CNI Plugin Binaries and Configs

Luke Hebert

August 19, 2025 - 2 minutes read - 275 words

This example node uses Flannel as its active Container Network Interface (CNI) plugin, which manages pod-to-pod networking via a configuration list (.conflist). The CNI directory includes 19 plugin binaries that support advanced networking capabilities like bridging, VLANs, MAC/IPvlan, firewalls, bandwidth shaping, and static IP assignment.

Active CNI Configuration

The configured plugin definitions reside in /etc/cni/net.d/:

File	Size	Modified
`10-flannel.conflist`	292 B	Aug 19 16:17
`.kubernetes-cni-keep`	0 B	Dec 11 2024

Flannel is the sole active network plugin, handling virtual network and virtual cable management between pods, containers, and virtual switches.

Available CNI Binaries

Located in /opt/cni/bin/, the following plugins are installed and ready for use:

Plugin	Size	Purpose
`bandwidth`	4.6 MB	Traffic shaping and rate limiting
`bridge`	5.3 MB	Linux bridge networking
`dhcp`	12.8 MB	DHCP client configuration
`dummy`	4.8 MB	Dummy interface creation
`firewall`	5.3 MB	iptables/nftables rules
`flannel`	2.4 MB	Overlay network (active)
`host-device`	4.8 MB	Attach existing host device
`host-local`	4.0 MB	Local IPAM
`ipvlan`	4.9 MB	IPvlan interface
`loopback`	4.1 MB	Loopback interface
`macvlan`	4.9 MB	MACVlan interface
`portmap`	4.7 MB	Port mapping (NAT)
`ptp`	5.1 MB	Precision Time Protocol
`sbr`	4.3 MB	Subnet broadcast relay
`static`	3.6 MB	Static IP assignment
`tap`	4.9 MB	TAP interface
`tuning`	4.2 MB	Interface tuning (mtu, qdisc, etc.)
`vlan`	4.9 MB	VLAN tagging
`vrf`	4.5 MB	Virtual Routing and Forwarding

Notes

The flannel binary was updated on Aug 19 16:17, matching the conflist timestamp, indicating a recent deployment or upgrade.
All other binaries date to Dec 11 2024, consistent with the base image build.
The .kubernetes-cni-keep file is a zero-byte marker used by the Kubernetes kubelet to prevent the CNI directory from being pruned.

Networking