tcp: restrict net.ipv4.tcp_adv_win_scale (#20312)

[cascardo/linux.git] / Documentation / networking / ip-sysctl.txt

diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index f350c69..3c5e465 100644 (file)
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -20,6 +20,15 @@ ip_no_pmtu_disc - BOOLEAN
 min_pmtu - INTEGER
        default 562 - minimum discovered Path MTU
 
+route/max_size - INTEGER
+       Maximum number of routes allowed in the kernel.  Increase
+       this when using large numbers of interfaces and/or routes.
+
+neigh/default/gc_thresh3 - INTEGER
+       Maximum number of neighbor entries allowed.  Increase this
+       when using large numbers of interfaces and when communicating
+       with large numbers of directly-connected peers.
+
 mtu_expires - INTEGER
        Time, in seconds, that cached PMTU information is kept.
 
@@ -135,6 +144,7 @@ tcp_adv_win_scale - INTEGER
        Count buffering overhead as bytes/2^tcp_adv_win_scale
        (if tcp_adv_win_scale > 0) or bytes-bytes/2^(-tcp_adv_win_scale),
        if it is <= 0.
+       Possible values are [-31, 31], inclusive.
        Default: 2
 
 tcp_allowed_congestion_control - STRING
@@ -1014,6 +1024,12 @@ conf/interface/*:
 accept_ra - BOOLEAN
        Accept Router Advertisements; autoconfigure using them.
 
+       Possible values are:
+               0 Do not accept Router Advertisements.
+               1 Accept Router Advertisements if forwarding is disabled.
+               2 Overrule forwarding behaviour. Accept Router Advertisements
+                 even if forwarding is enabled.
+
        Functional default: enabled if local forwarding is disabled.
                            disabled if local forwarding is enabled.
 
@@ -1075,7 +1091,12 @@ forwarding - BOOLEAN
        Note: It is recommended to have the same setting on all
        interfaces; mixed router/host scenarios are rather uncommon.
 
-       FALSE:
+       Possible values are:
+               0 Forwarding disabled
+               1 Forwarding enabled
+               2 Forwarding enabled (Hybrid Mode)
+
+       FALSE (0):
 
        By default, Host behaviour is assumed.  This means:
 
@@ -1085,18 +1106,24 @@ forwarding - BOOLEAN
           Advertisements (and do autoconfiguration).
        4. If accept_redirects is TRUE (default), accept Redirects.
 
-       TRUE:
+       TRUE (1):
 
        If local forwarding is enabled, Router behaviour is assumed.
        This means exactly the reverse from the above:
 
        1. IsRouter flag is set in Neighbour Advertisements.
        2. Router Solicitations are not sent.
-       3. Router Advertisements are ignored.
+       3. Router Advertisements are ignored unless accept_ra is 2.
        4. Redirects are ignored.
 
-       Default: FALSE if global forwarding is disabled (default),
-                otherwise TRUE.
+       TRUE (2):
+
+       Hybrid mode. Same behaviour as TRUE, except for:
+
+       2. Router Solicitations are being sent when necessary.
+
+       Default: 0 (disabled) if global forwarding is disabled (default),
+                otherwise 1 (enabled).
 
 hop_limit - INTEGER
        Default Hop Limit to set.