From 26fa9b0d0d23700ba87aba7862fcf2baa5c26f1e Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Oriol=20Franc=C3=A8s?= <oriolfa@gmail.com> Date: Sun, 26 Jul 2015 19:11:27 +0200 Subject: [PATCH] much improved wording for manual network config setup on arch install docs by @moxiegirl MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Signed-off-by: Oriol Francès <oriolfa@gmail.com> --- docs/installation/archlinux.md | 23 +++++++++++------------ 1 file changed, 11 insertions(+), 12 deletions(-) diff --git a/docs/installation/archlinux.md b/docs/installation/archlinux.md index 8b0c40f6ef..4447d59d62 100644 --- a/docs/installation/archlinux.md +++ b/docs/installation/archlinux.md @@ -66,11 +66,17 @@ If you need to add an HTTP Proxy, set a different directory or partition for the Docker runtime files, or make other customizations, read our systemd article to learn how to [customize your systemd Docker daemon options](/articles/systemd/). -## Running docker with a manually defined network +## Running Docker with a manually-defined network -Users of systemd-network >= v220 who have configured their network manually by -creating an `<interface>.network` file in `/etc/systemd/network/` may have to add -the following line to make sure IP Forwarding is not disabled: +If you manually configure your network using `systemd-network` version 220 or +higher, containers you start with Docker may be unable to access your network. +Beginning with version 220, the forwarding setting for a given network +(`net.ipv4.conf.<interface>.forwarding`) defaults to *off*. This setting +prevents IP forwarding. It also conflicts with Docker which enables the +`net.ipv4.conf.all.forwarding` setting within a container. + +To work around this, edit the `<interface>.network` file in +`/etc/systemd/network/` on your Docker host add the following block: ``` [Network] @@ -79,14 +85,7 @@ IPForward=kernel ... ``` -From systemd-network v220 onwards, the forwarding setting for a given network -defaults to *off* (instead of not being set). This prevents IP Forwarding to -happen, since docker only enables `net.ipv4.conf.all.forwarding` (which is -overriden by `net.ipv4.conf.<interface>.forwarding` being disabled) - -Adding `IPForward=kernel` to the `<interface>.network` file prevents this -behavior, allowing IP Forwarding to function as expected. - +This configuration allows IP forwarding from the container as expected. ## Uninstallation To uninstall the Docker package: