> For the complete documentation index, see [llms.txt](https://platform9.com/kb/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://platform9.com/kb/pmk/how-to/how-to-identify-the-virtual-interface-of-a-pod-in-the-root-name.md).

# How-To: Identify The Virtual Interface of a Pod in the Root Namespace Using Flannel as the Network B

## Problem

Identify the virtual interface of a particular pod in the root namespace of the node using ***flannel*** as Network backend.

## Environment

* Platform9 Managed Kubernetes - All Versions
* Flannel

## Procedure

1. Use the ***docker*** command to identify the ***pause*** container for the pod as it holds the network namespace for the pod.

{% tabs %}
{% tab title="None" %}

```none
# docker ps | grep -i busybox2 | grep pause

f15ae72287e0 k8s.gcr.io/pause:3.1 "/pause" 2 minutes ago Up 2 minutes k8s_POD_mybusybox2_default_2a12aac4-ed54-4c99-aa0e-be32f793f41d_0
```

{% endtab %}
{% endtabs %}

2. Run docker inspect on the container Id obtained from the above command and look for the SandboxKey to get the namespace created for the pod.

{% tabs %}
{% tab title="None" %}

```none
# docker inspect f15ae72287e0 | grep -i sandboxkey

"SandboxKey": "/var/run/docker/netns/5048a1a60e3b",
```

{% endtab %}
{% endtabs %}

3. Use ***nsenter*** to get the interface details within the pod namespace.

{% tabs %}
{% tab title="None" %}

```none
# nsenter --net=/var/run/docker/netns/5048a1a60e3b ip a

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever

3: eth0@if27: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1472 qdisc noqueue state UP group default
link/ether 86:5f:a6:c3:8a:61 brd ff:ff:ff:ff:ff:ff link-netnsid 0
inet 10.20.88.6/24 brd 10.20.88.255 scope global eth0
valid_lft forever preferred_lft forever
```

{% endtab %}
{% endtabs %}

{% hint style="info" %}
**Note**

***ip netns*** command can not be used for the docker namespaces as it only knows about namespaces listed in ***/var/run/netns/***
{% endhint %}

4. Run ***ethtool*** on the interface with the pod's IP in the namespace above to obtain the peer index of the *Veth*-pair for the interface

{% tabs %}
{% tab title="None" %}

```none
# nsenter --net=/var/run/docker/netns/5048a1a60e3b ethtool -S eth0 | grep -i peer

peer_ifindex: 27
```

{% endtab %}
{% endtabs %}

5. List the network interface on the node (root namespace) using ***ip*** command, the interface listed at the index obtained in the above step ( 27 in this case ) is the virtual interface for the pod in the root namespace.

{% tabs %}
{% tab title="None" %}

```none
# ip a
.
.
27: vetha2fb55e7@if3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1472 qdisc noqueue master cni0 state UP group default
link/ether b6:76:f3:c9:a4:3c brd ff:ff:ff:ff:ff:ff link-netnsid 2
inet6 fe80::b476:f3ff:fec9:a43c/64 scope link
valid_lft forever preferred_lft forever
```

{% endtab %}
{% endtabs %}


---

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