[Dnsmasq-discuss] Fake reverse lookups from cache

[Joachim Zobel]

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Am Montag, den 02.02.2015, 16:57 +0100 schrieb Niels:

> I do see the usefulness of such an option but only if implemented such
> that real reverse lookups can still function unchanged. One way would
> be to implement a separate dns service listening on some other port.
> 
> That is probably way too complicated to be acceptable as a general
patch.

The main point is that I do not see any way to have it work with an
unmodified client. The client needs to implement some way of saying it
wants to do fake reverses.

> I have been pondering the idea to make a log parser process that
builds
> a database from forward lookups that can then be queried on the
resulting
> ip. For CNAME expansion that would be problematic since the individual
log
> entries currently do not provide enough information, like in:
> 
> Feb  2 16:36:55 dnsmasq[852]: query[A] p05-btmmdns.icloud.com from
192.168.178.12
> Feb  2 16:36:55 dnsmasq[852]: cached p05-btmmdns.icloud.com is <CNAME>
> Feb  2 16:36:55 dnsmasq[852]: cached p05-btmmdns.icloud.com.akadns.net
is 17.172.100.68
> 
> The logs do not make clear that p05-btmmdns.icloud.com.akadns.net is
the
> value of CNAME p05-btmmdns.icloud.com and I found the extra dns query
needed
> to prove that would be too much of a hassle.
> 
> So one proposition would be to make the log entries for <CNAME> list
the
> actual value, which is a very small change, and leave the 0.01%
dnsmasq users
> that are interested in reporting which forward request resulted in an
actual
> ip being encountered alone with the task of writing their own report
tools.

It might be easier to use it if the log entry would provide an IP, e.g.

Feb  2 16:36:55 dnsmasq[852]: cached p05-btmmdns.icloud.com is <CNAME>
for 17.172.100.68

Not sure, if this is implemented easily.

But you are right, a log file parser is preferable. Building a tool that
replaces all IPs by the last used names and piping the netstat-nat -n
output would do it for my case.

So I request log files that enable looking up the last requested name as
a feature. Shall I implement this or could you be so kind?

Sincerely,
Joachim