amplified reflected attack on dns
- by Mike Janson
The term is new to me. So I have a few questions about it.
I've heard it mostly happens with DNS servers?
How do you protect against it?
How do you know if your servers can be used as a victim?
This is a configuration issue right?
my named conf file
include "/etc/rndc.key";
controls {
inet 127.0.0.1 allow { localhost; } keys { "rndc-key"; };
};
options {
/* make named use port 53 for the source of all queries, to allow
* firewalls to block all ports except 53:
*/
// query-source port 53;
/* We no longer enable this by default as the dns posion exploit
has forced many providers to open up their firewalls a bit */
// Put files that named is allowed to write in the data/ directory:
directory "/var/named"; // the default
pid-file "/var/run/named/named.pid";
dump-file "data/cache_dump.db";
statistics-file "data/named_stats.txt";
/* memstatistics-file "data/named_mem_stats.txt"; */
allow-transfer {"none";};
};
logging {
/* If you want to enable debugging, eg. using the 'rndc trace' command,
* named will try to write the 'named.run' file in the $directory (/var/named").
* By default, SELinux policy does not allow named to modify the /var/named" directory,
* so put the default debug log file in data/ :
*/
channel default_debug {
file "data/named.run";
severity dynamic;
};
};
view "localhost_resolver" {
/* This view sets up named to be a localhost resolver ( caching only nameserver ).
* If all you want is a caching-only nameserver, then you need only define this view:
*/
match-clients { 127.0.0.0/24; };
match-destinations { localhost; };
recursion yes;
zone "." IN {
type hint;
file "/var/named/named.ca";
};
/* these are zones that contain definitions for all the localhost
* names and addresses, as recommended in RFC1912 - these names should
* ONLY be served to localhost clients:
*/
include "/var/named/named.rfc1912.zones";
};
view "internal" {
/* This view will contain zones you want to serve only to "internal" clients
that connect via your directly attached LAN interfaces - "localnets" .
*/
match-clients { localnets; };
match-destinations { localnets; };
recursion yes;
zone "." IN {
type hint;
file "/var/named/named.ca";
};
// include "/var/named/named.rfc1912.zones";
// you should not serve your rfc1912 names to non-localhost clients.
// These are your "authoritative" internal zones, and would probably
// also be included in the "localhost_resolver" view above :
