[Dnsmasq-discuss] Announce: dnsmasq-2.85
simon at thekelleys.org.uk
Wed Apr 7 20:59:14 UTC 2021
I just released dnsmasq-2.85, available from
This release has a security fix which is mainly relevant to users of
NetworkManager, see CVE-2021-3448 for details.
Fix problem with DNS retries in 2.83/2.84.
The new logic in 2.83/2.84 which merges distinct requests
for the same domain causes problems with clients which do
retries as distinct requests (differing IDs and/or source
The retries just get piggy-backed on the first, failed, request.
The logic is now changed so that distinct requests for repeated
queries still get merged into a single ID/source port, but
they now always trigger a re-try upstream.
Thanks to Nicholas Mu for his analysis.
Tweak sort order of tags in get-version. v2.84 sorts
before v2.83, but v2.83 sorts before v2.83rc1 and 2.83rc1
sorts before v2.83test1. This fixes the problem which lead
to 2.84 announcing itself as 2.84rc2.
Avoid treating a --dhcp-host which has an IPv6 address
as eligible for use with DHCPv4 on the grounds that it has
no address, and vice-versa. Thanks to Viktor Papp for
spotting the problem. (This bug was fixed was back in 2.67, and
then regressed in 2.81).
Add --dynamic-host option: A and AAAA records which take their
network part from the network of a local interface. Useful
for routers with dynamically prefixes. Thanks
to Fred F for the suggestion.
Teach --bogus-nxdomain and --ignore-address to take an IPv4
Use random source ports where possible if source
addresses/interfaces in use.
CVE-2021-3448 applies. Thanks to Petr Menšík for spotting this.
It's possible to specify the source address or interface to be
used when contacting upstream name servers:
server=126.96.36.199 at 188.8.131.52
or server=184.108.40.206 at 220.127.116.11#66 or server=18.104.22.168 at eth0, and all of
these have, until now, used a single socket, bound to a fixed
port. This was originally done to allow an error (non-existent
interface, or non-local address) to be detected at start-up.
This means that any upstream servers specified in such a way
don't use random source ports, and are more susceptible to
We now use random ports where possible, even when the
source is specified, so server=22.214.171.124 at 126.96.36.199 or
server=188.8.131.52 at eth0 will use random source
ports. server=184.108.40.206 at 220.127.116.11#66 or any use of --query-port will
use the explicitly configured port, and should only be done with
understanding of the security implications.
Note that this change changes non-existing interface, or
non-local source address errors from fatal to run-time.
The error will be logged and communication with the
server not possible.
Change the method of allocation of random source ports for DNS.
Previously, without min-port or max-port configured, dnsmasq
would default to the compiled in defaults for those, which are
1024 and 65535. Now, when neither are configured, it
defaults instead to the kernel's ephemeral port range,
which is typically 32768 to 60999 on Linux systems.
This change eliminates the possibility that dnsmasq may #
be using a registered port > 1024
when a long-running daemon starts up and wishes to claim it.
This change does likely slightly reduce the number of random
ports and therefore the protection from reply spoofing. The
older behaviour can be restored using the min-port and max-port
config switches should that be a concern.
Scale the size of the DNS random-port pool based on the
value of the --dns-forward-max configuration.
Tweak TFTP code to check sender of all received packets, as
specified in RFC 1350 para 4.
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