FreeTDS Development Group

["Andi Clemens" <Andi.Clemens AT gmx.net>]

Hi,

I need to implement some proxy server that will filter all SQLBatch packages 
and check for invalid SQL statements (for example SELECT on columns in a 
table that are not allowed).
I then need to sent an error package telling the user / client that this 
operation is not allowed.
This works fine for now, but another feature should be "auto-login": The user 
types in some database unrelated information (the user shouldn't know the 
database IP, username and password), and the proxy server will examine this 
"fake" login and open a connection to the real SQLServer.
Setting up the connection is not the problem that I'm facing right now, but 
the login process is totally mystical to me ;-)

I looked for packages that start with 0x02, but I can not see them. I see the 
prelogin packages (0x12) and also the SQLBatch packages (0x01), but the login 
packages are "invisible".

I then read somewhere in the MS-SSTDS.pdf that the credentials are sent 
encrypted? Via TLS / SSL?

After looking through thousands of Google result pages I finally came across 
FreeTDS and now I hope that there is some simple login function that can 
handle the login for me :-)

Do you think it is possible to be a proxy server AND setup my own login 
(which makes the proxy a client)?
I mean do you think it is possible to login via the proxy server and have the 
client accept the connection? The client would be "SQLServer Management 
Studio" and "sqlcmd" in my case.

Has anybody done something like this before?
Maybe you can help me with ideas here. I took a look at the FreeTDS API, but 
the only login function I found so far was in the ODBC module?

Andi

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