ipv4: introduce ip_dst_mtu_maybe_forward and protect forwarding path against pmtu...

[~andy/linux] / Documentation / networking / ip-sysctl.txt

diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index 7373115407e489592d4717f814866c5c531e62fa..0d71fa962d8ae3899fc6720a799e49734fa1f738 100644 (file)
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -32,6 +32,19 @@ ip_no_pmtu_disc - INTEGER
 min_pmtu - INTEGER
        default 552 - minimum discovered Path MTU
 
+ip_forward_use_pmtu - BOOLEAN
+       By default we don't trust protocol path MTUs while forwarding
+       because they could be easily forged and can lead to unwanted
+       fragmentation by the router.
+       You only need to enable this if you have user-space software
+       which tries to discover path mtus by itself and depends on the
+       kernel honoring this information. This is normally not the
+       case.
+       Default: 0 (disabled)
+       Possible values:
+       0 - disabled
+       1 - enabled
+
 route/max_size - INTEGER
        Maximum number of routes allowed in the kernel.  Increase
        this when using large numbers of interfaces and/or routes.