Nmap Development mailing list archives

Re: [NSE Script] MySQL Server Information


From: jah <jah () zadkiel plus com>
Date: Wed, 19 Dec 2007 00:09:11 +0000

On 18/12/2007 19:56, Kris Katterjohn wrote:
I added a check for too many connections, which I saw in the probes 
file.  It should match the different little versions of it from 
there, though I didn't find a server with that error to test with.
This was my challenge for the day, find a server that reported 1040 
Too Many Connections.  I couldn't.  So I set about creating one and 
after much fiddling with users and the max_connections mysql variable 
and much hair-pulling, I conclude that the 1040 error seems only to 
occur after a login request is sent to the server.  I was able to put 
my sql server in a state where it would respond with 1040, but only 
after login request.  The Server Greeting is sent prior to this so 
the script can still get it's info.  Therefore, I would say that the 
extra portrule may be unnecessary.  I haven't made any changes though 
because it's not hurting anything and I may still be proved wrong...


That's odd because there are multiple match lines in the -probes file 
that look for too many connections from just the banner (NULL probe).  
I guess we'll just have to see about that! :)
You're right.  I've done alot of random scanning and not found anything 
though; yet.  I certainly couldn't get my installation of mysql to 
respond in this way and I read [1] that mysql always allows 1 extra 
connection for a user with SUPER privs. so that they can still connect 
to diagnose problems in the event of max_connections reached.  This 
would mean that a login request would have to be sent in order to verify 
that the login request was from a suitably privileged user.  Anyone else 
would get the 1040 response.  That still doesn't explain why it's in the 
service-probes file though, but I wonder if some servers simply run out 
of resources and report 1040....  Best to leave the portrule as it now, 
wouldn't you say?


jah

[1] http://dev.mysql.com/doc/refman/5.1/en/too-many-connections.html


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