Merge pull request #22594 from radar07/default-rootless-network-docs

[CI:DOCS] Update podman network docs

docs/source/markdown/options/network.image.md

@@ -15,7 +15,7 @@ considered insecure.
 - **ns:**_path_: path to a network namespace to join.
 - **private**: create a new namespace for the container (default)
 - **\<network name|ID\>**: Join the network with the given name or ID, e.g. use `--network mynet` to join the network with the name mynet. Only supported for rootful users.
-- **slirp4netns[:OPTIONS,...]**: use **slirp4netns**(1) to create a user network stack. This is the default for rootless containers. It is possible to specify these additional options, they can also be set with `network_cmd_options` in containers.conf:
+- **slirp4netns[:OPTIONS,...]**: use **slirp4netns**(1) to create a user network stack. It is possible to specify these additional options, they can also be set with `network_cmd_options` in containers.conf:
   - **allow_host_loopback=true|false**: Allow slirp4netns to reach the host loopback IP (default is 10.0.2.2 or the second IP from slirp4netns cidr subnet when changed, see the cidr option below). The default is false.
   - **mtu=MTU**: Specify the MTU to use for this network. (Default is `65520`).
   - **cidr=CIDR**: Specify ip range to use for this network. (Default is `10.0.2.0/24`).
@@ -26,7 +26,7 @@ considered insecure.
   - **outbound_addr6=IPv6**: Specify the outbound ipv6 address slirp binds to.
 - **pasta[:OPTIONS,...]**: use **pasta**(1) to create a user-mode networking
     stack. \
-    This is only supported in rootless mode. \
+    This is the default for rootless containers and only supported in rootless mode. \
     By default, IPv4 and IPv6 addresses and routes, as well as the pod interface
     name, are copied from the host. If port forwarding isn't configured, ports
     are forwarded dynamically as services are bound on either side (init

docs/source/markdown/options/network.md

@@ -30,7 +30,7 @@ Valid _mode_ values are:
 
 - **private**: Create a new namespace for the container. This uses the **bridge** mode for rootful containers and **slirp4netns** for rootless ones.
 
-- **slirp4netns[:OPTIONS,...]**: use **slirp4netns**(1) to create a user network stack. This is the default for rootless containers. It is possible to specify these additional options, they can also be set with `network_cmd_options` in containers.conf:
+- **slirp4netns[:OPTIONS,...]**: use **slirp4netns**(1) to create a user network stack. It is possible to specify these additional options, they can also be set with `network_cmd_options` in containers.conf:
 
   - **allow_host_loopback=true|false**: Allow slirp4netns to reach the host loopback IP (default is 10.0.2.2 or the second IP from slirp4netns cidr subnet when changed, see the cidr option below). The default is false.
   - **mtu=**_MTU_: Specify the MTU to use for this network. (Default is `65520`).
@@ -46,7 +46,7 @@ Valid _mode_ values are:
 
 - **pasta[:OPTIONS,...]**: use **pasta**(1) to create a user-mode networking
     stack. \
-    This is only supported in rootless mode. \
+    This is the default for rootless containers and only supported in rootless mode. \
     By default, IPv4 and IPv6 addresses and routes, as well as the pod interface
     name, are copied from the host. If port forwarding isn't configured, ports
     are forwarded dynamically as services are bound on either side (init

docs/source/markdown/podman-network.1.md

@@ -41,10 +41,13 @@ Podman requires specific default IPs and, thus, network subnets.  The default va
 ### Podman network
 The default bridge network (called `podman`) uses 10.88.0.0/16 as a subnet. When Podman runs as root, the `podman` network is used as default.  It is the same as adding the option `--network bridge` or `--network podman`. This subnet can be changed in **[containers.conf(5)](https://github.com/containers/common/blob/main/docs/containers.conf.5.md)** under the [network] section. Set the `default_subnet` to any subnet that is free in the environment. The name of the default network can also be changed from `podman` to another name using the default network key. Note that this is only done when no containers are running.
 
-### Slirp4netns
-When Podman is run as rootless, the internet connectivity is provided with slirp4netns by default. Slirp4nents uses 10.0.2.0/24 for its default network. This can also be changed in **[containers.conf(5)](https://github.com/containers/common/blob/main/docs/containers.conf.5.md)** but under the `[engine]` section. Use the `network_cmd_options` key and add `["cidr=X.X.X.X/24"]` as a value. Note that slirp4netns needs a network prefix size between 1 and 25. This option accepts an array, so more options can be added in a comma-separated string as described on the **[podman-network-create(1)](podman-network-create.1.md)** man page. To change the CIDR for just one container, specify it on the cli using the `--network` option like this: `--network slirp4netns:cidr=192.168.1.0/24`.
+### Pasta
+Pasta by default performs no Network Address Translation (NAT) and copies the IPs from your main interface into the container namespace. If pasta cannot find an interface with the default route, it will select an interface if there is only one interface with a valid route. If you do not have a default route and several interfaces have defined routes, pasta will be unable to figure out the correct interface and it will fail to start. To specify the interface, use `-i` option to pasta. A default set of pasta options can be set in **[containers.conf(5)](https://github.com/containers/common/blob/main/docs/containers.conf.5.md)** under the `[network]` section with the `pasta_options` key.
 
-When using the default network as rootless, i.e. --network podman/bridge, then it also uses the same subnet as described above in addition to the slirp4netns subnet.
+The default rootless networking tool can be selected in **[containers.conf(5)](https://github.com/containers/common/blob/main/docs/containers.conf.5.md)** under the `[network]` section with `default_rootless_network_cmd`, which can be set to `pasta` (default) or `slirp4netns`.
+
+### Slirp4netns
+Slirp4nents uses 10.0.2.0/24 for its default network. This can also be changed in **[containers.conf(5)](https://github.com/containers/common/blob/main/docs/containers.conf.5.md)** but under the `[engine]` section. Use the `network_cmd_options` key and add `["cidr=X.X.X.X/24"]` as a value. Note that slirp4netns needs a network prefix size between 1 and 25. This option accepts an array, so more options can be added in a comma-separated string as described on the **[podman-network-create(1)](podman-network-create.1.md)** man page. To change the CIDR for just one container, specify it on the cli using the `--network` option like this: `--network slirp4netns:cidr=192.168.1.0/24`.
 
 ### Podman network create
 When a new network is created with a `podman network create` command, and no subnet is given with the --subnet option, Podman starts picking a free subnet from 10.89.0.0/24 to 10.255.255.0/24. Use the `default_subnet_pools` option under the `[network]` section in **[containers.conf(5)](https://github.com/containers/common/blob/main/docs/containers.conf.5.md)** to change the range and/or size that is assigned by default.