conf: change default rate limiting parameters

Change the default NTP rate limiting leak to 2 (25%). Change the default
command rate limiting interval to -4 (16 packets per second) and burst
to 8, so the interval is the only difference between NTP and command
rate limiting defaults.

diff --git a/conf.c b/conf.c
index 7500fd9554d597677e3073af3ad8f32270327e47..5de7f427a7293a5846873d306683c98e3954cd3d 100644 (file)
--- a/conf.c
+++ b/conf.c
@@ -194,10 +194,10 @@ static char *pidfile;
 static int ntp_ratelimit_enabled = 0;
 static int ntp_ratelimit_interval = 3;
 static int ntp_ratelimit_burst = 8;
-static int ntp_ratelimit_leak = 3;
+static int ntp_ratelimit_leak = 2;
 static int cmd_ratelimit_enabled = 0;
-static int cmd_ratelimit_interval = 1;
-static int cmd_ratelimit_burst = 16;
+static int cmd_ratelimit_interval = -4;
+static int cmd_ratelimit_burst = 8;
 static int cmd_ratelimit_leak = 2;
 
 /* Smoothing constants */

diff --git a/doc/chrony.conf.adoc b/doc/chrony.conf.adoc
index d7710ad031431a376d51d9e568f1c5ef55c03e09..f1b5f0ebbfe86c55d7376ed8d6b99efda0d8891e 100644 (file)
--- a/doc/chrony.conf.adoc
+++ b/doc/chrony.conf.adoc
@@ -1238,9 +1238,10 @@ in any order):
 *interval*:::
 This option sets the minimum interval between responses. It is defined as a
 power of 2 in seconds. The default value is 3 (8 seconds). The minimum value
-is -19 and the maximum value is 12. Note that with values below -4 the rate
-limiting is coarse (responses are allowed in bursts, even if the interval
-between them is shorter than the specified interval).
+is -19 (524288 packets per second) and the maximum value is 12 (one packet per
+4096 seconds). Note that with values below -4 the rate limiting is coarse
+(responses are allowed in bursts, even if the interval between them is shorter
+than the specified interval).
 *burst*:::
 This option sets the maximum number of responses that can be sent in a burst,
 temporarily exceeding the limit specified by the *interval* option. This is
@@ -1252,20 +1253,20 @@ This option sets the rate at which responses are randomly allowed even if the
 limits specified by the *interval* and *burst* options are exceeded. This is
 necessary to prevent an attacker who is sending requests with a spoofed
 source address from completely blocking responses to that address. The leak
-rate is defined as a power of 1/2 and it is 3 by default, i.e. on average at
-least every eighth request has a response. The minimum value is 1 and the
+rate is defined as a power of 1/2 and it is 2 by default, i.e. on average at
+least every fourth request has a response. The minimum value is 1 and the
 maximum value is 4.
 ::
 +
 An example use of the directive is:
 +
 ----
-ratelimit interval 4 burst 4
+ratelimit interval 1 burst 16
 ----
 +
-This would reduce the response rate for IP addresses that send packets on
-average more frequently than once per 16 seconds or send packets in bursts
-of more than 4 packets.
+This would reduce the response rate for IP addresses sending packets on average
+more than once per 2 seconds, or sending packets in bursts of more than 16
+packets, by up to 75% (with default *leak* of 2).
 
 [[smoothtime]]*smoothtime* _max-freq_ _max-wander_ [*leaponly*]::
 The *smoothtime* directive can be used to enable smoothing of the time that
@@ -1394,8 +1395,8 @@ need to be run with the *-p 257* switch to inter-operate correctly.)
 [[cmdratelimit]]*cmdratelimit* [_option_]...::
 This directive enables response rate limiting for command packets. It is
 similar to the <<ratelimit,*ratelimit*>> directive, except responses to
-localhost are never limited and the default interval is 1 (2 seconds), the default
-burst is 16, and the default leak rate is 2.
+localhost are never limited and the default interval is -4 (16 packets per
+second).
 +
 An example of the use of the directive is:
 +