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Chapter 12. Setting container network modes


The chapter provides information about how to set different network modes.

12.1. Running containers with a static IP

The podman run command with the --ip option sets the container network interface to a particular IP address (for example, 10.88.0.44). To verify that you set the IP address correctly, run the podman inspect command.

Prerequisites

  • The container-tools meta-package is installed.

Procedure

  • Set the container network interface to the IP address 10.88.0.44:

    # podman run -d --name=myubi --ip=10.88.0.44 registry.access.redhat.com/ubi9/ubi
    efde5f0a8c723f70dd5cb5dc3d5039df3b962fae65575b08662e0d5b5f9fbe85

Verification

  • Check that the IP address is set properly:

    # podman inspect --format='{{.NetworkSettings.IPAddress}}' myubi
    10.88.0.44

12.2. Running the DHCP plugin for Netavark using systemd

Prerequisites

  • The container-tools meta-package is installed.

Procedure

  1. Enable the DHCP proxy by using the systemd socket:

    systemctl enable --now netavark-dhcp-proxy.socket
    Created symlink /etc/systemd/system/sockets.target.wants/netavark-dhcp-proxy.socket  /usr/lib/systemd/system/netavark-dhcp-proxy.socket.
  2. Optional: Display the socket unit file:

    # cat /usr/lib/systemd/system/netavark-dhcp-proxy.socket
    [Unit]
    Description=Netavark DHCP proxy socket
    
    [Socket]
    ListenStream=%t/podman/nv-proxy.sock
    SocketMode=0660
    
    [Install]
    WantedBy=sockets.target
  3. Create a macvlan network and specify your host interface with it. Typically, it is your external interface:

    # podman network create -d macvlan --interface-name <LAN_INTERFACE> mv1
    mv1
  4. Run the container by using newly created network:

    # podman run --rm --network mv1 -d --name test alpine top
    894ae3b6b1081aca2a5d90a9855568eaa533c08a174874be59569d4656f9bc45

Verification

  1. Confirm the container has an IP on your local subnet:

    # podman exec test ip addr
    1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1000
        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
        inet6 ::1/128 scope host
           valid_lft forever preferred_lft forever
    2: eth0@eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP qlen 1000
        link/ether 5a:30:72:bf:13:76 brd ff:ff:ff:ff:ff:ff
        inet 192.168.188.36/24 brd 192.168.188.255 scope global eth0
           valid_lft forever preferred_lft forever
        inet6 fe80::5830:72ff:febf:1376/64 scope link
           valid_lft forever preferred_lft forever
  2. Inspect the container to verify it uses correct IP addresses:

    # podman container inspect test --format {{.NetworkSettings.Networks.mv1.IPAddress}}
    192.168.188.36
Note

When attempting to connect to this IP address, ensure the connection is made from a different host. Connections from the same host are not supported when using macvlan networking.

Additional resources

12.3. Running the DHCP plugin for CNI using systemd

You can use the systemd unit file to run the dhcp plugin.

Prerequisites

  • The container-tools meta-package is installed.

Procedure

  1. Optional: Make sure you re sign the CNI network stack:

    # podman info --format "{{.Host.NetworkBackend}}"
    cni
  2. Enable the DHCP proxy by using the systemd socket:

    # systemctl enable --now cni-dhcp.socket
    Created symlink /etc/systemd/system/sockets.target.wants/cni-dhcp.socket  /usr/lib/systemd/system/cni-dhcp.socket.
  3. Optional: Display the socket unit file:

    # cat /usr/lib/systemd/system/io.podman.dhcp.socket
    [Unit]
    Description=CNI DHCP service socket
    Documentation=https://github.com/containernetworking/plugins/tree/master/plugins/ipam/dhcp
    PartOf=cni-dhcp.service
    
    [Socket]
    ListenStream=/run/cni/dhcp.sock
    SocketMode=0660
    SocketUser=root
    SocketGroup=root
    RemoveOnStop=true
    
    [Install]
    WantedBy=sockets.target

Verification

  • Check the status of the socket:

    # systemctl status io.podman.dhcp.socket
    # systemctl status cni-dhcp.socket
    ● cni-dhcp.socket - CNI DHCP service socket
       Loaded: loaded (/usr/lib/systemd/system/cni-dhcp.socket; enabled; vendor preset: disabled)
       Active: active (listening) since Mon 2025-01-06 08:39:35 EST; 33s ago
         Docs: https://github.com/containernetworking/plugins/tree/master/plugins/ipam/dhcp
       Listen: /run/cni/dhcp.sock (Stream)
        Tasks: 0 (limit: 11125)
       Memory: 4.0K
       CGroup: /system.slice/cni-dhcp.socket

12.4. The macvlan plugin

Most of the container images do not have a DHCP client, the dhcp plugin acts as a proxy DHCP client for the containers to interact with a DHCP server.

The host system does not have network access to the container. To allow network connections from outside the host to the container, the container has to have an IP on the same network as the host. The macvlan plugin enables you to connect a container to the same network as the host.

Note

This procedure only applies to rootfull containers. Rootless containers are not able to use the macvlan and dhcp plugins.

Note

You can create a macvlan network using the podman network create --driver=macvlan command.

12.5. Switching the network stack from CNI to Netavark

Previously, containers were able to use DNS only when connected to the single Container Network Interface (CNI) plugin. Netavark is a network stack for containers. You can use Netavark with Podman and other Open Container Initiative (OCI) container management applications. The advanced network stack for Podman is compatible with advanced Docker functionalities. Now, containers in multiple networks access containers on any of those networks.

Netavark is capable of the following:

  • Create, manage, and remove network interfaces, including bridge and MACVLAN interfaces.
  • Configure firewall settings, such as network address translation (NAT) and port mapping rules.
  • Support IPv4 and IPv6.
  • Improve support for containers in multiple networks.
Warning

The CNI network stack is deprecated and will be removed in a future RHEL release. Use the Netavark network stack instead.

Prerequisites

  • The container-tools meta-package is installed.

Procedure

  1. If the /etc/containers/containers.conf file does not exist, copy the /usr/share/containers/containers.conf file to the /etc/containers/ directory:

    # cp /usr/share/containers/containers.conf /etc/containers/
  2. Edit the /etc/containers/containers.conf file, and add the following content to the [network] section:

    network_backend="netavark"
  3. If you have any containers or pods, reset the storage back to the initial state:

    # podman system reset
  4. Reboot the system:

    # reboot

Verification

  • Verify that the network stack is changed to Netavark:

    # cat /etc/containers/containers.conf
    ...
    [network]
    network_backend="netavark"
    ...
Note

If you are using Podman 4.0.0 or later, use the podman info command to check the network stack setting.

Additional resources

12.6. Switching the network stack from Netavark to CNI

You can switch the network stack from Netavark to CNI.

Warning

The CNI network stack is deprecated and will be removed in a future RHEL release. Use the Netavark network stack instead.

Prerequisites

  • The container-tools meta-package is installed.

Procedure

  1. If the /etc/containers/containers.conf file does not exist, copy the /usr/share/containers/containers.conf file to the /etc/containers/ directory:

    # cp /usr/share/containers/containers.conf /etc/containers/
  2. Edit the /etc/containers/containers.conf file, and add the following content to the [network] section:

    network_backend="cni"
  3. If you have any containers or pods, reset the storage back to the initial state:

    # podman system reset
  4. Reboot the system:

    # reboot

Verification

  • Verify that the network stack is changed to CNI:

    # cat /etc/containers/containers.conf
    ...
    [network]
    network_backend="cni"
    ...
Note

If you are using Podman 4.0.0 or later, use the podman info command to check the network stack setting.

Additional resources

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