gadget run ghcr.io/inspektor-gadget/gadget/trace_sni:latest [flags]

ig

$ sudo ig run ghcr.io/inspektor-gadget/gadget/trace_sni:latest [flags]

Guide

kubectl gadget

Run the gadget in a terminal:

$ kubectl gadget run trace_sni:latest
K8S.NODE          K8S.NAMESPACE               K8S.PODNAME                 K8S.CONTAINERNAME           COMM                      PID            TID           UID           GID NAME

Run a pod on a different terminal and perform some requests:

$ kubectl run -it ubuntu --image ubuntu:latest -- /bin/bash
root@ubuntu:/# apt update && apt install -y wget && wget wikimedia.org
(...)
HTTP request sent, awaiting response... 301 Moved Permanently
Location: https://www.wikimedia.org/ [following]
(...)
root@ubuntu:/# wget www.github.com
(...)
HTTP request sent, awaiting response... 301 Moved Permanently
Location: https://github.com/ [following]
(...)

Go back to the terminal where the gadget is running. The requests will be logged by the gadget:

K8S.NODE          K8S.NAMESPACE               K8S.PODNAME                 K8S.CONTAINERNAME           COMM                      PID            TID           UID           GID NAME
minikube-docker   default                     ubuntu                      ubuntu                      wget                   693742         693742             0             0 wikimedia.org
minikube-docker   default                     ubuntu                      ubuntu                      wget                   693742         693742             0             0 www.wikimedia.org

ig

Start the gadget in a terminal:

$ sudo ig run trace_sni:latest --containername test-trace-sni
RUNTIME.CONTAINERNAME                      COMM                                PID                    TID                    UID                   GID NAME

Launch a container (in another terminal) that makes requests:

$ docker run -it --name test-trace-sni busybox /bin/sh -c "wget https://example.com"

Go back to the terminal where the gadget is running. The requests will be logged by the gadget:

RUNTIME.CONTAINERNAME                      COMM                                PID                    TID                    UID                   GID NAME
test-trace-sni                             wget                             697854                 697854                      0                     0 example.com

We can see that each time our wget client connected to a different server, our tracer caught the Server Name Indication requested.

Congratulations! You reached the end of this guide! You can now delete the pod you created:

kubectl gadget

$ kubectl delete pod ubuntu

ig

$ docker rm -f test-trace-sni