Skip to main content
Version: latest

top_tcp

The top_tcp gadget reports tcp send receive activity by connection.

Requirements​

  • Minimum Kernel Version : *5.4

*This is the minimal kernel version we have tried for this Gadget, however it's possible that it works with earlier versions.

Getting started​

Running the gadget:

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

Flags​

--family​

Trace traffic from the specified IPv family. Can be either 4 or 6. Specifying -1 equals to no filtering

Default value: "-1"

--pid​

Show only events generated by process with this PID

Default value: "0"

Guide​

First, we need to create one pod for us to play with:

kubectl run mypod --image busybox:latest sleep inf

You can now use the gadget, but output will be empty:

$ kubectl gadget run top_tcp:latest --podname mypod
K8S.NODE     K8S.NAMESPACE          K8S.PODNAME            K8S.CONTAINERNAME               PID SRC                                 DST                                COMM          SENT          RECEIVED

Indeed, it is waiting for TCP connection to occur. So, open another terminal and keep and eye on the first one, exec the container and use wget:

$ kubectl exec -ti mypod -- wget inspektor-gadget.io
Connecting to inspektor-gadget.io (188.114.96.0:80)
Connecting to inspektor-gadget.io (188.114.96.0:443)
wget: note: TLS certificate validation not implemented
saving to 'index.html'
index.html           100% |**********************************************************************************************************| 37851  0:00:00 ETA
'index.html' saved

On the first terminal, you should see:

K8S.NODE     K8S.NAMESPACE          K8S.PODNAME            K8S.CONTAINERNAME               PID SRC                                 DST                                COMM          SENT          RECEIVED
aks-agentpo… default                mypod                  mypod                       3602459 p/default/mypod:57076               188.114.97.7:443                   wget           320             42652
aks-agentpo… default                mypod                  mypod                       3602452 p/default/mypod:49538               188.114.96.7:80                    wget             0               582

These lines correspond to the TCP connection initiated by wget.

Finally, clean the system:

kubectl delete pod mypod