By default, Unbound neither keeps track of the number of unwanted replies nor initiates countermeasures if they become too large (DNS cache poisoning).
This sets the maximum number of tolerated unwanted replies to 1M, causing the cache to be flushed afterwards. (Upstream documentation recommends 10M as a threshold, but this turned out to be ineffective against attacks in the wild.)
See https://nlnetlabs.nl/documentation/unbound/unbound.conf/ for details. This version of the patch uses 1M as threshold instead of 5M and supersedes the first and second version.
Signed-off-by: Peter Müller peter.mueller@link38.eu --- config/unbound/unbound.conf | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/config/unbound/unbound.conf b/config/unbound/unbound.conf index 3f724d8f7..ce9ddcd62 100644 --- a/config/unbound/unbound.conf +++ b/config/unbound/unbound.conf @@ -61,6 +61,9 @@ server: harden-algo-downgrade: no use-caps-for-id: no
+ # Harden against DNS cache poisoning + unwanted-reply-threshold: 1000000 + # Listen on all interfaces interface-automatic: yes interface: 0.0.0.0