man: document IPForward=kernel option

diff --git a/man/systemd.network.xml b/man/systemd.network.xml
index bd061c270a3434628d880d54b8cc95c5bdd7d398..54fef4c9c499e9d8de072a76b19891f33f9c3ac3 100644 (file)
--- a/man/systemd.network.xml
+++ b/man/systemd.network.xml
@@ -366,7 +366,8 @@
           the routing table. Takes either a boolean argument, or the
           values <literal>ipv4</literal> or <literal>ipv6</literal>,
           which only enables IP forwarding for the specified address
-          family. This controls the
+          family, or <literal>kernel</literal>, which preserves existing sysctl settings.
+          This controls the
           <filename>net.ipv4.conf.&lt;interface&gt;.forwarding</filename>
           and
           <filename>net.ipv6.conf.&lt;interface&gt;.forwarding</filename>
@@ -375,8 +376,8 @@
           for details about sysctl options). Defaults to
           <literal>no</literal>.</para>
 
-          <para>Note: unless this option is turned on, no IP
-          forwarding is done on this interface, even if this is
+         <para>Note: unless this option is turned on, or set to <literal>kernel</literal>,
+          no IP forwarding is done on this interface, even if this is
           globally turned on in the kernel, with the
           <filename>net.ipv4.ip_forward</filename> and
           <filename>net.ipv4.ip_forward</filename> sysctl